March 2010 1

Fifteen years of ACECOMS

Creep Influence on Durability and Reliability of Prestressed Concrete Structures under Long-term Loads

Seismic Behaviour of Structure with Vertical Irregularities

Different Techniques for the Modeling of Post-Tensioned Concrete Box-Girder Bridges

Finding the Tension Side and Deflection Profile of a Structural Member by Observing Moment Directions

March 2010

MODELING• Object-Based Graphical Interface• Frame, Cable and Tendon Members • Area (Shell) and Solid Objects with Internal Meshing• Automatic Generation of Code Lateral Wind and Seismic Loads• Transfer of Loads from Area Objects to Framing Systems

ANALYSIS• P-Delta and Buckling Analysis • Post Tensioning in Frame, Area and Solid Objects • Layered Shell Element • Time History Analysis, including Multiple Base Excitiation • Moving Loads • Nonlinear Static Pushover Analysis • Nonilnear Time History – Wilson FNA, Direct Integration Methods

DESIGN • Steel Frame Design for Numerous International Codes• Concrete Frame Design for Numerous International Codes• Aluminum Frame Design for AA Codes• Cold-Formed Steel Frame Design for AISI Codes• Design for Static and Dynamic Loads• Member Selection and Optimization

BRIDGE DESIGN MODULE (Add-on) • Layout Line Definition using Bearings and Stations• Moving Loads with 3D Influence Surfaces• Cross Section Generation using Parametric Templates• AASHTO, LFD & LRFD Codes• Straight and Curved Girder Design with Post Tensioning conditions, etc.• Import of StruCAD*3D data files• Implementation of updated API functions

STAGED CONSTRUCTION MODULE (Add-on)• Sequencing Allowing Adding or Removing Objects/Loads/Supports• Time Dependent Creep, Shrinkage, Aging and Steel Relaxation• Explicitly Model Time Dependent Effects Using Tendon Objects

OFFSHORE/WAVE MODULE (Add-on)• Wave Load Generator• API Steel Frame Design with Punching Shear Checks• Simplified Fatigue Analysis Based on API Criteria

Chief Patron

Prof. Worsak Kanok-NukulchaiVice President for Resource Development Chief Editor

Dr. Naveed AnwarDirector, ACECOMS

Editor

Hafsa Hamid

Assistant Editor

Romeo D. Faller, Jr.

Graphic Designer

Khattiyanee Khancharee

Proof Editing

Faisal M. AlihAna Victoria S. Kebasen

The Asian Center for Engineering Computations and Software ACECOMS, 2010_________________________________School of Engineering and TechnologyAsian Institute of TechnologyP.O. Box 4, KlongluangPathumthani 12120THAILAND

Street Address:Km. 42 Paholyothin Highway,Klongluang, Pathumthani 12120THAILAND

Phone:+(662) 524 5539, 524 6416+(662) 516 0110 to 44

Fax:+(662) 524 6059, 524 5539 ext 105

Price : US $ 5.00

Finding the Tension Side and Deflection Profile of a Structural Member by Observing Moment Directions- Udit Rastogi

Articles

8

4

Creep Influence on Durability and Reliability of Prestressed Concrete Structures under Long-term Loads - Gnida Sossou

Fifteen years of ACECOMS

Different Techniques for the Modeling of Post-Tensioned Concrete Box-Girder Bridges - Naveed Anwar, Deepak Rayamajhi, Jimmy Chandra

24

30

Seismic Behaviour of Structures with Vertical Irregularities- Sekhar Chandra Dutta, Piyali Saha, Snehashis Sinha, Kundan Goswami

14

Some of the research being carried out by Structural Engineering Masters Students at AIT- Amelia Kusuma, Ja San Lu, Rojit Shahi, Stefani Reni

33

• IABSE Symposium: First time in Southeast Asia 13 • NEWS on Construction around the world 20 • ACECOMS Member's Profile 29 • Two Decades of rapid improvements in performance of Personal Computers 35 • Recent Trainings and Seminars 39 • NEWS and Updates 45 • Research and Consultancy Projects 47 • Natural Disasters 2009 49

ACECOMS

Vol: M37-0315-0310

Miscellaneous

March 20104

ACECOMSThe Asian Center for Engineering Computations and Software (ACECOMS) is a regional, non-profit and self-supporting Center established at the Asian Institute of Technology (AIT) Thailand. It was conceived in 1993, as a continuation and expansion of the activities of the MicroACE Club, an informal organization established at AIT as early as 1985 by Prof. Worsak Kanok-Nukulchai. That was when microcomputers were beginning to be popular in the Asian region. The basic objective was to promote the proper use of this emerging technology. It was achieved by first developing simpler and more “controllable” versions of structural analysis programs using (otherwise efficient and accurate) finite element methods and procedures, and then conducting extensive training on their effective use for the engineers already working in the field. This helped to dispel some of the mystery surrounding these tools and methods. The MicroACE Club conducted several training workshops under the banner of M/SEAP and developed the highly popular MICROFEAP software with Dr. Somporn Attesawarong, as one of the key authors, and the XETABS authored by Prof. Worsak. However, it was soon realized that to be more effective, this activity had to be carried out in a more formal and extensive manner, thus in 1995, ACECOMS was formally established.The prime mission of this Center is “to provide an impetus to the research in engineering computations and the development of quality computer software for engineering applications, its wide spread promotion, and training on the effective use of current computing technology in the Asian and the Pacific regions”. The Center continued the organization of M/SEAP series of workshops and added a new series of one-day seminars called O-SCAAD, short for One-day Seminars on Computer-Added Analysis and Design. On the software front, the Center released SDL-1 package consisting of several reinforced concrete design modules, originally developed by Dr. Naveed Anwar, now the Director of ACECOMS. The Center also expanded the XETABS software and developed a Windows version, called BATS, with extensive graphical capabilities. A completely new software development initiative, called GEAR, was launched in 1996. This software, consists of nearly 30 programs assisting civil and structural engineers with their design work. In addition to developing its own software, the Center also established closed associations with renowned software developers, including PROKON Software from UK, G+D Computing from Australia, RoboBAT from France and Computers and Structures, Inc. from USA. These associations have greatly helped in adding

1995-2010

Prof. Worsak, Founder of ACECOMS, (on the right), seen here with Dr. Naveed Anwar, the first ACECOMS employee and presently the Director of ACECOMS

Fifteen years of

The prime mission of this Center is “to provide an impetus to the research in engineering compu-tations and the development of quality computer software for en-gineering applications, its wide spread promotion, and training on the effective use of current computing technology in the Asian and the Pacific regions”.

depth and breadth to the activities and services provided by the Center to the professional engineers in the Asian region.

Another important milestone in the effectiveness of the Center to fulfill its mission, was the establishment of Satellite Centers (now called Associate Centers). The establishment of these centers started in 2000, with the view of bringing the benefits of the activities of ACECOMS to the doorsteps of the engineers in the region. These centers, generally formed in association with renowned universities, professional organizations and consulting firms, acted as local focal points for conducting training workshops and seminars, providing technical support for computing needs and for developing

networking. Currently, nearly twenty Associate Centers are in operation in twelve countries. ACECOMS also carries out direct research and provides consulting services on specialized computing needs, such as failure investigation, design reviews, testing and evaluation of structures. Other activities of the Center include publication of this magazine, books, technical notes, software manuals and workshop notes, in order to bring the latest developments in the computations and computing aspects of civil and structural engineers to the professionals.This is a special issue of Civil Computing that provides an in-depth account of the Center's activities. During the previous years, the Center received valuable contributions for magazines in the form of articles.

March 2010 5

1995-2010ACECOMS is one of the leading international centers in the research, development and application of computational technology tools in structural and civil engineering. For the past fifteen years, it has carried out its mission through several integrated and interconnected support activities. The Center focus its expertise on the following area:

System Development Structural Modeling Finite Element Analysis Structural Design Structural Design Review and Certifications Structural Evaluation and Remedial Measure Investigation of Failures Software Development Professional Training

Aside from these major fields of expertise, the Center also deals and performs research and consulting in association with and support of various faculty members in the school of Engineering and Technology from the following Field of Study:

Geotechnical Engineering Water Engineering and Management Construction Engineering and Infrastructure Management Transportation Engineering Off-shore Technology and Management

With this strong expertise and inputs from well-known experts, ACECOMS has contributed significantly to the Structural and Civil Engineering profession and its development in the region.Being part of an international academic institute, ACECOMS draws upon and is supported by the experience and expertise of several highly qualified professionals and researchers from the School of Engineering and Technology of the Asian Institute of Technology. The Center is run by a core group of professionals headed by a Director. The members of the core group include a Manager, several researchers and engineers, technical support staff, marketing and management assistants and a large pool of graduate student assistants. The Center is guided by an advisory board and the Coordinator of the Structural Engineering Field of Study.

Prof. Worsak Kanok-NukulchaiCurrently the Vice President for Resource Development of AIT, Prof. Worsak is the former Dean of the School of Engineering and Technology and Founder, Director and Principal Advisor of the Center. His vision, leadership and international standing is responsible for the establishment and success of ACECOMS.

Dr. Pennung Warnitchai The Coordinator of the Structural Engineering Field of Study, Dr. Pennung oversees the Center’s operations and provides technical inputs and expertise for research and development projects.

Dr. Naveed Anwar The Director of ACECOMS, Dr. Naveed was involved in the inception of the Center in 1993 and served as the Associate Director since the establishment of the Center in 1995. He manages the operations of the Center and is the Head of the technical aspects of research and development activities.

Engr. Keerati TunthasuwattanaAs the Manager of the Center, Engr. Keerati assists the Director in operations and management and provides technical inputs into projects, training activities, satellite activities, client coordination, etc.

March 20106

RESEARCh AnD COnSuLTInGOver the past 15 years, ACECOMS has been in-volved in a variety of projects with varying degrees of input. These projects range from a single sto-rey house to multi-storey buildings, from industrial structures to bridges. Most of these projects are carried out with the advice and support of the fac-ulty members of the Structural Engineering Field of Study in the School of Engineering and Tech-nology at AIT. The following is a summary of the kinds of inputs and expertise provided by ACE-COMS to various projects.

Investigation of failures caused by natural disasters, human errors or unexpected cir-cumstances. Such investigations require de-tailed analysis using state-of-the-art technologies and methodologies. The failures investigated include collapsed steel structure damage due to fire, cracked concrete members, collapsed bridges, crane impact on buildings, settlement issues and environmental damages.

Review of existing designs to validate the structure’s capacity and performance for expected loads and demands. It often re-quires tools and techniques generally not im-plied in the design stage. This includes seismic performance evaluation of tall buildings, design review of bridge structures and industrial com-plexes.

Development and verification of new struc-tural systems and materials proposed by the industry. This generally includes labora-tory testing leading to calibrated computer models used for verification of the system. The projects in this category include the develop-ment of several new housing systems, seismic verification of existing systems, development of new concepts, etc.

Design development of important special projects requiring state-of-the-art knowl-edge and its application. Examples include the design of the tallest chimney in Thailand and bridge design concepts in various coun-tries.

Wind tunnel-based investigation of struc-tures to determine their response to wind effects. This is carried out in collaboration with Thammasat University in Thailand.

Development of software application to cater to the specific needs of the industry. Software development uses the core of pro-gramming languages so that they do not have to rely on existing programs.

•

•

•

•

•

•

March 2010 7

• 3D Analysis of Building Structures • Advanced Analysis and Design of General Slab Systems• Analysis and Design for Wind, Earthquake, Fire and Vibrations• Analysis and Design of Bridges • Analysis and Design of Piers and Columns • Analysis and Design of Reinforced Concrete, Prestressed and Steel High Rise Buildings • Analysis, Design, Monitoring and Strengthening of Bridge Structures• Architectural Planning and Structural Design of Precast Concrete • Analysis and Design of Structures for Vibrating Loads • Analysis and Design of Tall Buildings • Cost Sensitive Design of Flat Slab Floor Systems • Design and Construction of Underground Structures• Design of Steel Structures • Design, Construction and Maintenance of Electricity & Telecommunication Towers • Dynamic Analysis and Design of Structures • Finite Element Modeling and Analysis of Structures • Forum and Hands-on Training on SAP2000 and ETABS • Graphical Modeling for Structural Analysis, Design and Detailing • Innovative Ways of Teaching Civil Engineering • Modeling and Analysis of Offshore Structures • Modeling, Analysis, Design and Detailing of Shear Walls • Nonlinear Analysis of Reinforced Concrete and Masonry Structures • Performance Based Design and Pushover Analysis of Buildings • Prestressed & Reinforced Concrete Design • Pushover Analysis of Reinforced Concrete and Masonry Structures• Real Project Based Hands-on Training on Structural Design of 27 Story RC Building• Structural Analysis & Design of RC Building for Earthquake Resistance • Structural Evaluation and Retrofit of Existing Buildings • Strut and Tie Model for Analysis and Design of RC Members

SEMInAR AnD WORKShOP TOPICS

Number of seminars/trainings/workshops Events

Number of events held in different Countries

One of the key activities of the Center is the dissemination of the latest information and to provide training to the professionals on the theoretical background and the application of new techniques, tech-nologies and tools. This is effectively done by conducting regular seminars, workshops and forums that are attended by practicing engineers, academia and public officials. These events are organized in many countries and cities on variety of topics. So far, more than 4,000 professionals from over 20 countries have benefitted from these valuable activities, in the last 15 years.

Some of the Topics presented in Seminars and Workshops Heading

50

40

30

20

10

01995-1999 2000-2004 2005-2009

March 20108

The development of precast and prestressed con-crete (PPC) main structural elements (Fig. 1) as an alternative to conventional monolithic elements is gaining serious attention in West Africa. PPC ele-ments exhibit the following merits in comparison to conventional monolithic members: lightweight, high tensile strength, corrosion-resistant, etc. Few theo-retical and experimental investigations have been carried out in our region on the problem of qual-ity, stiffness, strength, reliability, durability, fatigue, life safety and stability of these structural members. There is still a necessity of providing an adequate amount of safety factor for the said structural mem-bers and system.

