JOURNAL OF APPLIED ENGINEERING SCIENCES - · PDF fileANDREICA L., DUMITRAS M., COBIRZAN N. pp.7-12 3 Preface The first number of the magazine JOURNAL OF APPLIED ENGINEERING SCIENCES

CONTENTS pp.5-6

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JOURNAL OF APPLIED ENGINEERING SCIENCES

Volume 1 (16), Issue 1/2013

University of Oradea Publishing House

JOURNAL OF APPLIED ENGINEERING SCIENCES Volume 1(16), Issue 1/2013

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EDITORIAL BOARD

EDITOR-IN-CHIEF: Corneliu BOB ([email protected]), Politehnica University of Timişoara, Romania EXECUTIVE EDITORS: Sanda Monica FILIP ([email protected]), University of Oradea, Romania

Dan GOMBOŞ ([email protected]), University of Oradea, Romania Aurelian-Stelian BUDA ([email protected]), University of Oradea, Romania Marcela-Florina PRADA ([email protected]), University of Oradea, Romania

MEMBERS

Claudiu ACIU – Technical University of Cluj-Napoca, Faculty of Civil Engineering, Department of Civil Engineering and Management, Romania

József ÁDÁM – Budapest University of Technology and Economics, Department of Geodesy and Surveying, Hungary

Marian BORZAN – Technical University of Cluj-Napoca, Romania Alexandru CĂTĂRIG – Technical University of Cluj-Napoca, Romania

Daniel DAN – “Politehnica” University of Timisoara, Romania Petre DRAGOMIR – Technical University of Civil Engineering Bucharest,

Romania Gabriela DROJ – University of Oradea, Romania Mihai ILIESCU – Technical University of Cluj-Napoca, Romania

Ludovic KOPENETZ – Technical University of Cluj-Napoca, Romania Gábor MÉLYKÚTI – University of West Hungary, Faculty of Geoinformatics,

Székesfehérvár, Hungary Johan NEUNER – Technical University of Civil Engineering Bucharest,

Romania Md Azree OTHUMAN MYDIN – Universiti Sains Malaysia, School of Housing, Building

and Planning Maricel PALAMARIU – “1 Decembrie 1918” University of Alba Iulia, Romania

TECHNICAL EDITOR: Gabriela-Argentina POPOVICIU ([email protected]), University of Oradea,

Romania

Aims and Scope: Journal of Applied Engineering Sciences (JAES) is a scientifical journal devoted to presentation and discussion of information on the ultimate issues in the civil, installations, geodesic, electrical and energetical engineering fields. The journal addresses news and various problems which such fields confronts both national and international level. JAES is designed for scientists, researchers (including doctoral students), engineers and managers, regardless of their discipline, who are involved in scientific, technical or other issues related in the journal domains. Emphasis is placed on integrated approaches. These approaches require both technical and non-technical factors. Even the dissemination and application of innovative information is very important, the implementation of existing literature in the JAES related topics and the adress’s contributions also requires a clear understanding from as many other scientific areas as possible.

UNIVERSITY OF ORADEA, FACULTY OF CIVIL ENGINEERING AND ARCHITECTURE 4, Barbu Ştefănescu Delavrancea Street, 410058 – ORADEA – ROMÂNIA

www.uoradea.ro * http://arhiconoradea.ro * http://www.arhiconoradea.ro/JAES/HOME.htm * Phone/Fax: 004-0259-408447 Cover design by George-Lucian Ionescu

ANDREICA L., DUMITRAS M., COBIRZAN N. pp.7-12

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Preface

The first number of the magazine JOURNAL OF APPLIED ENGINEERING SCIENCES was published in 1997 under the name of Annals of University of Oradea – CONSTRUCTIONS AND HYDROEDILITARY INSTALLATIONS fascicle. Until 2010 the magazine has been issued annually. Since 2003 the magazine has been publishing scientific works presented within the National Conference – international event – MODERN TECHNOLOGIES FOR THE 3rd MILLENIUM, where valuable specialists have met, both from the major university centres in the country and world-renowned professors from universities from abroad. The national and international prestige of the magazine has been constantly increasing.

All scientific papers accepted to publishing are thoroughly analyzed by a scientific committee formed by Romanian and foreign university professors, internationally recognized in their area of expertise.

In 2009 the magazine has undergone an assessment by C.N.C.S.I.S. being rated in category B, and in June 15th 2010 it has been rated B+ by the same C.N.C.S.I.S., being accepted in four International Databases (IDB) – Ulrich’s, Index Copernicus, INSPEC and DRJI. Since 2011, the Journal is registered on SCIPIO, the Romanian Publishing Platform website.

Since 2010 the magazine has been issued twice a year, in July (containing scientific papers of Romanian and foreign specialists) and one in November, usually containing scientific papers that had been presented at the National Conference – international event – MODERN TECHNOLOGIES FOR THE THIRD MILLENIUM. Starting with 2011, the magazine is biannual published (in May and December) under its new name, JOURNAL OF APPLIED ENGINEERING SCIENCES (JAES), and is in competition for ISI classification.

As a result of the various subjects treated so far in our magazine’s pages, from the Civil engineering and installations, Geodesic engineering, Electrical and energetical engineering in constructions fields, JAES are included in the large Civil Engineering area. It means that the magazine, through the category domain established above, includes resources on the planning, design, construction, maintenance of fixed structures and ground facilities for industry, occupancy, transportation, use and control of water, even harbor facilities. At the same time, resources may cover the sub-fields of structural engineering, geotechnics, earthquake and geodesic engineering, ocean engineering, water resources and supply, marine engineering, transportation engineering, and municipal engineering.

Editorial Staff


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Responsibility for content of the published material exclusively belongs to the authors, the auditing team’s role being to get fit and verify accuracy of those included in these works.

JAES is registered in the International Databases:

Index Copernicus, Ulrichsweb, INSPEC, DRJI

and also in the Scientific Publishing & Information Online SCIPIO Platform http://www.scipio.ro/web/journal-of-applied-engineering-sciences

Since 2010 JAES was classified by C.N.C.S. with rate B+ (code 877, p.39) http://cncsis.ro/userfiles/file/CENAPOSS/Bplus_2011.pdf

ISSN / ISSN-L 2247 – 3769 / e-ISSN2284 – 7197 University of Oradea Publishing House May 31, 2013

CONTENTS pp.5-6

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CONTENTS

Andreica Ligia, Dumitras Macedon, Cobirzan Nicoleta

Considerations related to the axial load distribution in rehabilitated masonry walls

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Berindean Adrian D., Andreica Ligia, Berindean Alexandra C. Summarized observations upon connections of structural wood members using metallic elements ........................................................................................................

13

Cîrstolovean Ioan Lucian Implementation of a soil-air heat pump for the heating of a research laboratory of the Transilvania University of Braşov ……………………………………………...

19

Cobirzan Nicoleta, Dumitras Macedon, Andreica Ligia Axial deformability of rehabilitated stone masonry walls ………………………….

25

Didulescu Caius, Savu Adrian Aspects of volume calculation ……………………………………………………...

31

Kopenetz Ludovic, Cătărig Alexandru, Alexa Pavel, Deuşan Simona The membranes used for the lightweight structures with cables and membranes …. 35

Mancia Mircea Sebastian Land evaluation and the impact of hydrotechnical works on Crişul Repede River ...

43

Moga Ligia, Ousseynou Diao Temperature influence on the thermal resistance of a building wall when using phase changing materials …………………………………………………………...

47

Moga Ligia, Ousseynou Diao Determination of the equivalent thermal conductivity of a phase change material (PCM) ……………………………………………………………………………….

55

Moldovan Alexandra Raluca Core extrusions and convergence during deep tunnel construction ..........................

63

Nistor Sorin, Ionaşcu Anamaria Basic concept of the robust procedure applied on geodetic data …………………...

71

Pop Mariana, Cătărig Alexandru, Toadere Mihaela Teodora Some solutions for the rehabilitation of two methane tanks ………………………..

75

Prada Marcela Risk elements in modelling, designing and building-up portant masonry structures

83

Puskas Attila, Bindea Mihai Eablishing the design value of column moment according to P100-1/2006 ………..

87Rădulescu Adrian T. G., Rădulescu Gheorghe M.T.

Comparative analyses of two monitoring periods in dynamic regime (summer, winter) of the Waterford Stay Cable Bridge, Ireland .................................................

93


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Rădulescu Corina, Rădulescu Virgil Mihai G. M. Current support configuration elements in a database for mining industry from the MDB GIS category, Sasar Mine, Baia Mare ……………………………………….

101

Sabău Cristian, Stoian Dan, Dan Daniel, Nagy-György Tamás, FloruŃ Sorin-CodruŃ, Stoian Valeriu

Partial results of monitoring in a passive house …………………………………….

107

Saracin Aurel Displacement and deformation measurement using ground radar interferometry technique ……………………………………………………………………………

111

Savu Adrian, Didulescu Caius 3D modelling using laser scanning technique ………………………………………

119

Scheibner Emilia, Cîrstolovean Ioan Lucian, Mizgan Paraschiva Theoretic study concerning the application of the theory of the finite element to the mechanical calculation of the pipes that constitute a heating network …………

125

Stoian Dan, Dan Daniel, Stoian Valeriu, Nagy-György Tamás, Tănasă Cristina Economic impacts of a passive house compared to a traditional house ……………

135

AUTHORS INDEX ……………………………………………………………………. 141GUIDE FOR AUTHORS ………………………………………………………………. 143SPONSORS LIST ……………………………………………………………………… 145


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CONSIDERATIONS RELATED TO THE AXIAL LOAD DISTRIBUTION IN REHABILITATED MASONRY WALLS

ANDREICA Ligia*, DUMITRAS Macedon, COBIRZAN Nicoleta, Technical University of Cluj-Napoca, e-mail: [email protected] (corresponding adress)

A B S T R A C T The protection and conservation works imply a set of operations by which inoperable buildings, ruins or still-standing structures can be brought to operational state through repairing, restoring or partial reconstruction processes. These measures involve, at conception level, several structural intervention options, conditioned by the physical particularities of the protected structure and by external factors, such as the economic, aesthetic and theoretical settings and opportunities.Variations can be multiple, but what should be noted is that, regardless of the choices involved, these interventions should follow the principles of authenticity, reversibility, durability and sustainability, starting with the intervention phase and the material used must be compatible with the existing one. In this context, the paper briefly present a few comparative case studies considering some new masonry sections (reconstruction of destroyed masonry, closing door or windows, etc.) embedded in the structures of the existing building, and analyze deformability and stiffness of the wall subjected to axial load in order to determine the value of shear stresses.

Keywords: state of stresses, masonry works, fieldstone masonry, rehabilitation

Received: January 14, 2013 Accepted: March 10, 2013 Revised: March 31, 2013 Available online: May 31, 2013

INTRODUCTION Masonry is the building material resulted by the assemblage of masonry units and

mortars, where the mortar adhesion and the course staggering influence the monolithical behaviour and the complex state of stresses that occur even within masonry walls subjected only to gravitational loads. The complex state of stresses in masonry walls is determined by: the differences in the deformability of the masonry units (stone) and mortar, the unevenness of the mortar joints and stones, etc. In the specific case of fieldstone masonry, where mortar joints vary substantially in thickness and have significant deviations from the orthogonal position, the complex state of stresses is greatly increased. Thus, important concentrations of stresses appear in areas where joint thickness is reduced, resulting in the direct transmission of stresses from one stone to another. These can cause additional stresses that result in the shifting of the stones, additional shear stresses in joints, and, by the premature superseding of the adhesion between stones and mortar, the dislocations of some stones, resulting in the rapid progression of deformations, at the same time decreasing the compression strength of the masonry. MATERIALS AND METHODS

In stone masonry works, the elastic modulus of the stones is much superior to that of the mortar, therefore the elastic modulus of the masonry is mostly determined by the elastic modulus of the mortar and the relative heights of the joints. Thus, with the increase of the height of the stones, decreases and the masonry elastic modulus increases.

Thus, is considered the wall from the lower (Fig. 1) with the rehabilitated shaded portion (new masonry). If the modulus of elasticity of the new masonry (EN) differs from that of the old masonry (EV), then a redistribution of the compression stresses takes place, with a σ1 value for the consolidation area, and σ2 for the existing masonry.


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Assuming that EN> EV, it results that σ1> σ2 and ∆z1 < ∆z2, in terms of vertical deformations.

Fig. 1. Deformation diagrams in vertical sections 1-1 and 2-2 [1]

(1 – new masonry work; 2 – old masonry work)

Considered separately, the vertical deformation (shortening) for section 1 (rehabilitated)

and section 2 (existing masonry) are zero at the base of the wall and maximum on top. Accordingly, if: EN> EV follows: ∆z1 <∆z2.

Mortar adhesion and proper staggering of the old masonry with the new one prevent the free occurence of vertical deformations. As such, vertical shear stresses appear at the area of separation. In figure 1 the old section (more deformable) is prevented from deforming freely on the vertical direction by the consolidated area (less deformable).

To ensure the interaction between the two sections, staggering between the new and the old masonry is compulsory, and, in order to attain matching vertical deformation values, the deformability and the elastic modulus of the rehabilitated masonry have to be similar in value to those of the old masonry.

In order to determine and analyze the values of the vertical shear stresses shown in Fig. 2, three possible cases have been considered in terms of possible positioning of the rehabilitated area (marked red in the fig.) - at the top of the wall, in the middle area, or at the bottom. These situations are met in practice during reparation or partially reconstruction processes of the stone masonry works and require to solve the problem in this way.

1l 2ll

h

1

1

2

2

N N1 2

1

2

AA

B B

h

h2

1

1l 2ll

h

1

1

2

2

N N1 2

1

2

AA

B

C

B

C

h

h4

3

h2

D DD D

1l 2ll

1

1

2

2

N N1 2

1

2

AA

B Bh

h2

D D

h1

a. b. c.

Fig. 2. Different possibilities of masonry rehabilitation [1] (∆1 , ∆2 - Vertical deformation diagrams for sections 1 – 1 and 2 – 2)

The situation may somewhat vary where the rehabilitation masonry is positioned half-way along the wall, resulting in a succession of new and existing areas. Closing door or


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window openings (Fig. 3) in order to increase the bearing capacity of the structural walls or to modify the functionality of an existing building are interventions frequently used in curent practice and require a complex approach.

1l2ll

h

1

1

2

2

1

2

AA

B Bh

h2

1

1l 2ll

h 1

2

AA

B

C

B

C

h

h4

3

h2

D DD D

a. b.

2

22l

1

1

2

2

2

22l

Fig. 3. Different possibilities of masonry rehabilitation

(∆1 , ∆2 - Vertical deformation diagrams for sections 1 – 1 and 2 – 2)

In all cases, the length and the height of the rehabilitated area are l1 and h2. The

existent section has length l2 and h is the height of the wall. The rehabilitation of existing buildings in the context of sustainable development should

consider social, economic, as well as environmental protection aspects and the intervention solution should be in accordance with all of them [2]. RESULTS AND DISCUSSIONS

In all the five cases the total axial load (N) of the wall is distributed to the two different areas unevenly, in dependence with the rigidity of the wall sections.

N = N1 + N2 (1)

A variation of rehabilitation stances with more than two different sections can be illustrated with equation (1), given that all the sections are accounted for.

The axial loads N1 and N2 are proportional to the compressive stifness (k1, k2) of each area:

N1 = N21

1

kk

k

+ (2)

N2 = N21

2

kk

k

+ (3)

Rehabilitation methods depend on a number of factors, including: the size of the

rehabilitated areas, their size, the characteristics and dimensions of the natural stones, the value of the axial loads etc. It is important to note that after completing/ the rehabilitation and strengthening, the gravity load of the new masonry will affect the wall as well.

In the case of buildings located in seismic areas, it is important to take into account the vertical component of the seismic loads, which can lead to important supplementary axial loads within the walls [4], especially if they are built with heavy weight materials, which is a specific situation for most of the historical buildings.

Stiffness k1 and k2 can be calculated with equation (4) where for a deformation of ∆ = 1 the axial load N is equal in value to the rigidity.


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∆z = εzh = zE

σh =

ΑzE

Nh (4)

Stiffness vary with wall height, so they must be calculated at the top of the wall

(section A - A) and at the top and bottom of the new masonry works (sections B - B and C - C). The stiffness expressions k1 and k2 are given in Table 1 depending on the consolidation case (a, b, c) and the considered section shown in Fig. 2.

Table 1. k1 and k2 stiffness [1]

Case Section k1 k2

A - A

1

1

1

2

1

AE

h

AE

h

VN

�

h

AEV 2

a

B - B 2

1

h

AE N

2

1

h

AE N

A - A

1

43

1

2

1

AE

hh

AE

h

VN

��

h

AEV 2

b

B - B

1

3

1

1

1

AE

h

AE

h

VN

+

42

2

hh

AEV

�

A - A

1

2

1

1

1

AE

h

AE

h

VN

+

h

AEV 2

c

B - B

2

1

h

AEV

2

2

h

AEV

Vertical shear stress that occurs between the two areas results from the difference

between axial loads. L = N1 - N2 (5)

From (2), (3) and (5), L can be expressed as:

L = N 21

21

kk

kk

+

− (6)

Considering the relations (5) and (6) and the rigidity variations in Table 1, it results that the value of the shear stresses depends on the value of axial loads, the deformability properties of the areas (consolidated and unconsolidated) and the size of the two areas (horizontal and vertical).

The average tangential unit effort is thus [3]:


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fmed A

L=τ (7)

where: Af is the vertical area of the wall subjected to shear stress, which can be equated with the vertical area of a sheared section ( 1ht ⋅ , 2ht ⋅ , 3ht ⋅ )

For instance, in fig. 2, it can be considered that: case a), between A-A şi B-B section

1htAf ⋅= (8) case a), between B-B and D-D

2htAf ⋅= (9)

case b), between A-A and B-B

3htAf ⋅= (10)

where: t is the wall thickness. The areas subjected to shear stress for other sections and cases can be illustrated

correspondingly.

In a simplified manner, for each section, it can be considered that the axial load is constant. Smaller sections can be considered for more accurate calculations.

In the elastic domain the Jurawski relationship can be applied [2]:

medmed tI

LSττ ⋅== 5,1max (11)

where: maximum static moment (Smax) and the moment of inertia are calculated in the vertical

section of wall segments. CONCLUSIONS

Old masonry is an inhomogeneous and anisotropic material, consisting of heterogeneous materials both for the original construction elements and contemporary interventions (additions, reconstructions or the re-posing of the original bricks where the damaged masonry allows it). In cases of severely damaged masonry, the restoration process requires the dismantling and the re-posing of masonry blocks belonging to the original structure.Using high strength materials such as cement mortar instead of lime mortar, can lead to the occurrence of heterogeneous areas, which advance effort concentrations within the original masonry, and, as such, further the damage of the historica structures, contradicting the principles of durability and sustainability. In order to avoid the vertical shearing cracks that occur between areas with different deformation values, respectively to reduce the shearing to inconsequential values, it is required to that the new masonry work have deformability properties as similar as possible to the existing one, taking into account the size and position of the new masonry in the wall. Thus, for fieldstone masonry, it is recommended that the stones for the completing masonry to have the same provenance, the same shape, size, mechanical properties and general aspect as the original; that the mortar have similar mechanical streght and behaviour, and the bedding be similar in thickness and distribution


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with that of the original stonework, as, in the case of fieldstone masonry, the distribution of efforts can cause premature dislocations of the stones, resulting in significant increases of deformations and decreases in terms of bearing capacity. REFERENCES 1. ANDREICA GRATIELA-LIGIA (2012), ContribuŃii cu privire la compatibilitatea mortarelor în

intervenŃiile asupra zidăriilor istorice (Contributions in Regard to the Compatibility of Mortars in Interventions on Historic Masonry Works), Teză de doctorat, Cluj Napoca.

2. DUMITRAS M., COBIRZAN NICOLETA, MANEA DANIELA, ACIU C. (2010), Aspects concerning the structural changes and rehabilitation of the existing buildings – 10th International Scientific Conference “VSU 2010”, 3–4 June 2010, Sofia, Bulgaria, ISSN 1314 – 071X.

3. NEGOITA AL., FOCSA V., RADU A., POP I., TUTU L., DUMITRAS M., NEGOITA I, (1976), Constructii civile (Civil Constructions), Editura didactică şi pedagogică, Bucureşti.

4. *** Indicativ P100-3/2008. Cod de proiectare seismică- Partea a III-a - Prevederi pentru evaluarea seismică a clădirilor existente (Provisions for the Evaluations and Design of Consolidation Works at Seismically Eulnerable Existing Building).

BERINDEAN A.D., ANDREICA L., BERINDEAN A.C. pp.13-18

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SUMMARIZED OBSERVATIONS UPON CONNECTIONS OF STRUCTURAL WOOD MEMBERS USING METALLIC ELEMENTS

BERINDEAN Adrian D.*, ANDREICA Ligia, BERINDEAN Alexandra C., Technical University of Cluj-Napoca, e-mails: [email protected] (corresponding adress)*,

[email protected], [email protected]

A B S T R A C T The proper design and achievement of structural wood member connections are very important factors for exploitation and durability of construction. The purpose of this paper is to present recommendations to designers, contractors and users of wood constructions on how to choose the appropriate type of connection in different situations based on specific structural particularities. In the beginning, the paper describes the main classification criteria of connections using metallic elements and then an analysis of the means of connection design. Further down, the main causes which lead to the deterioration of connection with metallic elements are emphasized and a few explanations having the role to counter-balance these unwanted effects are given. Finally, the paper briefly presents a few connection solutions of wood structure members with metallic elements which are to be avoided and/or repaired in the unfortunate situation when they had already been used.

Keywords: timber structures, connectors, wrong design


INTRODUCTION In the design of a structure, in general, and of a wood structure, in particular, there are

several factors that are to be preliminary considered, i.e. structure configuration, load resisting system, dimensions of elements and workability. For wood structures, the concept and design of connections between members are very important factors in long term behavior and exploitation of construction. Connections between wood elements are necessary, firstly, due to their shapes and dimensions that they are usually delivered in, because most of the time the loading requirements for desired spans and cross sections can not be met. On the other hand, the necessity of connecting one or more elements that converge, forming nodes, appears very often during construction. MATERIALS AND METHODS

These days there are multiple systems of connections developed by designers and contractors [1], which have been adapted to suit wood particularities and to serve the following purposes:

- forming of built-up sections, when a simple cross section of a certain type of wood used does not have enough capacity to carry the load (interlocking joints);

- extension of wood elements to achieve the desired length (extended joints); - achieving the required effort transfer between wood elements connected under a

certain angle (node connections). Generally, the connections are created to ensure proper effort transfer under exterior

loading. For a given structure, selecting a certain type of connections is not only a matter of strength and loading requirements; there are other conditions such as: architectural aspects, fabrication and erection procedures, costs, etc. [2]. It is basically impossible to specify an assembly of rules which will establish the best system for a certain type of connection,


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however, when choosing the type of connection [3], the designer shall account for several conditions, of which the following are the most important:

- to minimize the weakening of connected members, meaning to keep as much as possible their initial load capacity;

- to keep the effort flow within the axis of member and to avoid eccentricities which could lead to changes of the load pattern and to necessity of increasing the cross section of connected members;

- to avoid overloading and to ensure uniform distribution of efforts within individual members that are part of built-up elements;

- to balance the efforts between connections and to avoid successive destruction of the joints by using a single type connection with same characteristics;

- to fraction the elements thru which the efforts are transmitted, ensuring a larger number of working sections, in which case the negative effect of possible wood defects can be avoided;

- to avoid negative effect of shrinkage and/or expansion and biodegrading phenomenon (water retaining, insufficient air circulation, etc.)

- correlation between type of connection, type of wood used (round wood, square-edged timber) and environment (interior, exterior, etc);

- to choose the type of connections suitable for shop fabrication, easy to assemble and maintain, and to allow for quality control during erection and building exploitation.

The main elements used as connectors for different types of connections (such as

extension, interlocking or node connection) between structural wood members are noted below:

- nails, pre-punched nail plates, screws for wood, bolts, timber dogs, pins [4]; - menig indented connectors, regular indented connectors [5]; - grip holder, clip angles, anchorage straps [4]; - standard connectors with custom modified parameters, exposed gusset plates, hidden

gusset plates, cut or bent plates [6]; - metallic spheres for nodes of 3D-systems, mixt systems for columns and beams [5].

1. Connection degradation of wood

The existence of wood constructions, sometimes of hundreds of years old, shows that, even though the wood is a natural product, in optimal conditions of exploitation, it could last for a very long period of time, without noticeable signs of degradation. There is a large spectrum of factors [7], generally related to the conditions of exploitation, but not only, which have an influence upon the durability or degradation of wood.

The generation speed of degradation and thus the durability of wood can be controlled thru the design of the elements and use of wood. In this respect, there are several principal directions in which action needs to be taken, such as:

- design and study of details in such way that wet wood, high humidity conditions or point sources of moisture are to be avoided as much as possible;

- avoiding water accumulation in certain areas (connections, supports, etc); - ensuring proper ventilation of wood in order to quickly evacuate water when

temporary moisture is impossible to avoid; - selecting the type of wood with natural durability in accordance with the environment; - providing an initial proper treatment of wood conservation.


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Of whole factors that lead to wood degradation, the most important is the one related to serviceability; however there are additional factors that could appear during construction’s life-time, such as earthquakes, high temperatures and fire, changes of occupancy, additional loading or exposure to biological xylophagous agents (fungi, insects).

The design and assembly concept of a structure [8] have to take into consideration the fact that the structure itself has to provide strength capacity under all possible load combinations which can affect the safety and serviceability during construction’s life time. In consequence, the design shall consider all the loads due to human activity (live loads, dead loads, reactions and accidental loads such as fire or overloading) and loads due to natural factors [9] [10] (wind, seism, snow, flooding, water accumulation and landslides). There are two components of the design that require a careful analysis: load combinations and temporary loads during constructions. The first one assumes the combination of loads having a high probability of occurring simultaneously during construction’s life time. The second one refers to the effect of local or natural loads upon the stability of the structural elements during the process of structure erection. In this matter, moisture variation should be taken into account, because it could cause large shrinkage or expansions, support settlements, eccentricities or partial failures of connectors.

The following aspects require a special attention when referring to wood constructions: - the elements have the tendency to deform under permanent and temporary service

loads. In some cases, residual deformations could occur and a nonlinear calculus may be required;

- on long term, the environmental factors could cause loss of strength capacity as a result of contractions and apparition of cracks in elements;

- for light and pre-engineered buildings, the dead load to live load ratio is large, resulting a high sensitivity to live load variation and possibility of construction overturning or lifting off supports;

- service state design [8] can be controlled thru rigidity requirements in order to limit transversal deformations, lateral sliding and vibration transmission.

2. Samples of wrong design of connections with metallic connectors

In the context of the above, there are several types of connections [5] shown and explained in the sketches below. They represent connections which have generated issues and should be avoided in the future or remedial work should be applied if rehabilitation of wood structure is considered.

A sudden change of a cross section (carving) at the end of an element will create two problems. First is that the shear resistance of the element is reduced; the second is that exposing the end of grains by carving the wood, the moisture will faster penetrate the lower section of the element and a crack as shown in Fig. 1 can occur. The problems shown in Fig. 2 are similar with the ones in Fig. 1, except that they are not as easy to observe.

Fig.1. Carving with partial bearin Fig.2. Carving with full bearing


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In Fig. 3 the clip angles and the bolts are attached to the upper section of the element. Similar to Fig. 1, this type of connection reduces the shear capacity and increases crack development problem.

The beam shown in Fig. 4 bears on a masonry wall and at the same time has the upper section bolted to the wall using clip angles or similar fasteners. For deep beams, the dry shrinkage will reduce the depth and it could develop a crack at the top connection because the deformations at the bottom are restricted.

Fig.3. Fastening of the upper section Fig.4. Fastening of the upper section for deep beams

Incorrect positioning of the gusset plates at the end of the beams (see Fig. 5, at upper

section) can lead to a defective behavior of connection. If the screw holes are not provided to allow for displacement of the upper section at the end of the beam, negative moments can occur. In the case of a connection that has not been designed to resist such efforts, cracks are most likely to appear. Hanging heavy or moderate weights (see Fig. 6) thru screws fastened to the area of the element having the grain in tension can produce cracks at the screw level.

Fig.5. Connection at the upper section Fig.6. Hanging weight

Fig. 7 shows how the upper section of a beam has been carved above an intermediate

support in order to connect with another element on perpendicular direction. In the case of continuous beams, this procedure can lead to the apparition of cracks along the grain (longitudinal cracks) starting at carving location. There are cases when the base of columns or arches is buried in poured concrete as shown in Fig.s 8 and 9. if the concrete has direct contact with the grade, the moisture will migrate thru capillarity to the base of the wood element and it will cause degradation.


17

Fig.7. Beam carved in tension area Fig.8. Column buried in concrete

These situations can be improved by providing ventilation holes that will allow water evacuation and evaporation. Fig. 10 shows a column with corbel. Fastening the gussets as shown in this fig., can lead to the crack development in the longitudinal direction of the column because the screws are installed in the stressed area of both, the column and the corbel. The perpendicular efforts to the stressed grain will produce cracks which can lead to a sudden failure.

Fig.9. Column or arch support Fig.10. Corbel to column connection

A very simple and very often used method of joining a secondary beam to a main beam

is that of using clip angles as shown in Fig. 11. Using bolts thru, the clip angles are fastened to the secondary beam over the full extent of its width. Having long and rigid clip angles in a connection where both beams will shrink, there is a possibility that splitting of the wood within the main beam can occur.

Fig.11. Connection of secondary beam Fig.12. Floor affected by humidity with clip angles

Fig. 12 shows problems that occur during erection when the upper floor is affected by

humidity. The expansion of the floor can develop horizontal loads which can lead to detachment of the secondary beam from the main one. The elements of a truss can be joined together by using metallic connectors. These are shop fabricated in one piece, providing constant angles between diagonal members and top and/or bottom chord. Once the truss is loaded and deformations occur, the angles between wood members will modify, but they are


18

restricted by the rigid connectors. This situation can lead to wood splitting along the placement direction of the thru rods

CONCLUSIONS

The necessity of connecting wood elements appears specially due the fact that wood selection for cross sections and lengths is limited. During design and erection of a wood structure consideration should be given to the fact that the overall structure has to provide strength capacity under all the loads applied to it. Poor positioning of connectors due to either, design or erection, as well as, using inappropriate connectors when joining wood elements, combined with shrinkage and/or expansion phenomenon and excessive loading, can produce cracks within the structural wood elements and jeopardize the safety of construction.

REFERENCES 1. ANDREICA H.-A., BERINDEAN A.-D., DARMON R. M. (2007), Structuri din lemn (Timber

structures), Ed. U.T.PRESS. 2. GÖTZ, K.-H., HOOR, D., MÖHLER, K., NATTERER, J. (1995) Construction en bois (Timber

constructions), Laussane, Suisse. 3. NATTERER, J., HERZOG, T., VOLZ, M. (1994) Construction en bois 2 (Timber constructions

2), Laussane, Suisse. 4. MARUSCIAC D., ANDREICA H.-A. (1997) ConstrucŃii moderne din lemn (Modern timber

constructions), U.T.C.-N. 5. *** http://www.strongtie.com/literature/c-2013.html, viewed at 10/12/2012. 6. *** http://www.herrmannframes.com/pdf/SHERPA%20Catalogue.pdf, viewed at 15/12/2012. 7. FURDUI C. (2009), ConstrucŃii din lemn (Timber constructions), Ed. Politehnica, Timişoara. 8. *** SR EN 1995-1-1-2005: Proiectarea structurilor de lemn (EN 1995 Eurocode 5: Design of

timber structures). 9. *** SR EN 1991-1-3-2005 AcŃiuni asupra structurilor. Încărcări date de zăpadă (EN 1992-1-3

Actions on structures. Snow loads). 10. *** SR EN 1991-1-4-2006 AcŃiuni asupra structurilor. AcŃiuni ale vântului (EN 1992-1-3 Actions

on structures. Wind actions).

CÎRSTOLOVEAN I.L. pp.19-24

19

IMPLEMENTATION OF A SOIL-WATER HEAT PUMP FOR THE HEATING OF A RESEARCH LABORATORY OF THE TRANSILVANIA

UNIVERSITY OF BRAŞOV

CÎRSTOLOVEAN Ioan Lucian, University Transilvania Brasov, Faculty of Buildings Engineering, e-mail: [email protected]

A B S T R A C T The soil represents an endless renewable source of energy. In the IRDT of the Transilvania University of Braşov there have been implemented in a research laboratory a soil-air heat pump and a consumer – a radiation heating system called heated concrete – the thermal agent for the heated concrete is produced by the soil-air heat pump. This paper presents the adopted solution, the projected installation, it justifies the importance of the use of the system and it claims for the necessity of implementation of the system in a large scale. This solution for the heating of the buildings corresponds to the 20-20-20 EU directive for the Brasov county in Romania.

Keywords: : heating pump; load for heating; concrete floor; consumption Received: January 10, 2013 Accepted: March 10, 2013 Revised: March 31, 2013 Available online: May 31, 2013

INTRODUCTION The building, research laboratory, where the heat pump was implemented, studied in this paper, has a reduced head necessary. The structure of the envelope was designed in such a way as to respond to the Directive which requires cuts on the energetic consumption of buildings. In this way, it was possible to use as source for the production of the thermal agent a soil-air heat pump and a radiaton heating system called ‘heated concrete’. The heat naturally accumulated in the crust triggers what is called geothermal energy. The soil has the property of accumulating and maintaining solar energy for a alonger period of time, which leads to an almost constant level of the heat source throughout the whole year . he energy is captured by the soil, either directly under the form of radiations, or indirectly under the form of heat from rains or air. Within the project IRDT (Institute for Research and Development of the Transilvania University) a surface geothermic field was projected. These thermal fields represents the source with lowered parameters of the heat pump and the consumer is represented by the radiation heating system called ‘heated concrete’ projected in the building under analysis called research laboratory. The efficiency of a heating installation which has as heat source a thermal pump needs to be estimated with a view to establishing the amortization period of the initial spending. The variation of the external temperature has a direct effect on the efficiency of the thermal pump since the functioning efficiency of the thermal pump is influenced by the thermal load of the building, that at its turn, depends on the exterior temperature In case of the use of thermal pumps for the heating of buildings, one needs to consider the heat contributions, interior heat and ventilation, for which reasons the use of the method based on the hourly frequency of the temperature proves to be convenient (the bin method) for which when calculating one considersthe stationary regime, characteristic to some time intervals when the temperature varies within restricted limits of 1...2 oC.. MATERIALS AND METHODS In the central heating of the laboratory, a 21,2 KW heat pump has been set up, as indicated in fig 2, that will function bivalently. The automation of the heat pump allows of a bivalent functioning of the pump with the 60 KW boiler. The pump will be interconnected to the heating installation so


20

that it can be used for the heating of the water’s temperature in the boiler in the outlet. The separation of the circuits is made by the help of the 1500 liters thermal agent tank situated in the central heating. This tank is chosen in such a way as to be able to take a possible second pump. For the pump to function optimally, the tank is connected to the inlet of the main ciucuit by a mixing valve. The command of this valve is done by the automation of the heat pump. If the exterior temperature is below the bivalence temperature, 2º C, fig.5, the automation of the heat pump turns on the tank. Similarly, the three-channel valves from the heating ciucuits: heated concrete and CTA circuit will be commanded by the automation of the heat pump. For the heating/ cooling of the spaces of the laboratory, the heated concrete system was adopted in the flooring for the semi-basement, groundfloor and first floor. The positioning mode of the pipes in the heated concrete, respectively, semi-heated is of the double meander type with dimensions 20x2,0 mm, of reticulate peroxide polyethylene at a pace of 15 cm fixed with iron mesh tying wire and the positioning of pipes will be in the middle of the floor. The fitting scheme for the polyethylene piping introduced in the concrete plates is reproduced in the fig. below, fig 1:

Fig.1. The structure of the heating radiant plate ‘heated concrete’

from the laboratory

Fig 2. Technological scheme

The projection and positioning of the installation of geothermal collectors in combination

with the heat pump was made by having the following data [8]: 1. The heating necessary and the performance factor, 22kw and COP 4, vaporization

capacity 16.5 kw.


21

2. The volumetric flow of the heat pump, 4400 l/h. 3. The specific earth-extraction capacity, 15 W/m².

The extraction capacity and the yield should not be exceeded because in this situation the

freezing of the pipe area becomes major and the freezing rays grow simultaneously. In case of defreezing, in the spring, the infiltration of pluvial waters and of the water resulted from the melting of the snow is significantly prevented. The pipes are placed at a depth of 2.8 m and at a distance of 0.5 m one form the other as illustrated in fig 3. The regeneration of the collectors is done by solar radiation, rainfall and dissipated water from the treating of sewage waters in sewage plants. The dissipators will be placed above the geothermal collectors. The fixing of the pipes will be done on the excavated surface and laid on a 15 cm sand bed. The positioning scheme of the collectors is presented in fig 3.

Fig.3. Placing scheme of the thermal collectors

The heat necessary for the heating of the building is of 54 kw, calculated with SR EN 1907/1 [5]. Fig. 4 presents the variation of the heat necessary for the heating with exterior temperatures:

At -22 º C the heat necessary is of 35,5kW, and at -2 º C the heat necessary is of 19,8 kW.

Fig.4. Thermal load variation with external temperature

The fuel consumption, natural gases, of the 60 kW boiler situated in the central heating room as background source, for the same exterior temperatures is represented in the following graph:


22

Fig 5. Gas consumption diagram

The connection between the thermal load of the heat pump for different values of the agent’s

parameters obtained in the secondary of the heat pump and the exterior temperature is represented in fig. 5. The diagram was obtained by drawing the two curves:

• The curve for the heat necessary of the building; • The load curve of the heat pump.

At the intersection of the two curves, the bivalent temperature has been obtained.

Fig. 6. Variation of heat load of Heat Pump with

external temperature at different external Temperature

Further on, we will illustrate how the heat provided by the implemented heat pump, B121, can ensure the heat load of the building by means of the heated concrete heating system. We have analyzed the capacity of the pump at external temperatures ranging between -4 and 10º C for a number of hours (the bin method – hourly frequency of the external temperature [2]) as it results from the table below:

Table 1. External temperature and number of hours

Temperature No. hours

-4 227

-2 336

0 489

2 473

4 390

6 492

8 633

10 693

The data from the table are real and they correspond to December 2009.


23

The heated concrete system requires low parameters in the thermal agent (35º C). From the technical file of the pump [8] we have extracted the parameters:

- COP standard, integrated thermal capacity, absorbed electric load. The efficiency of the heat pump depends on the thermal load of the building. The testing

conditions of the thermal pumps whose results provide their capacity curve depending on the external temperature are different from the conditions characteristic to real functioning [7]. When the thermal capacity of the heat pump exceeds the heat necessary of the building, the pump begins to enter a cycle: these successive starts and stops will be the more frequent that the difference between the already mentioned two values is greater. “The heat pump will suffer a diminution of its heat providing capacity. As a consequence the diminished providing capacity of the heat DPC will result after applying a diminution factor DF on the values obtained at the testing of the capacity of the heat pump QPT in the conditions of a stationary regime on the test desk” [7], [2].

In Fig.6. there is the diminished characteristic of the heat pump due to the calculated cycle for each temperature interval and for a degradation coefficient of 0,25 recommended for their heating regime [6], [7].

Fig 7. Heat capacity adjusted and real COP of Heat Pump

The heat provided by the pump in real simulation conditions is illustrated in fig.8.

Fig 8. Heat produce by Heat Pump


24

Table 2.Thermal energy produce by heat punp

External temperature

Thermal Energy produce by pump

[ kWh]

Building Heat load

[ kWh] -4 1947.6 1947.6 -2 2678.4 2678.4 0 3516.6 3516.6 2 3032.6 3032.6 4 2196.32 2196.32 6 2386.9 2386.9 8 2577.32 2577.32

10 2281.0 2281.0

By comparing the quantity of energy provided by the pump with the real load of the building,

it results that when the external temperature varies between -4 and 10 º C , Tab 2, we notice that the heat pump can cover the heat necessary of the building, therefore, it does not require the intervention of the gas heating boiler. CONCLUSIONS

• One can notice that there is only one point, the one of equilibrium, Fig 5, (corresponding to an external temperature) for which the capacity of the heat pump equals the heat necessary of the building.

• The heat pump ensures the heat necessary for heating for external temperatures between -4 and 100 C and it can register good results for external temperatures of -7-80 C.

• The analyzed building has a thermal protection which confers thermal stability to rooms (low variation of the confort temperature).

• The heated concrete heating system can ensure the heating of the building by a thermal agent provided by the pump at low parameters under climatic conditions specific to the Brasov area, thermal agent 350 C.

• The COP of the heat pump is situated between 3,4 and 4,7. This COP recommends the use of this equipment for the heating of buildings when external temperatures varies between 100 C and – 100 C. REFERENCES 1. *** (2004), ENERGUIDE, Heating and Cooling with Heat Pump, Natural resources Canada’s Office of

Energy Efficiency ISBN 0-662-37827-x. 2. *** (2001), AHSRAE Fundamentals Handbook, Chapter 31. 3. LAZZARIN R., BUSATO.F., NORO M. (2012), Heat pumps in refurbishment of existing

buildings.Rehva journal – december. 4. BJARNE W. O. (2011), Operation and control of thermally activated building system s(TABS), The

REHVA European HVAC Journal, Vol. 48,ISSUE 6, December, www.rehva.eu. 5. *** SR EN 1907/1.Method for calculation of the design heat load. 6. BOIAN, I. (2007), Dezvoltare durabilă. InstalaŃii pentru construcŃii bazate pe energie regenerabilă

(Sustenable development.Buildings services functioning by renewable energy). ISBN 978-973-635-978-1. Editura UniversităŃii Transilvania din Brasov.

7. BOIAN I., FOTA S. (2009), Evaluarea performanŃei termice a pompelor de căldură în condiŃii climatice diverse.(Thermal performance evaluation of heating pumps in different climate conditions).CIBv 2009.

8. *** VIESSMANN srl - Design instruction for Heat Pumps.

COBIRZAN N., DUMITRAS M., ANDREICA L. pp.25-30

25

AXIAL DEFORMABILITY OF REHABILITATED STONE MASONRY WALLS

COBIRZAN Nicoleta*, DUMITRAS Macedon, ANDREICA Ligia,

Technical University of Cluj-Napoca, *e-mail: [email protected] (corresponding adress)

A B S T R A C T Within natural stone walls subjected to centric compression, a complex state of stresses appears due to the different deformability of stones and mortar and to the unevenness of the joints, especially where irregular blocks of stone are used. The purpose of this paper is to determine the sources of variation in the module of elasticity of fieldstone masonry throughout calculation, in the context of employing compatible materials in works of consolidation, in order to ensure the interaction of the new and existing masonry in terms of durability and sustainability of the intervention. The results of this theoretical inquiry highlight the influence of the mortars and of the stone laying on the overall behaviour of the new masonry and on its compatibility with the existing one.

Keywords: masonry works, rehabilitation, shortening, deformability


INTRODUCTION Since ancient times, natural stone was a local, readily available and good quality material of

high strength and durability, which has facilitated the construction of important buildings. The importance, size and function of the buildings, as well as the time of their construction,

the available stone sources, processing capabilities and the laying techniques have conditioned the main types of natural stone masonry, of which some are: dry stone masonry, fieldstone masonry, quarry stone masonry, ashlar, cut stone, etc.

The durability and the resilience of the historical mortars, composites and stoneworks are undeniable. Still, the fact that each historical masonry carries a specific set of particular features in terms of mechanical strength, heterogeneity of materials and technology, due to multiple layers of masonry work superposed and juxtaposed over the centuries as additions, repairs, functional transformations, façade makeovers or simply as the ‘recycling’ of an ancient wall or still-standing structure that became at some point an organic part of an 18th century city house, for example, cannot be overlooked. Since these particular features are frequently difficult to assses by means other than non-intrusive testing, theoretical inquiry and comparison with other structures with known mechanical behaviour, the theoretical aspect of the investigation and assessment of a historical structure is more often than not a delicate task and a high priority concern, and requires a specific understanding of the role and behaviour of its composing elements within the whole.

The volume of stones or mortar for masonry and the array of stones courses and horizontal joints depend very much on the type of masonry. In the case of fieldstone masonry, the bed joint is by no means flat and doesn't have constant thickness, while for the cut stone masonry the horizontality and thickness of the bedding joints depend on the shape and size of stones.

The above issues are important in regard to the rehabilitation of masonry walls, more so since masonry mortars compatible in terms of strength and deformability are a requirement for correct and proper interventions on historical stone masonry.

The purpose of this paper is to determine the sources of variation in the module of elasticity of fieldstone masonry throughout calculation, in the context of employing compatible materials in works of consolidation, in order to ensure the co-operation of the new and existing masonry in terms of durability and sustainability of the intervention.


26

MATERIALS AND METHODS 1. Complex state of streses in masonry works

Within natural stone walls subjected to centric compression, a complex state of stresses appears due to different deformability of the stones and the mortar and unevenness of the joints.

Stones and mortar, each considered separately, are characterized by specific characteristic diagrams (Fig.1).

Fig 1. Stress-strain characteristic diagrams σ – ε for masonry stones (e) and mortar (m) [1]: (fe, fm – the unitary compressive strength of the stones (fe) and of the mortar (fm); εue, εum – the ultimate specific deformation values for stones

(fue) and for the mortar (fum) )

Due to the large deformability of the mortar, in comparison to that of the stone, the mortar in

the joints tends to squezee horizontally, but the phenomenon is prevented due to adhesion and friction of stones and mortar. Thus compressive horizontal stresses occur within the mortar, and the stones are subjected to horizontal tensile stresses.

High stress values can destroy the adhesion between stone and mortar and vertical cracks may appear in vertical joints. Also, the thickness variation of horizontal joints, due to the shape and size of stones, leads to the concentration of stresses and to additional local compression, shear and bending in the stones.

Fig. 2 shows supplementary compression stresses in mortar and tensile stresses in stones due to the differences in deformability between mortar and stones while Fig.3 shows the stress concentrations for fieldstone masonry with even, respectively uneven courses.

N

N N

Fig. 2 Supplementary stresses caused by the different deformability of the mortar and the masonry stones

Fig. 3 Local supplementary compression stresses

Local compression stresses lead to the rotation of stones and premature destruction of

adhesion, causing their displacement. This phenomenon concludes in increased deformations and the redistribution of stresses in stones unit.


27

2. Masonry deformability The complex state of stresses in stone masonry works, subjected to vertical loads, is mainly

determined by different deformability of stones and mortars joints. In almost all the cases the volume of stones is about 80-85% of it, while volume of mortars joints represent only 15-20%, however, the deformations of mortar as part of the overall masonry works deformation represent about 85% [2].

The percentage of deformations due to units (stones) only reaches 15 % of all the masonry works., however, modulus of elasticity is greater to that of the mortar joints. In this way the elastic modulus of the masonry works will be mostly influenced by the elasticity modulus and relative heights of the mortar joints. RESULTS AND DISCUSSIONS

Whatever the shape and size of stones and joints execution, the deformability (shortening) of a masonry wall (∆z), is a sum of deformation of mortar (∆m) and stone (∆e).

emz ∆+∆=∆ (1)

Depending on the type of masonry, the mortar and stone deformations can be emphasised

each by splitting the wall in corresponding sections, as the global deformation is the resulting sum of the deformations in the considered sections.

m

mimimimim E

hh

∑ ⋅=⋅∑=∆

σε (2)

where:

εei, εmi are the specific vertical deformations of the mortar in the considered sections (with a thickness of hmi) and of the stones in the considered sections, respectively (with a thicknesses of hei),

miσ , and eiσ are unitary stresses, and

Em, Ei- modulus of elasticity of mortars and stone units. In the case of masonry where the courses are relatively tight, the considered sections are the

horizontal mortar joints, and the stone courses respectively. Considering that compressive stress zσ is constant in a horizontal section with an area Az:

zz A

N=σ (4)

Relations (2) and (3), become:

∑=∆ mim

zm h

E

σ (5)

∑=∆ eie

ze h

E

σ (6)

e

eieieieie E

hh

∑ ⋅=⋅∑=∆

σε (3)


28

Mortar-bound stone masonry behaves as a monolithic element, with a global elastic modulus Ez and specific deformations zσ .

Fig. 4 illustrates the monothic behaviour and the global deformation of fieldstone masonry.

h

z

N

Fig. 4. The deformability of the compressed stone masonry [3]

The deformation (shortening) ∆z is calculated with the following equation:

hAE

Nh

Eh

zzz

zzz ⋅

⋅=⋅=⋅=∆

σε (7)

From equations (1) and (7) and considering (5) and (6) it results:

e

ei

m

mi

z E

h

E

h

E

h ∑+

∑= (8)

where the total height is the sum of the thicknesses of the (medium) horizontal joints and of the stone courses and is determined by:

∑+∑= eimi hhh (9)

The masonry modulul of elasticity result as follows:

e

mem

mz

E

EE

Eξξ +

= (10)

where mξ and eξ are the relative height of mortar layer and stones courses on h, height:

hmih

m∑

=ξ

(11)

heih

e∑

=ξ (12)

Equation 10 must be corrected by the use of experimentaly obtained coefficients, which are to

account for the heterogeneity of the stone masonry. For a simplified calculation, one can introduce an η coefficient will be used here, accounting

for the irregularities of the horizontal joints between the courses.


29

e

mem

mz

E

EE

Eξξ

η+

⋅= (13)

In case of a masonry made of regular stones and having constant courses, we can consider

1=η . In case of masonry rehabilitation works, using compatible mortars implies that they have a

much higher deformability than the stones, so that, in the equation 13, the Em / Ee ratio can be considered null and the equation becomes:

m

mz

EE

ξη ⋅= (14)

From equation 14 results that elastic modulus of the fieldstone masonry depends mostly on

the elastic modulus of the mortar joints and their volume, and depends indirectly on the size of the stones: if stones height increases, the coefficient mξ decreases and the global elastic modulus of the

masonry increases.

CONCLUSIONS Masonry is a non-homogeneous and anisotropy material for which the mechanical strengths,

mainly the unit resistance to shear or axial loads, depend upon numerous parameters [4]: the geometrical, physical or mechanical characteristics of the component materials, the different deformability of the materials (mortar and stone), the adhesion of the mortar, the quality level of the work performed, the aging of materials, etc. Historic masonry consolidation/ rehabilitation/ reconstruction works require that the new masonry work to be compatible with the existing one especially in terms of deformability and stiffness.

To this end, a direct relation has been established between the elastic modulus of the mortar and that of the masonry one, the elastic modulus of masonry being calculated depending of elasticity modulus of the mortar and the ratio of horizontal joints in the masonry. The correction factor η considered in the equation has to be determined experimentally, due to the considerable heterogeneity of the fieldstone masonry.

In regard to the practical implications of this theoretical inquiry, the resulting conclusion is that, for addition or consolidation interventions on fieldstone masonry that employ similar (or re-posed) stones and compatible mortars, the laying of the stones in similar courses, with bedding thickness similar to that of the original is strongly recommended, since in the case of fieldstone masonry the uncontrolled concentration of stresses within the masonry can prematurely trigger the displacement of stones and bear a negative effect on the mechanical streght of the masonry as a whole. REFERENCES 1. DUMITRAS M., COBIRZAN NICOLETA, DUMITRAS D. (2011), ConstrucŃii Civile II (Civil

Constructions II), Editura UTPES, Cluj-Napoca. 2. NEGOITA AL., FOCSA V., RADU A., POP I., TUTU L., DUMITRAS M., NEGOITA I, (1976),

ConstrucŃii civile (Civil Constructions), Editura Didactică şi Pedagogică, Bucureşti. 3. ANDREICA GRAłIELA-LIGIA (2012), ContribuŃii cu privire la compatibilitatea mortarelor în

intervenŃiile asupra zidăriilor istorice (Contributions in Regard to the Compatibility of Mortars in Interventions on Historic Masonry Works) - Ph.D. Thesis, Cluj Napoca


30

4. COBÎRZAN NICOLETA, DUMITRAŞ M., DUMITRAŞ D. (2011), The resistance to shear of the masonry walls,11th International Scientific Conference “VSU 2011”, Sofia, Bulgaria, ISSN 1314 – 071X.

5. *** Indicativ CR6-2006. Cod de proiectare pentru structuri din zidărie (Design Codes for Masonry Structures).

6. *** STAS 2917-51 Lucrări de zidărie din piatră naturală. Date constructive (Natural Stone Masonry Works. Construction Data).

DIDULESCU C., SAVU A. pp.31-34

31

ASPECTS OF VOLUME CALCULATION

DIDULESCU Caius*, SAVU Adrian, Technical University of Civil Engineering Bucharest, Faculty of Geodesy,

e-mails: [email protected] * (corresponding adress), [email protected]

A B S T R A C T This article deals with the problem of calculating volumes using the digital terrain model. Large majority of current programs for calculating volumes uses digital terrain model for volume calculation. Data acquisition using the terrestrial laser scanner is one of the newest techniques of data acquisition to achieve digital terrain model. In this article we use a digital terrain model obtained after measurements using a terrestrial laser scanner and we make a comparative study between the classical treatement using the Simpson’s formula and the automatic calculating of volume with a computer program.

Keywords: laser scanner, DTM, three-dimensional modelling, volume calculation


INTRODUCTION The current programs for calculating volumes use as entry data the digital terrain model.

There are several methods to acquire elevation data for digital terrain model: a) ground survey methods using total stations; b) photogrammetric methods based on the use of stereoplotting instruments; c) graphics digitizing methods using tablet digitizers; d) data acquisition using laser scanning technique.

At first using of an automatic calculation volumes program, it is important to solve at least one case study, using the classic version, to be compared with the program that automatically generates volumes.

MATERIALS AND METHOD

Laser Scanning is a new geodetic technique, whereas the geometry of a structure is measured (more or less) completely automated and reflector less with high precision and velocity. The origin result is a so-called point cloud [1]. The laser scanner records the points three-dimensionally by measuring the horizontal and vertical angle, as well as the spatial distance for each point. The coordinates of the points are obtained in a specific Cartesian system of the scanner using simple trigonometric functions. The horizontal and vertical angles are modified automatically in pre-established intervals.

An important application is the creation of digital terrain model DEM (Digital Elevation Model). The software used is Cyclone (Leica) and permits obtaining the TIN model (Triangulated Irregular Network), which is a spatial network of triangles, created as a Delaunay algorithm [2]. This method is being used to an ever-increasing extent in terrain modelling. The reasons for this development are that every measured data point is being used and honoured directly, since they form the vertices of the triangles used to model the terrain, from which the height of additional points may be determined by interpolation and the construction of contours undertaken. Furthermore, the use of triangles offers a relatively easy way of incorporating break-lines, fault lines, etc. Any triangular-based approach should attempt to produce a unique set of triangles that are as equilateral as possible and with minimum side lengths. Using digital terrain model it can perform calculations on cut and fill volumes for a given site.


32

At first using of an automatic calculation volumes program it is important to solve at least one case study, using the classic version, to be compared with the program that automatically generates volumes. 1. Volume calculation using simpson's formula

In numerical analysis, Simpson's formula is a method of numerical integration, numerical approximation of defined integrals [3]. Simpson's formula calculates an approximation of the integral function f(x) (in blue) by a second degree polynom, P(x) (in red), which takes the same values of the function f(x) at the ends a and b and at the midpoint m (m = (a + b)/2).

Fig.1. Approximation of integral function with Simpson's formula

( ) ( ) ( )∫

+

++

−≈

b

a

bfba

fafab

dxxf2

46

(1)

( ) ( ) ( )( )( )( )

( ) ( )( )( )( )

( ) ( )( )( )( )mbab

mxaxbf

bmam

bxaxmf

bama

bxmxafxP

−−−−

+−−−−

+−−−−

= (2)

If the approximation interval [a, b] is in some sense "small", Simpson's formula will provide a

suitable approximation for the exact integral. By small means that the function to be integrated is relatively smooth on [a, b]. For such a function, a second degree polynom, as used in Simpson's formula gives good results. However, it often happens that the function we are trying to integrate is not smooth throughout the range. This means that the function is powerful swing or there are missing function values at certain points. In these cases, Simpson's rule may give poor results. One way to solve this problem is to divide the interval [a, b] into a number of subintervals. Simpson's formula will be applied to each subinterval and summing the results will get an approximation of the integral over the entire interval. This is called Simpson's composite formula. Assuming that [a, b] is divided into n subintervals, where n is an even number, then Simpson's rule is as follows:

( ) ( ) ( ) ( ) ( )

+++≈ ∑ ∑∫

−

= =− n

n

j

n

jjj

b

a

xfxfxfxfh

dxxf

12

1

2

11220 42

3 (3)

where: xj = a + jh for j = 0,1,...,n − 1,n with h = (b − a) / n; in particular, x0 = a and xn = b

DIDULESCU C., SAVU A. pp.31-34

33

Therefore the steps are: selecting an even number of intervals (odd number of sections) and determine the area of each section on the profile of the section. The volume can be calculated by the Simpson’s formula: Volume = (h/3) (area of first section + area of last section + twice the amount of odd sectional areas + four times the amount of even sectional areas) (4)

2. Volume calculation using the cyclone software

Based on TIN model and a reference plane it can be calculated the volumes of different enclosures. The first step is to generate a reference plane (Fig.2), in the "Tools"/"Reference plane". It can be defined by the axes of the coordinate system and an origin point and the software calculates the volume of the enclosure from the reference plan to the surface generated by TIN model. For reference plane may be imposed grid size, grid extension to cover the desired volume to be calculated, color and thickness grid. Volume is calculated in units set to section ”Edit”/ "Preferences "/" Units ".

Fig.2. Reference Plane Parameters

3. Filling and excavation volume calculation Based on TIN model and a chosen reference plane can be calculated volumes of filling and

excavation in order to choose the most convenient situation in terms of volume of excavation, filling volume, the surface on which digging and area that will be filled.

Fig.3. Choosing grid parameters


34

The position of the reference plan is set in the menu "Tools" / "Reference plane" from the "Tools" / "Measure" / "Measure surface deviation". The program will generate (Fig. 3), based on square grid with edge length set, a table with grid square corners position, the heights of points, the reference height and the difference between the reference height and the field height.

Differences are positive and negative depending on the position of the reference plane. In each position of the reference plane, using the command "Tools" / "Measure" / "TIN volume" it can get cut and fill volumes and surfaces to be performed excavation and filling. (Fig. 4). Through successive attempts it can be obtained the best solution in technical and economical terms for the excavation and filling areas.