Taking in consideration the equation (1), equation (2) changes into

Creep Influence on Durability and Reliability of Prestressed Concrete Structures under Long-term Loads

About the Author

Dr. Gnida Sossou Kwame Nkrumah University of Science and Technology, Department of Civil Engineering P.O. Box KS 14479, Kumasi, Ghana gnidas59@yahoo.com www.knust.edu.gh

InTRODuCTIOn

COLuMnS

Main Theoretical Design Concepts

Figure 1. A typical multi-storey frame showing all the main structural elements

Figure 2. A perfectly straight pin-ended column subjected to axial compressive forces P and Pcr at each end

Pρcrγ

χ

ι

χ

ρcry

QM

y(χ)

N

a) b) c)

of the force P passes through the centroid of the cross-section of the column. By increasing the force P up to the critical force Pcr , this holds the column in a slightly deflected form as shown in (Fig. 2-b).

Now consider a fragment of the column shown in (Fig. 2-c). The bending moment M(x), the shear force Q(x) and the axial normal force N(x) = Pcr are acting at the ordinate x. The deflec-tions y(x) are small, and it is assumed the following differential equation is applicable.

Here, the negative sign is due to the sign convention: M(x) produces hogging in the positive y-direction.

As we can see from (Fig. 2-c) the bending moment could be calculated as

y"(x)+ y(x)=0Pcr EI

(3)

M(x)= - EI y"(x) (1)

M(x) = Pcr y(x) (2)

For the columns, the theoretical part of this study is based on the well-known concepts proposed by L. Euler, F.S. Yasinskiy, S.P. Timoshenko, B.Z. Vlasov, etc. and many other researchers, regarding the prob-lem of quality, stiffness, strength, reliability, durabil-ity, fatigue, life safety and stability of PPC struts.

Consider a perfectly straight column that is pin-ended (Fig. 2-a) and subjected to an axial compres-sive force P at each end. The line of action

March 2010 9

Article

Experimental Analysis The experimental program consist of some spe-cific subgroups (two columns per sub-group, Fig. 3) of twelve 120x18x18 cm precast and prestressed columns (with a specified characteristic material properties of 40 MPa for the concrete, and ESP = 195 GPa for the high-yield steel tendons with nom-inal diameters of 12.9 mm and 15.3 mm which will be contained in frames made of 5 mm bent mild steel mesh with Es = 200 GPa). The composite members were subjected to distinct but constant maintained vertical loads for a period of 7 months, and after will be tested to failure quasi-statically and under cyclic vertical loads at the last day of the experimental program. The extended interest will include the investigation of the variations of the concrete matrix strains in the boundary zone of the concrete matrix and the steel reinforcement.

For the evaluation of concrete matrix physical-mechanical properties, specific subgroups of 300x150∅ mm cylinders and 150 mm cubes were tested periodically. The variation in lateral deflec-tions influenced by concrete matrix creep and shrinkage was monitored continuously.

At the concrete matrix age of 9 days with natural curing, all of the columns, after the transfer of stresses from the prestressed steel tendons to the concrete matrix, were compressed by the prestress-ing forces, removed away from their forms and then taken away from the prestressing beds together with their deflection indicators, after cutting the steel tendons. Two of the members, marked C-11 with tendon nominal diameter 12.9 mm, and two other marked C-12 with tendon nominal diameter

Both ends of the column has 4 end conditions (x = 0; x = ℓ; y(x) = 0 and y”(x) = 0). It is easy to remark that the equation (3) is not complete.

Let us complete it with double differentiation by x and this gives

where

The general solution of the equation (4) is

where C1, C2, C3, C4 are constants which can be determined from the end conditions, and Pcr can be calculated finally.

15.3 mm after their compression by the prestress-ing forces are maintained in the laboratory with-out long-term loads. From these, are obtained the variations of the deformations in the prestressed steel tendons and in the concrete matrix, due to prestressing effects and due to the shrinkage of the concrete matrix.

b>a

a

Further, at the concrete matrix age of 36 days, eight other columns were tested under long-term static constant maintained axial loads with different load-ing intensities.

At the concrete matrix age of 300 days, all of the members were tested quasi-statically and after, un-der cyclic vertical loads up to their failure state.

Parallel to all of these tests, concrete matrix at ages of 9, 12, 15, 28, 36, 76, 118, 136, 200 and 300 days were also tested. Concrete matrix cylinders and cubes (3 cylinders and 3 cubes at each concrete matrix age) were used for the determination of the concrete matrix physical and mechanical properties, and for the evaluation of the creep and shrinkage characteristics of the concrete matrix.

During these creep tests, the specimens were mounted on the loading frame which consists of a hydraulic jack, a load cell, and a system of coil springs held in compression by a set of rods and plates. All the experimental data were related to the analytical objectives, resulting in the calibration and the validation of the predictive model. The theoreti-cal data of the deformations in the concrete matrix, the increases of the deformations in the prestressed steel reinforcement tendons and the deflections in the members were calculated using the finite-differ-ence method. The experimental data with the same

Figure 3. Typical Column Element

(5)ν2=

Pcr EI

yIV(x)+ν2 y"(x)=0 (4)

y(x)=C1 sin νx + C2 cos νx+ C3 x +C4 (6)

During these creep tests, the specimens are mounted on the loading frame which consists of a hydraulic jack, a load cell, and a system of coil springs held in compression by a set of rods and plates. All the experimental data will be related to the analyt-ical objectives, result-ing in the calibration and the validation of the predictive model.

March 201010

characteristics of the members, obtained by their deflection indicators were presented in a experi-mental database. It is expected that they will show a satisfactory simulation coincidence of theoretical and experimental data.

Figure 4. Typical Slab Element

SLABS

Main Theoretical Design Concepts

Experimental program for the slabs

This study is very crucial, as it is recognized that little information is available on the time depend-ent factors like the concrete matrix creep, shrink-age and loss of stresses, in relation to bi-directional prestressing of reinforced concrete slabs, with high yield tendons, subjected to long-term service loads. This present study is based on the mechanics of reinforced and prestressed concrete structures.It considers nonlinear differential equations of the concrete creep theory which reflects the correlation between the matrix stress and strain by its modulus of elasticity, using the nonlinear strain function, and based on the well-known geometrical preconditions of the theory of elasticity concerning thin plates and membranes with small flexural deformations.

Using the hypothesis of straight normal yields:

where εc = εc (x, y, z,φ);x x γ c = γ c (x, y, z,φ)xy xyεc = εc (x, y, z,φ);y y

εc = εx+ℜxZ;x εc = εy+ℜxZ;y γ c =γxy+2ℜxyZ,xy(7)

Here, indexes x, y show the stress-strain directions which correspond to coordinate axes.

Normal forces and flexural moments are supported by the steel reinforcement (with index s) and the concrete (with index b),which leads to the equation:

Article

Where, normal and shear strains of the slab layer, separated from the distance ze from the mid-plane; ex = ex (x, y, φ) ; ey = ey (x, y, φ); gxy = gxy (x, y, φ) - suitable strains of mid-plane of the slab; ℜx (x, y, φ) ; ℜy (x, y, φ) ; ℜxy (x, y, φ) - flexural cur-vature and torsion of the slab; φ - parameter of con-ditional time.

Deformation law of thin isotropic concrete plates and membranes in a uniform stress state is present-ed in the following form:

(8)εc = εx + ε"x = (σx/E0)-(σy/E0)

(x, y)

(9)Mx= Mb,x+ Ms,x; Nx = Nb,x+Ns,x (x, y)

Similar to columns this part of the theo-retical and experi-mental study relates to the details of a unified design and tests pro-cedure for analytical prediction of various durability, reliability and structural charac-teristics of slabs, pre-cast and prestressed in both directions

My

Nx

zt

x

Mxy

NyAty

Nyx

Mx Nxy

y

Atx

MyxZ 1

1

h zt

The experimental program consists of casting twelve 180x180x5 cm pre-tensioned concrete slabs with specified characteristic material properties of 40 MPa for the concrete matrix and ESP = 195 GPa for the high-yield steel tendons with nominal diam-eter of 10 mm which we contained in frames made of 5 mm bent mild steel mesh with ES = 200 GPa. Similar to the columns, at the concrete age of 9 days with natural curing, all of the slabs, after the trans-fer of stresses from the prestressed steel tendons to the concrete, were pressed out by prestresing effects and then taken away from the prestressing beds together with their deflection indicators, after cut-ting the steel tendons. Two of the composite slabs, marked S-1, were maintained in the laboratory without loads. From them were calibrated the vari-ations of the deformations in the prestressed steel tendons and in the concrete, due to prestressing ef-fects and due to the shrinkage of the concrete. Fur-ther, at the concrete age of 36 days, 10 other slabs were tested under long-term uniformly distributed static loads, with different force intensities.

Theoretical values of deformations in the concrete at upper facet of the slabs εb, increases deforma-tions in the prestressed reinforcement tendons ∆εSP and the flexures of the slabs ∆ will be calculated us-ing the finite-difference method. The experimental

Similar to columns, this part of the theoretical and experimental study relates to the details of a uni-fied design and tests procedure for analytical predic-tion of various durability, reliability and structural characteristics of slabs, precast and prestressed in both directions (Fig. 4). This analytical procedure is aimed to predict the quality, stiffness, strength, reli-ability and durability at the planning phase, includ-ing the nonlinear creep behaviour of these slabs.

March 2010 11

data of the same characteristics of the slabs, cali-brated from their deflection indicators were pre-sented in a table. It is expected that they will show a satisfactory coincidence of theoretical and experi-mental data.

1φ14AT-v

2φ5Bp-I

2φ5Bp-I

2φ5Bp-I

20

130

140

180

50

60

100

20 20

20

1φ14AT-v

800

700

600

617.3

500

4000 100 200

B145

400

σ sp/M

Pa

τ/J

B1sh

B124

BEAMS

Theoretical analysis for the beams The nonlinear equation of the concrete creep age-ing theory (the main base) reflects the correlation between the stress σb(t) and the strain εb(t) by its modulus of elasticity Eb(t), the nonlinear strain function f[εb(t)] = εb(t) + b(t) εb2(t), where the coefficient of non-linearity b(t) = E0 b0/[1 + k j(t)]2, (b0 and k are constant test data), and the relaxation measure r(t,t) which has been for-mulated by the matrix creep characteristic j like r(t,t) = E0 {1 - e- [j(t) - j(t)]}:

Experimental program and test results of beams

where t - loading duration; t - concrete age; t0 - loading beginning moment.

prestressing bench together with their deflection indicators; six beams cast with prestressed steel re-inforcement tendons diameter 14 mm were marked B1, and 6 other cast with diameter 18 mm - B2. Two of the beams B1 and two of B2, after their pressing out by the prestressing efforts were maintained in the laboratory without long-term loads.

Figure 5. Typical Beam Element

Figure 6. Experimental curves of time-dependent stresses in the steel reinforcement tendons of the beams. Theoretical values are shown in dotted lines

Figure 7. Experimental curves of time-dependent stresses in the steel reinforcement tendons of the beams. Theoretical values are shown in dotted lines

500

400

300

2000 100 200

373.3

300 400

σ sp/M

Pa

τ/J

B224

B240

B2sh

From the tests, callibration variations of the deforma-tions in the prestressed tendons and in the concrete, due to prestressing efforts and shrink-age of the con-crete were carried out. Further, at the concrete age of 76 days, two beams have been tested under long-term static forces F = 12 kN (fig. 6). At the same age of 76 days, two beams have been tested also under long-term static forces, F = 22,5 kN and F = 20 kN. (Fig. 7) Here, the super-scripts of the beams' series show two times the static forces values.

Article

σb(t)=εb(t0)Eb (t0)-f[εb(t0)]r(t,t0)

(10)+ ∫ { Eb (t)-t

t0

dεb (t) df[εb (t)]dt dt

r(t,t)} dt,

The program consists of casting twelve 180x100x1800 mm pre-tensioned reinforced precast and prestressed concrete beams (Fig. 5) with speci-fied characteristic material properties of 40 MPa for the concrete and ESP = 195 GPa for the high-yield steel tendons. One cubic meter of ready-mixed con-crete made from 430 kg of high early-strengthened Portland cement was used with concrete 50 MPa; 550 kg of quartz sand with fineness modulus of 1.42; 1120 kg of granite crushed aggregate with par-ticle size of 5-20 mm; 194 liters of water (water/ce-ment ratio = 0.45); and 2.15 kg of alcohol formiate plasticiser. The high-yield steel tendons with nomi-nal diameters of 14 mm and 18 mm were contained in frames made of 5 mm bent mild steel mesh with ES = 171 GPa. The concrete matrix properties were determined by testing 43 (number of) 100x100x400 mm prisms (based on currently used Soviet Codes) and 45 (number of) 100 mm cubes. The composite beams were prestressed to a target design force of 95 kN, after curing for 9 days. At the concrete age of 9 days, all of the composite beams were pressed out by prestresing effects and then they were taken away from the

March 201012

Table 1 shows the theoretical and experimental data of limit states exponents of the beams, calculated by formulas according to Soviet Codes of reinforced concrete structures. Here, also the experimental data were obtained by the testing of the beams under quasi-static short-term successive loads up to their failure state. These said data confirm the positive ef-fect of the long-term loads influences on the limit states exponents of beams Mcrc and Mu.

Experimental results indicated that the finite dif-ference method based on the displacement formu-lation is suitable and effective to solve systems of nonlinear equilibrium differential equations. The consideration of this proposed design and experi-mental model, and these said time-dependent effects ensure interdependence of design and construction for economy of reinforcement up to 5 -15 %.

1. Sossou G. ”Influence of concrete creep on limit states of reinforced prestressed concrete beams”. Ph.D. thesis Dnie-pro-petrovsk Civil Engineering Institute, Dniepropetrovsk ,Ukraine, 1991, 163 pp.

2. Edwin H. Gaylord, Jr, Charles N. Gaylord and James E. Stallmeyer, Structural Engineering Handbook, Fourth Edi-tion, McGraw-Hill, 1997.

3. Angus J. Macdonald, Structure and Architecture, Second Edition, Architectural Press, 2001.

4. Sossou G. Long-term Theoretical and Experimental Analysis of Limit States of Steel-Concrete Composite Beams for Structural Use. ICCM-12, July 5th –9th 1999, Paris, France.