Fig.4. Volum calculation To check the software we determined an odd number of sections in the interested zone. Using

digital terrain model, we obtained the surfaces of profiles using digital terrain model already created. We apply the Simpson's formula and we checked the volume calculation. The results showed that automatic volume calculation program is working correctly.

CONCLUSIONS

In calculating volumes obtained from computer programs automatically based on three-dimensional coordinate points are two important aspects: one is related to the mode of data collection in the field to provide sufficient three-dimensional points representing terrain configuration, depending on the desired accuracy to obtain volume and the second aspect is given by the decision to establish that the method for volume calculation presents correct results. Engineer's task is to establish and verify the values provided by automatic calculation of volumes programs. The first step is to verify, at least at first use of the software, the results obtained with a classical computing method. REFERENCES 1. COŞARCĂ, C., NEUNER, J., DIDULESCU C. (2005), Scanare Laser Terestră – O nouă tehnică în

Topografia Inginerească (Terrestrial Laser Scanning – A new technique in Engineering Survey), Buletinul ŞtiinŃific al UniversităŃii Tehnice de ConstrucŃii Bucureşti.

2. *** http://www.leica-geosystems.com/en/index.htm, viewed at 10.01.2013. 3. *** http://en.wikipedia.org/wiki/Simpson's_rule, viewed at 15.05.2009.

KOPENETZ L. CĂTĂRIG A., ALEXA P., DEUŞAN S. pp.35-42

35

THE MEMBRANES USED FOR THE LIGHTWEIGHT STRUCTURES WITH CABLES AND MEMBRANES

KOPENETZ Ludovic, CĂTĂRIG Alexandru*, ALEXA Pavel, DEUŞAN Simona,


A B S T R A C T The lightweight structures with cables and membranes into construction practice, was an important stage in the management of complex structural form, so that they lead to optimum economical results. The investigations are necessary to determinate the mechanical characteristics of structural membranes. For this reason, this article is about practical determination of these characteristics by experimental testing.

Keywords: cable, membrane, lightweight structures Received: 08.09.2012 Accepted: 02.10.2012 Revised: 07.01.2013 Available online: 31.05.2013

INTRODUCTION The characteristic demands for structural membrane foils [7] and the material choosing is

conditioned by a great number of factors such as: * Criteria of strength, * Criteria of rigidity, * Resistance to alteration, * Thermal insulating properties, * Acoustic properties, * Optical properties.

MATERIALS AND METHODS 1. Classification of structural membrane foils

The membrane is the result of several cut foils joining. Two kinds of materials are used for the foils: isotropic and anisotropic, [1], [2], [7].

A. Isotropic materials The isotropic materials are the foils made of metals (steel, aluminium), polyesters, polyethylene,

polyvinylchloride (PVC), polyvinylfluoride (PVF or Tedlar). In practice, the most used are the foils made of metals due to their durability and resistance in time

(practically, they don't present creeps and they don't relax). The disadvantage is their great sensibility to deformation before the site works, so special cutting problems occur here. The isotropic foils are one-layer or multi-layer materials like a co-operative assembly (Fig.1).

Fig.1. The isotropic foils


36

B. Anisotropic materials These materials, with properties orientated orthotropic or by more direction, are made especially by

ondulated or profiled sheet metal and by reinforcing the isotropic foils with fibbers - the so-called composite materials. (Fig, 1, 2), [3].

Fig.2. Composite material

Fibber used for reinforcing: a) organic: flax, hemp or cotton, b) mineral: glass, carbon or graphite fibbers, c) synthetic: polyesters (Trevina, Diolen), polyethylene (Fabrene), poiyamides (Perlon, Nylon),

polyacrylonitrile (Dralon), aramides (Kevlar).

The isotropic connection layer or the top layer (the coating) is made also by synthetic rubber (Neoprene), polyurethane, poiytetrafluoroethylene (Teflon), [4], [5], [6], [7]. Using the metal and glass fibbers, the tensile strength increase to unexpected high values. The testing of a Kevlar fibber reinforced and PVC coated membrane showed a 6.9 kN/cm tensile strength.

2. Experimental essays for structura1

The mechanical characteristics needed for a proper design of membranes depend on lot of factors, such as: the nature of the material, the speed and the time of loading, the climatic conditions, the presence of the joints, the aging of the foil, the storage conditions (for example, damages caused by the folding of the material or a not proper storage). 2.1. The tensile strength

The design standards for cable and membrane structures (Germany, USA, Hungary) give a formula for the calculus of the tensile strength:

k

RR = (1)

where:

- R is the average value of tensile strengths obtained with rapid essays, - k is the product between 1k , 2k , 3k , 4k , 5k ,

- 1k is the influence of the aging of the material; 211 .k = for an average life less or equal with

10 years, 411 .k = for an average life longer then 10 years,

- 2k is the influence of long term loading; 012 .k = if the solicitation from long term loading is

less then R.150 and 022 .k = if the solicitation is between R.150 and R.50 ,

- 41213 ..k −= ; represent the variation of R,

- 2514 .k = ; represent the influence of assembling inaccuracies,


37

- 51315 ..k −= ; represent the influence of the calculus model.

The tensile strengths are obtained using the following tests: - uniaxial test, - biaxial test, - "membrane" type test, - "cylinder" type test.

* The uniaxial test The used standard is STAS 9051/2-79 (Elasthomers or plastic materials coated textile fabrics -

determination of tensile breaking strength and tensile breaking elongation). This standard stipulates that the measurements must be taken on five samples, both on the warp and fill directions. The sample width is 50 mm, [7], [8].

The introduction of material in the testing machine is made by using special equipment (Fig.3).

Fig.3. Equipment for testing

* The biaxial test In this case the tensile test is made by simultaneous solicitation of the material after two orthogonal

directions in the plane of the sample. The solicitation is applied on both directions in different ratios. The sample has a central square form test region and the prolongation on both directions has a

clamping role. Fig. 4 presents the dimensions of a sample used in Germany. The testing is made with specialized equipment, [10].

Fig.4. Sample form used in Germany


38

Fig. 5 presents such testing equipment that belongs to the Mechanical Department of Technical University of Cluj-Napoca, made by the authors of this work.

Fig.5. Testing equipment used in Technical University of Cluj-Napoca

Other biaxial measurements are obtained from:

- Membrane type test The membrane is subjected to a uniform pressure. The membrane has its edges fixed on a circular

plane outline (Fig.6)

Fig.6. Membrane type test

- Cylinder type test The samples have a cylindrical shape with the ends fixed in special parts (Fig.7).

Fig.7. Cylinder type test

LEGEND:

1. Tensioning screw 2. Material sample 3. Jaws forfixing the material 4. Dynamometric spring 5. Frame 6. Comparing watch 7. Loading lever 8. Gas butner heater


39

2.2. The tear strength The used standard is STAS 6144-86 "Tear strength determination" for any type of tissues. The

samples are made with wings. Five measurements are taken on both warp and fill directions. Other countries use four more test types: tongue (Fig.8.a), paws (Fig.8.b), pendulum (Fig.8.c),

trapezium (Fig8.d).

Fig.8. Sample for the tear streligth

The knowing of tear strength is important in choosing of foils. 2.3. Adhesion strength

For the testing of elasthomers and plastic material coated textile fabrics the standard is STAS 9051/3-85. The adhesion strength is the average force required for a continuous propagation of the separation line between the coating and the fabric (Fig.8).

Fig.8. Sample for adneston strength

2.4. Compression strength This strength means the modifying of foil's thickness t, because of an orthogonal loading on the

material’s surface (Fig.9). The compression strength curve is obtained by representing the variation of foil's thickness in respect with the applied load.

The tangent line to the beginning part of the curve represents the compression modulus.

Fig.9. Sample for compreston strength

2.5. Stress determinations in soap films Introducing the metal trame shown in fig. 10 in a soap solution the mobile side A-B displace

upwards. The value of F force is known from physics; it is proportional to A-B side's length


40

lF α2= (2)

Where: α is a constant value depending on the liquid's nature, it is measured in m/N .

Fig.10. Soap films test

The superficial stress has an energetically interpretation. Thus, if the A-B side displace with s∆

downwards, the surface's increasing (considering both sides) is

slA ∆=∆ 2 (3)

The work done by F force is

AslsFW ∆=∆=∆=∆ αα2 (4)

This work is transformed in surface energy

sEW ∆=∆ (5)

From (4)

A

E

A

W s

∆

∆=

∆∆

=α (6)

So to change the soap film surface's with one is necessary a work equal withα .

3. The characteristic demands for polymers coated fabric's 3.1. Testing of non-coated fabrics

These tests were made in order to make a comparison between the coated and non-coated fabrics to see exactly what's the coating influence, [14], [15].

As shown in fig. 11, on the fill direction the material’s curves are very appropriate. This means that the coating has an insignificant contribution to the stress taking over. On the other hand this means that coating didn't modify the fill. On the warp direction the curves have different aspects. The US line shows at the beginning a stretch of the coated fabric and till %.11≅ε US is parallel to BS. This means that a stretched fill behave like a warp. The coating process modifies the fill comportment. [16], [17], [18], [19].


41

Fig.11. Testing curves

3.2. Strength characteristics The tensile breaking strength and the tensile breaking strain can be determinate by short time

essays, which are considered being instant. Usually, the strengths are not measured in 3cmdaN because of non-homogeneity of the material and the difficulty in finding a real cross section. The tensile strength is obtained from axial measurements and is measured in cmdaN 5 . The sample's width is mm50 , [18].

CONCLUSIONS

* The tensile strength for isotropic foils is cmkN.. 800100 − . For the PVC coated fabrics, the tear strength is different for the warp and fills direction. So, for the warp direction this strength is cmkN.. 301150 − . The tensile breaking elongation is %6010 − .

* The tear strength for PVC coated fabrics is kN.. 800100 − . * The initial elastic modulus for PVC coated fabrics is cmkN71− . * Other required characteristics for projecting the anisotropic PVC coated fabrics are: - the weight for mm1 thickness is 210 mkN ,

- the coefficient of thermal extension is 3102 ⋅=α oC , * After repeated essays on the PVC coated fabrics the conclusions are:

- On the fill direction the comportment is almost elastic, the charge-discharge curves are nearly identical. The lost energy after every cycle is small in respect with the useful energy. The remanent deformations are small. This behavior shows that the forces and strains are taken instantly by the material and the damping is very small.

- On the fill direction the behavior is of viscous-elastic type. The hysteresis curves are bigger and the remanent deformation increases more then on the warp direction. REFERENCES 1. ARGYRIS, J.H., SCHARPF, D.M. (1970), Berecfmung Vorgespannter Netzwerke. Bayrischen Akademie der

Wissenschaften, Munchen. 2. BÂRSAN, G.M., KOPENETZ, L.G., ALEXA, P. (1987), Forma structurilor uşoare cu membrană (The

Form of Lightweight Membrane Structures). (Construction Journal) Nr.4-5.


42

3. CĂTĂRIG, A., KOPENETZ, L., ALEXA, P. (1993), A New Conception for Reinforced Concrete Membrane Structures. Proceedings of the International Conference on "The Concrete Future", Kuala Lumpur (Malaysia).

4. CĂTĂRIG, A., KOPENETZ, L. (1994), Structuri uşoare cu rigle şi cabluri înclinate (Lightweight Structures with Inclined Beams and Cables). (Proceedings of VII Conference of Steel Structures, Vol. I, Timişoara).

5. CĂTĂRIG, A., KOPENETZ, L. (1994), Wooden Lightweight Structures. Calculation Models and Methods. Acta Technica Napocensis, nr.37, Cluj-Napoca.

6. PESCARU, V., (1984), ContribuŃii la studiul acoperişurilor din membrane metalice (Contributions for Analysis of Metallic Roof Structures). Teză de doctorat (Ph.D. Thesis), Institutul Politehnic, Iaşi.

7. CĂTĂRIG, A, KOPENETZ, L., ALEXA, P., DEUŞAN SIMONA, (1999), Mechanical essais for structural membranes.Acta Technica Napocensis, nr.42, Cluj-Napoca.

8. CĂTĂRIG, A, KOPENETZ, L., ALEXA, R (1995), Problems of Assesing the Wind Action on Cable Structures in Wind Tunnels. Acta Technica Napocensis, nr.38, Cluj-Napoca.

9. CĂTĂRIG, A, KOPENETZ, L., ALEXA, P. (1996), Rehabilitation of Structures via Membranes. Proceedings of the Eleventh World Conference on Earthquake Engineering, Acapulco (Mexico).

10. CĂTĂRIG, A., KOPENETZ, L., ALEXA, P. (1997), Light-Weight Composite Facades. Proceedings of the IAHS International Housing Congress.

11. CĂTĂRIG, A., KOPENETZ, L., ALEXA, P. (1997), Problems of Computation of Structures Mode up of Cables and Membranes. Acta Technica Napocensis, nr.40, Cluj-Napoca.

12. CĂTĂRIG, A., KOPENETZ, L. (1998), Structuri uşoare alcătuite din cabluri şi membrane (Lightweight Structures with Cables and Membranes). Editura U.T. Pres, Cluj-Napoca.

13. CĂTĂRIG, A. ş.a. (1998), Probleme privind datele primare necesare proiectării şi realizării structurilor cu membrane şi cabluri (Primary Date for Managment of Lightweight Membrane Structures). (Research Contract nr.34), tema 47/189, Beneficiar Ministerul EducaŃiei NaŃionale.

14. IRVINE, H.M. (1981), Cable Structures. The Massachusetts Institute of Technology Press, Cambridge, Massachusetts.

15. JENSEN, J.J. (1970), Eine Statische und Dynamische Untersuchung der Seil und Membrantragwerke. Report, Division of Structural Mechanics, NIT, Trondheim.

16. KOPENETZ, G.L., IONESCU, A. (1985), Lightweight Roof for Dwellings. International Journal for Housing and its Aplication, Vol.9, Nr.3, Miarni.

17. KOPENETZ, L., CĂTĂRIG, A. (1993), Flexible Structures for Hydrotechnical Buildings and Foundations. Proceedings of International Symposium, vol.4, Cluj-Napoca.

18. OTTO, F., TROSTEL, R. (1962), Zugbeanspruchte Konstruktionen. Vol.l, UHstein-Verlag, Frankfurt, Berlin. 19. OTTO, F., SCHLEYER, F.K. (1966), Zugbeanspruchte Konstruktionen. Vol.l, Ullstein-Verlag, Frankfurt,

Berlin.

MANCIA M. S. pp.43-46

43

LAND EVALUATION AND THE IMPACT OF HYDROTECHNICAL WORKS ON CRIŞUL REPEDE RIVER

MANCIA Mircea Sebastian,

University of Oradea, Faculty of Civil Engineering and Architecture, e-mail: [email protected]

A B S T R A C T Land is essential in life and our existence. Its importance was considered by lawyers, geographers, sociologists and economists. Evaluation of unoccupied land or land and buildings on it belongs to the field of economic issues. Unoccupied or built upon it, the land is called real property. Value is created by the use of property or the capacity to satisfy human needs and desires. The property is a legal concept. The property consists in private property rights. We should make a distinction between real property which is a physical entity and its possession which is a legal concept. Legal property includes all rights, interests and benefits related to possession of the property. Real property is usually represented by some possesion documents, only symbolic in nature. Therefore the real property is a nonphysical concept.

Keywords: evaluation, impact


INTRODUCTION

Evaluation of unoccupied land or pieces of land with buildings on it represents an economic issue. From the legal point of view it is not the physical characteristics of the land but about rights and obligations associated with various interests in these lands. Logically it means there are possible conflicts between private and public use of the land. The property is a legal concept consisting of private rights and obligations. Before 1989 real estate assessment issues were excluded, particularly those relating to evaluations of land, because the land was not considered an object that can be sold or bought, hence the uselessness of assessments and evaluators. The land represents a national wealth and therefore establishing its correct value is a categorical priority. In centralized economies price evaluation is identical to the price established by the state, there is no concept of free market. Real estate property is immobile and corporal and it includes the land and buildings on it. Real property includes all interests, benefits and rights of ownership of a property. The right over a real estate property is patrimonial right. Ownership includes the right to sell, to rent and others. The property size determines the interest in that particular property.

MATERIAL AND METHOD

Land uses (fig. 1) depend on geographical, legal, economic and social factors which are also the basis for that land evaluation. Starting with 1989 in Central and Eastern Europe began a rather difficult period of passing from centralized economy to market economy and from dictatorship to democracy [1]. For market economy, establishing a more accurate value of land is a necessity absolutely objective because the land is involved in many economic processes.


44

0%

0%

2%2%0%

0%

12%

37%

2%2%

0%0%

3%

17%

11%

0%

2%

9%

Accumulation of water

Streams

Orchards

Coniferous forests

Deciduous forests

Mixed forests

Natural forests

Secondary forests

Discontinuous urban space and urban space

Unirrigated arable land

Predominantly agricultural land mixed with vegetation

Industrial or commercial units

Subalpine vegetation

Vineyards

Leisure areas

Complex crop areas

Ore extraction areas

Transition areas with shrubs (generally cleared)

Fig. 1. Use of land in hydrographic basin Lacului Lugaşul de Jos [7]

One of the functions of the general cadastre is the economic one, outlining the economic value of real estate property necessary for determining taxes. Land value closest to the actual value is the value of land circulation, which is determined by market conditions. Land evaluation must be made in administrative regime, so as to ensure a unitary system for the whole country.

Value is an economic concept that refers to the relationship between goods and services available for purchase and those who buy them and sell them. Value is not a fact, only an estimate of how goods and services are estimated at a given moment, according to a particular definition of value [2]. Economic concept of value reflects the image on the market of the benefits belonging to the one who possesses goods or receives services at the respective date of evaluation.

RESULTS AND DISSCUSIONS

The concept of value on the market reflects the perceptions and collective actions on the market and is the basis for the assessment of most resources in market economies. Land is underlying the whole existence and, with rare exceptions, is a permanent fact beyond human existence. With the uniqueness and immobility of the land, each plot has a unique location. Due to its unique characteristics, when the land is assessed separately from the edifices on it, the economic principles require that those buildings are assessed as a contribution to the total value of the property. Therefore, the market value of the land, based on the concept of best use reflects land use and permanence to the buildings on it. And therefore many properties are assessed as a combination of land and edifices [3].

Hydrotechnical works from Crişul Repede basin (fig. 2), a certain area influences the development of the area, regulates the use of land, water output, preparation of territorial planning drafts. To attain these objectives there were set up two accumulation lakes (Lugaş and Tileagd) and for hydropower plants in Lugaşu de Jos, Tileagd (fig. 3), Săcădat and Fughiu. In this arrangement a whole complex occupies an area of 1500 ha, of which 600 hectares of arable land, 500 hectares of natural pastures and meadows and 400 hectares other surfaces.

They are component part of the National Strategy for Flood Management and include three types of objectives:

a) Economic objectives aimed at protecting against floods, the existing economic infrastructure and ensuring economic opportunities of future generations.

MANCIA M. S. pp.43-46

45

Fig. 2. Hydro energetic arrangements from Crişul Repede hydrographic reservoir [6]

Fig.3. Accumulation lakes Lugaşul de Jos and Tileagd [6]

These objectives include [4], [5]: • Preventing or minimizing economic losses by reducing flood risk of populated areas, of

economic objectives and goods, • Preventing or minimizing economic losses by reducing flood risk of existing

infrastructures, • Preventing or minimizing economic losses by reducing flood risk of cultivated

agricultural lands.

b) Social objectives aimed at protecting the population and the human communities against floods by ensuring to protect the population up to an acceptable level.

c) Environment objectives seek that through implementation of flood management strategy to achieve socio-economic goals while maintaining a balance between economic and social development and environmental objectives.


46

CONCLUSIONS Hydrotechnical works from hydrographical basin Crişul Repede have led to major changes in

the physical geographic background of the area under study. Negative effects: � 65 households and households annexes have been displaced, � 984 hectares of land in Lugaşul de Jos and 646 hectares in Tileagd were covered in

water, thus were taken out of agricultural circuit, � The price of agricultural land in the area has increased by reducing the available

surfaces (unincorporated area), � groundwater level in Tileagd has increased in wells, cellars, technical basements in

blocks of flats, producing unwanted effects, which meant additional expenses. Positive effects: � hydroelectric power plants produce electricity for the national energetic system, � farmlands, villages, roads are protected from flooding by maintaining constant levels

along Crişului Repede, � county and local access roads were made over the dams crests of wave ensuring

villages connection to E60 national road, � by soil erosion control and drainage works agricultural land areas were reclaimed, � hydrotechnical works allow water supply to localities and the development of

industrial-economic activities in the area, � pisciculture development in fish farms from RemeŃi, Măgeşti, Husasău de Criş, � practicing recreational fishing on reservoirs, � tourism and agro tourism development in Leş, Drăgan, Munteni, Bulz dams area.

The implementation of reservoirs in Lugaşul de Jos, Tileagd (fig. 2), Săcădat had the side effect of taking out over 1900 hectares of farmland. The villages affected are Lugaşu de Jos, łeŃchea, Tileagd, Ineu Săcădat and Oşorhei. Between 2004-2008, due to the economic growth the land demand lead to a price increase, since the offer was limited. After the economic crisis, staring with 2009, the market value of farmland was in a continuous regression. Depending on the location, neighbourhood, utilities and access roads, one hectare of agricultural land is sold today with prices ranging between 1000-1200 Euros / ha (fig. 3).

REFERENCES 1. DIACONU C., ŞERBAN P. (1994), Sinteze şi regionalizări hidrologice (Synthesis and hydrological

regionalization), Ed. Tehnică, Bucureşti. 2. GÂŞTESCU P. (2002), Resursele de apă ale bazinelor hidrografice din România (Water resources of river basins

from Romania), Ed. Terra, anul XXXIL, vol. (1-2), vol. 1-2, Bucureşti. 3. OPREA C.V. ş.a. (1970), InundaŃiile din 1970 şi efectele lor asupra agriculturii din vestul R.S.România (Floods of

1970 and their impact on agriculture from Western of R.S. Romania). Min. Agr. Bucureşti. 4. *** Standarde InternaŃionale de Evaluare 2011 (International Valuation Standards), Ed. IROVAL, Bucureşti. 5. *** Amenajarea hidroenergetică a râului Crişul Repede – studii ISPM – studiu de fezabilitate (Crisul Repede

River hydro power – ISPM studies – study of feasibility). 6. *** (2004), Planul de management al spaŃiului hidrografic Crişuri (Management plan Crisuri catchment area),

DirecŃia Apelor Crişuri Oradea (Crisuri Water Directorate Oradea). 7. *** Anuarul Statistic al României (Statistical Yearbook of Romania).

MOGA L., OUSSEYNOU D. pp.47-54

47

TEMPERATURE INFLUENCE ON THE THERMAL RESISTANCE OF A BUILDING WALL WHEN USING PHASE CHANGING MATERIALS

MOGA Ligia*, OUSSEYNOU Diao,

Technical University of Cluj-Napoca, e-mail: [email protected] (corresponding adress) Université Cheikh Anta DIOP de DAKAR-SÉNÉGAL

A B S T R A C T The Materials with phase shift (PCM- Phase Changing Material) have as a characteristic the ability to store energy in the form of latent heat. Heat is absorbed or restored when the material passes from a solid state to a liquid one and vice versa. The PCM operation is based on the application of a simple physical principle. Beyond certain temperature characteristic for each material, due to the absorbed heat from the surrounding air the liquefying process begins and when the temperature drops the process restores.

Keywords: Phase Changing Material, Matlab program, heat transfer, thermal resistance


INTRODUCTION The use of the PCMs in buildings is a relatively old concept which could never be really

exploited because of the inherent difficulties of implementing these materials [1]. Nowadays in several sectors of the building industry the PCMs are or will be incorporated in their products or materials [2], [3]. A continous research on the PCM functioning in building walls was made and the first part of the research is presented in this paper. The research was made considering Senegal climatic conditions, which means that the exterior temperature is higher than the interior one.

MATERIALS AND METHODS 1. Heat equation in thermal stationary regime

By applying the thermal balance equations in the discretization network from fig. 1, the temperature of the central node T(i,j) will be given by relation (1) where gq−Λ is the thermal

permeability between the bridges q and g.

)1,()1,(),1(),1(),(

10

40

10

30

10

20

10

10 +Λ

Λ+−

Λ

Λ++

Λ

Λ+−

Λ

Λ=

∑∑∑∑ −

−

−

−

−

−

−

− jiTjiTjiTjiTjiTk

k

k

k

k

k

k

k

(1)

where:

x

yy

∆

∆+

∆

=Λ −22 21

10

λλ (2)

x

yy

∆

∆+

∆

=Λ −22 34

20

λλ (3)


48

y

xx

∆

∆+

∆

=Λ −22 23

30

λλ (4)

y

xx

∆

∆+

∆

=Λ −22 41

40

λλ (5)

Fig.1. Discretization of a normal node

2. The influence of the thermal conductivity variation on the thermal behaviour of the wall We considered a wall made up of three materials having different thermal conductivities λ1,

λ2 and λ3.For the given case as considered the assumption that the material in the thermal medium i.e. of conductivity λ2 is not yet a phase changing material but a traditional one. This stage is the initial behavior of the considered system before the phase shift of the material takes place.

Fig.2. Diagram of the wall

From a 1D model and equations 1, 2, 3, 4 and 5 and the boundary conditions (the exterior and interior temperatures), the following simulations were made by using the next parameters:


49

Table 1. Simulation parameters Thickness of material 1 L1 0.3 m Thickness of material 2 L2 0.1 m Total thickness of the wall L 0.7 m Pas following space (x) dx 0.01 m Exterior temperature Text 30°C Interior temperature Tint 20°C Average thermal conductivity 1 λ1 1 W/(m.K) Average thermal conductivity 2 λ2 0.3 W/(m.K) Average thermal conductivity 3 λ3 1 W/(m.K) Internal convection coefficient hi 5 W/(m2.K2) External convection coefficient he 8 W/(m2.K2)

In addition to the preceding relations, the general relation of the thermal conductivity

variation was used: ).02.01()( mmm TT += λλ (6)

where: Tm is the average temperature of each material λm is the average thermal conductivity

With the Matlab software an iterative program was developed, in order to determine the

temperature change in the wall according to the thermal conductivity )( mTλ [4]. An initial case

was considered first, when the heat flow on the exterior surface of the wall has constant value and the thermal conductivities of the three materials have also constant values. Then, five cases were considered for a variable heat flow on the exterior surface of the wall and different thermal conducivities for the three materials.

Table 2. Studied cases

initial thermal conductivity 1 1 W/(m K) initial thermal conductivity 2 1 W/(m K) First case data initial thermal conductivity 3 1 W/(m K) initial thermal conductivity 1 5 W/(m K) initial thermal conductivity 2 3 W/(m K) Second case data initial thermal conductivity 3 1 W/(m K) initial thermal conductivity 1 1 W/(m K) initial thermal conductivity 2 3 W/(m K) Third case data initial thermal conductivity 3 5 W/(m K) initial thermal conductivity 1 3 W/(m K) initial thermal conductivity 2 5 W/(m K) Fourth case data initial thermal conductivity 3 1 W/(m K) initial thermal conductivity 1 1 W/(m K) initial thermal conductivity 2 5 W/(m K) Fifthcase data initial thermal conductivity 3 3 W/(m K)

RESULTS AND DISCUSSIONS

The fig. illustrates the results obtained for the initial situation, respectively the temperature change in the wall according to the thermal conductivity of various materials when considering a constant heat flow on the exterior surface of the wall. The blue curve gives the temperature variation that corresponds to the thermal conductivities in the initial state (λ1=1W/(m.K), λ2=0.3W/(m.K), λ3=1W/(m.K)). The green diagram and the red one correspond to the first and the second iteration.


50

0 10 20 30 40 50 60 70 8021

22

23

24

25

26

27

28

29les lamdas sont egales

noeud suivant l'epaisseur

Fig.3. Temperature change in the wall for constant values of the thermal conductivities

Fig.4. Temperature change according to thermal conductivity

The next fig.s are illustrating the temperatures variation in the wall and the evolution of the thermal conductivities values when considering a variable heat flow on the exterior surface of the wall.

First case:

Fig.5. Temperature change for each iteration when considering table 2 data

0 10 20 30 40 50 60 70 8021

22

23

24

25

26

27

28

29

30

noeuds suivant l'epaisseur

Evolution de la temperature dans la paroi


51

Fig.6. Thermal conductivity evolution for each iteration when considering table 2 data

Second case:

0 10 20 30 40 50 60 70 8022

23

24

25

26

27

28

29lamda1>lamda2>lamda3

noeuds suivant l'epaisseur Fig.7. Temperature change for each iteration

when considering table 2 data



52

Third case:

0 10 20 30 40 50 60 70 8022

23

24

25

26

27

28

29


lamda1<lamda2<lamda3

Fig.9. Temperature change for each iteration



Fourth case:

0 10 20 30 40 50 60 70 8022

23

24

25

26

27

28

29

noeud suivant l'epaisseur

lamda2>lamda1>lamda3

Fig.11. Temperature change for each iteration



53


Fifth case:

0 10 20 30 40 50 60 70 8022

23

24

25

26

27

28

29


lamda2>lamda3>lamda1

Fig.13. Temperature change for each iteration when considering table 2 data


It can be noticed that for a variable flow on the exterior surface of the wall, the intersection

point of the interior temperatures moves according to the phase change case and it always compensates between external flow and that interior one. Also, with the increase of the wall


54

temperature the thermal conductivity of the wall will increase and the thermal resistance of the wall will decrease (see the top left of the fig. 15).