COnCLuSIOnS

REFERENCESTable 1: Theoretical (numerator) and experi-mental exponents of beams’ limit states

Series of beams

P, kN

e0P, cm

Mcrc, kN.cm

ξ ξR Mu, kN.cm

acrc, mm

B224 67,26 - 4,5 0,39 0,40 _1089

120032143248

B240 135,6 - 4,5 0,45 0,38 0,05_ 3159

3135

Series of beams

P, kN

e0P, cm

Mcrc, kN.cm

ξ ξR Mu, kN.cm

acrc, mm

shB1 70,53 -3,1 0,34 0,33 _10041050

26612555

B2sh 60,26 - 3,0 0,39 0,37 _941

98530923075

B124 76,86 - 4,5 0,34 0,33 _1151

137526612529

B145 128,8 - 3,6 0,38 0,33 0,12_ 2661

2555

At the concrete age of 378 days, all of the beams were tested under quasi-static short-term successive loads up to their failure state. Parallel to all these tests, the beams were tested at different concrete ages of 9, 12, 15, 24, 36, 76, 118, 192, 208 and 378 days, concrete prisms and cubes (3 prisms and 3 cubes at each said concrete age) for the determina-tion of the concrete physical properties, and for the evaluation of the creep and shrinkage behaviour of the concrete.

The 2010 Haiti earthquake was catastrophic with a magnitude 7.0 earthquake. Its epicentre was near Léogâne, approximately 25 km (16 miles) west of Port-au-Prince, the capital of Haiti. The earthquake occurred at 16:53:10 local time (21:53:10 UTC) on Tuesday, 12 January 2010 at a depth of 13 km (8.1 miles). The International Red Cross estimate that about three million people were affected by the quake. Haitian Prime Minister Jean-Max Bellerive announced that over 230,000 bodies have been buried in mass graves.

Towns west of Port-au-Prince were report-ed to have extensive and catastrophic dam-age. They were further isolated by debris blocking connecting roads, thus, unable to receive supplies that were slowly getting into the capital. The Secretary-General of the UN estimated that fifty percent of the buildings in the affected regions were de-stroyed. There was also significant damage to communications. Haiti's largest cellular server, Digicel, was damaged but opera-tional by 14 January. A hospital in Pétion-ville and the main prison collapsed during

Haiti Earthquake

Many houses were destroyed in the impoverished neighborhood of Bel Air

The earthquake occurred on a fault system between the North American and Caribbean tectonic plates

the earthquake.

As of 15 January 2010, reported damage to the Port-au-Prince seaport includes the col-lapse of cranes and containers into the water, structural damage to the pier, and an oil spill, rendering the facility unusable for immediate rescue operations.

The apparel industry, which accounts for two-thirds of Haiti's annual income $350 million in exports to the United States, re-ported structural damage at manufacturing facilities around the country.

Article

March 2010 13

Prof. Worsak Kanok-Nukul-chai, the chair of the organizing commitee

FIRST TIME IN SOUTHEAST ASIAIABSE Symposium

9-11 September 2009, Bangkok

Close to 600 international academics, researchers and practitioners from around the world gathered on 9 September at the opening of the 33rd In-ternational Association for Bridge and Structural Engineering (IABSE) Symposium 2009 hosted in Bangkok. The annual international symposium was brought to Southeast Asia for the first time.

Supported by the Ministry of Transport of Thai-land, the symposium under the theme "Sustaina-ble Infrastructure: Environment Friendly, Safe and Resource Efficient" was organized by the Thai group of IABSE, Chulalongkorn University and the Asian Institute of Technology, under the auspices of many professional organizations from around the world.

The three-day meeting allowed experts from 43 countries to discuss ways and means to mitigate the ever-present risk of man-made disasters at a global scale. Engineers agreed that future sustainable in-frastructure around the world should adopt more reusable materials and less energy-intensive meth-ods of construction.

As Chair of the Organizing Committee for the in-ternational event, AIT Vice President for Resources and Development, Prof. Worsak Kanok-Nukulchai, addressed the symposium and welcomed its partici-pants. The symposium accepted 474 papers for oral and poster presentations.

AIT ACECOMS, provided support to the organi-zation of the symposium as the Coordinator of scientific activities, including abstract review, paper review, preliminary registration etc. ACECOMS Di-rector Dr. Naveed Anwar was also the master of ceremonies for the opening and closing sessions of the symposium.

Thailand’s Deputy Transport Minister, Mr. Prajak Klaewklaharn, commented on the significance of Thailand being the first country in Southeast Asia to host an IABSE Symposium. This event will bring benefits to Thai people, as well as people in other countries.

The deputy minister added that attendees would gain knowledge and information from researchers and experts in the field of engineering to achieve sustainable infrastructure through planning, de-sign, construction, operation, renovation, retrofit-ting and repairs.

Participants were exposed to the latest information on engineering technologies related to infrastruc-ture development, such as sustainable develop-ment of transportation systems, green buildings and structural engineering, and the role of struc-tural engineering in disaster risk reduction and re-silience.

This year’s IABSE symposium coincided with the 80th Anniversary of IABSE, the 90th Anniversary of the Faculty of Engineering, Chulalongkorn University, and the 50th Anniversary of AIT. The event was held in collaboration with Consulting Engineers Association of Thailand, Thailand’s Council of Engineers, Engineering Institute of Thailand, and the Thai Contractors Association.

Founded in 1929 in Zurich, Switzerland, the In-ternational Association for Bridge and Structural Engineering (IABSE) is a scientific and technical association with 3,900 members in 100 countries around the world. The current President of IAB-SE is Mr. Jacques Combault, from France.

Haiti Earthquake

Organized by

The Thai Group of IABSE

Chu l a l ongko r n University, CU

Asian Institute of Technology, AIT

March 201014

Seismic Behaviour of Structures with Vertical

Irregularities

About the Authors

Dr. Sekhar Chandra Dutta Professor of Civil Engineering, Head, School of Infrastructure I.I.T. Bhubaneswar 751 013 Orissa, India scdind2000@yahoo.com

Piyali Saha Engineer, M. N Dastur and Company Limited, West Bengal, India piyalish@yahoo.com

Snehashis Sinha Director, Sinha and Associates, Engineers and Design Consultants, West Bengal, India and formerly Post-Graduate student sanda@cal2.vsnl.net.in

Kundan Goswami Final Year Under Graduate Student, Department of Civil Engineering, Bengal Engineering and Science University, Shibpur, West Bengal, India kundanciv@gmail.com

InTRODuCTIOn Urban development in seismically active regions has increased significantly all over the world. This devel-opment is accompanied by an increased demand for aesthetic buildings that often have irregular shapes. Such buildings, having irregular configuration, are prone to earthquake damage due to coupled move-ments in various directions producing non-uniform displacement demands in building elements and concentration of stresses and forces on structural elements.

A structure having a regular configuration is one in which there is a minimum coupling between the dis-placements and the rotations in various directions for the mode shapes associated with the lower fre-quencies of the system whereas a structure having an irregular configuration is one which has a certain irregular geometric shape or in which irregularities in stiffness or mass distribution or both exist.

In most of the Seismic Design Codes, design guide-lines and formulations of regular or symmetric buildings are well framed. But the codes fall short of providing recommendations regarding design of irregular structures. Plan asymmetry and develop-ment of its design guidelines has been given focused attention over the last twenty years. A detailed list of such studies is available in various literature [1-4.]As compared to that vertically irregular building has got relatively little attention by the researchers [5-6.]Complete understanding is yet to be reached for the vertically irregular buildings.

In this context, present paper makes a limited at-tempt to study the seismic response of all vertically irregular structures possible to emerge from two bay two storey and three bay three storey frames. The response is obtained due to representative earthquake time histories (for both artificial as well as real) through time history analysis and that due to design spectrum of IS: 1893-2002 [7] through CQC analysis. The common trends observed in all the cases may help to frame guidelines regarding the speciality in seismic behaviour of such irregular frames.

MODELInG FOR STRuCTuRE

Figure 1. Spectrum of Simulated Ground Motion, Design Spectrum of IS: 1893-1984 Corresponding to 5% Damp-ing and Acceleration-Time History

To look into the seismic behaviour of buildings with irregularity particularly in the form of verti-cal setback, the response of a typical three storeyed regular building frame with three bays in both hori-zontal principle directions (shown in Figure 2(a) and named as Frame-R) is regarded as the standard while the deviation of the responses of all the irregular frames with respect to that of the regular ones are chosen as criteria to judge the complexities involved in their behaviour. For this purpose 16 probable forms of three storeyed building frames having vertical irregularity have been considered and are shown in Figures 2(b) to 2(q). Some of the build-ing frames have vertical irregularity in one princi-ple horizontal direction (X or Z direction) whereas other structures have the same in two principle hori-

March 2010 15

Seismic Behaviour of Structures with Vertical

Irregularities

METhOD OF AnALYSIS Time history analysis has been carried out for all the frames under an artificial as well as a real ground motion using the equation of motion [8] [m]{χ}+[c]{χ}+ [k]{χ}=-[m]{1}üg and solving it numerically using Wilson-θ method [9] (time stepping tech-nique) to obtain different response quantities and thereby calculating the member force (shear force, bending moment etc.) histories. The accuracy of the computation within a single time step has been improved by employing iterations through modi-fied Newton-Raphson technique. For the purpose of present study, the maximum value of member forces are noted from the corresponding histories as they generally have design implications.

[m], [c], [k], as mentioned in the previous equation, represents mass, damping and stiffness matrix re-spectively and {x} is the displacement vector in the structure corresponding to the ground acceleration üg. For all the cases of this present study, consistent mass matrix is used to make the formulation as ac-curate as possible and 5% of the critical damping in each mode is considered as this is the characteris-tics code specified damping for reinforced concrete buildings.

The response due to the design spectrum corre-sponding to IS: 1893-2002 for soft soil is consid-ered to study the behaviour of all irregular frames, by standard CQC method as outlined in IS: 1893-2002.

A B

ED

HF

LJ

QN

Article

Figure 2. Irregular Structures with Dynamic Characteristics, Seismic Base Shear and per-centage change in member forces (under spectrum consistent ground motion and design spec-trum corresponding to IS: 1893-2002 by CQC method both along X direction)

zontal directions (X and Z directions). The frames having similar types of irregularity are considered to be in the same groups and six such groups are made to categorize the all 16 frames considered in the present study.

All these frames are designated by a triple let-ter nomenclature in the manner of ‘Frame-I 1_1’, ‘Frame-I 2_3’ etc. where, the first letter ‘I’ is for irregular frame, the following number denotes the group of the structure and the serial number of the structure in the broad group.

The geometrical dimensions and member proper-ties of different elements in similar location of all the frames are considered to be the same in order to have a better understanding of the isolated ef-fect of setback. In-plane stiffness due to concrete diaphragms and slabs for transmission of seismic horizontal forces to the vertical structural elements has not been taken into consideration.

March 201016

GROUP

Regular

Irregular 1

Irregular 2

Irregular 1

Irregular 2

Irregular 3

Irregular 3

Irregular 5

Irregular 6

NOMEN CLATURE

Frame-R

Frame-I 1_1

Frame-I 2_1

Frame-I 1_3

Frame-I 2_2

Frame-I 3_1

Frame-I 3_3

Frame-I 5_1

Frame-I 6_2

NATURAL PERIOD (SEC)

1.07318

1.07542

0.79009

1.08531

0.79360

1.05120

1.04048

1.04804

0.99921

BASE SHEAR (KN)

514.19, 311.77

522.14, 315.64

360.66, 240.70

536.72, 320.28

303.57, 187.65

393.75, 269.78

342.70, 241.79

305.94, 207.26

373.92, 206.14

A

B

E

D

F

H

J

N

Q

RESuLT AnD DISCuSSIOn On SEISMIC RESPOnSE The configuration of irregular frames along with their dynamic characteristics (namely lateral period), seismic base shear and change in member forces un-der both spectrum consistent ground motion and design spectrum corresponding to IS: 1893-2002 are presented in Figures 2(b) to 2(q).

Out of a large number of three storeyed irregular building frames considered, the base shear is found to vary as compared to the same in their symmetric counter part. The frame grouped as ‘Irregular 1’ and marked as ‘Frame-I 1_3’ exhibits a highest increase of 5% under spectrum consistent ground motion and 3% under design spectrum corresponding to IS: 1893-2002 by CQC method both along X direction as compared to the regular frame. On the other hand, the irregular frame belonging to Group ‘Irregular 2’ and marked as ‘Frame-I 2_2’ exhibits maximum decrease of about 41% under spectrum consistent ground motion and 40% under design spectrum both considered to be applied along X direction. One of the major factors contributing to such change is the change in mass due to absence of various panels in various storey levels. On the other hand, the changed natural period of systems because of irregularities causes a change in spectral acceleration.

The primary stress parameters considered for un-derstanding the seismic effect in member level is bending moment. However, the change in seismic shear can be expected to be same as the change in seismic bending moment and hence, the percentage increase in bending moment presented here can also be expected to be applicable for seismic shear. These quantities obtained from the seismic analysis of the building frames with vertical irregularity are com-pared with the same in the corresponding regular but otherwise similar building frame. For easy under-standing of the change in member stresses in the ir-regular structures under spectrum consistent ground motion and under design spectrum corresponding to IS: 1893-2002 by CQC method both along X direc-tion, absolute values of bending moment in mem-bers of the irregular structures are normalised with respect to the same in similar member of the regular building frames and expressed in terms of percent-age. These values are indicated over the lines denot-ing the member themselves in the line diagram of the frames shown in Figures 2(b) to 2(q). First value indicates the percentage increase in bending moment in the members under spectrum consistent ground

GROunD MOTIOn To assess the seismic vulnerability of buildings due to the presence of irregularity, an ensemble of earthquake records needs to be considered and the response may be interpreted in a statistical man-ner to minimize the dependency of seismic behav-ior on the input ground motion. In this context, present paper selects two uncorrelated artificial ground motions generated following the proc-ess described in a well accepted literature [10] and consistent with the spectrum depicted in the In-dian standard IS: 1893-1984 [11] along with a real earthquake (El Centro earthquake, May 18, 1940). Since the response spectrum regenerated using one of these two ground acceleration histories shows very small deviation between the target and gener-ated spectra, these two synthetic ground motions have the frequency contents as desired through the design spectrum of IS: 1893-1984. The response spectrum and the corresponding Acceleration-Time history for design spectrum corresponding to IS: 1893-1984 is shown in Figure 1.

Excitation of vertically irregular structures in verti-cal direction is not considered in this study as it seems that the seismic behaviour of the same will not be considerably influenced by vertical compo-nent of the ground motion. The results are only given for spectrum consistent ground motion as more or less similar kind of results is obtained for El-Centro earthquake.