Fig.15. The thermal resistance of the wall according to the change of the temperature

CONCLUSIONS The simulation pointed out that even for a homogeneous wall, the thermal conductivity varies

with the variation of the temperature in the interior of the wall. Therefore, with the increase of the temperature a thermally conductive material becomes increasingly conducting. The research emphasizes the need of considering in thermal resistance calculation of a structure build with phase changing material, the variation of the thermal conductivity which if not considered can have a negative effect on the assessment of the energy performance of the building. ACKNOWLEDGMENTS

The paper was made possible due the participation of Diao Ousseynou at the post-doctoral research scholarship „Eugen Ionescu” .

REFERENCES 1. NOEL, J. (2007), Amélioration du confort d’été sur des bâtiments à ossature légère par des matériaux à

changement de phase (Improvement of summer comfort in buildings with light-frame phase change materials), Journée thématique SFT-IBPSA, 25 avril 2007, Aix les Bains, http://www.jnlog.com/pdf/ ibpsa2007.pdf .

2. SCHNEIDER,M., SYLVAIN, J.D, BERGER, X., JAFFRIN, A., Materiau accumulateur de calories a temperatures constantes et application de ce materiau. (Material for absorbing and storing calories in the form of latent heat, and its application), Brevet français no. 79-13296, Brevet européen no. 80430010-1.

3. BOURDEAU, L. (1982), Utilisation d’un materiau a changement de phase dans un mur trombe sans thermocirculation (Use oa a phase changing material in a trombe wall without thermal circulation), Rev. Phys. Appl. (Paris) 17, pp. 633-642, http://dx.doi.org/10.1051/rphysap:01982001709063300.

4. *** Matlab - technical computing software for engineers and scientists in industry, government, and education.


55

DETERMINATION OF THE EQUIVALENT THERMAL CONDUCTIVITY OF A PHASE CHANGE MATERIAL (PCM)

MOGA Ligia*, OUSSEYNOU Diao,

Technical University of Cluj-Napoca, e-mail: [email protected] (corresponding adress) Université Cheikh Anta DIOP de DAKAR-SÉNÉGAL

A B S T R A C T Nowadays a true need emerges in solving the problem of thermal mass in light structures. The announced climatic reheating (e.g.: the 2003 heat wave), as well as the obligation to reduce energy consumptions on a worldwide level, requires the research and development of effective solutions which will allow a more comfortable leaving space, while consuming less energy and while contributing at the reduction of greenhouse gas emissions. Due to this reason an ongoing research on phase change materials PCMs (Materiau a changement de phase - MCP) is carried on, although that the use of PCMs in the building structure is a relatively old concept which was never really exploited because of the inherent difficulties of implementation of these materials. A research was made by considering a phase change material placed in the structure of a wall and senegalesian climate conditions. Thermal simulations were made using the finite differences method and the Matlab software, for a better understanding of the PCMs behavior.

Keywords: Latent heat, phase change process, heat storage, heat transfer, Matlab progra


INTRODUCTION The social habitat in tropical environments knows a major problem of thermal comfort,

because the traditionall buildings (houses) that are built do not give desired thermal comfort.Within the research framework of improving thermal comfort, studies were made at the Laboratory of Applied Energetics (Laboratoire d’Énergetique Apliquee - LEA) for a proper characterization of the thermophysical properties of the local materials which can be used for building structures.The desired building is the one that is thermically, mechanically and acoustically “powerful”. Currently, researches are made for the optimization of energy systems, and one of the means of saving energy is energy storage. The thermal storage techniques known are: sensible heat storage and latent heat storage. The latent heat storage is defined by a heat absorption or release process when a storage material undergoes a phase change from liquid to gas or solid to liquid or vice-versa. The latent heat storage method provides much higher storage density, with a smaller temperature difference between storing and releasing heat. In the field of latent heat storage systems, the PCMs were given a special attention in the past years. The imperative reason of using these systems is due to their great energy capacity available at certain PCMs during fusion (melting) or solidification compared to the sensible heat storage systems.In order to improve thermal comfort by increasing the wall inertia, we conducted a research on a wall having a layer made of a phase change material, layer that made it possible to store energy.

MATERIALS AND METHODS 1. Definition of Phase Change Material

The materials with phase shift or PCMs have as a main characteristic the ability to store energy in the form of latent heat. Heat is absorbed or restored when the material passes from a solid state to a liquid one and vice versa. The PCM operation is based on the application of a simple physical principle. Beyond certain temperature characteristic for each material, due to the absorbed heat from the surrounding air, its temperature will rise and the liquefying process will begin and


56

when the temperature drops the process restores. At most of the PCMs the low thermal conductivity helps in prolonging the charging and discharging processes. For the storage of energy, other phase shifts are theoretically possible (solid-solid, solid-gas, liquid-gas and vice versa), but in practice it is the solid-liquid transition which offers the most application. The majority of the liquid-gas and solid-gas transitions imply significant volumes or high pressures to store material in its gas state. Moreover, these transitions require temperatures (and therefore energy) more significant than in the case of the solid-liquid transitions. As for the transitions solid-solid, the process is generally very slow and have weak energy of transformation.

The choice of a PCM whose latent heat is high and to which the phase shift temperature is close to the ambient temperature allows the time to reduce considerably the thermal losses for the period of storage. Energy is then stored in the form of latent heat thanks to the fusion of the PCM, then restored in the ambient conditions due to solidification. The study of the PCM use in the solar habitats now left its prospective phase. Indeed the recent availability of various materials [1, 2] made it possible to carry out laboratory experiments or even experiments in real climatic conditions.ntegration of these materials in composite walls, made it possible to obtain significant inertia in a reduced volume and under a weak interval of temperature, which resulted in the development of new solutions in the field of passive solar heating. The simplest of them is that of a wall type Waterspout-Michel [3] in which a phase change material replaces usual materials of storage (concrete-water) in order to create an isothermal wall. However, the systems of storage of energy by latent heat are not very widespread because their design is slowed down by the complexity of the thermal phenomena of transfer which takes place in its core. When choosing PCMs, there exists various criteria that must be considered. Various types of PCMs were studied along the years like hydrates, salts and their mixtures, fatty acids, paraffins and non-paraffins. The PCM choice is guided by the range temperature for which there is the need of using it. Materials that melt between 15oC and 90oC are the ones that have been studied the most because those can be applied in solar heating and heat load leveling applications [4].

The paper presents the research conducted on a PCM made of N-octadécane paraffin of 99 %, which is an organic phase change material. The organic PCM have the ability to melt and freeze repeteadly without phase segregation and degradation of their latent heat of fusion. The non-paraffin organics are the most used PCMs because of their higly varied properties [5]. The melting point for the N-octadécane paraffin gived by the manufacturer is at 28oC. Similar to a phase change material, the paraffin has a very high latent heat and can be found everywhere. Several studies already established the thermophysical properties of the paraffin [6].

2. Numerical simulation of the isothermal walls

Digital simulations of the solar systems through software means, had experienced a very significant development andhe number of programs available is enormous [7]. The reason is obvious because experiments on solar systems take a long period of time and are expensive. Therefore, specialists seek to build mathematical models of equations that describe the best possible physical phenomena that takes place in the system.Analytical solutions exist only for very simple systems and unrealistic boundary conditions. Therefor a software approach is needed. The digital model obtained is then a very useful tool of research for the system study and in particular for its optimization. The behavior of the model is then compared with the behavior of the real system in the greatest number of possible conditions. In the presented research the finite difference method was used. This method, of very simple design, practically does not have any limitations and makes it possible to treat complex configurations with reasonably operating times. It was largely used under its two formulations by Los Alamos Scientific Laboratory (implicit formulation) in Pasole [8]


57

and by the University of California with San Diego (formulation clarifies) [9]. Here, the explicit method was extrapolated in order to be able to treat the case of PCMs.

3. Finite differences method applied to PCM

The heat equation for an inert homogeneous material for an unidimensional case:

2

2

x

T

t

TC p ∂

∂⋅=

∂∂

⋅ λρ (1)

where: T is the temperature, t the time and α=λ/(ρCp) is the thermal diffusivity In the presence of phase shift bringing into play a latent heat of fusion LF, the speed of

propagation V of the phase shift zone is given by:

2

2

x

T

t

VLF ∂

∂⋅=

∂∂

⋅ λρ (2)

These equations can be numerically resolved by discretizing variables x and t, variables T or V are then constant in each ∆x segment during an interval of ∆t time.The equations (1) and (2) discretized will give:

( )11 2 −+ +−⋅∆

=∆

∆∆⋅⋅ nnn

np TTT

xt

TxC

λρ (1’)

( )11 2 −+ +−⋅∆

=∆

∆∆⋅⋅ nnn

nF TTT

xt

YxL

λρ (2’)

Yn is a variable without dimension ranging between 0- solid state and 1-liquid state.Yn, rate of fusion of the segment, is the ratio between the melted mass of the material and the total mass of the material in the considered segmentIt must be noticed that the introduction of new equations that are making it possible to treat the case of phase shifts materials, does not modify the usual conditions necessary to ensure the stability of the explicit formulation.

4. Thermal simulation of N-octadécane paraffin behavior

A simulation of the PCM (N-octadécane paraffin) behavior was done, considering first an initial constant exterior heat flow and then a variable exterior heat flow. The PCM behaves in an ideal way, i.e. the phenomena of superfusion, segregation, separation of phases are ignored and that the phase shift is carried out at constant temperature. In this phase the thermal convention in the liquid part was not taken into account and also the fact that the thermophysical properties are the same in the two phases. The PCM was discretized in three nodes and two constant temperatures were considered on the interior and exterior surface of the wall.

Fig.1. Unidirectional discretization of the PCM wall


58

0 20 40 60 80 100 12020

22

24

26

28

30

32

34

36

38

40

Tem

pera

ture

s

Temps

0 20 40 60 80 100 12025

30

35

40

45

Tem

pera

ture

exte

rieure

Temps

Table 1. Thermophysical properties of PCM [1] Phase change temperature 28°C Thermal conductivity of solid (W/m K) 0.376 Specific heat (J/kgK) 1900 Latent heat (J/kg) 242000 Thermal conductivity of liquid (W/m K) 0.120 Density (kg/m3) 814


The evolution in time of the equivalent thermal conductivity was studied, by differentiating thermal conductivity from the solid and the liquid state. The other parameters of the liquid are equal to those of the solid. The following results are given in the nodes of the discretized element, presented in fig. 1. For a ∆T=35 the following results were obtained

Fig.2. Exterior temperature

Fig.3. Variation in time of nodes temperatures


59

0 20 40 60 80 100 120

0.2

0.25

0.3

0.35

0.4

Temps

Conductivite e

quiv

ale

nte

0 20 40 60 80 100 1200

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Temps

Fra

ction liq

uid

e

Fig.4. Liquid fraction of the nodes

Fig.5 Variation in time of the nodes thermal conductivity

For a ∆T = 45 the following results were obtained:

0 20 40 60 80 100 12035

40

45

50

55

Temps

Te

mp

era

ture

ex

reri

eu

re

Fig.6. Exterior Temperature


60

0 20 40 60 80 100 12020

25

30

35

40

45

50

Temps

Tem

pe

ratu

res

0 20 40 60 80 100 1200

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Temps

Fra

cti

on

liq

uid

e

Fig.7. Variation in time of nodes temperatures

Fig.8. Liquid fraction of the nodes in time


61

0 20 40 60 80 100 120

0.2

0.25

0.3

0.35

0.4

Co

nd

uc

tiv

ite

th

erm

iqu

e e

qu

iva

len

te

Temps

Fig.9. Variation in time of the nodes thermal conductivity We notice that the equivalent thermal conductivity of each melted point decreases with time

until it reaches the one of the liquid state. It is worth mentioning that along with the increase of the average exterior temperature the equivalent thermal conductivity decreases due to the fact that the volume of liquid state will become higher than the solid one.

CONCLUSIONS

The software simulation was made in order to investigate the effects of themperature fluctuation on the thermal conductivity in the nodes of the PCM wall.

In selecting a PCM a special attention should be given to their phase change temperature that should be close to the average room temperature and also approapiate values should be required for latent heat and thermal conductivity of the PCM. Therefore the PCMs capacity in stabilizing the internal environment when there are exterior temperature changes and solar radiations, should be a an ongoing research through new tehniques of applying PCMs at buildings.

ACKNOWLEDGMENTS

The paper was made possible due the participation of Diao Ousseynou at the post-doctoral research scholarship „Eugen Ionescu”.

REFERENCES 1. SCHNEIDER,M., SYLVAIN, J.D, BERGER, X., JAFFRIN, A., Materiau accumulateur de calories a

temperatures constantes et application de ce materiau. (Material for absorbing and storing calories in the form of latent heat, and its application), Brevet français no. 79-13296, Brevet européen no. 80430010-1.

2. TELKES, M., Sel de Glauber stabilisé (Stabilised Glauber salt). University of Delaware, US patent 3986969 de 1976.

3. TROMBE, F. (1974), Maisons solaires (Solar Houses), Technique de l’ingénieur. 4. FARID, M.M., KHUDHAIR, A.M., RAZACK, S.A.K., AL-HALLAJ, S. (2004), A review on phase

change energy storage: materials and applications,Energy Conversion and management 45, pp 1597-1615, http://dx.doi.org/10.1016/j.enconman.2003.09.015.

5. SHARMA, A., TYAGI, V.V., CHEN, C.R., BUDDHI, D. (2009), Review of thermal energy storage with phae change materials and applications,Renewable and Sustainable Energy Reviews 13, pp 318-345, http://dx.doi.org/10.1016/j.rser.2007.10.005.

6. UZABAKILIHO, P. (1995), Etude expérimentale de la fusion et de la solidification de la paraffine N-


62

octadecane (Experimental study of the N-octadecane paraffin melting and solidification), universite de Sherbrooke, Faculte de Sciences Applique, Departmenet de genie mecanique, Sherbrooke, Quebec.

7. SERI (1980), Analysis methods for solar heating and cooling application: passive and active systems, January, SERI/SP 35-232 R., Solar Energy Research Institute.

8. Mc FARLAND, R.D, PASOLE (1978): A general simulation programme for passive solar energy, October 01, Informal Report LA -7433-MS, Los Alamos Scientific Laboratory, NM, USA.

9. *** Doe Final Report: Impact of controls in passive solar heating and cooling of building DE AC 04AL010 891.

10. BOURDEAU, L. (1982), Utilisation d’un materiau a changement de phase dans un mur trombe sans thermocirculation (Use of a phase changing material in a trombe wall without thermal circulation), Rev. Phys. Appl. (Paris) 17, pp. 633-642, http://dx.doi.org/10.1051/rphysap:01982001709063300.

11. PUSKAS, A., KISS, Z. (2011), Testing of a wide reinforced concrete beam, The 7th central European Congress on Concrete Engineering, Balatonfured, Hungary, 22-23 September, pp. 315-318.

12. *** Matlab - technical computing software for engineers and scientists in industry, government, and education.

MOLDOVAN A.R. pp.63-70

63

CORE EXTRUSIONS AND CONVERGENCE DURING DEEP TUNNEL CONSTRUCTION

MOLDOVAN Alexandra Raluca,

Technical University of Cluj, e-mail: [email protected]

A B S T R A C T The aim of this paper is to present a back-analyze based on the in-situ and finite element result. As a real case the Gotthard tunnel is going to be analyzed. The tunnel was monitored during construction, and based on the results obtained during construction; computational calculation will be developed in order to assess the differences between the two measurements in terms of axial and radial displacements.

Keywords: back analysis, finite element methods, deformations, in-situ monitoring

Received: October 28, 2012 Accepted: January 13, 2013 Revised: March 31, 2013 Available online: May 31, 2013

INTRODUCTION This paper presents a back-analyze based on the in-situ and finite element results. Axial and

radial deformation induced due to tunneling construction will be analyzed. As a real case the Gotthard tunnel is going to be discussed. In-situ monitored data will be compared to the prediction of the convergences and core extrusion interpreted with the help of Abaqus software. Before the tunnel construction, the ground is in total equilibrium. When the excavation is taking place, the support of the core is not working anymore. Due to the lap of no support effect, a stress redistribution is occurring, which implies a deformation around the tunnel. In addition, the lining which is to be installed will be subject to pressure. It is well known and understood the interaction of core and convergence phenomenon, but the prediction of tunneling in squeezing conditions still remains one of the difficult tasks to be taken into account. The aim of this paper is to make a so called “back-analyses” which will ease the understand of this uncertain situation. Since the Gotthard tunnel posses one of the most appreciable packages of in-situ data monitoring, for both convergence and core extrusion, this will give the chance to understand the deformations that occur in construction site during the tunnel construction. The reason of a back-analyze is to outline an idea of how tunnel will behave before the tunnel is constructed, if the back analyses will be cogent. In this way, having more back-analyses can be created a principle of design for future tunneling construction. The FEM analyze will be based on a plastic behavior of the soil, and will simulate the tunnel construction steps as the stages which were developed in the construction site. MATERIALS AND METHODS

Gotthard tunnel is one of the world’s longest railway tunnel which links Switzerland to Italy (fig. 1), having a total length of 57 km. In addition, the tunnel encounters the most difficult geology and has a maximum rock overburden of 2300 m. This enormous project will shorten the journey time and will allow the increase of transport transfer [2]. The tunnel itself is composed by two galleries (west and east), which are constructed parallel, having a diameter equal to 10 m.


64

Fig.1. Route of Gotthard axis [2]

In order to „break” the rock eight TBM (tunneling boring machines) (fig. 2) were used, each

of them weighting around 3000 tones. Where difficult zones of rocks were encountered (fissures) the rock was excavated using conventional tunneling methods (fig. 3) [3].

Fig.2. TBM (Tunnel boring machine) [2]

Fig.3. Conventional drill and blast [2]

1. Theoretical aspects

The RH- Extensometer (fig. 4) is a recent development for the axial displacement, which comes to overcome the lack of sliding micrometers. In comparison to the normal extensometer measurements the RH-Extensometers is installed at the end of a borehole far ahead of the face, not influencing the deformations. “The so called zero reading-effect can be avoided by installing the extensometer at a sufficient distance from the face in undisturbed ground, or by installing a series of overlapping extensometers (the new extensometer must be installed before the influence zone of the advancing tunnel face reaches the reference point of the preceding extensometer)” [1].

Fig.4. RH Extensometer [1]


65

The convergence was monitored optically with seven points per cross section (fig. 5). The measurement was done from 2 to 2 meters.

Fig.5. Radial displacement- with measuring points

2. Data analysis – finite element method The studied zone (fig. 6, 7) is near to the TZM formation and the Clavaniev formation. Both sides are characterized by narrow layers of squeezed rock, having vertical layers which make the construction of a tunnel more difficult [3].

Fig.6. Longitudinal section geology – Gotthard Tunnel [2]

Fig.7. Area of interest [2]

For the finite element analysis an elastic-plastic behavior was considered for the soil. Mohr

Coulomb criterion was developed, having the input parameters presented in the following table (table 1).

Table 1. Analysed materials

Friction angle Dilation Angle Cohesion Poisson’s Coeficient Young’s Modulus Rock Type

[0] [0] [MPa] [-] [GPa] Am-1a 29,8 7 1,1 0,25 11 TZMN-2 26 5 0,5 0,3 4

TZMN-3 26 5 0,3 0,3 2


66

The model created in Abaqus is just a half part (fig. 8) from the tunnel itself, considering the other part to have an identical behaviour as the analysed one. The model is composed by 69706 nodes and 75624 elements. For the entire model continuum elements were used C3D8 types, having 8 nodes each element. The aim of the model was to determine the deformation surrounding the tunnel which occurs during tunnel construction. For this reason only the steel arches are modelled, since the lining is installed after the deformation stabilises. For the steel arches linear elements were used B31 type.

Fig.8. FEM Model

The analysed model in composed by 60 excavation steps, where in the first 10 steps the

tunnels is excavated and the steel arches are installed in the same step, in order to allow to model to converge. For the area of interest finer mesh is used, which allow a better evaluation of the displacements.

The vertical stress is considered to be depth dependent, and the tunnel is considered to be at depth of 900 meters. The model is composed by 4 variables, each variable having a different cohesion and Young’s Modulus. The cohesion is changed to different radius to permit the simulation of anchors. The variables are presented below for the whole model (table 2).

Table 2. FEM - Material variables

c1 c2 c3 c4 Phi Psi UCS 1 UCS 2 UCS 3 UCS 4 Material

[MPa] [MPa] [MPa] [MPa] [0] [0] [MPa] [MPa] [MPa] [MPa]

1 0.5 0.53 0.56 0.63 26 5 1.6 1.7 1.79 2.02

1* 0.5 0.58 0.56 0.63 26 5 1.6 1.86 1.79 2.02

2 0.3 0.38 0.365 0.43 26 5 0.96 1.22 1.17 1.38

2* 1.1 1.18 1.16 1.23 29.8 7 3.8 4.07 4 4.24

3 1.1 1.1 1.1 1.1 29.8 7 3.8 3.8 3.8 3.8

3. FEM results

In the following plots (fig. 9, 10, 11) the axial and radial displacements are presented. In order to present the deformations ahead the tunnel face, influences lines were plotted with the help of MathCAD software. The deformations are presented for the whole model, and in more detail for the area of interest.


67

Fig.9. Influence lines- whole model

Fig.10. Influence lines- area of interest

For the whole model radial deformation equal 40 cm can be observed. Since the interest of this analysis is only the area where the material 2 is placed we can notice that the maximum radial displacement in this zone is around 25 cm.


68

Fig.11. Axial deformation

The axial deformation shows the deformation of the ground ahead the tunnel face. Since Mohr-Coulomb criterion does not allow a time dependent computation, the excavation steps are considered to be linear, as can be noticed in the plot above. The maximum axial deformation is around 23.5 cm. 4. In situ results

The in-situ monitoring data available for the Gotthard tunnel are at this time the most detailed monitors. The perimeter of the tunnel was monitored to each 2 meters having from 5 to 7 points of measurements per cross section. In addition, the deformation of the of the tunnel face are available. This was achieved with the help of RH Extensometers, allowing the determination of the deformation at the tunnel face, and ahead the face of the tunnel. A number of 6 extensometers with a length of 24 m were used, with an overlap of 4 to 8 m.

The following plot (fig. 12) present the measurements of radial deformation, where only the plot for one point encountered at the top head is presented. The area of interest is placed between 2090-2010 m.

Fig.12. Radial deformation The following picture (fig. 13) present the axial deformation measured with the RH-

Extensometers. This plot presents the axial deformations only for the area of interest.


69

Fig.13. Axial deformations DISCUSSIONS AND CONCLUSIONS

The FEM analyze shows a good correlation with the in-situ results. Both the radial and axial deformation are approximately similar with the ones obtained during tunnel construction. The maximum radial deformation obtained from the FEM analyze in the area of interest is around 25 cm. The in-situ monitoring data show a radial deformation equal to 25 cm.

In the case of axial deformation it can be seen that in-situ result are slightly higher than the ones obtained with the FEM. The plots resulted from the calculation show an axial displacement equal to 21 cm, whereas the monitoring data show an axial displacement equal to approximately 23 cm. This was expected, since as stated before, the Mohr Coulomb criterion is not a time dependent criterion, meaning that does not take into account the creep deformation.

The formulation of deformation is the following [4]. The Mohr Coulomb takes into account only the first two terms from the equation. In the in-situ data the last term of the equation is also included.

As a following research different failure criterion should be realised and time dependent ones. The results are satisfactory, but in order to asses an design principle more back-analysis should be developed for different ground conditions. ACKNOWLEDGMENTS

This paper was supported by the project "Improvement of the doctoral studies quality in engineering science for development of the knowledge based society-QDOC” contract no. POSDRU/107/1.5/S/78534, project co-funded by the European Social Fund through the Sectorial Operational Program Human Resources 2007-2013.

The study of the Gotthard Project was possible thanks to professor Robers Galler from Mountain University, Leoben Austria. REFERENCES 1. LINARD, C. (2011), Spatial effects in tunnelling through squeezing ground, Dissertation submitted to

EZH ZURICH. 2. *** (2012), AlpTransit Gotthard. New traffic route through the heart of Switzerland. 3. *** (2003), Alp Transit Gotthard AG documentation.


70

4. *** Abaqus 6.10 Documentation: Abaqus/CAE User's Manual, Abaqus Benchmarks Manual, Abaqus Verification Manual.

NISTOR S., IONAŞCU A. pp.71-74

71

BASIC CONCEPT OF THE ROBUST PROCEDURE APPLIED ON GEODETIC DATA

NISTOR Sorin*, IONAŞCU Anamaria,

University of Oradea, *e-mail: [email protected] (corresponding adress) Technical University of Civil Engineering Bucharest, e-mail: [email protected]

A B S T R A C T When we are thinking about geodesy and geodetic computation we think about observation, estimation and Least Square Method. This method it is considered to be the best method of parameter estimation after the demonstration made by Gauss concerning the normal distribution of the errors. The main idea is that the sum of squares of errors has to be minimum. This assumption is not always correct so the least square method is not all the time optimal for parameter estimation. The presence of outlier it is a fact not a presumption so we will need the presence of the statistics. In this article we will present different robust estimators for finding and neutralizing outliers even when the distribution is not normal.

Keywords: least square method, parameter estimation, normal distribution, outliers, robust estimators


INTRODUCTION

Different number of assumptions is used in all statistical methods. This assumption generally aimed at the “flexibility“ of the model from computation and theoretically point of view. We can understand that the model is a simplification of reality and is validity it best case the model is a “very good” approximation. The most utilized model is the one where we accept the presumption that the data are normal distributed. They are a few methods that justify the normal hypothesis but this can be demonstrated to be wrong. The main justification of the normal distribution is that it is offering a good approximation of many sets of data and in the same time is convenient from theoretically point of view. This is the classical statistics and nowadays it is easy to write a computational sequence containing the least square method.

MATERIALS AND METHODS 1. Outlier detection

Although many data sets have errors that obey the normal distribution can appear a small part of date that is atypical called outliers. Even one outlier can have great influence that is able to distort the entire model. In the presence of this outlier the distribution appears to be normal in the central region but they have tails that are heavier or “fatter“ then those how are normal distributed [5] (Fig. 1).


72

Fig.1. Normal distribution in the presence of outlier

If we use the normal distribution supposition and the distribution has long tails or are “ fat “

then the least square estimator give us wrong results. Even if we use different statistical test their level can be questionable also the confidence level can be uncertain.

The objective of the robust approach for statistical modeling and data analysis is to find methods that obtained reliable estimation of the parameters, associates tests and level of confidence not only when the data are under the normality assumption even when we make approximate assumption [3].

If the data doesn’t contained outliers then the robust estimator is responding like the least square method obtaining the same results, but if there is an outlier even if they are in a small proportion the robust method obtained the same result as the least square method without any outlier.

As a consequence of the good adjustment of the data the robust method assure us a viable method of detection and neutralization of the outliers.

A known method of detecting the outliers is the approach called diagnostic approach. The diagnostic approach is based on classical estimation that as an objective graphical or numerical clue for detecting the data whose behavior is to move away from the designed model.

This method has two deficiencies. One of this deficiency is that the classical methods are not viable enough for detecting the presence of the outliers, and the second is that an “ suspect “ observation is marked and the necessary action is left in the hands of the analysis from where the problem of subjectivity of the method for resolving the estimation problem.

2. Robust estimation

To be able to handle the presence of the outlier in the bulk of the data we can use the so called robust estimators. Caspary stated some qualities and characteristics that a robust estimators should have [1, 2]:

a) A robust estimator should have high breakdown point. This mean that the estimator is capable to handle outliers

b) A robust estimator should have a continuous and bounded influence function. This mean that the outliers should not influence the estimator in comparison to the rest of the data

c) The estimator should have a high asymptotic efficiency. With other words the estimator dispersion should be very small

NISTOR S., IONAŞCU A. pp.71-74

73

d) The estimator should have the property to distinguish very clearly the observations – week observation should received high corrections and the good observations should received small corrections The main question is witch and when the mentioned characteristics above is more important

than the other, because the results of the estimators are directly related with the level of contamination, the number of parameter that need to be estimated.

For example, for compensation of a geodetic network where the number of the observation and the number of the parameter can vary from a few dozens to hundreds, the robust estimators are adequate because if the data are contaminated than the characteristic of the high break down point is very important [4]. We have to retain the fact that the characteristics mentioned above are interconnected.

Depending on the model of central tendency indicators are of 2 types: � control average indicators:

• arithmetic mean, • geometrical mean, • harmonic mean,

� position average indicators: • mod, • median,

The fundamental of the central tendency indicators are: � arithmetic mean, � median, � mod.

Conclusively we can state the following:

� arithmetic mean can be used when the data is approximating the normal distribution; � median can be used when the data is profound asymmetric or there is extreme atypical

values; � mod can be used when we are interested which is the most important category from

numerical point of view or when the series is rated; � when the distribution is absolute symmetrical then the three indicators of the central

tendency – arithmetic mean, median, mod – are equals; � median is part of the quantiles category – does points that divide the frequencies in equal

parts; � because of mentioned properties the median is a robust parameter.

CONCLUSIONS

The most commonly and formalized model used in geodetic data computation is the model where we accept the assumption that the data are normal distributed. This supposition is present in statistics for over two century and is cradle of the classical methods: regressions, variance analysis and multivariate analysis. The robust approach for statistical and data analysis aim’s at founding method’s that are able to obtain viable estimation of the parameters, associate test, level of confidence not only when the data is obliging exact or normal distribution even when we are using approximate distributions. We can state that robust analysis is very powerful tools for reducing the influence of outliers. That way we can reach to the conclusions fast and reliable.


74

REFERENCES 1. OLIVE DAVID J. (2008), Applied Robust Statistics. 2. KANANI ENTELA (2000), Robust Estimators for Geodetic Transformation and GIS. 3. HAMPEL FRANK (2001), Robust statistics: A brief introduction and overview. 4. KOCH KARL-RUDOLF (2010), Parameter Estimation and Hypothesis Testing in Linear Models. 5. MARONNA RICARDO, MARTIN DOUG and YAHAI VICTOR (2006), Robust Statistics Theory And

Methods.

POP M., CĂTĂRIG A., TOADERE M.T. pp.75-82

75

SOME SOLUTIONS FOR THE REHABILITATION OF TWO METHANE TANKS

POP Mariana*, CĂTĂRIG Alexandru, TOADERE Mihaela Teodora,

University of Oradea, Faculty of Civil Engineering and Architecture, *e-mails: [email protected] (corresponding adress), [email protected]

Technical University of Cluj-Napoca, e-mail: [email protected]

A B S T R A C T The paper deals with the rehabilitation of two methane tanks with Carbon Fiber wraps and Glass Fiber wraps by partial wrapping. The reason for strengthening these tanks is primarily lack of compliance with new code requirements regarding the concrete compressive strength. The concrete compressive strength of these tanks is determined using the combination of ultrasonic pulse velocity method and rebound hammer test. The characteristics of confined concrete are calculated according with FIB Bulletin 14/2001 and ACI 440.2R-02 (2002) and then the results are compared. The results reveal that the rehabilitation solution with Glass Fiber wraps is more effective than the rehabilitation with Carbon Fiber wraps in terms of ductility and the rehabilitation solution with CFRP fabrics is more effective than the other one in terms of concrete compressive strength.

Keywords: non-destructive tests, rehabilitation, CFRP, GFRP, confinement, methane tanks Received: January 21, 2013 Accepted: March 10, 2013 Revised: March 31, 2013 Available online: May 31, 2013

INTRODUCTION

Confinement of concrete is an efficient technique used to increase the compressive strength and ductility of reinforced concrete members. In the case of circular cross sections, confinement can be achieved by applying external FRP wraps continuously all over the surface or discontinuously as strips. The paper aims to compare the characteristics of confined concrete in the case of partial wrapping of two methane tanks with CFRP and GFRP fabrics. The concrete compressive strength of the tanks is determined using the results of ultrasonic pulse velocity method and rebound hammer test. The characteristics of confined concrete are calculated according with FIB Bulletin 14/2001 and ACI 440.2R-02 (2002) code and then the results are compared.

MATERIALS AND METHODS 1. Degradradations of the tanks and their causes

In a previous work [1] there are presented the deficiencies of two methane tanks from Wastewater Treatment Plants Oradea. These tanks are cylindrical structures 10.75 m in height and 19 m in diameter The main deficiency consists in concrete degradation caused by the action of temperature variation, inefficient use of insulating materials and an inefficient fluoride silicatization of the inner surface of the tanks. This degradation decreases the sustainability of these types of structures. The main reason for rehabilitation of these tanks is lack of compliance with new code requirements regarding the concrete compressive strength. 2. Determination of concrete compressive strength

The non-destructive testing is the most practical and widely used because it estimates the strength of concrete without destroying the structure. Some combined methods were developed, in order to estimate concrete strength by using the results of two or more non-destructive tests.

The concrete compressive strength of the methane tanks was determined using the combination of ultrasonic pulse velocity method and rebound hammer test.


76

The ultrasonic pulse velocity method involves measuring the travel time over a known path length of a pulse of ultrasonic waves. The pulses are introduced into the concrete by a piezoelectric transducer and a similar transducer acts as receiver to monitor the surface vibration caused by the arrival of the pulse [2]. The ultrasonic pulse velocity measurement were conducted using an ultrasonic instrument from PROCEQ company with transducers with 50 mm in diameter, and had maximum resonant frequency of 54 kHz (fig. 1).

Fig. 1. Ultrasonic instrument The rebound hammer test involves measuring the rebound height of a hammer, that is

dropped from a fixed height above the test surface. The degree of rebound is an indicator of the hardness of the concrete. The rebound number was determined using Digi-Schmidt 2000 rebound hammer ND/LD model (fig. 2).

Fig. 2. Digi-Schmidt rebound hammer

The results of non-destructive tests are presented in the table 1.

Table 1. Results of non-destructive tests Structural

element Cross section

n d

(cm) t

(µs) v

(m/s) Rc

ref (N/mm2)

Rcmed

(N/mm2) Concrete

class

1 41.33 30

86.7

3460

17.3

2 43.66

30

84.7

3540

22.7

Methane tank

3 44.3 30 83.1 3610 23.9

25.52 C16/20

where: n – rebound number, d – distance between transducers, t – travel time of a pulse of ultrasonic waves,


77

v - ultrasonic pulse velocity, Rc

ref – reference value of concrete compressive strength, Rc

med – medium value of concrete compressive strength.

3. Rehabilitation solution Fiber reinforced polymer (FRP) composites are widely used in strengthening solutions due to

some advantages such their features in terms of strength, corrosion resistance, lightness and ease of application. FRP composites can consist of epoxy, polyester or vinyl-ester matrices and carbon, glass or aramid fibers. These composites can be manufactured as flexible sheets or fabrics (wraps) with fibers in one or at least two different directions.

CFRP fabrics consist of two components, epoxy based impregnating resin and carbon fiber fabric and can be used to strengthen reinforced concrete structures or to confine concrete.

GFRP wrap is an unidirectional woven glass fiber fabric for structural strengthening. GFRP wrap can be used for every kind of strengthening requirement; it has an excellent cost performance and it is non conductive [3].

The rehabilitation solution proposed for these tanks is partial wrapping with CFRP and GFRP fabrics. The CFRP and GFRP dimensions that were calculated according with FIB Bulletin 14/2001 and ACI 440.2R-02 (2002) are as follow: FIB Bulletin 14/2001

- SikaWrap Hex 100C: thickness 0.76 mm, width 150 mm, centre-to-centre distance 450 mm and thickness 0.38 mm, width 150 mm, centre-to-centre distance 225 mm;

- SikaWrap Hex 100G: thickness 1.08 mm, width 150 mm, centre-to-centre distance 450 mm and thickness 0.72 mm, width 150 mm, centre-to-centre distance 225 mm

ACI 440.2R-02 - SikaWrap Hex 100C: thickness 0.76 mm, width 150 mm, centre-to-centre distance 450

mm and thickness 0.38 mm, width 150 mm, centre-to-centre distance 225 mm; - SikaWrap Hex 100G: thickness 1.44 mm, width 150 mm, centre-to-centre distance 300

mm and thickness 1.08 mm, width 150 mm, centre-to-centre distance 225 mm.

Arrangements of strips is shown in fig. 4. The characteristics of confined concrete were calculated according with FIB Bulletin

14/2001 [4] and ACI 440.2R-02 (2002) code [5].

The calculus according with FIB Bulletin 14/2001: The volumetric ratio of FRP jacket ρj is given in Equation (1):

( ) s

b

dd

td f

ie

jej ⋅

−

⋅⋅= 22

4ρ (1)

where: tj – FRP jacket thickness, de – outer diameter of the tank, di – inner diameter of the tank, bf - width of FRP strip in partial wrapping, s – pitch in partial wrapping.


78

CFRP (GFRP) strips

Fig. 3. Arrangements of strips

The lateral confining pressure σl was determined using Equation (2):

juconflconfl kk εεσ ⋅=⋅= (2)

where: kconf – stiffness of the FRP confinement (see Eq. 3), εl – circumferential strain of the concrete, equal to the strain εj in the FRP jacket, εj = 0.017 (CFRP); εj = 0.028 (GFRP).

(3)

where: Efu – modulus of the FRP jacket; Efu = 230000 N/mm2 (CFRP), Efu = 76000 N/mm2 (GFRP), ke – the confinement effectiveness coefficient that is given in Eq. (4) in case that concrete is partially wrapped:

2

21

⋅

′−=

D

ske (4)

where: s' – clear spacing between the FRP wraps, D – diameter of the tank.

The confined peak strength fcc is expressed with an equation (Mander et al. 1988) that has been extensively tested against experimental data [5]:

2fuje

conf

Ekk

⋅⋅=

ρ


79

−⋅−⋅+⋅⋅= 254.1294.71254.2

co

l

co

lcocc ff

ffσσ

( 5)

where: fco – unconfined concrete strength; fco=10.67 N/mm2 (C16/20).

The compressive strain εcc at confined peak strength fcc is given in Eq. (6):

−⋅+⋅= 151

co

cccocc f

fεε (6)

where: εco – compressive strain of unconfined concrete.

c

coco E

f=ε (7)

where: Ec – modulus of elasticity of concrete; Ec=27000N/mm2 (C16/20).

The formula for ultimate axial compressive strain of confined concrete (Spoelstra and Monti, 1999) [6] is:

( )ljuccocu fE ⋅⋅⋅+⋅= εεε 25.12 (8)

where: cE - concrete tangent modulus:

co

cc f

EE = (9)

lf - maximum confining stress:

co

ll f

ff = (10)

The calculus according with ACI 440.2R-02 (2002)

The design ultimate tensile strength of the FRP material ffu is determined using the environmental-reduction factor for the appropriate fiber type and exposure condition [7].

(11)

where: f*

fu – ultimate tensile strength of the FRP material as reported by the manufacturer,

CE – environmental-reduction factor. The design rupture strain can be written as in Eq. (12):

*fuEfu C εε ⋅= (12)

*fuEfu fCf ⋅=


80

where: ε*fu- ultimate rupture strain of the FRP reinforcement.

The volumetric ratio of FRP jacket is given in Eq. (13):

s

b

dd

tnd f

ie

fef ⋅

−

⋅⋅⋅= 22

4ρ (13)

where: tf – FRP jacket thickness, n – numbers of plies.

The confining pressure σl is given in Eq. (14):

2ffefa

l

Ekf

⋅⋅⋅=

ερ (14)

where: Efu – modulus of the FRP jacket, εfe – effective strain level in FRP reinforcement, equal to the design rupture strain of FRP

reinforcement; εfe = εfu, ka – efficiency factor; ka=1 for circular sections.

The apparent confined concrete strength f'cc for a circular concrete member wrapped with an

FRP jacket is expressed with Eq. (15):

(15) 25.129.7125.2

−′

⋅−′

⋅+⋅⋅′=′c

l

c

lccc

f

f

f

fff

where: f'

c– specified compressive strength of concrete; f'c =10.67 N/mm2.

The maximum usable compressive strain in concrete for FRP-confined reinforced concrete members is given in Eq. (16):

( )c

ccccc E

ff ′⋅−′⋅⋅=′ 4571.1

ε (16)


The results for both rehabilitation solutions are presented in Table 2.

Table 2. Results obtained for the confined concrete characteristics Rehabilitation

solution n

bf

[mm] s'

[mm]

fcc

[N/mm2] εcu n

bf

[mm] s'

[mm]

f'cc

[N/mm2] ε'cc

FIB 14/2001 ACI 440.2R-02 (2002)

2 150 300 18.0 0.00836 2 150 300 17.34 0.00278 Rehabilitation with CFRP 1 150 75 18.27 0.0091 1 150 75 17.36 0.00279

3 150 300 16.6 0.0117 4 150 150 16.85 0.00263 Rehabilitation with GFRP 2 150 75 18.44 0.0137 3 150 75 16.85 0.00263


81

where: n – number of FRP plies, bf - width of FRP strip in partial wrapping, s' – clear spacing between FRP wraps, fcc, f'cc –confined concrete compressive strength, εcu, ε'cc – ultimate axial compressive strain of confined concrete.

Based on the results presented in table 2 the following conclusions are drawn: • In order to provide confinement strengthening it is required a larger amount of GFRP fabrics

in the case of calculus according with ACI 440.2R-02 (2002) than in the case of calculus according with FIB Bulletin 14/200. ACI 440.2R-02 (2002) code accounts for environmental degradation and long-term durability by suggesting reduction factors CE for various environments. In the case of wastewater treatment plants this reduction factor is less than 1 and that decreases the design rupture strain.

• The ultimate axial compressive strain of confined concrete and the confined concrete compressive strength obtained from the calculus according with FIB Bulletin 14/200 are bigger than in the case of calculus according with ACI 440.2R-02 because ACI code doesn't specify how the confined concrete modulus changes beside the unconfined one. FIB 14 is taking into account this change by calculating a concrete tangent modulus.

• The number of CFRP plies required to provide confinement strengthening is less than the number of GFRP plies in both cases of calculus.

• In the case of wrapping with CFRP strips the ultimate axial compressive strain of confined concrete calculated according with FIB Bulletin is less than in the case of wrapping with GFRP strips. The compressive strength and ultimate axial compressive strain of confined concrete obtained from the calculus according with ACI 440.2R-02 are bigger in the case of wrapping with CFRP than in the case of wrapping with GFRP.

CONCLUSIONS The rehabilitation solution by partial wrapping with CFRP fabrics is more effective than the solution with GFRP in terms of concrete compressive strength and the solution with GFRP is more effective in terms of ductility. ACI 440.2R-02 code is more restrictive than FIB Bulletin 14/2001. The american code ACI 440.2R-02 accounts for environmental degradation by suggesting a reduction factor CE that decreases the design rupture strain. ACKNOWLEDGMENTS The results presented in this paper are obtained by the authors found on the collected datas for elaboration a PhD Thesis for the prime author of this paper. The authors of this paper collaborated with Prof.dr.eng. Corneliu BOB and Prof.dr.eng. Dan TUDOR from University of Timisoara.

REFERENCES 1. POP, Mariana, TOADERE Mihaela, POP, Maria (2011) - A comparision between some characteristics

for rehabilitation of two methane tanks, Journal of Applied Engineering Sciences, Volume 1 (14), Issue 3/2011, University of Oradea Publishing House.

2. CARINO N.J. (1994) - Nondestructive Testing of Concrete: History and Challenges, ACI SP – 144, Concrete Technology – Past, Present and Future, P.K. Metha, Ed., American Concrete Institute, Detroit, MI, 1994, pp 623 – 678.

3. *** www.sika.com accesed at: 02.11.2012. 4. *** Technical Report in the Design and Use of Externally Bonded FRP Reinforcement for Reinforced

Concrete Structures, fib TG9.3, 2001.


82

5. *** Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures, ACI 440.2R-02, 2002.

PRADA M. pp.83-86

83

RISK ELEMENTS IN MODELLING, DESIGNING AND BUILDING-UP PORTANT MASONRY STRUCTURES

PRADA Marcela,

University of Oradea, e-mail: [email protected]

A B S T R A C T The paper emphasized conforming, designing and execution problems revealed in curent practice. Will be discuss about portant masonry walls structure, wich, according to Romanian standards, have to respect even from conformation phase, rules and prescriptions. The study shows frequently faults in conceptual and finishing these structures and propose some discharging solutions of these, as like: preliminary architectural-structural design, introducing mandatory complet structural project for authorising begin of works, establishing crafts and vocational schools in construction field.

Keywords: ceramic blocks, confinement, thermal bridge, building site supervisor


INTRODUCTION Over the time, normatives of design and execution has changed, new approach concept of

designing and effectve buidilng are born. In our days buidings with some high seismic resistance are designed and built up. The direct consequnce of these low seismic risk class, is the high price of the new buildt properties, also interventional high costs on existing constructions.

Masonry structures have always been a constant subject of concern for manufacturers. These, without a rigurous conformation, according to curent specific norms, can get a comparable cost to frames structures buildings due to materials consumption.

Existing ediffice, majority from masonry, become oftenly target of interventional works caused by seismic unconformed status, changing functionality, perturbating phenomenons, new standars of loadings reckoning. It can be obtained a lower seismic risk grade buildings by using curent standars and codes for rehabilitation.

Earthquake risk class of a structure is the direct result of conformating, designing, buildworking and building exploaitation. For assuring this aspect the architect, designer and constructor of the structure, are responsive. MATERIALS AND METHODS

Choosing entire wiev buildings configuration is the architect main job. Structure concept is the structural engineer computition but can not be independent from functions and plastics-esthetic wishes of investor and architect [1]. Effective works are the appanage of executor engineer, of building site supervisor. This paper shows problems resulting in non-respecting current standards during tehnical project elaboration or during works of building with portant masonry structure. 1. Architectural-Structural design

It required going through an iterative process of “proposal-evaluation” that have to attend, from an early stage of the project, the architect and structural engineer. 1.1. Choosing materials respectively ceramic blocks, also imposed materials commisioning work by project, are very important. In table1 is a study report on 20 structures of portant masonry with residential homes function, about using of ceramic blocks required by the project.


84

Table 1. Study report comissioning work of designed materials Number of executated structures with:

No. of structures Ceramic blocks indicate in project

Ceramic blocks diferent that indicate in project

Other structure than indicate in initial project

20 14 6 1*

* Beneficiary achieved materials considering energy savings and termal insulation and modified project from portant masonry structure to concrete frames structure, to use the purchased materials.

1.2. Structure conformation are made fully according to CR6 standard rules, both by architect and structural engineer. Oposite, a non conforming of the building depending of its structure, involve a high price of the works.

Horizontal and as vertical conforming, choosing masonry type, same time how many floors, stay in focus of both, architect and structural engineer. Also, in their attention will stay tickness of the walls, spaletti dimensions and slabs stiffness.

Coroborrating architectural plans with structural design is mandatory. In case of missing of pillars from architectural plans, it may cause errors in execution works, because the constructor achieve masonry just consulting the arhitectural drafts. Thus, many times, gaps larger than 2,50 msq are not bordered, resulting the masonry cracking (fig 1).

Fig.1. Wrong disposal of reinforced concrete pillars

a. Ceramic blocks cracking at diaphragm end; b. Lack of gaps bordering 2. Structural design versus execution 2.1. Masonry confinement, according to pillars disposal rules, is very important. Most times, gaps bordering are missing from structural designers plans. Noncompliance of standards, in case when ceramic blocks with thin walls are used, result in masonry cracking risk (fig. 1).

Anchoring masonry pillars by streps and wiskers, depending on ceramic blocks dimensions, must respect the practice and executiion masonry works code. oftenly, in buiding site, anchoring is missing or it is faulty, vicious accomplished (fig. 2).

a b

PRADA M. pp.83-86

85

Fig.2. Reinforced concrete pillars execution

a. Wrong execution; b.Corect execution; c.Pole anchoring in masonry (source: http://www.diypedia.ro/constructii/lucrari-din-zidarie, accessed in 30.12.2012)

2.2. Thermal bridges discharge it is mandatory to health and hygiene confort assurance, most design faults are non disposing in project or non executing a suplementary thermal insulation measures at reinforced concrete confinement elements (fig 3):

Fig.3. Thermal bridge discharge (a. Wrong execution; b. Corect execution)

(source: a. http://heavybrick.wordpress.com/2012/07/04/, accessed in 30.12.2012) (source: b. http://mikaprojects.com/cofrarea-grinzilorcenturilor-si-a-placii-peste-parter/, accessed in 30.12.2012)

2.3. Accurate details execution is a current problem, especially in case of present legislation, when authorisation building construction not compel structural project, just only for foudation plan and details. A consequnce of this deficiency is in figure 3 exposed , where wrong executions of the lintels is shown.

Fig.3. Wrong execution of the lintel


It can reduce substantially costs around 25% for a portant masonry structure versus reinforced concrete frames structure according same building, due to a preliminary architectural-structural and a good conformation. In table no. 2, are emphasized concrete, reinforcements and

b a c

a b


86

brick consumption for a construction bound for the family home with a usable area of 97.60 square meters; it was considered in, two solutions to achieve the structure: - confined masonry block bearing ceramic hollow vertical; - reinforced concrete frames with masonry filler perimeter closings of vertical hollow ceramic blocks in initial design and redesigned according to materials effciency [1].

Table 2. Consumption per square foot due to constructive solution Consumption/square meter place:

Main materials reinforced concrete frames with masonry filler perimeter

confined masonry block bearing ceramic hollow vertical

redesigned confined masonry block bearing ceramic hollow

vertical

Concrete 0,75 mc 0,68 mc 0,60 mc

Reinforcements 24,12 kg 20,10 kg 18,2 kg

Bricks 0,40 mc 0,45 mc 0,50 mc

The true measure of a house lies in details. It must be evaluated by details quality and must

known every detail even from designing phase. Here is the role of executor, of the building site supervisor, and Construction State Inspectorate to enforce the building execution according to detailed technical project. CONCLUSIONS

To eliminate the risks of poor execution it is required: - a preliminary architectural-structural and a good conformation; - mandatory buildings execution, according to a detailed technical project, even low

importance buildings, like residential homes; - knowing and respecting regulations in force, for all actors participating to the investment

process: architect, structural engineer, executor, building site supervisor; - future specialist education from highschool, the idea of teamwork, of a solid bond between

architect, structural engineer and instalation engineer, between designer and executor; - Romanian education orientation to crafts and vocational schools.

ACKNOWLEDGMENTS

The work is original, and refers especcially on structural masonry design and execution elements. Some of the shown images were taken in situ on recently designed buildings, and the other images of good practice are from references. REFERENCES 5. PRADA MARCELA, SCURT ADRIANA, GOMBOS DAN (2010), Construction Impact on

Environment, Case Study for a Residential Building, în Rev. Analele UniversităŃii din Oradea, Fascicula „ConstrucŃii şi InstalaŃii Hidroedilitare” (Constructions and Hydro-Utility Installations), pp. 373-378;

6. *** http://www.icase.ro/articole.php?id=73&type=articol, viewed at 30/12/2012. 7. *** http://mikaprojects.com/cofrarea-grinzilorcenturilor-si-a-placii-peste-parter/, accessed in 30.12.2012 8. *** http://heavybrick.wordpress.com/2012/07/04/, accessed in 30.12.2012

PUSKAS A., BINDEA M. pp.87-92

87

ESTABLISHING THE DESIGN VALUE OF COLUMN MOMENT ACCORDING TO P100-1/2006

PUSKAS Attila*, BINDEA Mihai


A B S T R A C T The paper is presenting a comparative study for establishing the design value of the bending moment for a column of a multistorey, multi-bay reinforced concrete frame building, being located in regions characterised by ag=0.16g and ag=0.28g respectively, designed, dimensioned and detailed in accordance with specific earthquake resistant provisions for high ductility class, according to seismic norm P100-1/2006 (and P100-1/2011). Beside the necessary differences due to lateral flexibility in the size of the structural elements (columns, beams) in the calculus of the column design moments important differences appear also in the calculated magnification factors of the column bending moments obtained from the analysis of the used spatial model. Even if the presented method, applied as recommended in the norm, respects the main requirements in order to ensure an overall dissipative and ductile behaviour of the structure, the obtained results are driving to over-dimensioning of the structural elements, hence to higher steel reinforcement consumption in the column.

Keywords: seismic design, reinforced concrete column, design recommendations


INTRODUCTION For multi-storey buildings choose of an RC frame structure seems to be the easiest possible

structural solution; simplicity and static-wise clarity of the frame structure presents advantages in design and execution phase too. In case of RC frame structures designed for seismic areas, following the enrollment of the structure into ductility class, global and local ductility conditions have be considered , in order to assure a proper ductility for the whole structure, especially avoiding the formation of a soft storey plastic mechanism, due to excessive local ductility demands in the related columns. Scope of the principles is quite clear, but it still can cause difficulties in the day-by-day design processes, since the main tool in hand of the designer, in order to assure the proper ratio at every beam-column joint between the design values of the columns' resistance moments with respect to the beams' resistance moments, is the alternative procedure presented in the national seismic code P100-1/2006 (recently P100-1/2011), based on P100-92(1992). The authors are presenting appreciation of this method, since for regions with increasing value of ground acceleration leads to decreasing value of column moment magnification factor.

MATERIALS AND METHODS 1. Designed structure. Applied loads and materials used

The studied RC frame structure has five longitudinal openings and three transversal openings, of 5.00 m and 5.80 m, respectively 6.00 m and 6.50 m, disposed alternatively, as presented in the typical layout on the structural elements (fig.1). The frame has five levels, considering the structural height 4.00 m for the first level and 3.60 m for the levels above.

Beside the own weight of the structure the loads are given by the dead load of the finishings (1.5 kN/m2 for the intermediate levels and 2.5 kN/m2 for the last level), snow load on the roof level of 1.60 kN/m2, live load on the intermediate levels of 2.50 kN/m2, supplemented with 0.80 kN/m2 for internal partitioning walls. The loads given by the external walls were taken into account as distributed loads of 10.50 kN/m along perimetral beams of the building.


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Fig.1. Typical layout of the structural elements

In order to calculate the structure for seismic load the building was considered to be located

in regions characterized by the upper limit of the period of the constant spectral acceleration branch Tc=0.7 sec and the design ground accelerations ag=0.16g (named model A) and ag=0.28g (named model B) respectively, the different values of ground accelerations consisting the two studied cases. Both structures were designed in accordance with earthquake resistant provisions for high ductility class, even if recommendations regarding use of medium instead of high ductility class for regions having ag=0.16g was pointed out in [1] and [2]. The importance class of the building is II.

The concrete class used for the calculus is C25/30. For longitudinal reinforcements in the beams and columns Bst 500S type bars are calculated. Dimensions of the structural elements have been established using simplified formulas and simplified calculus, obtaining hsl=13 cm for slab, 50x25 cm (hbxbb) for longitudinal and 60x25 cm for transversal beam and 50x50 cm for the columns. Dimensions of the structural elements were confirmed by later verification of displacements and story drifts as well as limiting the normalised design axial force according to [3].

2. Theoretical background of the study

The global and local ductility condition for buildings having frame structures, according to [3][4][5] can be transposed to the satisfying of the relation (1)[3] at all joints of primary or secondary seismic beams with primary seismic columns by use of relation (1).

∑ ∑≥ RbRdRc MM γ (1)

The alternative procedure presented in [3] and [4] allows calculation of the column design

moments using relation (2)[3] taking into consideration a magnification factor defined by the ratio between the sum of the design values of the moments of resistance of a certain beam for all the openings for the same rotation direction caused by the considered seismic action and the sum of the moments of the beam obtained from static analysis in the same condition.

∑∑=

''

Edb

RbEdcRdEdc

M

MMM γ (2)


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3. Static analysis of the structure for ag=0.16g and ag=0.28g For analyzing the structure Autodesk Robot Structural Analysis Professional 2012 software

was used, generating the seismic forces based on the first 20 modes of vibration. For the first two modes of vibration (translation in X and Y direction associated with rotation imposed by the 5% excentricity) the vibration periods become 1.11 sec and 1.05 sec (for the X and Y direction respectively). The high values of vibration periods for the building having only 5 levels are obtained due to the relatively high flexibility of the structural system. Since the calculated structure satisfies the regularity criteria in plan and elevation the seismic action was considered to act separately along the two main orthogonal horizontal axes of the structure, in both directions. Moment envelopes of the transversal frame for the two models are presented in (fig. 2).

Fig.2. Moment envelope of a transversal frame (a. Model A and b. Model B)

4. Beam and column calculations In order to establish the design value of moment for the column at the second level, prior

design of the upper and lower beams in both directions is necessary. Values of the moments obtained from static analysis for Model A and Model B are presented in (table 1) and (table 2).

Table 1. Moments obtained from static analysis for Model A,

upper and lower beams

Joint

1 2 3 4 Upper beam

right left right left right left

Moment - Y+ [kNm] 7.63 -151.06 -18.81 -158.42 4.65 -157.39

Moment - Y- [kNm] -157.23 4.84 -158.22 -18.61 -150.87 7.79

Joint

1 2 3 4 Lower beam


Moment - Y+ [kNm] 21.52 -161.06 -19.17 -159.52 1.60 -154.22

Moment - Y- [kNm] -154.05 1.83 -159.29 -18.94 -160.83 21.69

a b


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Table 2. Moments obtained from static analysis for Model B, upper and lower beams

Joint

1 2 3 4 Upper beam


Moment - Y+ [kNm] 69.45 -204.53 33.47 -205.85 62.98 -219.34

Moment - Y- [kNm] -219.06 63.31 -205.49 33.82 -204.19 69.73

Joint

1 2 3 4 Lower beam


Moment - Y+ [kNm] 87.36 -224.14 33.38 -212.23 62.52 -220.19

Moment - Y- [kNm] -219.89 62.91 -211.83 33.78 -221.75 87.65

In order to establish the design value of the bending moments for the columns at the second

level, prior designing of the upper and lower beams in both directions is necessary. In order to simplify the calculations, the values of the beams moments presented in previous tables are not reduced. The longitudinal reinforcements obtained for beams at the joints, considering the provisions of [3] and [7], are presented in (table 3) and (table 4).