Article

March 2010 17

(Under Spectrum consistent ground motion) (a)

Normalised Shear force distribution across storeys for regular frame

(Under Design spectrum)

(Under Spectrum consistent ground motion) (b)

Normalised Shear force distribution across storeys for Frame-I 4_1

Frame-I 4_1

Normalised Storey Shear

Normalised Storey ShearNormalised Storey Shear

Normalised Shear force distribution across storeys for Frame-I 5_1

Frame-I 5_1

Normalised Shear force distribution across storeys for Frame-I 6_2

Figure 3. Storey shear variation for selected frames under spectrum consistent ground motion and design spectrum corresponding to IS: 1893-2002 by CQC method both along X direction

Frame-I 6_2

(Under Design spectrum)

(Under Design spectrum)

Normalised Storey Shear

Normalised Storey Shear

Normalised Storey Shear

Normalised Storey Shear

(Under Spectrum consistent ground motion) (d)

(Under Spectrum consistent ground motion) (c)

(Under Design spectrum)Normalised Storey Shear

Frame R

Sto

rey

Sto

rey

1 1

2 2

3

Sto

rey

1

2

3

Sto

rey

1

2

3

Sto

rey

1

2

3

Sto

rey

1

2

3

Sto

rey

1

2

3

Sto

rey

1

2

3

30.33 0.33

0.77 0.77

1.00 1.00

0.00

0.00

0.000.20

0.20

0.200.40

0.40

0.400.60

0.60

0.600.80

0.00 0.20 0.40 0.60 0.80

0.00 0.20 0.40 0.60 0.80

0.00 0.20 0.40 0.60 0.80 0.00 0.20 0.40 0.60 0.80

0.00 0.20 0.40 0.60 0.80

0.80

0.801.00 1.001.20 1.20

0.24

0.19

0.21 0.20

0.20

0.24

0.63

0.57

0.44 0.45

0.55

0.64

0.74

0.60

0.73 0.66

0.66

0.75

March 201018

motion and the second one is for design spectrum corresponding to IS: 1893-2002 obtained by CQC method.

Lateral load on any structure develops axial tension and compression in columns located on either side of the center of stiffness. However the axial forces developed in beams are insignificant and hence, are not discussed here. Generally the tensile force de-veloped in the columns due to lateral seismic load-ing is offset by the compressive load due to gravity (dead load and live load) and hence this does not lead to any criticality. Furthermore, the increase in the axial compressive force due to seismic loading on another side of the frame is also insignificant. Hence, both axial tension and compression are not presented here.

The observations on increase/decrease in design seismic force quantities of various members of three storeyed irregular building frames with respect to the same in their regular counterpart are present-ed below.

1) The members of the top storey are generally severely affected in irregular buildings. Out of the corner and peripheral columns in the top storey, the ones which are close to the irregularity exhibits maximum increase, which may go up to the extent of 105%.

2) Out of the top storey beams, the edge beams are greatly affected. In fact, such increase may shoot up to about 140%.

3) Intermediate beams and columns of top storey or edge beams of other storey exhibits a moderate increase to the extent of 50% while the intermediate beams of other storeys exhibits a marginal increase.

Though the results are primarily presented for ground motion along X direction, the results due to ground motion along Z direction also exhibited the similar trend. For instance, a highest increase of about 140% is observed in beams under ground motion along X direction, whereas the same value is only 75% for spectrum consistent ground motion along Z direction for frame marked as Frame-I 4_1. On the other hand, no increase in column bend-ing moment is observed for spectrum consistent ground motion and design spectrum correspond-ing to IS: 1893-2002 along Z direction. For irregu-lar structures which are symmetrical about both X and Z directions, for instance Frame-I 2_1, separate analysis under ground motion along Z direction is not required. As the increase in member forces for ground motion along Z direction are almost the

same as the corresponding values obtained due to ground motion in X direction, results are not pre-sented for the sake of brevity.

From a brief study on the behaviour of dynamic response of two storeyed irregular buildings with respect to their regular counterpart, the maximum increase in beam and column bending moment can be summarized in the following manner. Out of the top storey columns near the irregularity, the maximum increase may go up to 65% and the edge beams of top storey level show a maximum increase of 100%.

It may be interesting to see the nature of storey shear distribution of irregular frames. The varia-tion of storey shear is presented for regular frame (Frame-R) and three irregular frames (namely, Frame-I 4_1, Frame-I 5_1 and Frame-I 6_2 re-spectively) in a pictorial form in Figure 3(a) to 3(d) after normalizing them by base shear of regular frame. The normalized values of storey shear at ground storey level are 0.74, 0.60 and 0.73 respec-tively for these irregular frames under spectrum consistent ground motion whereas the same values for design spectrum corresponding to IS: 1893-2002 are 0.75, 0.66 and 0.66 respectively which may be consistent to be of same order of the pre-vious set of values. There is not so much varia-tion in base shear at ground storey level for first and third irregular frames considered, whereas for Frame-I 5_1 lower base shear value indicates less-er participation of mass than other two frames. The same values at second storey level are 0.63 to 0.64 for Frame-I 4_1, 0.55 to 0.57 for Frame-I 5_1 and 0.44 to 0.45 for Frame-I 6_2. For the first two frames the normalized storey shear values are very close whereas for third one, the value decreases to a greater extent. This may be due to larger partici-pation of second mode shape for this frame as the first mode consists of displacement components of various storey levels in the same direction while the displacement of the first storey is generally in the direction opposite to that of second and third storey in second mode shape. If the values of the normalized storey shear obtained for third storey of the irregular frames are compared (0.24, 0.19 to 0.2 and 0.2 to 0.21 respectively) with each other, the variation is found not to be very high. But the second mode shape has a tendency to decrease the third storey shear also. So apparently it seems that the third storey shear for Frame-I 6_2 should come much lesser than the other two frames due to predominating participation of second mode shape. But the result is otherwise. This implies that for Frame-I 6_2 the participation of both second and third mode shape are much higher than other two irregular frames as in the third mode shape the displacement of first and third storey are in

Article

March 2010 19

REFERENCES 1. Dutta, S.C. Effect of strength deterioration on inelas-tic seismic torsional behaviour of asymmetric RC build-ings. Building and Environment, December 2001. Vol. 36, pp. 1109-1118.

2. Dutta, S.C and Das, PK. Validity and applicability of two simple hysteresis model to assess progressive seismic damage in R/C asymmetric buildings. Journal Sound and Vibration, October 2002. Vol. 257, pp. 753-777.

3. Dutta, S.C and Jain, S.K and Murty, C.V.R. Tor-sional failure of elevated water tanks: the problem and solutions. Eleventh World Conference on Earthquake Engineering, 1996. Acapulco, Mexico.

4. Das, P.K and Dutta, S.C. Effect of strength and stiffness deterioration on seismic behaviour of asymmetric RC buildings. International Journal of Applied Mechan-ics and Engineering, 2002. Vol. 7.

5. Ali, A. A. and Krawinkler, H. Effect of vertical irregularities on seismic behaviour of structures. The Jhon A. Blume Earthquake Engineering Center, Stanford University, Stanford, California, October 1997.

6. Chintanapakdee, C. and Chopra, A.K. Seismic Re-sponse of Vertically Irregular Frames: Response History and Modal Pushover Analyses. ASCE, Journal of Struc-tural Engineering, August 2004. Vol. 130, pp. 1177-1185.

7. Indian Standards. Criteria for earthquake resistant design of structures: Part 1 general provisions and build-ings. IS 1893-2002. Bureau of Indian Standards, New Delhi.

8. Chopra, A.K. Dynamics of structure. Prentice Hall, 1998. New Delhi, India.

9. Paz, M. Structural Dynamics, Theory and Computa-tion. CBS, New Delhi, India.

10. Khan, M.R. Improved method of generation of artifi-cial time histories, rich in all frequencies, from floor spectra. Earthquake Engineering and Structural Dynamics, Feb-ruary 1987. Vol. 15, pp. 985-992.

11. Indian Standards. Criteria for earthquake resistant design of structures. IS 1893-1984. Bureau of Indian Standards, New Delhi.

the same direction while the displacement of sec-ond storey is in opposite direction which reduces the effect of second mode shape on third storey shear and maintain the shear value closer to other two frames.

COnCLuSIOnS The limited study presented here yields a few ef-fective clues for preliminary design as well as cross checking of final design of irregular buildings for seismic forces.

1) The design values of seismic moment or shear forces in the top storey corner or peripheral col-umns of the irregular buildings may be obtained by multiplying the corresponding force quantities of regular buildings by 2.1.

2) A factor of 2.4 may be taken for design of top storey edge beams.

3) Intermediate beams and intermediate columns of top storey and edge beams of other storeys may be designed using a multiplication factor of 1.6.

4) The same design values as exhibited in similar member of regular frame may be chosen for inter-mediate columns and beams of the storeys other than top storeys.

As a whole, this study shows that the overall base shear of the irregular frames may be lesser than that obtained for similar regular structure. This is perhaps due to lesser seismic mass and changed natural periods and mode shapes. Still the increase in the element force in some of the elements may be considerable and hence these forces should be the real guiding parameters instead of overall base shear or storey shear for ensuring seismic safety of such structures. The results for the varieties of ir-regular frames presented in the paper and the cor-responding generalized observations may make it useful as a guiding literature for this purpose.

Silicon Republic (12/23/09) Kennedy, John

Top Inventor Says Talking Computers Are the Future

Google research director Peter Norvig recently discussed several aspects concerning the future of innovation, search programs, artificial intelli-gence, advertising, and media distribution. Norvig says that Google researchers are "always reinventing things," which he says creates an environment that attracts the top people. "We're driven by the fact that we've got to have more users, more documents, and more speed," he says. The future of searching is in video, Norvig says. Google is working on indexing the actual content of the video as well as develop-ing speech-recognition technology to index the words spoken in the video. Norvig anticipates more voice-activated commands in the future

of computing and Internet manipulation. He says computers will be able to analyze searches and help users make sense of how group search results can be used together. Norvig's personal interests are in artificial intelligence and how it relates to advertising online. The goal is to create as many different modes of interaction as possible, so us-ers can choose how to receive information. Speech recognition and computer vision also are very im-portant to the future of online advertising. "You have a phone with a compass in it and there's StreetView that you can orient to the real world and it's not a big step from there to put advertising on it," Norvig says.

Article

Source: ACM TechNews (December 28, 2009 Edition)

March 201020

on Construction around the worldNEWS

Shanghai Centre

Dublin's skyscraper

While the rest of the world is catching the con-struction slowdown sniffles, Shanghai seems to have contracted a case of Dubai's mega-building mania.

Three months after opening the world's second tallest skyscraper, the Chinese city will start the construction of an even taller building - the 632m Shanghai Centre.

The 121-storey steel and glass skyscraper was de-signed by Gensler and has been nicknamed the Dragon because it will supposedly look like a dragon's tail.

In China, dragons are believed to be able to con-trol the weather, and this skyscraper could possi-bly do just that. Design-ers say its spiral shape will minimize wind re-sistance and energy con-sumption and that 54 wind turbines will sit at the top of the building.

Like all developers of super-tall buildings, Gu Jianping, managing di-rector of the Shanghai Tower Construction and Development Group says that by the time the building is open in 2014 the economy will be booming.

"Launching construc-tion at this time will help boost Shanghai's confi-dence in fighting the fi-nancial crisis," he said.

The Dubai Smile, an eye-catching inverted metal bridge, has been approved as the seventh river crossing the Emirate and will be completed in 2012.

The 12 lane bridge, which is 61.6m wide and has a 100m high arch, will be capable of handing 24,000 ve-hicles an hour and costs about $177.5 million to build. The bridge will replace Dubai's Floating Bridge over Dubai Creek and aim to reduce appalling traf-fic congestion.

ShAnGhAI CEnTRE

DuBAI SMILE

Dubai Smile

DuBLIn'S SKYSCRAPER

About the Editor

Hafsa HamidACECOMS, AIT

http://www.contractjournal.com/blogs world-construction-blog/2008/11/

http://www.contractjournal.com/blogs/world-construction-blog/2008/11/good-weather-ahead-for-shangha.html

http://www.landmark-advisory.com/index.php?dxbnews-jan09

The Dublin Docklands Development Authority has decided to suspend negotiations to build the tower on the River Liffey for 12 months in the hope the market recovers.

The 120m skyscraper was to become Dublin's tall-est building and include a recording studio for the super group in a pod on top.

The proposed roof was to house wind-generated electrical turbines and solar panels, while the sides of the building were to be metal-paneled to look like fish scales.

But many have doubted the ambitious plans would ever be realized, as conservationists have managed to shoot down other skyscraper projects proposed for low-rise Dublin.

March 2010 21

on Construction around the world

SInGAPORE FLYER

Inspiration for the Singapore Flyer sparked from national icons like the Eiffel Tower and the London Eye. On this inspiration, Dr. Kisho Kurokawa of Japan and DP Architects, Singapore developed the initial concept behind Singapore Flyer's design.

The Singapore flyer is currently the world’s largest observation wheel as of 2008, standing at an im-pressive 165m in height (42 stories) and sitting on the southeast tip of the Singapore Marina Centre reclaimed land.

The glass windows of the flyer are made with pho-tography in mind, as they are anti-glare tempered glass which do not offer much visual artifacts or reflections in images when shot through them.

Four sets of stay cables, six cables per set, brace the support columns for the observation wheel. The cables are anchored at four locations around the base of the terminal building and are con-nected to the terminal’s ground-floor slab. The drive system and the braking equipment, that control the movement of the observation wheel are located in steel framework atop the curved steel and concretes composite decks in the upper portion of the terminal building on either side of the space through which the capsules pass.

The observation wheel is designed to withstand peak wind gusts of 33 m/s, although the wheel will be stopped temporarily if wind speeds exceed 10 m/s.

Singapore Flyer capsules are fitted with the latest cooling system, supported by a back-up air condi-tioning system and a solid roof. Passengers need

Grand Vision

BuRJ KhALIFA

http://www.toursingapore.com.sg/attractions/singapore-flyer/

http://www.singaporeflyer.com/en/about-us/design-concepts.html

http://www.burjdubaiskyscraper.com/

not suffer from the heat when the capsule is 165 meters above the ground, for the capsules are fitted with UV protection to shield them from the blaz-ing Singapore sun. The precision wind engineering also allows passengers to sit back, relax, and enjoy the spectacular skyline without worrying about any movements or vibrations.

Ergonomically designed, each capsule measures 4 meters by 7 meters and has an interior space of 28 square meters, comfortably accommodating a maximum of 28-30 passengers. The flyer also has elderly and wheelchair friendly synchronized dou-ble door entry/exit systems.