Table 3. Reinforcement for upper and lower beams, Model A

Joint

1 2 3 4 Upper beam


Top reinforcement 2d18+d16 2d18+d16 2d18+d16 2d18+d16 2d18+d16 2d18+d16

Bottom reinforcement 2d14+d10 2d14+d10 2d14+d10 2d14+d10 2d14+d10 2d14+d10

Joint

1 2 3 4 Lower beam



Bottom reinforcement 2d14+d10 2d14+d10 2d14+d10 2d14+d10 2d14+d10 2d14+d10

Table 4. Reinforcement for upper and lower beams, Model B

Joint

1 2 3 4 Upper beam



Bottom reinforcement 2d18 2d18 2d18 2d18 2d18 2d18

Joint

1 2 3 4 Lower beam



Bottom reinforcement 2d18 2d18+d8 2d18+d8 2d18+d8 2d18+d8 2d18

The resisting moments calculated based on the earlier obtained longitudinal reinforcement are presented in (table 5) and (table 6). For calculating the ratio between the sum of the moments of


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resistance for all the openings for the same rotation direction and the sum of the moments of the beam obtained from static analysis, results were extracted from the load combination with the seismic load acting in the way it produces the considered rotation, for both upper and lower beams of model A and model B.

Table 5. Resisting moments corresponding for the obtained reinforcement, Model A

Joint

1 2 3 4 Upper beam


MRb [kNm] - top 162.05 162.05 162.05 162.05 162.05 162.05

MRb [kNm] - bottom 91.71 91.71 91.71 91.71 91.71 91.71 Joint

1 2 3 4 Lower beam


MRb [kNm] - top 162.05 162.05 162.05 162.05 162.05 162.05

MRb [kNm] - bottom 91.71 91.71 91.71 91.71 91.71 91.71

Table 6. Resisting moments corresponding

for the obtained reinforcement, Model B Joint

1 2 3 4 Upper beam


MRb [kNm] - top 221.59 209.32 209.32 209.32 209.32 221.59

MRb [kNm] - bottom 118.48 118.48 118.48 118.48 118.48 118.48 Joint

1 2 3 4 Lower beam


MRb [kNm] - top 221.59 238.48 238.48 238.48 238.48 221.59

MRb [kNm] - bottom 118.48 129.55 129.55 129.55 129.55 118.48

Design moments of a column at a specific level can be determined using relation (2). In transversal direction the columns at the second level of the studied frame can be calculated using the fractions (magnification factors) shown in table 7. For transversal direction for a given level the same values can be used for all the columns, increasing the moments obtained from static analysis with that specific value beside the factor accounting for overstrength due to steel strain hardening and confinement of the concrete in the compression zone.

Table 7. Magnification factors upper and lower beams, model A and model B

Model A Model B Rotation direction

upper beam lower beam upper beam lower beam

+ 1.529 1.472 1.275 1.272

- 1.530 1.474 1.276 1.275

RESULTS AND DISCUSSIONS By calculating the magnification factors in the above presented way the design moments for

all the columns entering in the calculated beams/joints becomes easy. The calculated structure presents structural symmetry in both direction, differences between the values obtained for the two different directions of rotation are only results of the imposed mass excentricity. The openings are in the typical range of RC frame structures, without major differences between the openings, which


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allows choosing of the same longitudinal reinforcement in beams at crossings with columns. It can be remarked that for the structure calculated for seismic loads given by ground acceleration ag = 0.16g values of the magnification factors are sensibly higher than for the structure calculated for a higher seismic load given by ag = 0.28g, even if all the other loads and characteristics are the same for the two different structures. Decreasing of the magnification factor can be observed with increasing of the level shear force given by the horizontal seismic forces acting above the studied storey. For openings with significant differences the magnification factor is also increasing, as well as with increasing the number of openings. These remarks are questioning the efficiency of the alternative calculation method. Use of the magnification factor leads to fulfillment of relation (1) in excessive manner for buildings acted by lower seismic loads and in a less excessive way for the ones loaded by higher values of the seismic load.

CONCLUSIONS

Use of relation (2) for establishing design moment for columns, i.e. use of the alternative method presented in [3] and overtaken in [4] gives the opportunity of finding relatively fast results and the possibility of automatizing the design of the reinforced concrete columns. Values of design moments obtained in the presented way are leading to oversizing the reinforcement of the columns especially in regions characterized by lower values of ground acceleration, as consequence the authors recommend use of relation (1) for beam-column joints in iterative way instead of relation (2) in order to achieve structures designed in an engineering way.

ACKNOWLEDGMENTS

This article is result of the major interest of the authors regarding the application of specific provisions of the national seismic code P100-1/2006(2012) for multi-strorey reinforced concrete structures and their attempt to develop time-efficient calculation methods for practical use.

REFERENCES 1. PUSKAS, A., SANDOR, G.A. (2010), Comparative Study of a Reinforced Concrete Structure for High and

Medium Ductility, Treci International Naucho-Strucni Skup GNP 2010, Žabljak, Montenegro, 15-19 February 2010, pp. 529-534.

2. PUSKAS, A., SANDOR, G.A. (2009), Studiul unui stâlp de beton armat în clasa de ductilitate H şi M (Study of a reinforced concrete column for ductility class H and M), A 4-a ConferinŃă NaŃională de Inginerie Seismică, Bucuresti, 18 decembrie 2009, pp. 435-440.

3. *** P100-1/2006, Cod de proiectare seismică — Partea I — Prevederi de proiectare pentru clădiri (Earthquake resistance design code – Part I - General design rules for buildings).

4. *** P100-1/2011, Cod de proiectare seismică — Partea I — Prevederi de proiectare pentru clădiri (Earthquake resistance design code – Part I - General design rules for buildings).

5. *** SR EN 1998-1:2004 (2004), Eurocode 8, Design of structures for earthquake resistance - Part 1: General rules, seismic actions and rules for buildings.

6. *** P100-92 (1992), Normativ pentru proiectarea antiseismică a construcŃiilor de locuinŃe social-culturale, agrozootehnice şi industriale (Standard for seismic design of socio-cultural, agricultural and industrial constructions).

7. *** SR EN 1992-1-1-2004 (2004), Eurocode 2, Design of concrete structures. Part 1-1: General rules and rules for buildings.

8. MOGA L., MOGA I. (2008), The influence of the thermal insulation of the window frameworks on the energy performance of the window, Bauphysik Journal, 30(6), Ernst und Sohn 2008, pp. 420-426.

9. KISS, Z., BALINT, K., PUSKAS, A. (2009), Earthquake resisting reinforced concrete structure, Prefabrikovane Armiranobetonske Konstrukcije na Teritoriji Srednje I Istocne Evrope, III. Medunarodna Savetovanke, Subotica, 8-9. Octobar 2009, p. 31-54.

RĂDULESCU A.T.G., RĂDULESCU G.M.T. pp.93-100

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COMPARATIVE ANALYSES OF TWO MONITORING PERIODS IN DYNAMIC REGIME (SUMMER, WINTER) OF THE WATERFORD STAY

CABLE BRIDGE, IRELAND

RĂDULESCU Adrian T. G., RĂDULESCU Gheorghe M.T.*, Technical University of Cluj Napoca, *e-mail: [email protected] (corresponding adress)

A B S T R A C T The emergence of new methods and technologies for structural monitoring has occurred slowly, until two decades ago, while developing new methods, tools and also conventional techniques, nowadays the information explode, appearing practically endless combinations in shaping the time behavior monitoring of an objective. The evolution of technologies for monitoring the behavior of buildings and lands over time, from the known methods of leveling and angular intersections to the sensory techniques, gives rise to the natural question: can the ongoing activity of structural monitoring still be seen as a part of the coverage of engineering surveying? Answer can be given only by analyzing specific cases in different monitoring conditions. The case study, in continuous dynamic condition, was performed on The Waterford Stay Cable Bridge, located near Waterford, Ireland. The tracking period started on September, 2009, the summary results were uploaded at the company' Vienna Consulting Engineers Company in Vienna.

Keywords: Wind Speed, Sensor, Strain Gauge, Acceleration Sensor


INTRODUCTION

The building of special constructions, which have particular construction features, requires permanent Structural Monitoring - the action starting during execution and continuing throughout the life of the work [1]. Three big categories of Civil Engineering fall in this category: very tall utility-type buildings: smoke towers/chimneys and TV towers, bridges and more recently, very tall civil / residential constructions. For these examples, case by case, monitoring can be carried out in static or kinematic regime. In the case of bridges, tracking the behavior over time, in special, quasi-static, quasi-dynamic and / or is dynamic regime, is done depending on the constructive parameters of the work. Meanwhile, the surveyor observes, records and presents data on the behavior of the structure, in various combinations of stress factors, to the designer [2]. The designer will then decide: which element should be tracked, under what conditions, using which monitoring system, which stress factors should be analyzed, the frequency of the recordings, the accuracy etc. Based on these conditions, the surveyor will choose the methods and tools capable of providing the required data. In this case we speak of unconventional methods belonging to Dynamic Topography [3, 4]. The case study presented is made, once again, with the support of Vienna Consulting Engineer, who committed to perform the difficult task of monitoring, geometrically active and continuous, the execution and behavior over time in dynamic regime of a bridge in Ireland. In this case study we make an overview of the monitoring work while simultaneously carrying out a critical analysis of the recordings from two distinct periods (summer / winter) [4].

MATERIALS AND METHODS 1. The monitoring of the Waterford stay cable bridge, Ireland

The case study for dynamic regimen was performed on the Waterford stay cable bridge part of the Waterford Bypass N25 [5, 6], located nearby Waterford, Ireland, Coordinates: 52°, 26 latitude, -7°,12 longitude. The N25 Waterford Bypass route crosses the River Suir near the bend in the river at Granny. This necessitates a new River Suir Bridge (fig.1). Following an examination of


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a number of different kinds of bridge, a cable-stayed bridge which virtually crosses the river in a single leap has been selected. When constructed, the 230 metre main span will be the longest span bridge in Ireland. The cable-stayed bridge with its 100 meters tall tower, will be a landmark structure for Waterford City and surrounding areas. This landmark structure reflecting modern “high tech” engineering and graceful and simple aesthetics will become a symbol for the southeast, of which the region can be proud. The cable stayed bridge has a span configuration 40, 70, 90, (230), 35 m = 475 m and a deck with of 30.60 meter. The concrete pylon has a height of 95.6 meter above deck. The bridge was completed in September 2009. Before traffic opening VCE performed cable measurements of all 76 stays. The results are the actual cable forces and the cable damping. On the bridge a permanent monitoring system was installed by VCE. The system includes 62 measurement channels. The data is automatically analysed on site and presented via internet by the BRIMOS© Web-Interface.

Fig. 1. River Suir Bridge, Waterfor, Ireland

Fig. 2. Displacement sensor at bearing of pier one west

Fig. 3. Print screen of the recordings, Vienna Consulting Engineer Site,

Brimos, Bridge Monitoring System


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Fig. 4. The meteorological and displacements recording systems a. Capacitive Acceleration Sensor, b. Air Temperature Sensor, c. Magnetostrictive Desplacement Sensor,

d. Cable Resistor Thermometer, e. Vibrating Wire Strain Gauge, f. Wind Direction Sensor, g. W. Speed Sensor

Fig. 5. The situation of the meteorological and displacements current recordings,

Cockpit - River Suir Stay Cable Bridge

a b c

d e

f g


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Fig. 6. The situation of the meteorological current recordings,

for the monitoring period 08.12.2012-08.12.2012 and 15.07.2012-15.08.2012

Fig. 7. The Maximum Cable Vibration,

for the monitoring period 08.12.2012-08.12.2012

Fig. 8. The Maximum Cable Vibration,

for the monitoring period 15.07.2012-15.08.2012


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Fig. 9.Displacement for the monitoring period 08.12.2012-08.12.2012

Fig. 10. Displacement for the monitoring period15.07.2012-15.08.2012

a b c

Fig. 11. Cable Vibration for the monitoring period

a. 08.12.2012-08.12.2012, b. 15.07.2012-15.08.2012, c. Displacement sensor at bearing of pier one west

a b

Fig. 12. Movement of Bearing abutment 2 and pier 3 for the monitoring period

a. 08.12.2012-08.12.2012, b. 15.07.2012-15.08.2012


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Fig. 13. Strain for the monitoring period 08.12.2012-08.12.2012

Fig. 14. Strain for the monitoring period15.07.2012-15.08.2012

The paper consists of the recording of six meteorological parameters (Fig. 6), 24

meteorological monitoring points mentioned in Table 1, three categories of motion parameters with 44 points of data acquisition, and four categories of process analyses. Basically, the direct sensors (Fig. 2, 4, 5) are 68 in total, plus transmission cables, and the central station where all monitored data are sent to. From there they are retransmitted (Fig. 3) to the Vienna base via the Internet, where they are processed and delivered to the beneficiary of the monitoring contract – the designer. Emergency situations are very rare in such cases, but there are special cases reported, such as the failure of a sensor, the interruption of transmission for various reasons, bridge maintenance works affecting / influencing recordings.


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Table 1. Meteorological and motion parameters recorded on the River Suir Stay Cable Bridge, Waterford (Ireland)

No. Parameter Point of recording

A. Meteorological parameters 1. Wind direction Deck, Pylon 2. Wind Speed Deck, Pylon 3. Air temperature AT East, AT West 4. Cable temperature CT North, CT South 5. Deck temperature Concret Bottom East, West, Concret Top East, West, Steel

Bottom East, West, Steel Top East, West 6. Pylon temperature In Bottom East, West, In Top East, West, Out Bottom East,

West, Out Top East, West B. Mouvement parameters 1. Displacement Abutment 2 Left, Right, Pier 1 Left, Right, Pier 2 Left, Right,

Pier 3 Left, Right, Pylon Left, Right 2. Maximum cable vibration BS 18, 16, 11, Max X, Y, Z; MS 09, 12, 17, Max X, Y, Z 3. Strain S 01-16 4. Alarms thresholds on air temperature and

wind, at permanent monitoring AT East, Wind direction, Wind speed

5. Mouvement of bearings abutment 2 and pier 3

Diagramm Abutment 2 Left/ Pier 3 Left

6. Cockpit 7. Cable vibration caused by wind MS 09 max Z

Analyzing the degree of involvement of Topography through its new branch called dynamic

topography, which analyzes the structural behavior in kinematic regime, we find that the mission which started with the completion of the first resistance element. For bridges, as for the other two categories of kinematically monitored structures, i.e. tall cylinder-type (chimneys/smoke towers and TV towers) and residential-type buildings, structural monitoring contains two stages: 1. Monitoring during the execution of each structural element, after its completion or only for one part of the structural elements considered vulnerable or “weak resistance points”; 2. Post-execution monitoring, usually done on the same structural elements. Our paper, “Structural Monitoring Handbook”, will present all the details of this important action in the life of any construction, which, in accordance with the law (Norm P130 in Romania) and based on the construction’s technical book, requires the tracking of the behavior over time. CONCLUSIONS

Comparing the results from winter / summer, for a month of monitoring randomly selected from the entire monitoring period which began in September 2009 continuing to this day, one can find the following: • Vibrations in winter are higher than in summer; so, during winter they can reach 1000 mg and

500 mg during summer, but only accidentally - under the same wind speeds, in this case the maximum sizes are around 14-16 m / s (Fig. 7, 8);

• The motion (deformations) are also higher in winter than in summer; so, during winter they can reach (Fig. 9, 10) 290 mm, with a variation between days of 80 mm, respectively for the same element one can see a deformation of no more than 240 mm, with a maximum variation between days of 80 mm, similar to the previous deformation. In conclusion, absolute deformations are greater during the winter and the relative ones are comparable between seasons;


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• The ratio of deformations (Fig. 11, 12) is also greater during winter, but increases linearly in both cases;

• One cannot find significant differences between tension(strain) states created in the structural elements from one season to another; for some elements they are greater in winter for other in summer (Fig. 13, 14);

• Based on the ratio between the recorded request, in this case wind speed and direction, air temperature and effects, i.e. deformations / displacements, vibrations and oscillations, a correlation between the behavior of various parts of the structure can be made at a general or global level, for the entire monitoring period, up to a five-minute analysis interval. We need to take into account the response time of each element which can be determined by lengthy correlations between different recordings in different monitoring conditions, at different times and intervals. As seen from the analysis of the recordings presented, the gathering of data is carried out in

a continuous dynamic regime, but the presentation is done sequentially, at a certain interval - in this case 5 minutes - considering that in this time period the building behaves linearly. Thus, through simple interpolation we can obtain data for any time frame. The same happens for meteorological data. We proceed to centralize data locally, then we transmit it over the Internet to the base in Vienna where the data is posted for analysis, the interval being of approximately one hour, meaning that data taken at time T can be viewed at time T+60 minutes. However, crisis / emergency situations are warned synchronized with the time of occurrence in order for authorities to act accordingly. REFERENCES 1. CHRZANOWSKI A., SZOSTAK-CHRZANOWSKI A., BOND J., (2007) Increasing public and

environmental safety through integrated monitoring and analysis of structural and ground deformations, in „Geomatics Solutions for Disaster Management” (eds: J. Li, S. Zlatanova, A. Fabbri) Springer, pp. 407- 426.

2. GLIŠIC B., INAUDI D. & VURPILLOT S. (2002), Structural Monitoring of Concrete Structures Procedeengs of Third World Conference on Structural Control, 7-12.4.2002, Como, Italy, pp. 1-10.

3. RĂDULESCU GH.M.T, (2003), Modern topographic technologies used in the execution and exploitation of high-rise buildings, PHD Thesys, Technical Construction University of Bucarest, Faculty of Geodesy, its support 25.06.2003, Scientific Coordinator, Prof. univ. dr. ing. Vasile URSEA.

4. RADULESCU A.T.G. (2011), Modern surveying technologies used for tracking the time behavior of Civil Engineering within mining perimeters, PHD Thesys, University of Petrosani, Faculty of Mines, its support 21.01.2011, Scientific Coordinator, Prof. univ. dr. ing. Nicolae DIMA.

5. ***, BRIMOS, Bridge Monitoring System, Vienna Consulting Engineer, http://www.brimos.com/DMA/ DMAFrames.aspx, accesed 2009-2012.

RĂDULESCU C., RĂDULESCU V.M.G.M. pp.101-106

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CURRENT SUPPORT CONFIGURATION ELEMENTS IN A DATABASE FOR MINING INDUSTRY FROM THE MDB GIS CATEGORY, SASAR

MINE, BAIA MARE

RĂDULESCU Corina, RĂDULESCU Virgil Mihai G. M., Technical University of Cluj Napoca, e-mail: [email protected]

A B S T R A C T The management activity of a mining organization is characterized, as in most cases when operating with spatial data, by the speed at which a decision must be made. Intervention in an accident in a mine is an extreme case, but not the only one that can represent an argument of the previous statement. The decision (s) will be taken on the basis of a managerial policy related to information (data) available when needed. Timeliness and reliability of data are essential conditions in the management process and will be true "passports" in the implementation of MDB GIS. All this data must be digitized. Therefore, there will be material and time costs in order to create a mining database with GIS as the main operating axis (or not). Each company will decide how and when this costly computer operation will be activated and solved. In this case, this paper cannot provide solutions, but merely suggest tools, since the goal is to create a new concept of computerization of the mine, this so-called MDB GIS. Solutions for concrete cases may come later on, as this will be the next stage of our research and that of the team wee belong to. Case study is: Opportunities for implementing the MDB GIS computer system in Romania’s mining activity. Analysis of data from the National Company of Precious and Nonferrous Metals "REMIN" Baia Mare for the computerization of activities through the MDB GIS system.

Keywords: MGIS (Mining Geographical Information System ), mining database combined with a GIS platform


INTRODUCTION

Following the severe reduction of mining in Romania and the closure of mines, the company "REMIN" Baia Mare initially entered into a restructuring process and is currently in insolvency. Its mines are preserved pending a possible reopening, when it will be considered that a profitable mining operation can be conducted. In these circumstances, conducting studies of any kind, except those related to final closure of business or, at best, preserving the state of a mine in natural technical and physical degradation, is useless. That is why the analysis we made covers a period from 2004-2006, when the company was still operating at average capacity, but when the reduction of activity had already begun. I can say that the organization, the nature and content of the information gathered can be found with some customizations in any state-owned mining company in the country, and not only. I was able to gather all the information from the company's current headquarters, located in the former headquarters of a mine, i.e. the Săsar mine located within the city of Baia Mare. We obtained all required data except for graphics, because all documentation, plans, digital and analog maps (a very small part of them), reflecting the company's activity, were no longer to be found at company headquarters [1].

MATERIALS AND METHODS 1. Overview of the national company of precious and nonferrous metals “REMIN” Baia

Mare, general information about the company The National Company of Precious and Nonferrous Metals “REMIN” S.A. is located in

Baia Mare, was established by Government Decision no. 832 of 17 December 1997, is organized and runs on economic management and financial autonomy, according to legal provisions and its status, is a Romanian legal entity, owned by the state, with the legal form of a joint stock company and it operates under the Romanian law. The company’s aim was to meet the national strategy


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established for the extraction of minerals by performing, in compliance with Romanian legislation, acts of trade corresponding to its activity. The company's main activity (in compliance with NACE codes of classification in Government Decision no. 656*/1997): 1320 - Extraction and preparation of nonferrous and rare ores (excluding radioactive ores).

Fig. 1. Ortophotoplan:

The National Company of Precious and Nonferrous Metals “REMIN” S.A.

The structure of the company is approved by the general assembly of shareholders, at the proposal of the General Director, with the approval of the Board of Administrators. In performing its duties, the company has in its structure a department located in Baia Mare, and several other subsidiaries and sub-units around the country, depending on each specific activity: production subunits, respectively mines, factories, sectors, departments, workshops, laboratories and other subunits needed for the activity.

Mining has produced, due to its specific features, a large amount of mining waste and multiple and varied negative effects on the environment. Due to outdated technology and equipment, which generated technological losses and because, at that time, all of the metals from ores processed could not be recovered by existing technology, large amounts of ferrous metals (copper, lead, zinc), precious (gold, silver) and rare metals (tungsten, molybdenum, cadmium) can still be found in ponds, which were considered uneconomic to recover [2]. 2. Activities that influences direct activities. Information on the impact of the environmental

on mining, utilities A. Water and sewerage networks [4]

There is a well established computer system in the company S.C. VITAL S.A,. the one managing water and sanitation in the municipality of Baia Mare. Thus all networks are topographically organized with GIS - Autocad operated - using layers with descriptive attributes. Such examples are presented below: the attribute for sewages is the data regarding manholes, in Fig. 2 is the topographic plan of the water supply and sewage networks in the municipality of Baia Mare.


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Fig. 2. The topographic plan of the water supply and sewage networks in the municipality of Baia Mare

B. Electrical networks

The company Electrica S.A., managing the electrical networks in the municipality of Baia Mare, has a filing system using GIS that is also being administrated in Autocad. Electric derivations of REMIN were identified at the Săsar mine, on groups of power. There is no site plan of these networks. Fig. 3 is the topographic plan of the electrical networks in the municipality of Baia Mare.

Fig. 3. The topographic plan of the electrical networks

in the municipality of Baia Mare

C. The network of roads and access ways to the REMIN premises There is a GIS organized cadastre of the roads in the county, also in Autodesk (CAD

software), which shows the access routes to the REMIN premises.


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Table 1. Evaluation record regarding the degree of informatization in the organization

No. Theme No. Theme 1. Institution, identification data 20. Information in networks 2. Institution is subordinated.... 21. Intranet 3. Institution is in charge of.... 22. Internet access 4. Current status of the institution... 23. Institutional web 5. Basic mining activity... IV. Data Intentions Computerization I. System Information 24. Computerization projects 6. Organizational chart 25. Software used compartments 7. Direct management* 26. Software used functions resolved

7.A Hierarchical superior 27. Databases 7.a. Information processed 28. Graphic documentation digitizing 7.b. Information received 29. Digitization analytical documentation 7.c. Decisions processed 30. Databases 7.B Hierarchical inferior 31. Information networks 7.a. Information processed 33. Intranet 7.b. Information received 33. Internet Access 7.c. Decisions processed 33. Web institutional 8. Coordination department "X" ** 34. Computerization priorities

8.A Hierarchical superior V. Budget for Computerization 8.a. Information processed 35. Total 8.b. Information received 36. Broken down into stages and functions 8.c. Decisions processed VI. Current software skill level of staff 8.B Hierarchical inferior 37. Highly qualified personnel in the field 8.a. Information processed 38. Special education staff, qualified staff 8.b. Information received 39. Personnel currently using specialized software 8.c. Decisions processed VII Opportunities for training personnel 9. Executive department "Y" *** 40. Describe the desired measures, of project implem.

9.A Hierarchical superior VIII. Space allocated to the system 9.a. Information processed 41. Existing 9.b. Information received 42. Projected, potential 9.c. Decisions processed IX. Intentions for outsourcing the project or parts 9.B Hierarchical inferior 43. Intention to accept full project implem. by desc. Serv. 9.a. Information processed 44. Intention to accept project implem. on components**** 9.b. Information received X. Concl. on the timeliness and accuracy of the approach

for MDB GIS project implementation 9.c. Decisions processed 45. Concl. of the analyst carrying out the assessment 10. Other infor. circulating in the system 46. Suggestions from management (decision unit) II. Equipment 47. Suggestions from staff members 11. Hardware XI. Proposals for implem. of the MDB GIS project 12. Software 48. System changes III. Current Data regarding comput. 49. Changes on information flow 13. Computer. projects implemented 50. Changes on content of the information 14. Software used on compartments IV. Data intentions Computerization 15. Soft. used on resolved functions 24. Computerization projects 16. Existing databases 25. Software used compartments 17. Degree of digit. of the graphic doc. 26. Software used functions resolved 18. Degree of digit. of the analyt. Doc. 27. Databases 19. Existing databases

* All members and management functions in the institution ** Including all departments in the company’s coordination unit *** Including all executive departments in the company **** Outsourced functions will be identified and given a name

Note: All information analysis will show content, level of system integration according to MDB GIS information classification scales, information update speed and extent. MDB GIS System Analyst .................. Participants in the analysis from the unit subject to it Date.......... ............................................................................ Place of analysis..................... .............................................................................


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3. Evaluation of the information system within C.N. REMIN Baia Mare Basically the only software used in C.N. Remin Baia Mare was the one related to solving

accounting and financial-supply-sale problems. Although there had been a Surpac software present, it was never used. For technical services, engineering, production planning, there was CAD software that had also been used for the few underground digitized plans. The level of technical equipment was limited to a few networked computers and the Internet. There was no Intranet, taking into account the fact that the decline of the organization took place since the beginning of the 2000s. The management's concern for better computerization of work was average, compared to similar institutions in the country. There was and still is a computer service concerned only with the current issues regarding the operation of existing computers. In the background created ,but also in similar cases,our proposal is to design a qestionaire which could facilitate the implementatiopn of the information system in the organization (Table 1). 4. MDB GIS, SWOT analysis

Performing a SWOT analysis on the implementation of an information system, be it even MDB GIS, for a company that is in liquidation, is difficult. It is therefore necessary, in these circumstances, to create a framework in which presumably one would implement, apply and develop the information system. C.N. "Remin" Baia Mare is a state owned unit coordinated by the Ministry of Economy, coordinating several mines, each with one or several mines exploiting non-ferrous metalliferous ores. Initial data is a follows: some mining software is being used in the company, also, some economic ERP-type software, there are digital cartographic materials and part of the information is digital. The company also holds GIS licenses and has used them experimentally for certain topo-cadastral documentations. Because the unit is operating at capacity, unit leadership is concerned with streamlining its activity by using computers and is willing to invest in such projects. In this respect, the SWOT analysis of Mining GIS would look like the one in Matrix 1.

Matrix 1. SWOT Analysis of MDB GIS for "Remin"

STRENGTHS WEAKNESSES � High level of concern from management to use MDB

GIS technology to solve problems of informatization in the company;

� Basic GIS files already created; � Many of the topographic plans are already digitized; � The widespread use of digital mapping methods; � There is some basic understanding and experience in

MDB GIS in several departments of the company; � The power of MDB GIS to visually present all

information entered into the system; � Integration of all information flowing into the

organization in a single, homogeneous system with a unique way of accepting and analyzing data;

� Ability to implement the system in stages, in modules, based on the cost-funds ratio;

� The use of ERP-type production planning software was a success;

� The successful use of the SURPAC software for coordinating production activity.

� The potential for GIS development is missing, in order to reduce costs and improve services, because this policy is not in line with the current business strategy;

� Limited technical skills in using MDB GIS among company personnel;

� Existing hardware and software infrastructure are obsolete; � Clear misunderstanding of the potential benefits of MDB

GIS among most of the company's decision makers (board members for example);

� The complexity of the system; it is very complex and its operation requires multidisciplinary knowledge;

� High cost of the maximum rank of implementation; � Not knowing how the modularization of the information

system is taking place; not knowing how to implement the computer system in stages, on modules;

� Weak computer links between the company and component units, i.e. between mining operations and mines.