World's tallest building. A living wonder. Stunning work of art. Incomparable feat of engineering. Burj Khalifa is all that. In con-cept and execution, Burj Khalifa has no peer.

More than just the world's tallest building, Burj Khalifa is an unprecedented example of international cooperation, symbolic beacon of progress, and an emblem of the new, dy-namic and prosperous Middle East.

It is also tangible proof of Dubai's grow-ing role in a changing world. In fewer than 30 years, this city has transformed itself from a regional centre to a global one. This success was not based on oil reserves, but on reserves of human talent, ingenuity and initiative. Burj Khalifa embodies that vision. Height, Facts & Figures

Bringing Burj Khalifa to life required a combina-tion of visionary ideals and solid science. In the process, the project amassed an awe-inspiring number of facts, figures, and statistics.

Design - Capsule

March 201022

around a central hexagonal reinforced concrete core satisfies both of these requirements. The resulting “buttressed core” is an extremely efficient solution to the potentially conflicting structural requirements of a supertall residential tower.

Core walls in each wing are arranged in a 9-meter module that matches the setbacks of the tower. This allows the building to be shaped without transfers; the columns in the nose of each setback sit directly on the walls below. The result is an easily construct-ed system that is significantly less expensive to build than one requiring transfers.

The perimeter columns on the sides of each wing match the width of the adjacent shear walls, thus permitting them to be engaged by infill walls at each mechanical level. This engagement of the perimeter columns leads to high levels of structural efficiency in resisting loads as well as a high degree of redun-dancy.

http://www.burjdubai.com/

Reference:

William F. Baker, PE SE1

1Structural Engineering Partner, Skidmore, Owings & Merrill LLP, Chicago, USA

Designing the Wind

Buttressed Core System

High Performance Concrete

The specified material and the configuration of the structural elements utilize the high performance concrete and formwork systems readily available in Dubai. Very strong, high density concrete composed of Portland cement in combination with silica fume, fly ash, and ground granulated slag is available and results in a structure which is stiff, strong and highly constructible.

The mat utilizes C60 self-compacting self-consol-idating concrete (SCC). Advantages of this type of concrete include the high uniformity of placed concrete, ease of placement, elimination of vibra-tion, reduced bleed water and reduced labor. The mat was placed in four sections in order to minimize thermal effects.

The superstructure uses concrete strengths that vary between C80 to C60 for the lateral system. Lower concrete strengths are specified for the horizontal framing. Higher strength concretes were considered but since the structural system distributes the loads so effectively, higher strength concrete was not re-quired.

The superstructure is supported by a large 3.7 meter thick reinforced concrete mat, which is in turn sup-ported by 1.5 meter diameter bored reinforced con-crete piles. The design of these elements is based on extensive geotechnical and seismic investigations and analysis. The high density and low permeability of the concrete used for the foundations minimize the detrimental effects of high chlorides and sul-phate content in the local ground water. The foun-dations are further protected by waterproofing and cathodic protection systems.

The Burj Dubai structure represents the state of the art in super tall buildings. It capitalizes on the latest advances in wind engineering, structural engineer-ing, structural systems, construction materials and construction methods to result in a structure that goes beyond anything that has been achieved be-fore. The tallest structure ever built, it realizes the aspirations of mankind to reach the sky.

World Records

At over 800 metres (2625 feet) and more than 160 stories, Burj Khalifa holds the following records:

• Tallest building in the world • Tallest free-standing structure in the world • Highest number of stories in the world • Highest occupied floor in the world • Highest outdoor observation deck in the world • Elevator with the longest travel distance in the world • Tallest service elevator in the world

The Burj Khalifa structure represents the state-of-the-art in tall building design. Once completed, it will not only be the world’s tallest building but the tallest man-made structure ever created. From the project’s initial concept design through construction, the combination of several important technological innovations results in a building of unprecedented height. The following is a description of some of the innovative structural design methods which en-able the creation of a superstructure that is both ef-ficient and robust.

The primary concern in the engineering of tall buildings is the effect of the wind on the building’s structure. The shape of the Burj Dubai is the re-sult of collaboration between Skidmore, Owings & Merrill LLP (SOM) architects and engineers to vary the shape of the building along its height, thereby minimizing wind forces on the building. In effect, each uniquely-shaped section of the tower causes the wind to behave differently, preventing it from becoming organized and minimizing lateral move-ment of the structure.

The modular, Y-shaped structure, with setbacks along each of the three wings, was part of the origi-nal concept design entered in an invited design com-petition at the beginning of the project. From this starting point, the SOM team refined the tower’s shape over several months of extensive wind tun-nel tests. Through these tests, the team determined the harmonic frequency of wind gusts and eddies under various wind conditions. This information was used to set targets for the building’s natural fre-quencies, thereby “tuning” it to minimize the effects of the wind.

Concurrent with the wind tunnel studies, the team performed a detailed climatic study which consid-ered the unique meteorological conditions of the Dubai wind climate. These studies considered both frequently occurring and rare wind events to address occupant comfort and building strength. Together, the wind tunnel testing and climatic studies resulted in a highly engineered solution that is appropriate for the Dubai wind climate.

As a residential tower, the Burj Dubai requires floor plates with shallow lease spans that maximize the amount of exterior window area (and therefore nat-ural light) in the living spaces. As a very tall tower, it requires a wide footprint to provide sufficient stability to resist high wind loads. The Y-shaped arrangement of reinforced concrete shear walls

Foundations

March 2010 23http://www.burjdubai.com/

Analysis and Design of StructuresVenue : Yangon, MyanmarDate : 24-26 March 2010

Computer Applications in Civil and Structural EngineeringVenue : University of the Cordilleras, Baguio, PhilippinesDate : 17-18 May 2010

Mega Project Challenges for Structure EngineersVenue : Westin Grand, Bangkok, ThailandDate : 1-2 April 2010

2010Important seminars and training programs planned

Upcoming

Seminars

Public Works Department (PWD)

Seismic Evaluation of Fire Stations in Dhaka, Bangladesh

Project Evaluation and Design Review of Pharmaceuticals Building

In this project, ACECOMS is getting the opportuni-ty to conduct performance based seismic evaluation and retrofitting of two-storey fire station buildings in Dhaka, Bangladesh in collaboration with the Public Works Department (PWD), Bangladesh. The typical building has moment resisting frames as well as un-re-inforced, un-confined masonry brick walls. However, the building was built during 1960’s and was designed by considering gravity loads only. Furthermore, the

One of the largest pharmaceutical companies in Bangladesh has recently engaged ACECOMS to carry out independent project evaluation and de-sign review of their new building. This new build-ing is a 4-story steel structure with an approximate area of 100,000 ft2 per floor. The main objectives of this project are to evaluate the proposed building structural systems and perform the design review of the selected structural building system in such a way

structural detailing of the building is not based on criteria for ductile design and it may be vulnerable to severe damage during strong earthquake. In this project, the objective is to evaluate and enhance the performance of the building by appropriate retrofit techniques. The performance of the building is evalu-ated using non-linear analysis and several retrofitting options are being considered.

that the overall design compliance, general perform-ance, reliability and cost effectiveness are achieved. The work involves developing the project design cri-teria, evaluation of proposed structural system from bidders, detailed design review of selected structural system and also preparation of alternate structural building system if substantial cost saving can not be achieved from selected structural system.

New Projects and Research

March 201024

Nowadays, the use of computer models to per-form structural analysis in the field of bridge engi-neering has become a common practice. Engineers are supposed to use proper models in order to ac-curately predict the response of the bridge model for design purposes. In recent years, researchers have been developing many modeling techniques that can be used to model a bridge. Each type of modeling techniques requires some set of as-sumptions to simplify the problem, thus, results obtained from these techniques vary according to the assumptions made. Moreover, each type of modeling techniques has its own advantages and disadvantages. Therefore, sometimes engineers use several modeling techniques to model complex bridge structures in order to compare the results and to use them for various purposes.

Several bridge modeling techniques are discussed by Hambly [3] for the modeling of different types of bridges. The modeling techniques being used by engineers to model a bridge range from the simplest one to the highly complex one. The sim-plest model (spine model) usually comprises only one single girder to model the bridge deck and hinge or roller supports to model the bearing and abutment. Even though this model is very sim-ple, it is able to give reasonable prediction of the bridge responses under dead load such as maxi-mum displacement and moment at the mid span and support reactions. However, there are many limitations of this model such as transverse analy-sis of moving load in bridge deck cannot be per-formed, inaccurate prediction of modal analysis, etc. Therefore, nowadays most engineers use this model only to do preliminary analysis or sizing of a bridge’s components.

To overcome limitations in spine model, a frame/grid model was developed. In this model, the bridge deck is modeled using frames and these frames are connected each other using the diaphragms at sup-ports. In this model, transverse analysis of moving load in bridge deck can be performed. Further-more, this model gives more accurate prediction

of modal responses as compared to spine model. Nevertheless, slab behavior cannot be modeled properly in this model, especially the two-way re-sponse including twisting.

Frame shell model can be used to improve the ac-curacy of frame/grid model. In this model, the slab is modeled using shell elements, which means the effects of the slab (both for out-of-plane loads and in-plane stresses) are included explicitly in the model for analyzing purposes. Thus, it can improve the accuracy of analysis results under several load cases.

Full shell model is considered as complex modeling technique for bridge. In this model, all elements are modeled using shell elements. Due to its complex-ity, sometimes it is difficult to extract information from analysis results for design purposes. However, with the help of powerful analysis software and computers that are available nowadays, this prob-lem can be overcome. Therefore, many engineers have started to use this model in order to get an ac-curate prediction of bridge responses under many load cases.

In this study, a typical concrete box-girder bridge is modeled and analyzed. The bridge has a total length of 80 m. The box-girder bridge has two spans of 40 m each and 10 m wide. The clearance of the bridge above the ground level is 7 m. The elevation and cross section of the bridge can be seen in Figure 1 and 2, respectively.

DESCRIPTIOn OF BRIDGE

About the Authors

Naveed Anwar Director, ACECOMS Affiliate Faculty, SET, AIT

Jimmy Chandra Lecturer Petra University, Indonesia

Deepak Rayamajhi Research Associate, ACECOMS, AIT

Figure 1. (a) Plan view of the bridge; (b) Elevation view of the bridge

Different Techniques for the Modeling of Post-TensionedConcrete Box-Girder Bridges

March 2010 25

First the bridge cross section is divided into two sections, top concrete slab (or deck) of 0.18 m depth and remaining ‘U’ shape section. The re-maining section is also divided into two girders along the longitudinal direction where each of them represents a half part of ‘U’ shape section. The two girders are connected in transverse direc-tion by frame elements with spacing of one meter. These frame elements represent the top concrete slab as defined before. As in the case of spine model, in grid model, rigid links are also used to modify the supports location and the results be-tween models with unmodified and modified sup-ports are compared (refer to figure 5).

In this study, finite element models of bridge are developed in SAP2000. The bridge is modeled with five different modeling approaches in which the complexity of the model is gradually increased. They are spine model, frame model, grid model, frame shell model and full shell model. Descrip-tion, details as well as assumptions made in each model are discussed below.

MODELInG TEChnIquES

Frame Model

Grid Model

Here, the concrete compressive strength (fc’) for the box-girder is 41 MPa and modulus of elasticity of the concrete is 30442 MPa. In this study, the se-lected bridge has only two lanes for the vehicles.

The connection between the deck and pier I re-stricts the displacement of the deck in X, Y, and Z direction and permits the rotation about X, Y, and Z direction (i.e. hinge support). The connections between the deck and pier II and III permit the displacement along X direction and rotation about X, Y, and Z direction but restrict the displacement along Y and Z direction (i.e. roller support).

In frame model, instead of modeling the bridge with a single girder, the bridge is divided into two girders (along the longitudinal direction) where each of them represents a half part of the entire cross section. These two girders are connected transversally with each other with diaphragms at the support locations (refer to figure 4). As in the case of spine model, rigid links are used to mod-ify the supports location and the results between models with unmodified and modified supports are compared.

Figure 2. Cross section of the bridge

Figure 4. (a) Simple Frame model; (b) Frame model with modified supports

Figure 5. (a) Simple Grid model; (b) Grid model with modified supports

Figure 3. (a) Simple Spine model; (b) Spine model with modified supports

(a) (b)

(a)

(b)

(b)

(a)

Article

In this study, finite ele-ment models of bridge are developed in SAP2000. The bridge is modeled with five different modeling ap-proaches in which the complexity of the model is gradually increased. They are spine model, frame model, grid mod-el, frame shell model and full shell model.

MODELInG APPROACh

In spine model, the bridge is modeled using a sin-gle girder which represents the entire cross section of the bridge. The section designer function in SAP2000 is used to model the cross section. Since the centroid of the single girder which represents the whole cross section of the bridge is not located at the bottom side of the box-girder, it thus gives improper supports location. Therefore, the loca-tion of the supports is modified with the addition of rigid links which connect the single girder and the supports. Furthermore, the supports are con-strained to eliminate the instability in torsional re-sponse of the deck (refer to figure 3). Later on, the results between models with unmodified and modified supports are compared.

Spine Model

March 201026

Figure 6. (a) Simple Frame shell model; (b) Frame shell model with insertion point; (c) Frame shell model with beam offset

Frame Shell Model Full Shell Model

The summary of all modeling techniques

Load Cases and Analysis Cases

In this model also, the bridge cross section is di-vided into two sections, top concrete slab (or deck) of 0.18 m depth and remaining ‘U’ shape section. The remaining section is divided into two girders along the longitudinal direction where each of them represents a half part of ‘U’ shape section. The concrete slab (or deck) is modeled using shell elements and girders are modeled using frame ele-ments. Generally, in FEA model if the slab and girder are drawn normally without any modifica-tions, it will give an improper cross section shape as well as properties. This is because the mid-plane of the shell elements will be located at the same el-evation with that of frame elements. In this study, two methods to solve this problem are presented. The first one is to modify the insertion point of the frame elements and the second one is to draw the frame elements at a different elevation than that of shell elements and connect them with rigid links. In frame shell model, rigid links are used to modify the supports location as in the case of spine model. However, only the results with modi-fied supports are presented (refer to figure 6).

In this study, the bridge is analyzed and reviewed for static and modal analysis cases. Static analysis is used to study the responses of the bridge for dead load, moving load and post-tensioning load cases whereas modal analysis is used to study the mode shapes of the bridge. Dead load is considered from the self weight of the bridge. The standard truck HSn-44 in accordance with American Asso-ciation of State Highway and Transportation Offi-cials (AASHTO) [1] is used for moving load cases. The moving truck loads are applied in both two lanes in opposite direction with particular vehicle speed. For post-tensioning load cases, tendon ele-ments are used as a load pattern on the bridge. The post-tensioning is estimated in such a way that moments produced by the post-tensioning effect should be able to balance most of the moment from dead load.

In full shell model, the entire box-girder section is modeled using shell elements. One of the ad-vantages of this model is that the supports can be directly put under the Box-girders. However, rigid links are still being used to model the bearings (re-fer to figure 7).

Table1. Summary of modeling techniques

(a)

(b)

(c)

Figure 7. Full shell model

Article

Code Model Type

1a 1b 2a 2b 3a 3b 4a 4b 4c 5

Simple Spine model Spine model with modified supports Simple Frame model Frame model with modified supports Simple Grid model Grid model with modified supports Simple Frame shell model Frame shell model with insertion point Frame shell model with beam offset Full shell model

March 2010 27

Analysis Results and DiscussionsThe response results from different modeling tech-niques are compared in terms of natural time peri-ods or frequencies, mode shapes, support reactions, deformations and internal forces. The comparison of the analysis results is shown in the following tables. All the output results are normallized with respect to full shell model results.

Comparison of Natural Periods

Comparison of Maximum Moment at Mid Span

Comparison of Exterior Support Reaction

Comparison of Interior Support Reaction

From the modal dynamic analysis result, it can be seen that all models give first and second mode as longitudinal mode. However, for third mode, spine model shows transverse mode; frame mod-el shows longitudinal mode, and the other mod-els show torsional mode. The natural periods for the first and second mode obtained from all model on average (excluding frame shell model natural periods for calculating average) is around 0.45s and 0.44s. Other than frame shell model, all the model predicts first and second natural period lower than full shell model. Furthermore, it should be noted that in all three modes, frame shell model without any modifications always gives higher natural period which means the structure is more flexible. This happens due to incorrect girder location, which in this model, the girder centroid is located at the same elevation as the slab centroid. Thus, it reduces the moment of inertia of the whole section of the bridge and reduces the bridge stiffness.

For maximum displacements and moments at middle span, almost all models give approxi-mately the same values. The major difference can be found in frame shell model without any modifications. As explained before, incorrect modeling of the girder location causes reduction in the bridge stiffness. Therefore, in this model, the displacement values are higher as compared to other models in all load cases (dead, live, and post-tensioned).

Furthermore, almost all models give approxi-mately same values for external support reactions as well as internal support reactions for dead and post-tensioned load cases. However, a major dif-ference can be found for live load case in spine model in which the values are much less as com-pared to other models.

Besides accuracy of analysis results from differ-ent techniques, it is equally important to account the computational time for each technique. It is found that relative to model 1a, computational time required for 1b,2a, 2b, 3a,3b, 4a, 4b, 4c, and 5 model are 1.03,1 .01, 1.06, 1.61, 1.25, 3.75, 2.89, 4.31, and 17.06 times higher respectively.

Article

Model type

Nat

ural

Per

iod

(S)

01a 1b 2a 2b 3a 3b 4a 4b 4c 5

0.20.4

0.60.8

11.2

1.4

1.6

Mode IMode IIMode III

Comparison of Displacement at Mid Span

Nor

mal

ized

Dis

plac

emen

t (m

m)

0

0.5

1

1.5

2

2.5

3

1a 1b 2a 2b 3a 3b 4a 4b 4c 5

Model type

Dead (-)Live (-)Post-tensioned (+)

Model type

Nor

mal

ized

Max

imum

Mom

ent (

kNm

)

01a 1b 2a 2b 3a 3b 4a 4b 4c 5

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Dead (+)Live (+)Post-tensioned (-)

Model type

1a 1b 2a 2b 3a 3b 4a 4b 4c 5

Nor

mal

ized

Rea

ctio

n

Dead (+)Live (+)Post-tensioned (+)

0

0.5

1

1.5

2

2.5

4.5

Model type

1a 1b 2a 2b 3a 3b 4a 4b 4c 5

Nor

mal

ised

Rea

ctio

n

0

0.5

1

1.5

2

2.5

3

3.5

4

Dead (+)Live (+)Post-tensioned (-)

March 201028

COnCLuSIOnSThis paper compares the responses of a post-tensioned concrete Box-girder bridge which that is modeled with different modeling techniques. The models used are spine model, frame model, grid model, frame shell model, and full shell model. From the two analysis cases (static and modal), which can be classified as longitudinal analysis, the responses are quite similar between different mod-eling techniques, except for some cases. It should be noted that proper assumptions are needed to achieve these similar results. Indeed, this is an ad-vantage for engineers who want to do a preliminary design or analysis with a simple model and they can achieve reasonable results. This can save computa-tional effort, cost, and time. However, it may not be the case for transverse analysis which is quite com-plicated and is not considered in this study. There-

Wireless Smart Sensors Inspect Bridge

fore, further research is recommended to investi-gate the effect of different modeling techniques in the response of post-tensioned concrete Box-girder bridge for the transverse analysis case.

Futurity.org (12/24/09) La Montagne, Jennifer; Bragorgos, Celeste

Researchers at the University of Illinois at Urbana-Champaign (UIUC), the Korea Ad-vanced Institute of Science and Technology, and the University of Tokyo have developed and deployed a network of wireless smart sen-sors on a bridge in South Korea to monitor its structural health. Dubbed the Illinois Struc-tural Health Monitoring Project, the sensor network was designed to create a reliable alter-native to traditional structure inspection tech-niques, which can be expensive and unreliable. The researchers' technology uses concurrent and distributed real-time processing to solve the issues of cost effectiveness and safety, which are problematic with traditional central-ized approaches. "Our research in distributed struc-tural health monitoring using wireless sensor networks overcomes these problems and promises a robust, signif-icantly lower-cost safer alternative to traditional struc-ture inspection techniques," says UIUC professor Gul Agha. The research also produced a cus-tomized software framework, which makes the development of structural health monitoring applications easier. More than 40 institutions around the world are using the framework of sensors and software, says UIUC professor Bill Spencer.

South Korea’s Jindo Bridge connects the mainland to Jindo Island. A network of wire-less sensors, affixed to the bridge in boxes attached with strong magnets, continuously monitors the bridge’s structural health. It’s the first monitoring system of its kind on a cable-stayed bridge and the largest of its kind for civil infrastructure to date

Source: ACM TechNews (December 30, 2009 Edition)

http://blog.xbow.com/xblog/2009/10/structural-health-monitoring-part-1-hard-ware.html

Article

REFERENCES1. AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFI-CIALS (AASHTO), LRFD Bridge Design Specifica-tions, 2nd Ed. with Interims, Washington, D.C., U.S.A., 2003.

2. CHEN, W.F., DUAN, L., Bridge Engineer-ing Handbook, CRC Press LLC, Boca Raton, Florida, U.S.A., 2000.

3. HAMBLY, E. C., Bridge Deck Behaviour, Routledge Mot E. F. & N. Spon, 2nd Edition, 1990

March 2010 29

Prof. Dr. Abdul Samad (Sami) Kazi, chief research scientist and research coordinator for process and ICT in the built envi-

ronment at VTT, the Technical Research Centre of Finland, and adjunct Professor at Hanken School of Economics, is a Civil Engineer by profession, and Construction Manager by area of specialisation. His main areas of interest and expertise include construction and project management, construc-tion IT, virtual organisations, knowledge management, strategic roadmapping, systemic innovation, groupware solutions, and inter-enterprise collaboration. Sami has industrial experience and maintains close links with the construction industry throughout his research. He has

been involved in more than thirty five international research, development, and innovation projects (each project having a budget ranging from 500,000 to 25,000,000 Euros) on con-struction IT, virtual organisations, strategic roadmapping, systemic innovation, IT for energy efficiency in buildings, and knowledge management. From a national research perspective, Sami is actively involved with the industry on development of programme on Building Information Model (BIM) based Business. He additionally consults industry and research organisations on strategic roadmapping and implementation action planning, construction IT, systemic innova-tion, and knowledge management. He has furthermore served the European Commission in various capacities, as an evaluator for Knowledge Management and eGovernment proposals in the IST (Information Society Technologies) programme, reviewer of IST projects on knowl-edge management, construction, mobile devices, and expert evaluator for portfolio of knowl-edge management projects (more than 20) in the IST programme. Sami has authored in excess of 90 refereed scientific publications and has been the lead editor of more than ten books in the areas of ICT for construction projects and processes, knowledge management, systemic innovation in construction projects, open building manufacturing, etc.

Sami holds a Doctor of Engineering degree in Construction Engineering and Management (Asian Institute of Technology, Bangkok, Thailand), a Master of Engineering degree in Construction En-gineering and Management (Asian Institute of Technology, Bangkok, Thailand), and a Bachelor of Science degree in Civil Engineering (Middle East Technical University, Ankara, Turkey).

Sami is listed in the Marquis Who’s Who in Science and Engineering, 7th , 8th , and 9th editions, and in the Marquis Who’s Who of Emerging Leaders (1st edition). He is fellow of the Entovation E100 Global Knowledge Leadership network, and roadmap co-champion and academic council chair of FIATECH. Sami is of Pakistani origin. His academic, research and industrial career span, Pakistan, Saudi Arabia, Tur-key, Thailand and Finland. Sami currently resides with his family in Espoo, Finland. He has been an ACE-COMS member since 1997, and has contributed several articles to its publication, “Civil Computing”.

I have had the honour and pleasure of being

engaged with and follow-ing up on the progress of

ACECOMS since its estab-lishment in 1995 under the

able guidance of Prof. Wor-sak Kanok-Nukulchai and the hard work of Dr. Naveed An-war. What initially started as a centre for providing relevant software to civil engineers has now blossomed to provide con-sultancy, training and educa-tion, and research of relevance to its stakeholders. ACECOMS has made significant contri-butions towards the training, and skills renewal of many civil engineers in Asia over the years. It is therefore no surprise that it is represented by more than 15 associate centres across Asia and in the USA. I look forward to the continued success of ACECOMS in all its ac-tivities and hope to soon see it as the premier re-search, development, and innovation centre on civil engineering in Asia.

Dr. Nirand Anunthanakul joined the Department of Civil Engineering, Faculty of Engineering at

King Mongkut’s University of Technology North Bangkok, Thailand in 1994. He received his Ph.D. in Civil Engineering from the George Washington University, Washington DC, USA in 2003. He was the Head of the Department of Civil Engineer-ing from 2006 to 2007. He is a member of the American Society of Civil Engineer (ASCE). His main research and professional interests in-

volve the application of structural failure—with emphasis on structures subjected to dynamic and cyclic loadings—and the effects of earthquakes and other natural forces on infrastructure such as high-rise buildings, bridges.

COURSES TRAIN-ING EXPREIENCES

WITH ACECOMS

With a tremendous staff, ACE-COMS assembled training cours-

es that allowed the engineering team to understand how to start

from an existing design, build a finite element model SAP2000,

and ETABS, define the applicable loads and boundary conditions and to achieve reliable results. It was ex-tremely informative, very useful and the training booklets contained perfect examples and information. I am happy to have ACECOMS available to sup-port unique training needs.

ACECOMSMember’s Profile

Prof. Dr. Abdul Samad (Sami) Kazi Views on ACECOMS

Dr. Nirand Anunthanakul

March 201030

Udit Rastogi BE (Civil), Associate Member – Indian Association of Structural Engineers udit.rastogi@gmail.com

EXAMPLE 1Let us start with a simple case of simply supported beam loaded with UDL. We will also see about the general sign convention for shear force and bend-ing moment in this case.

Figure 1 (a) shows a simple supported beam ‘AB’ of span 10 m with a UDL of 2 k N/m acting on it. Support reactions – shown in Figure 1 (b) – can be easily calculated using the 3 equations of equilib-rium. And, Figure 1 (c) shows the deformed shape of the beam ‘AB’.

Since portion ‘CD’ is in the middle of the structure and it will be in +ve bending or sagging; we will observe the portion ‘CD’ for understanding the sign convention assumed for shear force and bend-ing moment.

First, we shall draw the free body diagrams (FBD) of portions ‘AC′, ‘CD′ and ‘DB′. Figure 2 shows the FBD of ‘AC′; whereas Figure 3 shows the FBD of ‘DB′. The unknowns can easily be calculated and checked.

Figure 1(a-c). A Simple Beam

About the Author

InTRODuCTIOnThis article discusses the deflection profile and visualizing tension side of a structural member, subjected to transverse loading, by looking at the bending moment direction. The examples given here can be found in any text book of strength of material. However, the aim of this article is to make the bending moment diagram easier to understand. One can draw a BMD profile just by observing clothes on a rope/wire. Just hang a towel on the rope and it will show the BMD profile for UDL; use a hanger and you will observe the BMD profile for point load, and if you want to observe a combina-tion – just hang clothes in different arrangements.

COnCEPTWhen we draw the moment diagram through the member, the side of the member from where the moment emerges represents the tension side of the member.

Let’s consider an analogy to the similar situation; remember when we try to insert a pin on paper (or bundle of papers), it tries to compress the nearby area - at the side where the pin is being inserted - and on the other side it tries to stretch the paper. One can easily tell which side is under tension or compression. In this case – obviously the side from where the pin is coming out will be in tension. Simi-larly, the concept of drawing moment through the member helps us to visualize the tension side of any member. And, this compression and stretching of paper is similar to the bending of beam if the pin is considered as a moment and beam is assumed to be made of paper. The concept of tension side is of importance while drawing deflection profile, bend-ing moment diagram and also in the RCC design of structures since the main reinforcement is provided on the tension side of the member. This concept will be further explained by two examples.

This article is intend-ed for developing better understanding of simple structural behavior for the structural engineer-ing students

Finding the Tension side and Deflection Profile of a Structural Member by Observing Moment Directions

B

B

B

(a)

(b)

(c)

D

D

C

C

10 mRB

2m

2m

1m

1m

7m

7m

A

A

A

HA

VA

VA= RA= 10kN RB= 10kN

2kN/m

2kN/m

2kN/m

March 2010 31

Figure 4 shows the FBDs of point ‘C’and ‘D’. Now, the FBD of portion ‘CD’ – Figure 5– has been drawn deducing the information from Figure 4.