OPPORTUNITIES THREATS � Create a GIS project portfolio to improve services and

reduce costs; � Facilitate collaboration and knowledge sharing

between departments; � Contribute to the city's green agenda by participating

in environmental protection;

� Competition for funding with other new technological initiatives;

� The effects of implementation are not immediate and results may not correspond to initial expectations;

� Possible major changes in the company's development strategy due to prices decreasing for metals resulting


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� Possibility for some of the information to circulate in multi-media;

� The cost of software used is decreasing; � The cost of hardware systems used is decreasing; � Better collaboration, exchange of information between

the company and the Ministry of Economy; � Better collaboration, exchange of information between

the company and the mines; � Better collaboration, exchange of information between

mines; � Better collaboration, exchange of information between

services, departments, corporate offices, mines; � Ability to qualify for certain discounts for software

purchased under a larger operation regarding the computerization of the organization;

� A company / mine that is entirely or mostly computer-based is easier and more efficient to run and control;

from processing; � Mining software become more efficient and can cover,

with lower costs, certain chapters in the computerization of the company;

� Low return of the mining activity due to low concentrations of ore in the area;

� Low demand for raw materials of the type operated by the company;

� Decreased prices for raw material in the international specialized market;

� Competition from potential producers in the Asian region of raw materials of the type operated by the company;

� The upgrading of acquired software is faster than the rate of depreciation, which will lead to a decrease in unit competitiveness through technical gap, or will require new investments before the depreciation of the original purchase.

CONCLUSIONS

The degree of computerization of mining companies is extremely varied from mine to mine, but the before mentioned transnational nature of the extractive industry paradoxically makes some mines in Africa, Senegal, Ghana, South Africa, Botswana or Latin America, Chile, Peru to have a higher rate of computerization compared to mining organizations in countries with a centuries old mining activity like the ones in Europe [3]. The impact of GIS on human society: GIS has emerged recently, has evolved explosively and has become indispensable in all fields that manipulate data related to the "territory"; in 1990 municipalities in most North American, Australian and some European cities (Oslo, Copenhagen, Amsterdam) had the management based on Geographical Information Systems but in 2011 no city in Romania has such a system in place. There are various applications (water, sewer, electrical networks, surveying, planning) but we cannot yet speak of urban GIS in our country, the GIS application in mining is and remains extremely limited, in a bizarre way. REFERENCES 1. RĂDULESCU M.V.G., RĂDULESCU A.T.G.,RĂDULESCU G.M.T. (2009), GIS in mining &

exploration, as a tool to based mining revenue management system, THE NATIONAL TECHNICAL-SCIENTIFIC CONFERENCE „Modern technologies for the 3RD Millenium” – ORADEA, 2009, Analele UniversităŃii din Oradea, fascicula ConstrucŃii şi InstalaŃii hidroedilitare, ISSN 1454-4067, Vol.XII, Cod CNCSIS 877.

2. RĂDULESCU M.V.G. (2012), Contributions to the realization of a concept on creating mining data bank, PHD Thesys, University of Petrosani, Faculty of Mines, Scientific Coordinator, Nicolae DIMA.

3. RĂDULESCU C., RĂDULESCU M.V.G. (2011), Approaches of the management informational systems regarding the implementation of the Geographic Information Systems (GIS) in the mining basins of Romania, International Multidisciplinary Scientific GeoConference & expo SGEM, the 12th international geoconference SGEM 2011, 17 - 23 june, 2011,. paper 92, Section 7. "Geodesy and Mine Surveying" http://www.sgem.org/ sche_pub_schedule.php, scientific data based indexing ISI Web of Science, Web of Knowledge, CrossRef and Scopus.

4. *** Documentation and informations of C.N.Remin S.A; Vital S.A.; Electrica S.A.; Baia Mare Municipality.

SABĂU C., STOIAN D., DAN D., NAGY-GYÖRGY T. pp.107-110

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PARTIAL RESULTS OF MONITORING IN A PASSIVE HOUSE

SABĂU Cristian*, STOIAN Dan, DAN Daniel, NAGY-GYÖRGY Tamás, FLORUł Sorin-CodruŃ, STOIAN Valeriu,

“Politehnica” University of Timisoara, *e-mail: [email protected] (corresponding address)

A B S T R A C T This paper presents a strategy for data monitoring into a Passive House. The Passive House has been built and is under monitoring since November 2011. After one year time there is sufficient data recorded to be able to calculate the annual energy consumption of the building and validate the design method. The monitoring system records data from 41 sensors, with the measuring pace set to 1 minute. Thus, in one year it records over 21 million different values. Therefore, a strategy is required in order to efficiently substract the relevant and important information. Because not all measured data are equally relevant at a certain stages of optimising the energy efficiency of the building, this paper will focus on the parameters relevant for evaluating the overall energy performance of the monitored building.

Keywords: energy efficiency, passive house, energy consumption, design


INTRODUCTION To pave the way for low-energy residential buildings in Romania, a Passive House has been

design and built. Then after, a monitoring system was implemented, providing a planning and evaluation of the demonstrative project for future energy efficient houses in Eastern Europe. The construction of the house began in 2010 and ended by November 2011. Since then, the building is under continuous monitoring. After one year of monitoring there is sufficient data recorded to be able to assess the annual energy consumption of the building and to assess its energy performance.

MATERIALS AND METHODS 1. Analysis of energy use in the building

As it is known, a passive house is defined as a building with very low energy consumption (max 15kWh/m2/year for heating and cooling and a total energy footprint of less than 120kWh/m2/year) [1]. The house has approximately 144 m2 living space, corresponding to the needs of an average family. The project complies with Passive House Standards, being built in a newly developing urban area nearby the city of Timisoara. [2] The exterior envelope of the passive house is composed of masonry structural walls from ceramic hollow blocks of 25 cm thickness, complemented with 300 mm thickness thermal insulation, for the vertical surfaces (fig. 1) [3] .

Fig.1. Facade detalil and exterior finishing of the passive house


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In the design phase, the end energy use of the house has been evaluated using specific design tools, including PHPP (Passive House Planning Package). The total energy consumption was estimated to 83 KWh/m2/year, accordingly to the Romanian thermal insulation building code [4]. According to the Romanian code, the building has A class of energy performance on a scale from A to G. It is to note that the unique source of energy is electrical.

In order to verify the design concept, the total energy consumption of the building has been monitored through a series of 5 electric data recorders (table 1).

Table 1. Electrical energy consumption sensors

Recorder ID Electrical energy consumption Unit EL_1 house hold [W] EL_2 lighting [W] EL_3 heating, ventilation, hot water [W] EL_4 exterior [W]

ELms_tot Monthly total [kWh] The Romanian building code uses an annual energy balance method to establish the buildings

energy performance. It is relatively easy to compare the buildings estimated energy consumption with the actual energy consumption obtained through monitoring.

From the data recorded by the monitoring system there are 3 modalities in which we can determine the monthly energy consumption. The first one is using an electricity counter that resets itself every month to zero. The second method is to determine the monthly average value of power consumption recorded by EL_1, EL_2, EL_3, and EL_4 and multiply by number of hours in a day and number of days in the month (1):

∑⋅⋅

=i

iELAveragetotELms

1000

3024)_(_ (1)

The third method is a variation of the second one, in which ELms_tot is the sum of all

recorded values. The recorded value by the sensor is multiplied by the recording interval relative to one hour. In this case the measuring is one minute which means that the multiplication factor is 1/60 (2):

∑∑

=i

iELtotELms

1000

_60

1

_ (2)

The advantage of method 2 and 3 is that we can see how much each of the 4 energy

consumers affects the total energy consumption of the building, as can be seen in Fig. 2. The major part of the energy consumed by the building is used for heating, cooling,

ventilation and domestic hot water (EL_3). Another notable amount of energy is consumed by household appliances (EL_1). EL_1 can be subject to major variation depending highly on the occupants behaviour, on their level of education, lifestyle and also of the number of household appliances. EL_2 and EL_4 also increase the building total energy consumption but, in our case, don’t have a major impact as it can be seen.

To obtain the specific energy consumption of the building for one year, it is necessary to sum ELms_tot, which represents the total energy consumption of the building for one month, for each of the 12 months, and than divide the total consumption with the heated/cooling the total floor area according to expression (3):

SABĂU C., STOIAN D., DAN D., NAGY-GYÖRGY T. pp.107-110

109

areafloorHeated

totELmsnconsumptioenergySpecific

__

___

12

1∑

= (3)

Fig.2. Monthly electric energy consumption

It can be noticed, from Fig.2, that significantly more energy is consumed during the cold winter months mainly because of the building heating demand. Also a slight ascend can be noted in the 7th month associated with the need of cooling caused by overheating.

RESULTS

The total specific energy consumption of the building, obtained through monitoring, is 45kWh/m2/year, which is less than 83 KWh/m2/year as predicted by design, confirming that the building is in class A of energy efficiency without any doubt. That leads to the conclusion that the building can be considered as a good example for future low-energy buildings. DISCUSSIONS

Obviously, there are differences between to actual Romanian code and the passive code design. The difference between the predicted energy consumption according to the Romanian code and the real consumption of the building is about 45%. This means that the actual code is not devoted to evaluate the performance of low-energy buildings.

Passive code design specification limits the total use of energy of the building to 120 kWh/m2/year, and represent one of the conditions to for a residential building to be considered a Passive House. Another condition is that the energy required for heating and cooling must not exceed 15kWh/m2/year. The last criteria is more restrictive than the firs one. At this stage of the experiment, a clear and exact value for the building energy consumption only for heating and cooling has not been compared. However we can easily calculate the energy used for heating, cooling, ventilation and domestic hot water, which is about 37 kWh/m2/year. If we substract from this last value the energy required for domestic hot water, which is commonly around 25 to 35 kWh/m2/year considering the daily hot water consumption of 4 people per household, the result would indicate that the building complies with the Passive House standard. However, further results must be precessed before certifying the real energy used for heating and cooling.


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CONCLUSIONS Monitoring is essential for validating the energy performance of low-energy buildings;

especially in countries where national codes don’t have special recommendation for such type of buildings. Low-energy buildings are more and more used; monitoring these buildings can lead to further improvement in energy efficiency. One of the most important characteristic that needs to be measured is the energy consumption. It is fundamental to monitor each main consumer/equipment individually, or if not possible, the total energy consumption must be divided into at least 4 relevant categories (Table 2).

Table 2. Relevant categories to be monitored

Nr. Category

1 heating, cooling and ventilation

2 household

3 lighting

4 other

ACKNOWLEDGMENTS

This work was partially supported by a collaborative project between “Politehnica” University of Timisoara and ArchEnerg Cluster (SolarTech Nonprofit PLC.), project number HURO/1001/221/2.2.3. This work was partially supported by a grant of the Romanian National Authority for Scientific Research, CNDI– UEFISCDI, project number PN-II-PT-PCCA-2011-3.2-1214-Contract 74/2012. REFERENCES 1. FEIST, W et. al. (2007), Passive house Planning Package 2007, Technical information. PHI-2007/1,

Darmstadt: Passivehouse Institut. 2. STOIAN, D., BOTEA, IOANA (2012), A Passive House in Western Romania – an affordable Passive

House. 16th INTERNATIONAL PASSIVE HOUSE CONFERENCE 2012. 3. STOIAN, D., DENCSAK, T., PESCARI, S., BOTEA, IOANA (2012), Life cycle assessment of a passive

house and a traditional house - Comparative study based on practical experiences. IALCCE 2012: Third International Symposium on Life-Cycle Civil Engineering.

4. *** C107/2005 – Normativ privind calculul termotehnic al elementelor de construcŃie ale clădirilor (Normative regarding termo-technic calculation of construction elements of buildings). Ministry of Regional Devel-opment and Tourism (in Romania).

5. *** http://www.sdac.ro, viewed at 12.12.2012.

SARACIN A. pp.111-118

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DISPLACEMENT AND DEFORMATION MEASUREMENT USING GROUND RADAR INTERFEROMETRY TECHNIQUE

SARACIN Aurel,

Tehnical University of Civil Engineering Bucharest, Faculty of Geodesy, e-mail: [email protected]

A B S T R A C T This article brings to the attention of specialists in terrestrial measurements, using radar interferometry for tracking movements and deformations land and buildings, using systems already on the market surveying instruments.

Keywords: sensor module, linear rail, scenario, real-time monitoring


INTRODUCTION Increasingly be required to perform fast and accurate measurements, low-cost, sometimes in

difficult environmental conditions and terrain. Using electromagnetic waves and processing of data can lead to achieving these desiderata and more, radar interferometry can collect real-time lowest shape changes of monitored object.

MATERIALS AND METHODS

An ground radar interferometry system (Ground-Based Synthetic Aperture Radar (GB-SAR)) is an active sensor for information acquisition, based on the emission and reflection of microwaves to and from the object being examined (fig.1) [10].

Fig.1. Harmonic waves form

There are three techniques [2], according to the fig.s below (fig. 2-4):

Fig.2. Stepped Frequency Continuous Wave (SF-CW)


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Fig.3. Synthetic Aperture Radar Technique (SAR)

Fig.4. Technique interferometry (InSAR)

Such radar works by transmitting short pulses of electromagnetic energy that will be reflected

by the land surface and the object examined:

c

Rt

2= (1)

1. GB-SAR concept

Fig.5. Real Aperture Radar (RAR) Fig.6. Synthetic Aperture Radar (SAR)


113

B

ccR

⋅≈

⋅=∆

22

τ

L⋅=∆

2

λϕ (2)

Displacement sensor on a track approximately parallel positioned with the scenario to be

monitored and to acquisition some radar images from slightly different angles (fig.7).

Fig.7. Principle takeover radar images Interferometry technique is based on measuring the difference in path by comparing

components of phase at two radar images, results as master and slave (fig.8) [4].

Fig.8. Referral displacement

SMd −∆Φ⋅

−=πλ

4 (3)

Influence of weather conditions and ambiguities:

noisenatmSM R ∆Φ+∆Φ+∆Φ+∆Φ=∆Φ − )( (4)

Determining the actual displacement d (fig.9) [1]:

h

Rdd p= (5)


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Fig.9. Actual displacement GB-InSAR system consists of four main components (fig.10, 11, 12 and 13):

- Sensor module that contains the proper radar and antennas. - Alignment of scan, consisting of a 2-3 meters of linear rail and motor used to move parallel

the sensor module to the observed scene for getting more radar images of the same scene from slightly different positions, using SAR technique.

- Control unit, PC with software to control the radar system. - Power supply, containing two 12 volt car batteries connected in series, and external power

supplies for the safety of your PC.

Fig.10. All components of GB-InSAR system Fig.11. Sensor module and linear rail

Fig.12. PV panel as power supplies Fig.13. Mobile system

In Europe, this technique is developed and promoted by the Politechnic di Milano, "Scuola

di Ingegneria dei Sistemi" (IDS) by IBIS systems designed for various types of applications. IBIS technology revolutionizes the traditional approach of measuring the movement and

deformation of land and structures, both in the slow movement (static) and vibration measurements (dynamic).


115

Among its innovative features include: • remote monitoring of movements in very inaccessible areas to investigate scenario at a

distance of up to 4 km; • monitoring some areas of 1-2 km square order while other sensors measure the

displacement of selected points at a time, IBIS measures the simultaneous movement of the whole scenario, in real time;

• sub-millimeter accuracy of measurement: 1/10 mm, in normal circumstances, up to 1/100 mm in special situations;

• operation at any time, in any weather conditions: day, night, fog and rain; • autonomous operation: the system can work continuous monitoring or running without

human intervention. Real-time feedback for movement allows its use as early warning risk; • dynamic measurement: IBIS allows continuous monitoring of slow movements and

deformations, but can also measure the vibrations of structures (resonant frequencies, vibration modes), up to 100 Hz.

2. IBIS terrestrial radar system types 2.1. IBIS-M (M-exploitation of surface mine)

IBIS-M system was developed for the mining industry, which allows monitoring of slopes in long-term, providing an early warning system of landslides and forecasting future operating. This not only increases the safety of surface mining, but also increases productivity by allowing a better assessment of the volume of ore mined (fig.14) [9].

IBIS-M360 is an integrated monitoring system based on multiple fixed and / or mobile units, controlled by interface using a single advanced software to provide a complete 360 degree coverage of slopes a career in real time, rendering engineers an overview of the entire career pits, providing comprehensive information about potential areas of instability.

IBIS-M360 is based to a long-range, high resolution and fast scanning capabilities, was adapted to the specific requirements of the user, therefore, is ideal for all types of operations in open pits (fig.15) [9].

Fig.14. IBIS-M in mining Fig.15. IBIS-M360 system 2.2. IBIS-L (L from land) [8]

IBIS-L system was designed for monitoring the 2D displacements of the land, such as landslides, slopes, volcanoes and glaciers, and large structures, for example dams. It can cover several square kilometers at a distance until 4 km, without being necessary the access in monitored area without manually installing reflectors. It can operate a continuous monitoring with real-time feedback of displacements or its use as a risk warning device (fig.16) [3], [5]. 2.3. IBIS-S (S for structure) [8]


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IBIS-S system is designed to monitor displacement and deformation structures such as bridges, towers and buildings in dynamic conditions (measurements of vibration) and static (slow displacement in time) (fig.17) [6].

Fig.16. IBIS-L system Fig.17. IBIS-S system

3. Software required

IBIS-M and IBIS-L is provided with Guardian software package that is specifically designed for monitoring. Guardian offers automatic radar data processing in real-time, view maps of displacement with multiple options for analysis (extraction time series for displacement, speed, settlements, etc.), and the ability to create multiple scenarios warning of danger, defining the criteria used for alarm monitoring (fig.18).

Fig.18. Guardian software window Guardian IBIS uses automatic atmospheric correction algorithms to provide accurate and

reliable displacement maps that are fully geo-referenced on a digital terrain model. Ability to manage long-term projects with large data sets makes Guardian software to be

appropriate for long-term follow movements, geotechnical and geological analysis that can be useful for the authorities in case of landslide risk .


117

IBIS-S system can work with specially developed software IBISDV who process raw files generated during sessions of measurements. The software has a complete set of features for evaluating static and dynamic overall structural movements.

Static information that can be obtained is the image in the power spectrum monitored scenario to select the monitored points and displacement time history of investigated points belonging to monitor structures (bridges, dams, landslides, etc.) [7].

Can retrieve and process data together with IBIS-S, data from dynamic sensors installed on the monitored structure to identify the resonance frequencies of the structure.

This information may lead to a complete monitoring system of efforts and viability status in a structure (fig.19).

Fig.19. Monitoring efforts in a structure

RESULTS

Advantages over traditional techniques: • remote sensor at a distance of 1 km, • accuracy of the displacement up to 1/100 mm • simultaneous mapping (for hundreds or thousands of points) of real-time deformation, • quick installation and operation, • static and dynamic monitoring, • sampling vibration of structures with frequencies up to 100 Hz, • work day and night, in all weather conditions, • provide direct displacements, which are not derived from other components of the

movements [8].

Monitoring applications: Static:

• structural load tests, • structural displacement and danger of collapse, • cultural Heritage.

Dynamic:


118

• measuring the resonance frequency of the structures, • modal analysis of structural forms, • real-time monitoring of deformation structures.

CONCLUSIONS

Determining with sub-millimeter accuracy (0.1-0.01 mm) of displacements and deformations. Possibility to observe at large distances up to 4 km of the monitored objectivs, considering the rough terrain sometimes or very difficult availability monitored surface structures. The objectiv can be monitored continuously at predetermined intervals both day and night. An important disadvantage is the very large volume of necessary equipment (130 - 150 kg) and high energy use (100-200 W). It is necessary to realize a stable platform whith concrete fasteners in the same position at each stage of observations, for the systems IBIS-L and IBIS-M. A good geo-referencing is very useful when many points are needed to observe with ground radar interferometry systems.

REFERENCES 1. ALBA, M., BERNARDINI, G., GIUSSANI, A., RICCI, P. P., RONCORONI F., SCAIONI, M.,

VALGOI, P.and ZHANG, K., 2008. Measurement of dam deformations by terrestrial interferometric techniques. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol. XXXVII, Part B1, pp. 133-139.

2. BERNARDINI, G., PASQUALE, G. D., GALLINO, N., and GENTILE, C. (2007). Microwave interferometer for ambient vibration measurement on civil engineering structures: 2. Application to full-scale bridges. In Proc. Experimental Vibration Analysis for Civil Engineering Structures (EVACES'07).

3. LUZI, G., MONSERRAT, O., CROSETTO, M., COPONS, R.and ALTIMIR, J., 2010. Ground-Based SAR Interferometry applied to landslides monitoring in mountainous areas. Proceedings of the International Conference ‘Mountain Risks’, Florence.

4. SIMONS, M. and ROSEN, P., Interferometric Synthetic Aperture Radar Geodesy, Treatise on Geophysics, Schubert, G. (ed.), Volume 3- Geodesy, Elsevier Press, pp. 391-446, 2007.

5. BURGMANN, R.; ROSEN, P. and FIELDING, E., Synthetic Aperture Radar Interferometry to measure Earth's surface topography and its deformation, Ann.~Rev.~Earth Planet.~Sci., 2000, 28, 169-209.

6. MADSEN, S. N. and ZEBKER, H. A., Synthetic Aperture Radar Interferometry: Principles and Applications, Manual of Remote Sensing, Artech House, 1999, 3.

7. BERARDINO, P., FORNARO, G., LANARI, R. and SANSOSTI, E., (2002) A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms. IEEE Transactions on Geoscience and Remote Sensing 40: 2375–2383.

8. *** www.drilline.com/files/IBIS-S.pdf , www.drilline.com/files/IBIS-L.pdf , viewed at 09/01/2013. 9. *** www.idscorporation.com/en/georadar/our-solutions-products , viewed at 15/12/2012. 10. *** http://en.wikipedia.org/wiki/Interferometric_synthetic_aperture_radar , viewed at 14/12/2012.

SAVU A., DIDULESCU C. pp.119-124

119

3D MODELLING USING LASER SCANNING TECHNIQUE

SAVU Adrian, DIDULESCU Caius*, Technical University of Civil Engineering Bucharest, Faculty of Geodesy,

e-mails: [email protected], [email protected] * (corresponding adress)

A B S T R A C T The three tehniques used in the collection of elevation data for digital terrain modelling: ground survey methods, photogrammetric methods and graphics digitizing methods are adds one: data acquisition using laser scanning technique. This article discusses the stages for three-dimensional modelling using laser scanning technique.

Keywords:terrain modelling, laser scanner, DTM, three-dimensional modelling


INTRODUCTION Digital terrain modelling is a particular form of computer surface modelling which deals with

the specific problems of numerically representing the surface of the Earth. The initial concept of a digital terrain model (DTM) originated in the USA during the late 1950s. Since then, considerable advances have been achieved, particularly in the methods of acquiring and processing terrain information. The term DTM originally referred to the use of cross-sectional height data to describe the terrain. Nowadays, however, the definition is more general and includes both gridded and non-gridded data sets. Several other terms are also used to describe essentially the same process. Among the more common are Digital Elevation Model (DEM), Digital Height Model (DHM), Digital Ground Model (DGM), and Digital Terrain Elevation Model (DTED). MATERIALS AND METHODS 1. Data acquisition

Since data acquisition is so important to all practitioners of terrain modelling, this immediately poses the question as to which techniques should be considered for use in the collection of elevation data. The four main methods which can be used to acquire elevation data are:

1. Ground survey methods normally using total stations 2. Photogrammetric methods based on the use of stereoplotting instruments 3. Graphics digitizing methods by which the contours shown on existing topographic

maps are converted to strings of digital coordinate data and the required elevations derived from them.

4. Laser scanning technique. Nowadays, terrestrial laser scanning has become an additional technique for geodetic

applications. The use of laser scanners is continuously increasing. Different laser scanners of several companies are available. The measurement result is represented by a set of points, called point cloud. Usual steps taken to collect data (point cloud) to geometrical model of the surface or manually constructing primitives are:

- Data acquisition: measuring the point cloud; - Referencing: defining a reference coordinate system and converting all data sets in the

system (in photogrammetry, the process is called orientation); - Calibration: eliminating systematic errors;


120

- Minimizing noise measurement: the process is called filtering or smoothing; - Surface modelling: estimating surface terrain using Triangulated Irregular Network or

estimation of free surfaces. 3D modeling is the process of developing a mathematical representation of a three

dimensional surface of object via specialized software, aimed at studying the properties and transformation of respective object. The product obtained is called a 3D model. It can be displayed as a two-dimensional image, following a process called 3D rendering or used in computer simulation of physical phenomena. 2. Three-dimensional modelling steps

The main methods for creating 3D models are: 1. Polygonal modelling - most models used in games and movies are polygonal models. This

method developed 3D surfaces from a large number of polygons, grouped in a network. These models are very flexible and can be rendered by computer very quickly. The disadvantage is that the surfaces cannot be created very smoothly [1].

2. Parametric modelling - this method use parameters to specify properties of object. 3. 3D solid modelling - in this method are used basic geometric objects such as cubes,

cylinders, cones and spheres, to build more complex models. This modelling technique is simple and fast.

4. NURBS modelling (Non-Uniform Rational B-Spline), as opposed to polygonal surfaces modelling, allow to create smooth curves, but the rendering is slower [2].

5. Modelling based on Spline curves or Patch type surfaces - is similar with NURBS modelling, except that the surfaces are made of curved lines, which are their edges.

3. Three dimensional modelling using cyclone software Step 1. Filtering data The first operation in the process of post-processing of point cloud data is filtering the results, which implies to eliminate the points that are not subject of the scanned area, removing items containing noise generated by: wind influence, poor reflection on the scanned surface, obstacles, moving people, scanning resolution, etc. (Fig. 1).

Fig.1. Raw point cloud (unfiltered)

It is recommended that additional items taken by the instrument to be removed manually by

the operator, which can identify them easily by analyzing the scanned area (Fig. 2).


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In the study case of this article, the removed items were the points taken from more than 50 m from the tunnel entrance and exit, points representing the crowns of trees, bushes on the side of the track. These operations were performed with the commands "Polygonal Fence Mode" and "Rectangle Fence Mode", benefiting from the program viewing modes that allow top view, front view, left, right, forward or orthographic views [3].

Fig.2. Filtered point cloud

Another filter, automatic this time, was made to eliminate very close points. The instrument is

set to start scanning for scan resolution at a certain distance (10 cm to 50 m). During the scan the instrument collects a large amount of points at close distances that define generally the same object. They are useless and slows work and information management.

Operation for removal from density of the points can be implemented with the five standard modes in the command "Point Cloud Density": without reduction, minimum reduction, average reduction, high reduction and very high reduction. In this case, the points are random reduced by different percentages from 0% to 75%, depending on the chosen reduction. The procedure is recommended for scanning short distances when the density of points is uniform in the point cloud.

After filtering and setting these operations it can proceed to data modelling based on final desired / required products.

Step 2. Obtaining TIN model (Triangulated Irregular Network) Another important milestone is the creation of digital terrain model DEM (Digital Elevation

Model) and contours lines. The software uses TIN model (Triangulated Irregular Network) , which is a network of triangles that are created as a Delaunay algorithm (Fig. 3).

In practice, for obtaining a digital terrain model are used modelling functions or geometrical models (Grid, contours and TIN). Compared with other models, TIN model has a lot of advantages and best expresses the surface, with the triangle modeling unit. The TIN model reduce redundant data from Grid model, especially in regions where land is kneaded and sudden changes appears. TIN model accuracy is higher than other models of the terrain representation because this model uses 3D triangles to generate the surface [4].


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Fig.3. The TIN model

TIN generation is done from the menu " Tools"/"Mesh”/"Create mesh". This operation can

take a long time depending on the complexity of the surface and the number of points. It is recommended that for complex objects, the generation of TIN model to carry on portions (Fig. 4).

Fig.4. Achieving TIN model piecewise

Step 3. Correct model imperfections To correct inherent imperfections: gaps or peaks (Fig. 5), occurring in creating TIN model,

the software provides tools for editing the model. These imperfections are due to the low density of points in some areas, due to shadows when scanning, due to faulty points caused by moving objects when scanning.


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Fig.5. Faults of TIN model

Elimination of peaks is done by marking the area and delete them using the

"Tools"/"Mesh"/"Delete” section. To fill gaps the routine used is "Tools"/"Mesh"/"Fill selected hole" through which gaps are filled by interpolating triangles located closest to the fault zone. In Fig. 6 are shown the effects of the two routines implemented in the fault zone from Fig. 5.

Fig.6. Correction mistakes of TIN model

The final result of three-dimensional modelling can be seen in Fig. 7 in which all the steps above are

covered.

Fig.7. 3D Modeling and Rendering


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CONCLUSIONS The number of points acquired by terrestrial laser scanning, in a short time, leads to a very

accurate interpretation of the terrain. Processing software for both registration and analysis and interpretation are modular and does not require special resources. Filtering the resulting data (point cloud) which involves removing items that are not subject of the scanned area, removing items containing noise generated by: the wind influence, poor reflection on the scanned surface, obstacles or people in motion, scanning resolution, the elimination of too close points, is automatically done at user-defined parameters. Creating digital terrain model DEM (Digital Elevation Model) based on TIN model (Triangulated Irregular Network) is relatively easy and simple, and subsequent it can automatically calculate, based on a reference level, volumes, sections, filling and excavation volumes, etc. The software provides a wide range of possibilities for exporting and importing data in different formats. This allows the use of products resulting from scanning in other softwares for various applications, especially for modeling and rendering applications. REFERENCES 1. ABDELHAFIZ A., NIEMEIER W. (2007), Automatic Texturing For Laser Scanner Meshes, 18th Conf.

Optical 3 D Measurement Techniques, Zurich, Switherland, 9-12 July. 2. AEBI U., EUGSTER H. (2004), Laserscanning & 3D-Modellierung, Vertiefungsblock am IGP der ETH

Zürich, 2004. 3. COŞARCĂ C. NEUNER J., DIDULESCU C. (2005), Scanare Laser Terestră – O nouă tehnică în

Topografia Inginerească (Terrestrial Laser Scanning – A new technique in Engineering Survey), Buletinul ŞtiinŃific al UniversităŃii Tehnice de ConstrucŃii Bucureşti, 2005.

4. *** - www.gim-international.com, viewed at 10.01.2013.

SCHEIBNER E., CÎRSTOLOVEAN I.L., MIZGAN P. pp.125-134

125

THEORETIC STUDY CONCERNING THE APPLICATION OF THE THEORY OF THE FINITE ELEMENT

TO THE MECHANICAL CALCULATION OF THE PIPES THAT CONSTITUTE A HEATING NETWORK

SCHEIBNER Emilia, CÎRSTOLOVEAN Ioan Lucian*, MIZGAN Paraschiva,

University Transilvania Brasov, Faculty of Buildings Engineering, e-mails: [email protected], [email protected] * (corresponding adress), [email protected]

A B S T R A C T The curent research represents a comparative study between the theoretical calculation method, by using resistence calculation relations of the pipes in the case of the L configuration, and the method of the finite element applied to the same L structure in the case of a pipe which transports thermal agent and which is submitted to mechanical stress. By this calculation we aim at dimensioning the thickness of the pipe’s walls, the establishment of the type and size of the tensions which appear in the most stressed points of the network.

Keywords: thermal network , finite element, straight pipes Received: January 20, 2013 Accepted: March 10, 2013 Revised: March 31, 2013 Available online: May 31, 2013

INTRODUCTION

Mechanical calculation has an essential importance for the good functioning of a thermal network, since it guarantees its fiability. We propose in this paper to analyze and to develop the method of the finite element in the mechanical calculation of the pipe networks which transports a thermal agent at high parameters. The application developed in the paper intends to demonstrate that the use of this calculation method offers precise results on the tension state in the points of maximum tension, eliminates approximations si offers data for the following calculation of supports and dilatation compressors throughout the thermal network.

MATERIALS AND METHODS

Mechanical calculation [2], [7], together with the hydraulic and thermal calculations for a thermal network, has a special importance because it guarantees for the functioning of the network’s functioning, its functioning safety and fiability.

The main elements [2], [7] which need to be known for doing the hydraulic calculation are: - The parameters of the transported fluid; - The requirements specified by the technological process; - The characteristics of the materials that the network is made of.

The primary stress that appears in a pipe is determined by the loads which influence the pipe and it is the result of the condition of equilibrium of the external and internal forces and moments.

The secondary stress which appears in a pipe is due to displacement (obstructed dilation, deformings, etc.) or differetnly said, structure constraints.

The top stress in a pipe appear due to local thermal requirements, as they are taken into consideration as possible source of damage by overlapping to the primary and secondary stress.

The primary, secondary and top stress lead [2], [7] to differnt types of damage and because of this the calculation norms for pipes introduce limitations of the stress to admissible values for each category separately as well as for their combinations.


126

1. The theoretic calculation method in the case of the naturally elastic configuration in the shape of „L”

One considers the ABC system fixed in the extremities A and C, fig.2 , by an angle φ = 90° + β between its sides [1]. In order to establish the charghing state from real functioning, one considers as eliminated the A extremity and the deformation of the configuration which makes possible for this extremity to reach A'. The real status is obtained by bringing back A' in A by the introduction of a force P and of a bending moment MA (which actually represents reactions of the rigid support). In fig.1, one evidences B’ position, after the dilatation of the sides L1 and L2.

The calculation stages [1], [5], [6], [7] are organized in the following succession: • The calculation of the maximal lateral displacement D1 and D2, fig.1, in the area of the pipes’

bendings: ( )0- tt fα=ε ;

EBFED +=1 ; βε= tgLFE 1 ; β

ε=

cos2L

EB ;

( )ββ+

α=

β

+ββ

ε=cos

sin-

coscos

sin10

211

nLtt

LLD f ; (1)

EMEBD += '2 ;

;cos

' 1

βε

=L

EB ;cos

sin2 β

βε= LEM

( )ββ+

α=

ββ

+β

ε=cos

sin1-

cos

sin

cos 1021

2

nLttL

LD f , (2)

where: ε – specific deformation; α – the dilation coefficient of the material used [mm/m·K]; tf – the fluid’s temperature in nominal conditions [°C]; t0 – the temperature of the surrounding environment in the assembly period [°C]; L1, L2 – the values of the configuration’s sides [m]; n – the ratio of the configuration’s sides (n = L2/L1); β – the supplement above 90°C of the angle φ between the sides of the compensator.

Fig.1. The calculation scheme for the displacement of the pipes’ bendings [1]


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These displacements impose to be lower than the values of the maximally admited displacements (0,16...0,17 m) for forestalling the fall of the pipes from their supports or the occurence of some reactions from the lateral walls of the thermal ditches where pipes are placed. • The calculation of the AA' displacement (fig. 2), by using the relations

22, yxAA ∆+∆= ; (3)

( )0120 -cos ttnLTLxx ft βα=∆α=ε=∆ ; (4)

( )( )0120 -sin1 ttnLTLyy ft β+α=∆α=ε=∆ , (5)

where: ∆x and ∆y – movements on the x and y axes; εt – specific thermal deformtion; ∆T – temperature difference [°C].

Fig.2. The calculation scheme of the elastic configuration in the shape of „L”[1]

• The calculation of the coordinates of the weight centers G1 and G2 of the section AB and BC

xG1 = 0 xG2 = βcos2

11nL (6)

yG1 = 21L

yG1 = L1+ βsin2

11nL

• The calculation of the static moments of the system in comparison to the axes x and y: 2211 LyLyM GGsx += ; 2211 LxLxM GGsy += , (7)

G2 G1


128

where: Msx, Msy – the static moments of the system in comparison to the axes x and y; xG1,xG2, yG1,yG2 – the coordinates of the weight centers in comparison to the axes x and y.

• The calculation of the coordinates of the weight center of the system

1111

;nLL

M

nLL

Msxsy

+=η

+=ξ . (8)

• The calculation of the inertness moments of the system in comparison to the axes x and y ( )β+β++= 2323

1 sin3/1sin3/1 nnnLI x ;

( )β= 2331 cos3/1 nLI y ; (9)

( )β+ββ= cos2/1cossin3/1 2331 nnLI xy .

• The calculation of the inertness moments of the system in comparison to the axes xG and yG )( 21

2 LLII xsG +η−= ;

)( 212 LLII yyG +ξ−= ; (10)

)( 21 LLII xysyG +ηξ−= .

• The calculation of the X and Y components, which are obtained from the general relations

2-

GGG

GG

xyyx

xyy

III

yIxIEIX

∆+∆= ; (11)

2-

GGG

GG

xyyIx

xyx

IIl

xIyIEIY

∆+∆= ,

where: E – longitudinal elasticity module for the steel the pipe is made of [MPa]; I – the inertness moment of the pipe’s section [cm4].

• The calculation of the bending moments in the points A, B, C by placing the forces X and Y in the G weight center of the configuration

ξ−η= GGA YXM ; (12) ξ−−η= GGB YLXM )( 1 ; )]sin1([)cos( 11 η−β+−ξ−β= nLXnLYM GGC . • The calculation of the maximal bending stress

atW

Mσ=σ ≤max

max , (13)

where:

σat – admitted stress of the steel in the pipe (100-110 MPa); W – the resistence mode of the pipe in the section [cm3].


129

2. The analysis of a “L” type pipe under the action of some thermal charges by using the method of the finite element The analysis of the “L” type pipe is made in what follows by using the method of the finite

element [3], [4]. By its help, one checks the calculations for: the components of the point A displacement under the effect of the thermal deformation in the direction x and y; the components of the reaction elastic force in the direction x and y as well as the bending moments in the direction x and y.

The study of this type of pipe has been done according to two analysis scenarios: 1. Scenario 1 – the C end of the pipe through which circulates thermal agent at the

temperature of 150°C is fastened, and the A end of the same pipe is free. On the basis of this scenario we studied the displacements in points A and B of the pipe under the action of the thermal charge;

2. Scenario 2 – the ends A and C of the pipe through which circulates thermal agent at the temperature of 150°C is fastened, in this way being simulated the placement of the pipe. Similarly, a thermal charge was applied to the pipe and on its basis the reactions (the forces and the moments) which appear in the placement areas were determined.

The schemes for the scenarios taken into consideration are presented in fig. 3 and fig. 4. The material the pipe is made of is OL38, with the following mechanical properties:

elasticity module E = 195000 [MPa]; the coefficient of the transversal contraction Poisson μ = 0,3; density ρ = 7,8·10-9 [tones/mm3]; thermal dilatation coefficient α = 1.17·10-5 [mm/m·K].

Fig. 3. The scheme for Scenario 1 of analysis

Fig. 4. Scheme for Scenario 2 of analysis


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The external diameter of the pipe is De = 620 mm, and the thickness of the pipe’s wall is s = 8 mm. The internal diameter di is calculated in the following manner:

di = De - 2s = 620 -2·8 = 604 mm

In table 1 are presented the geometrical parameters of the pipe that were determined by the

help of the Pro/Engineer program.

Table 1. Geometrical parameters of the pipe that were determined by the help of the Pro/Engineer program

Coordinates of the weight centers in comparison to the reference system x, y of the

segments AB and BC [mm]

The origin of the system is A

The inertness moments of

the transversal

section

[mm4]

Coordinates of the weight

centers of the system in

comparison to the system xAy

[mm]

The inertness moments of the system in

comparison to the axes x si y

[tones·mm2]

The inertness moments of the system in

comparison to the axes xG and yG

[tones·mm2]

segment AB x = 0 y = 20000,152

segment BC

x=18793,647 y =46841,281

Iz = Iy = =7.2024·108

x = 33420,814 y = 9396,0527

=

IyyIyx

IxyIxx

⋅⋅

⋅⋅=

99

910

1026.21045.4

1045.41032.1

=

IyyIyx

IxyIxx

⋅⋅

⋅⋅=

99

99

1041.11042.1

1042.11045.2

2.1. The results of the analysis with the finite element for Scenario 1

In figure 5 are presented the maximal lateral dispalcements in the area of the pipe’s bending (point B) and the free end, and in fig. 6 are presented the maximal vertical displacements. The displacements resulted from the pipe are evidentiated in fig. 7.

Fig. 5. Maximal lateral displacements in the points A and B of the pipe


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Fig. 6. Maximal vertical displacement in the points A and B of the pipe

Fig. 7. The displacement field resulted from the pipe


132

2.2. The results of the analysis with the finite element for Scenario 2 Within this scenario (the fastening of the pipe in points A and C) we will determine the

maximal lateral dispalcement of the pipe in point B (fig. 8) and the reaction forces obtained in the placement areas, in the points A and C (fig. 9).

Fig. 8. The maximal lateral displacement of the pipe in the point B

Fig. 9. The reaction forces obtained in the points A and C of the pipe

The reaction bending moments obtained in the placement areas, respectively in the points A and C are graphically evidenced in fig.10.


133

Fig. 10. The reaction bending moments obtained in the placement areas in the points A and C

The maximal deformation is obtained in the area of the bending, respectively in the point B

(fig. 11) and has the value of 39,64 MPa. The stress that appears in the pipe is produced by dilatation due to the temperature difference, thus in the bending area, where the effect of stress concentration is highest deformations will become evident which will trigger the change of the pipe’s path.

Fig. 11. The distribution of the equivalent stress in the area of the bending in point B

CONCLUSIONS 1.The theoretical calculation by using acknowledged calculation relations is difficult and

imprecise; 2.The method of the finite element applied to pipes offers precise and detailed solutions; 3. The method of the finite element can be applied to all kinds of natural configurations;


134

4. The method helps to the determination of the stress state and to the precise dimensioning of the fix points placed in the path of the pipe.

5. The dimensions of the supports for pipes are established with great precision, in this way, overdimensioning is avoided.

REFERENCES 1. ILINA M., BERBECARU D. ş.a. (2002), Manualul de instalaŃii - InstalaŃii de încălzire (Installation

Course Book – Heating Installations), vol I, Ed. Artecno, Bucureşti, ISBN 973-85936-1-1. 2. LECA A. ş.a. (1974), Conducte şi reŃele termice (Pipes and Thermal Networks), Ed. Tehnică, Bucureşti. 3. MOTTRAM J. T., SHAW C. T. (1996), Using Finite Elements in Mechanical Design. McGraw-Hill

Publishers, New York, ISBN 978-0-077-09093-7. 4. PARISHER R., RHEA R. (2012), Pipe drafting and design. Editura Elsevier Ltd, ISBN 978-0-12-

384700-3. 5. URDEA M. (2010), Natural Elastic Compensators, in Academic Jurnal of Manufacturing Engineering,

vol. 8, ISSUE 3, ISSN 1583-7904. 6. URDEA M., SCHEIBNER E. (2009), Calculation of Natural Elastic Compensators Configurations.

Technical University Press, Sofia, Bulgaria, Nov., ISSN 1313-7530. 7. SCHEIBNER E.-M. (2011), Theoretical and practical research on structural optimization of pipe

supports and fastening components in industrial plants. Teza de doctorat (Ph.D. Thesis). Universitatea „Transilvania” din Brasov (“Transilvania” University of Brasov).

STOIAN D., DAN D., STOIAN V., NAGY-GYÖRGY T., TĂNASĂ C. pp.135-140

135

ECONOMIC IMPACTS OF A PASSIVE HOUSE COMPARED TO A TRADITIONAL HOUSE

STOIAN Dan*, DAN Daniel, STOIAN Valeriu, NAGY-GYÖRGY Tamás, TĂNASĂ Cristina,

“Politechnica” University of Timisoara, *e-mail: [email protected] (corresponding address)

A B S T R A C T This paper presents the economic impact and construction costs of a passive house in the Romanian building sector. Energy efficiency achieved through energy performance of the buildings is a relatively new field in Romania and most people are skeptical in approaching it because of the higher initial investment. In the city of Timisoara, a residential house was designed and built as passive house complying with the European passive house standard. In order to enhance the main advantages of the passive house, the same residential house was designed as a traditional house. Further, a comparative study was made between the passive and the traditional house. The main purpose of this paper is to enlighten that investing in a passive house brings great economical and comfort advantage despite the higher initial investment.

Keywords: passive house, energy efficiency, construction costs


INTRODUCTION Reducing the energy consumption in the building sector is a topic of great importance at

international level. The continuous growth of the energy price determined authorities and specialists to develop methods and technics to build up houses with high energy performance. Measures and ways of rising the energy performance of buildings are quite new in the Romanian building sector. Adopting energy efficient solutions in order to achieve the Passive House standards implies a higher initial investment for the construction costs. Therefore, most of the people are skeptical in approaching the energy efficient buildings standards when building a house. MATERIALS AND METHODS

The Passive House standard is one of the most suitable solutions when taking in consideration the construction of an energy efficient building. This type of construction is described as an energy efficient building (max. 15 kWh/m2/year for heating and cooling and a total energy footprint of less than 120 kWh/m2/year) [1]. A house built complying the passive house standard ensures good comfort conditions during winter and summer, without active cooling or traditional space heating system. The main characteristics of the passive house are the higher level of thermal insulation, airtightness of the envelope and very good-quality indoor air ensured by a mechanical ventilation system with heat recovery. A passive house might use renewable energy sources when possible [2].

Building a house at a passive house standard implies the disadvantage of a higher initial investment than a traditional house but it has advantages that overcome the higher construction costs. Recently, in the city of Timisoara a passive house was built and is under monitoring. The same house was designed and analyzed as a traditional house in order to obtain a relevant comparison between the costs of the two types of buildings [3]. The Passive House built in Romania, near the city of Timisoara has approximately 144 m2 living space and fulfils the space need of an average family. From architectural perspective, the passive house has an advantageous south orientation of the facades with large windows and presents a very compact form (Fig.1). These features help reducing heat losses. The south orientation of the windowed facades avoids overheating during summer times and ensures sunshine penetration during winter times.


136

The infrastructure system of the house consists in isolated concrete blocks connected with foundation beams in order to ensure sufficient stiffness. The foundation system reduces the amount of used concrete and facilitates the thermal insulation of the entire ground floor, the polystyrene plates being applied from the foundation beams upwards (Fig.2).

Fig.1. The studied passive house Fig.2. Thermal insulation of the foundations The house is built on masonry system with vertical hollow ceramic blocks of 25 cm

thickness, confined by RC columns and belts (Fig.3). The traditional house has a continuous foundation system under the resistance walls but the structural skeleton is identical with the one of the passive house.

The main difference between the two houses is the level of thermal insulation. The exterior envelope of the passive house has a thermal insulation of 300 mm thickness for the vertical areas (Fig.4) and 150 mm for the upper part of the parapet. In return, for the traditional house was considered a layer of thermal insulation of 80 mm thickness.

Fig.3. The structural system Fig.4. Thermal insulation of the facade The high level of thermal insulation is a key point when considering building a passive house

and one of the reasons of the higher prices. The roof of the passive house is a non-traffic terrace that has a 425 mm thickness of thermal insulation. The layers of the roof are the same for both buildings, passive and traditional (Fig.5), the only difference consists in the thermal insulation thickness which is 100 mm for the traditional house.


137

Ballast 50mmGeotextileBituminous membrane 5mmSandCement mortar, slope 2% min. 50mmPolyethilen foilThermal insulation(Polystyrene expanded) 320mmVapour barrierWooden floor 50mmMineral wool 100mm,between timber beams 150x250mmSteel profiles 60mmGypsum plaster board 10mmInterior finishing

Fig.5. Layers used for the flat roof of the passive house

All the elements of the envelope of the passive house must have a heat transmission

coefficient U of maximum 0.15 W/m²K. Besides the good thermal insulation, windows used in the passive house should have U-values for around 0.70 – 0.90 W/m²K. For the discussed passive house, the used windows are not quite at passive house level but they have an appropriate heat transmission coefficient at on much lower cost. The limit value for the air leakage rate of a passive house must not exceed 0.6 volumes per hour and it must be verified through measurements.

With the high thermal insulation level and very efficient U-values for the other envelope element, the built passive house is air tighten. Therefore, a ventilation system is required. The passive house does not dispose of traditional heat generators such as radiators. In order to solve heating and cooling, the studied passive house uses a mechanical ventilation system with heat recovery. The process consists in preheating the intake air for the ventilation system through underground heat exchangers. The house is equipped with an air-water heat pump. The heat pump assures the heating of the house. The necessary equipment (with heat pump, heat recovery ventilation unit, air heating unit, 3-way valves, heat buffer tank, solar pump and domestic hot water tank) of the passive house are functioning in a mechanical room (Fig. 6). The passive house also disposes of a solar panel used for heating.

Fig.6. Mechanical room of the passive house

The interior finishing of the passive house is quite simpler, with nothing in particular:

laminated parquet in rooms, ceramic tiles and faience in bathrooms, kitchen and access hole, water


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solvent wall-plaster-paint and interior doors of wood panel. For the traditional house the same interiors were considered. The interior compartment walls are in both cases gypsum plaster boards of 150 mm thickness on metal structure. As it is presented, the two studied house are not different from structural and architectural point of view. The differences appear when it comes about airtightness, heat transmission coefficient of the envelope elements, heating and cooling methods. The passive house uses high quality materials for the envelope, in order to ensure airtightness and eliminate heat losses. Another extra cost that a passive house implies compared with the traditional house is the heat pump, the ventilation system with heat recovery, the solar panel. The evaluation of construction costs for the two buildings is made considering that the traditional house uses the same technologies and materials when possible. It is proved that standard materials and techniques can turn a traditional house into an energy efficient house if they are used properly.

The initial investment for the studied houses represents the cost for the field, project, field studies, technical assistance, execution of building with all the materials and equipment. After the evaluation and comparison of the initial investments, it is relevant to determine the future costs with the energy consumption for the two houses.

The passive house from Timisoara is under monitoring over a year ago [4]. The purpose is to determine the building’s energy consumption and control comfort parameters.


After designing the two houses, an evaluation of the construction costs was made. As we expected, the initial investment for the passive house was higher than for the conventional house. While for the passive house was needed an amount of 149,033 €, for the traditional house the construction costs limit at 117,290 €. There is a considerable difference between the two investments (Fig. 7). The 27% difference comes from: 3 times higher level of thermal insulation used for the passive house, triple glazed windows and special mechanical installations.

Fig.7. Initial investment evaluation Using the data from the monitoring system, a monthly energy consumption evaluation for

the passive house was made (Fig.8) taking in consideration energy consumptions for heating, cooling, ventilation, hot water and lightning.

149,033

117,290

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

Passive House Traditional house

EUR

Initial investment


139

1302,84

180,21

0

200

400

600

800

1000

1200

1400

12 1 2 3 4 5 6 7 8 9 10 11

kWh

Total Energy

Consumption

Fig.8. Monthly energy consumptions for the passive house

The passive house achieved a total energy consumption of 6410.12 kWh. This result was

obtained after a year of monitoring of the passive house, starting December 2011. The maximum value of the energy consumption was registered in February and the minimum in August. The total energy consumption for the entire house, is then divided by the area of the building (144 m2) in order to obtain the energy consumption per unit m2. The result is 45 kWh/(m2year). To see the energy consumption difference between traditional and passive house we used a conventional calculation method to determine the energy consumption for the traditional house [5]. The result is an annual energy consumption of 205 kWh/(m2year) [6]. In 2011-2012, the price for electrical energy in Romania is approximately 0.1 €/kWh. Therefore, the cost with the energy for the passive house in a year is for about 712 €. On the other hand, for the traditional house the costs are around 3280 €/year. As it can be noticed, the energy consumption costs in a year for a traditional house are for about 4.5 times higher than for a passive house.

CONCLUSIONS

The paper mainly presented methods to build a passive house compared to a conventional house. The purpose was to enhance that a passive house can easily be built by using almost the same conventional materials and methods as the traditional house. of course, in order to obtain the passive house standard, a high level of thermal insulation is required completed with high quality materials and technics. Also, special mechanical systems are needed in order to ensure and maintain the indoor comfort with a low energy consumption. It is relevant to conclude that even though building a passive house implies a higher construction cost, in a few years the additional expense will be recovered thanks to the energy savings. The main advantage of the passive house is that the invested many are recovered and after that, the house continues saving energy, and therefore money, for its owner.

ACKNOWLEDGMENTS

This work was supported by a collaborative project between “Politechnica” University of Timisoara and ArchEnerg Cluster (SolarTech Nonprofit PLC.), project number HURO/1001/221 /2.2.3. REFERENCES 1. FEIST W. (2007), Passive house Planning Package 2007, Technical information, PHI-2007/1,

Darmstadt: Passive House Institute.


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2. STOIAN D., DENCSAK T., PESCARI S. and BOTEA I. (2012), Life cycle assessment of a passive house and a traditional house - Comparative study based on practical experiences, Third international Symposium on Life-Cycle Civil Engineering IALCCE, 3-6 October 2012, Vienna, Austria.

3. STOIAN D., BOTEA I. (2012), A passive house in western Romania-an affordable Passive House, 16th International Passive House Conference 2012, 4-5 May 2012, Hannover, Germany.

4. *** (2005), Normativ privind calculul termotehnic al elementelor de construcŃie ale clădirilor-C107/2005 (Normative regarding the thermo technical calculation of construction elements of the buildings), Ministry of Regional Development and Tourism, Romania.

5. STOIAN D., PESCARI S., STOIAN V. (2010), Life-cycle cost concept applied for traditional and passive house design, Buletinul AGIR.

6. *** http://www.sdac.ro, viewed at 12.12.2012.

AUTHORS INDEX pp.141-142

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AUTHORS INDEX

Alexa Pavel Ph.D. Professor Eng., Associated at Technical University of Cluj-Napoca, Dep. of

Structural, Romania, e-mail: [email protected]

Andreica Ligia Ph.D. Teaching Assistant Arch., Technical University of Cluj-Napoca, Faculty of Civl Engineering, Dept. of Civil Engineering, 25, G.Baritiu Street, 400027, Cluj-Napoca, Romania, tel: +40-264 401557, e-mail: [email protected]

Bindea Mihai PhD Assistant Eng., Technical University of Cluj-Napoca, Structures Dep., tel: 0040-264-401545, Romania, e-mail: [email protected]

Berindean Adrian D. Lecturer Eng,., Technical University of Cluj-Napoca, Faculty of Civl Engineering, Dept. of Civil Engineering, 25, G.Baritiu Street, 3rd floor, Room 215, 400027 Cluj-Napoca, Romania, tel: +40-264 401529, e-mail: [email protected]

Berindean Alexandra C. Assistant Eng., Technical University of Cluj-Napoca, Faculty of Civl Engineering, Dept. of Civil Engineering, 25, G.Baritiu Street, 3rd floor, Room 215, 400027 Cluj-Napoca, Romania, tel: +40-264 401529, e-mail: [email protected]

Cătărig Alexandru Ph.D. Professor Eng., Associated at Technical University of Cluj-Napoca, Dep. of Structural Mechanics and Faculty of Civil Engineering and Architecture fromUniversity of Oradea, Romania, e-mail: [email protected]

Cîrstolovean Ioan Lucian Ph.D. Lecturer Eng., University Transilvania Brasov, Faculty of Building Engineering, Romania, e-mail: [email protected]

Cobîrzan Nicoleta Ph.D. Lecturer Eng., Technical University of Cluj-Napoca, Faculty of Civl Engineering, Dept. of Civil Engineering, 25, G.Baritiu Street, 400027, Cluj-Napoca, Romania, tel.: +40-026 4401553, e-mail: [email protected]

Dan Daniel Politehnica University of Timisoara, Romania

Deuşan Simona Technical University of Cluj-Napoca, Romania

Didulescu Caius Technical University of Civil Engineering Bucharest, Faculty of Geodesy, Romania, e-mail: [email protected]

Dumitraş Macedon Ph.D. ProfessorEng., Technical University of Cluj-Napoca, Faculty of Civl Engineering, Dept. of Civil Engineering, 25, G.Baritiu Street, 400027, Cluj-Napoca, Romania, e-mail: [email protected]

FloruŃ Sorin-CodruŃ Politehnica University of Timisoara, Romania

Ionaşcu Anamaria PhD Eng., Technical University of Civil Engineering Bucharest, Romania, e-mail: [email protected]

Kopenetz Ludovic Ph.D. Professor Eng., Technical University of Cluj-Napoca, Faculty of Civl Engineering, Romania, e-mail: [email protected]

Mancia Mircea Sebastian Eng. PhD student, University of Oradea, Romania, e-mail: [email protected]

Mizgan Paraschiva Ph.D. Lecturer Eng., University Transilvania of Brasov, Romania, e-mail: [email protected]

Moga Ligia Eng. PhD, Assistant Professor, Dept. of Buildings and Management, Faculty of Civil Engineering, Technical University of Cluj-Napoca, Romania e-mail: [email protected] ; http://constructii.utcluj.ro ; www.utcluj.ro

Moldovan Alexandra Raluca Eng., Student PhD, Faculty of Civil Engineering, Technical University of Cluj-Napoca, Romania, e-mail: [email protected]


142

Nagy-György Tamás Politehnica University of Timisoara, Romania

Nistor Sorin Assistant Eng., Student PhD, University of Oradea, Faculty of Civil Engineering and Architecture, Dep. of Cadastre and Architecture, 4 B.St.Devrancea, Romania, e-mail: [email protected]

Ousseynou Diao Docteur, École Supérieure Polytechnique, Université Cheikh Anta Diop de DAKAR-SÉNÉGAL, Chercheur au laboratoire d'énergétique Appliquée, e-mail: [email protected]

Pop Mariana Lecturer Eng., Student PhD, University of Oradea, Faculty of Civil Engineering and Architecture, Dep. of Civil Engineering, 4 B.St.Devrancea, Romania, e-mail: [email protected]

Prada Marcela Associated Professor Ph.D. Eng., University of Oradea, Faculty of Civil Engineering and Architecture, Dep. of Civil Engineering, 4 B.St.Devrancea, Romania, e-mail: [email protected]

Puskas Attila PhD Lecturer Eng., Technical University of Cluj-Napoca, Structures Dep., Romania, e-mail: [email protected]

Rădulescu Adrian T. G. Technical University of Cluj Napoca, Romania

Rădulescu Corina Technical University of Cluj Napoca, Romania

Rădulescu Gheorghe M.T. Technical University of Cluj Napoca, Romania, e-mail: [email protected]

Rădulescu Virgil Mihai G. M. Technical University of Cluj Napoca, Romania

Sabău Cristian Politehnica University of Timisoara, Romania, e-mail: [email protected]

Savu Adrian Technical University of Civil Engineering Bucharest, Faculty of Geodesy, Romania, e-mail: [email protected]

Sărăcin Aurel Tehnical University of Civil Engineering Bucharest, Faculty of Geodesy, Romania, e-mail: [email protected]

Scheibner Emilia Ph.D. Eng., associate professor toUniversity Transilvania Brasov, Faculty of Building Engineering, Department of Installations for Constructions, Romania

Stoian Dan Politehnica University of Timisoara, Romania

Stoian Valeriu Ph.D. Professor, Politehnica University of Timisoara, Romania, e-mail: [email protected]

Tănasă Cristina Politehnica University of Timisoara, Romania

Toadere Mihaela Teodora PhD Lecturer Eng., University of Oradea, Faculty of Civil Engineering and Architecture, Dep. of Civil Engineering, 4 B.St.Devrancea, Romania, e-mail: [email protected]

GUIDE FOR AUTHORS pp.143-144

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