This signifies a point for what we did to the simple problem with complex approach. Observe the di-rection of SF and BM in Figure 5

For portion CD, we must consider the equilibrium of point C and point D. On the left side of point C – towards end A – there is a downward force of 6 kN and an anticlockwise moment of 16 kNm. So, for point C to be in equilibrium, there should be an upward force of 6 kN on right hand side of point C – towards end B – and a clockwise moment of 16 kNm. Similarly, the balancing forces for point D can also be calculated by observing the portion BD in Figure 3.

2kN/m

10kN

21kNm

4kn 7m

D B

2kN/m

10kN

HD

MD

VD 7m

D B

(a)

(b)

2kN/m

16kNm

6kN10 kN

2m

A C

2kN/mMc

Hc

Vc10 kN

2m

A C

16 kNm

6 kN

1 m

4 kN

21 kNm2 kN/m

DC

If we draw the moments like in Figure 6, then we have more information regarding the behavior of the member. As stated, we can identify the ten-sion side of the member just by looking at the ar-rowhead of the moments. In other words, the side from where the moment is emerging is the tension side of the member. Once we have the tension side of the member, we know the deflection profile; and drawing the deflected shape and BMD is simple. Since all the arrowheads are at the bottom side, hence the bottom side will be in tension.

16 kNm 16 kNm

D

C

6 kN

C

16 kNm

6 kN

6 kN

D

21 kNm21 kNm

4 kN

4 kN

Point D

Point C

4kN

21 kNm

• The portion CD is in +ve bending (sagging).

• The direction of shear force (resistance offered to loading) is as was assumed in +ve sign conven-tion for shear.

• The direction of bending moments (resistance offered to loading) is as was assumed in +ve sign convention for shear.

Hence, we can say that the sign convention for shear force and bending moment is not some-thing which was assumed randomly but it is corresponding to +ve bending.

Now we shall observe Figures 3, 4, and 5. Most of us are used to draw bending moments like drawn in Figures 3, 4, and 5.

16 kNm

6 kN

1 m

4 kN

21 kNm21 kNm

DC

(e)

6kN

16kNm

10 kN2m

A C

2kN/m

10kN4kN 7m

D B

(d)

16 kNm

1 m

4 kN

2 kN/m

DC

(b)

6 kN

2kN/m

10 kN2m

A C

2kN/m

10kN

21kNm

4kN 7m

D B

(a) (c)

6kN

(f)

Figure 2(a,b). Part AC of Beam

Figure 3. Part DB of Beam

Figure 4. Point C and D

Figure 5. Part CD of Beam

Figure 6 (a-f). Moment Convention

Article

Finding the Tension side and Deflection Profile of a Structural Member by Observing Moment Directions

March 201032

We will arrive at Figure 8 if we do the analysis and draw the moments on the Figure. These moment directions can also be obtained from any software available.

EXAMPLE 2Let us refer to Figure 7. We have to draw the ex-pected shape of the BMD for this frame. Load val-ues are not given as we are only interested to know the expected shape of the deflection profile and BMD.

The point behind this example is that we should feel the structure and its behavior. Nowadays there are numerous softwares available which give us the analysis results, however, the user must be confi-dent about the results and should always get the expected results from software. Here, we will draw the expected profile of BMD by observing the mo-ment and bending moment directions.

Figure 7

Figure 8

Figure 9

Figure 10

Most of us will draw the results like Figure 8. Now, if we draw the moment directions through the mem-ber, we will get Figure 9.

Compare Figures 8 and 9. Both the figures are same; however, in Figure 9, the moments are drawn through the members. If we observe the arrow heads only in Figure 9, we can easily draw the BMD without any confusion; and once we have correct BMD, the deflection profile will be easy to observe.

Figure 12 shows the BMD of the frame. Please note here that the bending moment has been drawn on the tension side of the members.

Now, one can easily draw the deflection profile as it would be on the tension side of the member as well.

If we want the deflection profile or the tension side of the entire frame, we just have to see the arrow-heads of moments in figure 9. The arrowheads of moments are on the tension side of the frame.

Please note that this concept holds good even for any moment which is acting as an external load. Just ob-serve the sides where the arrowhead is emerging out; that will be the tension side. Tension side will change direction at the point where the moment is acting.

Figure 11

Figure 12

REFERENCES 1. Basic Structural Analysis – C S Reddy

2. Structural and Stress Analysis – Dr. T H G Megson

3. Strength of material and structures – John Case, Lord Chilver & Carl T F Ross

4. Structural Analysis – C K Wang

5. Structural Analysis – Pandit and Gupta

6. Elementary Structural analysis – A K Jain

7. Matrix Analysis of Framed Structures – William Weaver, Jr. and James M. Gere

8. Finite Element Analysis – C S Krishnamoorthy

9. And class room notes by –Dr M T Venuraju, Dr A Krishnamoorthy, Mr. B H V Pai, and Mr. Kiran Kamath.

If we observe the ar-row heads only in figure we can easily draw the BMD with-out any confusion and once we have correct BMD the de-flection profile will be easy to observe.

Article

March 2010 33

several enhanced pushover methods in predicting the response characteristic of RC and steel frame building through comparison with benchmark high rise responses obtained from NL-THA as an “exact” solution.

ASSESMEnT OF EnhAnCED PuShOVER AnALYSIS METhODS COnSIDERInG hIGhER-MODE EFFECT FOR TALL BuILDInGSThe shape, height, and complexity of building structures are essentially increasing nowadays. Cli-ents, Architects and Engineers compete with each other to prove themselves in designing “unique” structures. Performance Based Design (PBD) is a logical design process that gives a solution to achieve a specified performance. Most Codes now incorporate a PBD option as an alternative to its prescriptive requirements. So that the need of the analysis tool to determine the performance of the structure becomes important. Non-linear Static Pushover Analysis (NSPA) has already become a popular tool for analysis these days. For practi-cal reasons, people may choose NSPA over Non-Linear Time History Analysis (NLTHA). However, NSPA has an inherent deficiency that its invariant load distribution cannot take the higher-mode effect into consideration which will take an important role for high-rise structures. Attempts had been made to develop NSPA so that the higher-mode effects can be considered. With the increasing number of the modified pushover procedure that have been pro-posed, it will be useful to identify the limitations of each procedure and compare their effectiveness in determining the seismic demand of the structure. This research investigates high rise effectiveness of

by Structural Engineering Masters Students at AIT

The Master degree students at the AIT are generally required to carry out an extensive research as part of the requirement for obtaining the degree. This research, in several programs, including the struc-tural Engineering Field of Study may extend to one year (26 credits). The research carried out by the students’ ranges from purely experimental studies, to purely theoretical development. This year, many of the research topics are following the theme of seismic performance, nonlinear modeling and analy-sis and related topics. Most of these topics are be-ing supervised by Dr. Pennung Warnitchai and Dr. Naveed Anwar. This article presents a brief over-view of some of these topics.

Performance point evaluation through a set of inelastic spectra

Elevation view of the structures: 3 basements and 42 floors Total height : 140.2 m

Some of the Research being carried out

by Amelia Kusuma, Indonesia

DIAPhRAGM EFFECTS On TALL BuILDInGS, CuRVED In PLAn Floor and roof systems in buildings have an im-portant role in transferring the lateral load to vertical lateral load resisting (VLLR) elements through diaphragm action. Diaphragm flexibility is one of the major concerns for different con-figurations of building. Rigid floor diaphragm as-sumption is reasonable for the seismic analysis of buildings with rectangular or nearly square shape but may not be appropriate for irregular build-ings or curved shaped buildings. Most architects and engineers choose the curved shaped build-ings than straight building because it is more fas-cinating from an architectural point of view; also, curved shaped buildings are assumed to increase the lateral load resistance by the nature of their shapes. The main purpose of this paper is to in-vestigate the difference between the rigid floor and flexible floor analyses of the buildings. In this study, a 60-story rectangular building is taken for the analyses and then the rectangular configu-ration is changed into different curvatures with central angle of 600, 1200 and 1800 by keeping the same overall dimension in each configurations.

Knight Bridge Building, Philippines, a building curved in plan

March 201034

APPROPRIATE MODELInG TEChnIquES FOR nOn-LInEAR DYnAMIC AnALYSIS OF ShEAR WALLS Reinforced concrete (RC) shear walls are widely used in medium to high rise buildings as these walls are very effective in providing resistance and stiffness against the lateral loads imposed by earthquake. RC shear walls in multistory buildings are slender, and behave essentially as vertical cantilever walls. These RC shear walls are expected to deform well into in-elastic range and dissipate the energy input by the base motion through stable hysteretic behaviour of structural components. So proper modeling of the load versus deformation behaviour of RC shear walls is essential to predict the important nonlinear response quantities. Flexural behaviour is one of the major concerns in the medium or high rise RC shear walls. In this paper, different modeling techniques like single column model, fiber model and nonlin-ear layered shell model are presented that represent the flexural behaviour of RC shear walls to various degree of accuracy. The nonlinear responses of RC shear walls are assessed by performing both 2D and 3D nonlinear static (pushover) and nonlinear direct integration time history analyses.

DETERMInATIOn OF ABuTMEnT RESPOnSE FOR LOnGITuDInAL LOADS AnD MOVEMEnTS The problem of soil structure interaction and non-linear response of bridge bearings has been studied extensively by many researchers. However, there are not many references dealing with the overall response of the complete abutment system which includes the bearings, the restraining blocks, the abutment walls, the wing walls, the foundation components and the soil. This paper studies and compares vari-ous modeling techniques to effectively capture the response of the abutment system for longitudinal forces and movements including the non linearity and the dynamic characteristics. The paper consid-ers a range of the models including simple support, simple spring model, combination of simple sup-port and linear link model, combination of simple support and non linear link model, full shell model, and combination of shell, solid, and link model.

-by Rojit Shahi, Nepal

-by Stefani Reni, Indonesia

cx

kθ

Fixed Support DF1

kx

kx

k1m

k2 k3

kx

kθ kθ

kθ

cx

c1 c3

DF2 DF3

Wrinkler pile Foundation

Abutment: Typical Detail

Various Abutment Models

-by Ja San Lu, Myanmar

All the buildings are analyzed assuming both rigid and flexible diaphragm assumption by using equiva-lent static analysis, response spectrum analysis and time history analysis.

Article

Girder

Bearing

Wall

Approch SlabGap

Footing

Soil

shell element with linear properties

shear link with linear property

Rigid element to enforce deformation compatibility

Uniaxial line element with non-linear properties (Axial Hinge or Nonlinear Link)

Fiber or Frame Model for Representing Shear Walls

Discretization of wall cross section into small segments

March 2010 35Sources: www.meshcomputer.com, www.pcworld.com

Two Decades of rapid improvements in performance of

Personal ComputersThe PC hardware industry develops and enhances the performance and capabilities of systems at a very fast rate. In contrast, the hardware cost continues to drop. The selection of a good system these days does not depend so much on the price tag, but rather on what configuration is required. In this article, we briefly review the specifications of a typical high-end Personal Computer and compare it with the computer hardware available twenty and ten years ago. We also suggest a typical configuration if you need a system with a punch.

Main Processor The Intel® Core™ i7 975 Extreme Edi-tion Quad Core Processor is the newest generation of Intel microprocessor. It is brilliantly fast with a Clock speed of 3.33GHz, L2 Cache of 8MB and with a Quick Parth Interface of 6.4GT/s. With faster, intelligent, multi-core technology that applies processing power where it's needed most, new Intel® Core™ i7 processors deliver an incredible breakthrough in PC performance. They are the best desktop processor family on the planet.

You’ll multi-task applications faster and unleash incredible digital media creation. And you’ll experience maximum performance for everything you do, thanks to the com-bination of Intel® Turbo Boost Technology and Intel® Hyper-Threading technology (Intel® HT technology), which maximizes performance to match workload.

Hard Disk The 2TB (2x 1000GB) Serial ATA 2 Hard Drive with 32MB Buffer has almost 30 times the disk space a decade ago. It has a serial ATA 2 interface, with a speed of 7200rpm and a cache of 32MB buffer. And it can be upgraded up to 6TB (4x 1500GB). This hard disk is ideal for performance desktop comput-ing storing high-resolution images, gaming, multimedia content, and personal and business information.

Memory The 8GB 1333MHz Dual Channel DDR3 SDRAM - (4x2GB). It has a memory speed of 1333MHz, with a storage capacity of 2GB x 4 which equals to 8GB and the technology from DDR3 SDRAM. It can also be upgraded up to 12GB 1333MHz Triple Channel DDR3 SDRAM - (6x2GB). These specifications can run any high end graphics, com-puter models or any 3D applications. SDRAM gives you the advantage of a faster rate.

Display The 2 GB 5970 ATI Radeon Graphics Accelerators GDDR5 is engineered for speed, the ATI Radeon™ HD 5970 the fastest graphics card on the planet. This graphics card is recommended for top performance on both 2D and 3D graphics on computer models.

In the last two decades, there has been 130 times increase in the main processor speed, 16000 times increase in hard disk capacity and 15000 times increase in RAM.

Feature 1989 1999 2009

Processor Speeds

Hard Disk

Memory

Video Graphics

Monitor

CD/DVD ROM Drive

Removable Storage

Sound Adapter

Modem/Ethernet

Mouse

Keyboard

Installed Software

Printer

I/O Port

Cache

80486 DX-25 MHz

120 MB

512 KB

512 KB

Monochrome / VGA 400 x 600 Resolutiuon

CD-ROM Single Speed

Tape

8 Bit Sound Blaster Card

Optional / Rare

Serial Mouse

88 Keyboard

MS DOS 4.0 Windows 3

Dot Matrix 8 pin

Mouse 1 se-rial parallel

-

Pentium III 600 - 733 MHz AMD Athlon 700 MHz

13-36 GB Ultra ATA/66 / Ul-tra Wide SCSI

64-768 MB

8-32 MB

17" - 19" CRT/LCD Display, 1600x1200 Resolution

50X speed CD Drive / 8x DVD Drive

Zip or LS-120 Drive Recordable CD ROM

64 / 512 voice PCI audio card

56K V.90 Compat-ible Data/Fax PCI

Intillimouse / Mouse Man Wheel

102 Keyboard

MS Windows98/ 2000 plus Internet Explore or Netscape 4.x to 5.x

Laser/Ink Jet 600-1200 dpi, Color Inkjet, 720 dpi

USB, Serial, Parallel, Mouse, Keyboard

8GB 1333MHz Dual Channel DDR3 SDRAM - ( 4x2GB )

8MB Cache

2GB 5970 Graphics Accelerator

30", High Resolution 2560 by 1600

Blu-Ray Combo Optical Drive (Blu-ray ROM, DVD/CD RW)

External 1TB Hard Drive

7.1 PCIe Sound Card

IEEE 802.11n_2009, 600 Mbit/s

Cordless Mouse

Cordless Keyboard

Windows 7

Multifunction Color Inkjet with High Resolution 5760x1440, Black & White and Color

USB, Serial, Parallel, Mouse, Keyboard

512 KB Integrated L2 Cache

Intel® Core™ i7 975 Extreme Edition Quad Core Proces-sor (3.33GHz,8MB Cache) - LGA1336

2TB (2x 1000GB) Serial ATA 2 Hard Drive with 32MB Buffer

March 201036

• Geo-modeling with Google Building Maker

Google Building Maker is an online application specifically for geo-modeling. If the buildings you want to model are located in an area where Building Maker imagery is available, you should choose this method. The process of geo-modeling with Building Maker involves matching basic "building blocks" with images of buildings to create 3D models. The aerial imagery used by Build-ing Maker is provided by Google; you don't need to have any of your own photographs to use it. Building Maker is a free applica-tion that runs in your web browser, and imagery is available for dozens of cities around the world.

EarthGeo-Modeling on

Google Earth introduces Geo-Modeling, the process of making 3D models of real-life buildings that will appear in Google Earth. There are two ways to make geo modelling. These are Geo-modeling using Google Building Maker and Geo-modeling using Google SketchUp.

Source:http://sketchup.google.com/support/www.earth.google.com

Google Earth in 3D Bangkok

Baiyoke and Bangkok in 3D

Rama 8 Bridge

• Geo-modeling with Google Sketchup

Google SketchUp is a tool you can use to build 3D models of any-thing you like – including buildings for Google Earth. You should use SketchUp for geo-modeling if you can't use Building Maker or if the buildings you want to model are very complex or unusual. Depending on your level of proficiency with SketchUp, you might choose one of two following modeling methods.

SketchUp Beginner: If you're new to SketchUp, you should use the Extruded Footprint method. This method is the easiest to fol-low and it produces very good results.

SketchUp Advanced: If you've been using SketchUp for awhile and are comfortable with how it works, you should try the Matched Photo method of geo-modeling. This technique uses SketchUp's photo-matching feature to build a model based on one or more perspectival photographs of your building. Note that this method only works with uncropped photographs taken from certain an-gles – if you're not able to photograph the building yourself, you should use the Extruded Footprint method.

• Google 3D Warehouse

The 3D Warehouse is an online repository for sharing 3D mod-els. These models are a combination of user-generated content (models created by non-Google employees) and Google generated content (models created by Google employees).

ANALYSIS• The Equivalent Frame Method (EFM) for designing of 2D reinforced concrete and post-tensioned frames. • General 3D analysis model with new fast solvers, including dynamics • Stiffness effects of columns, walls and ramps are included• Nonlinear analysis for long term creep using moment-curvature and cracked conditions• Automatic analysis for secondary post-tensioning stresses for design• Nonlinear analysis for no-tension soil supports with uplift • Automated prestress loss calculations• Lateral loads (wind and seismic) can be considered in models• Response-spectrum analysis based on loads and modes imported from ETABS®

12.2 Version

Geo-Modeling on

All-new SAFE is the ultimate integrated tool for designing reinforced and post-tensioned concrete floor and foundation systems. This version introduces versatile 3D object based modeling and visualization tools. Charged with the power of SAPFIRE this release redefines standards in practicality and productivity. From framing layout to detail drawing production, SAFE integrates every aspect of the engineering design process in one easy and intuitive environment.

MODELING• Automated generation of P/T tendon layout for flat slabs• Horizontal and vertical tendon profiles with interactive graphical editing• Multi-segmented design strips including skews and varying widths• Powerful mesh generation options • New edge constraint connects mismatched slab meshes• Design-strip width automation• Automated generation of pattern loading based on panels • Automated generation of tendon-profiles using load balancing• Strip-based automatic tendon layouts• Automated finite element meshing

New Features

DESIGN • Slab and beam design for numerous international codes• Strip-Based Design with General Strip Definitions• Finite Element (FEM) Based Element Design• Design of punching-shear reinforcement (stud rails) • Automated T-beam Effects• Design considers post-tensioning and lateral loads • Serviceability and load-transfer design checks for post-tensioning• Post-tensioning strength checks with secondary locked-in stresses

Detailing• Fully automated and customizable detailing of slabs, beams and footings • Detailer includes post-tensioning, general design strips, slab, and beam offsets• User-defined section cuts on slabs, beams, and mats • Synchronization of Drawings after Model Modifications• Export of detailing output to AutoCAD• Simplified Fatigue Analysis Based on API Criteria

March 201038

ACEE 2010

Tokyo Institute of Technology (TIT)

Asian Institute of Technology (AIT)

Association of Structural Engineers of the Philippines, Inc. (ASEP)

The Engineering Institute of Thailand (EIT)

The 3rd ASIA Conference on Earthquake Engineering

1 June 20101 July 2010

15 August 201030 September 2010

01-03 Dec. 2010

Important DatesDeadline for receipt of abstracts (online submission possible) Notification of provisional acceptanceDeadline of receipt of camera-ready manuscriptsNotification of acceptance of the papersConference

Organized by

Learning from the brain: Computer Scientists Develop

New Generation of Neuro-Computer

The human brain consists of a network of several billion nerve cells. These are joined together by independent connections called synapses. Synapses are changing all the time – something scientists name synaptic plasticity. This highly complex system represents a basis for independent thinking and learning. But even today there are still many open questions for researchers. “In contrast to today’s computers, the brain doesn’t carry out a set programme but rather is always adapting functions and reprogramming them anew. Many of these effects have not been explained,” comments IGI head Wolfgang Maass together with project co-ordinator Robert Legenstein. In co-operation with neuroscientists and physicists, and with the help of new experimental methods, they want to research the mechanisms of synaptic plasticity in the organism.

Revolutionising the information society

The researchers are hoping to gain new knowledge from this research about the learning mechanisms in the human brain. They want to use this knowledge of learning mechanisms to develop new learning methods for artificial systems which process infor-mation. The scientists’ long-term goal is to develop adaptive computers together which have the potential to revolutionise today’s information society. The three-year project is financed by the EU funding framework “Future Emerging Technologies” (FET), which supports especially innovative and visionary approaches in information technology. International experts chose only nine out of the 176 applications, among which was “Brain-i-Nets”. Partners of the research initiative worth 2.6m euro include University College London, the Ecole Polytechnique Federale de Lausanne, the French Centre National de la Recherche Scientifique, Ruprecht-Karls-Universität Heidelberg und the University of Zurich.

First Announcement

& Call for Papers

Graz University of Technology researchers co-ordinate “Brain-i-Nets” EU project

http://presse.tugraz.at/pressemitteilugen/2010/01.02.2010_englisch.htmSource: ACM TechNews (February 01, 2010 Edition)

Theme : “Disaster Risk Reduction and Capacity Building for Safer Environments”Venue : Grand Millenium Sukhumvit, Bangkok, ThailandDate : 01-03 Dec. 2010

March 2010 39

In the past few months most of the professional training and seminar activities were carried out either in AIT, Thailand or in Manila, Philippines. The events in the Philippines were mostly customized as special seminars for engineers in some consulting firms whereas the seminars and workshops in AIT were more of general and international nature.

SY∆2 + Associates, Inc., maintained a continuous practice of engineering consulting since its incep-tion in 1983. They are one of the largest engineering firms involved in the design of tall buildings in the Philippines.

SY∆2 + Associates, Inc. is a close associate of ACE-COMS and has jointly worked in the past and is cur-rently involved in several projects for Performance Based Evaluation and Design, Wind Tunnel Testing etc.

ACECOMS has been regularly conducting training and staff development for SY∆2 + Associates, Inc. On 14-18 September 2009, the President & CEO Engr. Jose A. Sy and Senior Associates Engr. Al-exander L. Ty and Engr. Edwin Anthony N. Mag-salansan came to ACECOMS and joined one week of extensive interactive discussions and exchange of knowledge on various aspects of Performance Based Seismic Design for their new project, the Lot G Project in the Philippines, which is a high-rise building with a ductile core wall system. During this visit, they were accompanied by ACECOMS Engi-neers Thaung Hut Aung and Deepak Rayamajhi.

Customized Consultancy

ACECOMS Engineers and Engineers from SY∆2 + Associates, Inc.

ACECOMS staff and Managing and Senior Directors of SY∆2 + Associates, Inc.

IN THAIlAND

The engineers from AEC Engr. Idris Lawal Akinremi, Engr. Adekunle Abidemi Allo, and Engr. Yinka Temitope Ayantoyinbo with ACECOMS Director in his office

Recently, ACECOMS carried out the structural anal-ysis and design of Lagos Badagry crossing bridge project in Nigeria, in association with the local de-sign firm Advanced Engineering Consultants Co. Ltd. (AEC). In 22-28 September 2009 three senior structural engineers from AEC visited ACECOMS to undergo a special training and seminar on the effective modelling, analysis and design of bridges using SAP2000. The engineers also visited many bridge projects in Bangkok and discussed possible future collaborations.

Recent Training and Seminars

SY∆2 + Associates, Inc.

Customized Training on Analysis & Design of RC/PTAdvanced Engineering Consultants Co. Ltd. (AEC)

March 201040

ACECOMS Director Structural Engineering Field Coordinator ACECOMS Manager ACECOMS Structural Engineer ACECOMS Structural Engineer Senior Structural Engineering Student Senior Structural Engineering Student

PresentersDr. Naveed Anwar Dr. Pennung Warnitchai Engr. Keerati Tunthasuwattana Engr Thaung Hut Aung Engr. Deepak Rayamajhi Ms. Amelia Kusuma Mr. Rojit Shahi

The awareness and demand for Performance Based Structural Design is increasing significantly in many countries especially in high seismic risk areas such as Philippines. In October, ten members of the As-sociation of Structural of the Philippines (ASEP) including the present and past Presidents of ASEP and members of the executive committees visited ACECOMS for a three day special workshop on Performance Based Design and its applications. During their stay they also visited the AIT structural laboratories and the AIT-Thammasat Wind Tunnel facilitated by Dr. Pennung Warnitchai, the Structural Engineering Field of study Coordinator. In addition to the main presenters, some of the structural engi-neering students presented their research work relat-ed to non-linear modelling and push over analysis.

ASEP participants during the workshop

Dr. Pennung Warnitchai and the ASEP participants inside the wind tunnel

Engineers from AEC and ACECOMS on a site visit to Mega Bridge in Bangkok

Participants

Harry Ting Wong Vickie Tan Wong Adam C. Abinales Cesar C. Pabalan Christopher P.T. Tamayo

The Department of Highways (DOH) oversees the design, construction and management of all of the Highways and Bridges in Thailand on 4-5 November 2009. ACECOMS carried out a customized training and work-shop for the 30 engineers of DOH on effective modeling, analysis and design of structures using hands-on approach.

Intensive Workshop on Performance Based DesignAssociation of Structural Engineers of the Philippines (ASEP)

Customized Workshop on Modeling, Analysis and Design of Structures Engineers from Department of Highway, Thailand

Frederick Francis M. Sison Virgilio B. Columna Maricon C. Pineda Tony C. Pimentel Woody M. Cabardo

Recent Training and Seminars Recent Training and Seminars

March 2010 41

The DOH engineers attending the hands-on seminar

A group photo of DOH workshop participants

A Software Users Forum was held in Quezon City at the Quezon City Sports Club from 18-20 March 2009. The forum had different topics each day; Day 1 - Analysis and Design of Buildings using ETABS 9.5, Day 2 – Analysis and Design of Slabs and Foundation System using SAFE12.0 and Day 3 – Analysis and Design of Structure using SAP2000 V12. This forum was conducted by Dr. Naveed Anwar, Engr. Keerati Tunthasuwattana and Engr. Thaung Hut Aung who specially travelled to inter-act with the engineers and discuss their modelling and analysis issues.

After Thailand, Philippines is fast becoming the centre of ACECOMS activities in almost all ar-eas including conferences, seminars, workshops, projects and professional collaboration. The high-lights of some of the activities are included below.

Hyder Consulting is a multi-national advisory and design consultancy with particular specialisation in sructural, transport, utilities, property and environ-mental solutions. With nearly 5,000 people across the UK, Europe, Middle East, Asia and Australia, they offer clients the benefit of global expertise cou-pled with local knowledge. Their office in the Philip-pines is located in Makati City at the 9th floor, Tower 2 of The Enterprise Center.

In PHILIPPInES

Dr. Naveed interacting with the participants of the forum

A special seminar was conducted by Dr. Naveed Anwar on 21 March2009 for the structural engi-neers at Hyder Consulting office in Manila working on the design of tall buildings, the seminar focused on the special modelling issues and techniques and effective use of ETABS and SAFE software. The seminar was attended by more than twenty engi-neers ranging from heads of the design section to the fresh graduates.

Seminar Hyder Consulting Philippines Inc.

Software users Forum for Structural Analysis DesignQuezon City Sports Club

Dr. Naveed Anwar, presenting during the forum

Recent Training and Seminars Recent Training and Seminars

March 201042

honorary Membership of the Association to the ACECOMS Director naveed Anwar, D. Eng.

The President of the Association of Structural En-gineers of the Philippines (ASEP) Adam C. Abinal-es, F. ASEP along with several members of the ex-ecutive board and other prominent engineers from the Philippines bestowed the Honorary Member-ship of ASEP to Dr. Naveed Anwar, ACECOMS Director on 16 November 2009 at the International Hotel, Makati City. He was also presented with a plaque that reads “As resolved by the incumbent Board of Directors, in profound recognition of his valuable contribu-tion to the Association of Structural Engineers of the Phil-ippines, Inc. (ASEP) for more than ten years as a resource speaker or member of the international advisory committees of various International Conferences and Seminars organ-ized by ASEP geared towards the professional developement of structural engineers in the Philippines specifically in the field of advanced computing technology, and in grateful ap-preciation of his efforts of making relevant trainings and quality software more accessible and affordable to ASEP members, making Filipino structural engineers more globally competitive.”

This is a great honour for Dr. Naveed Anwar as well as ACECOMS and it is highly appreciated.

The Association of Structural Engineers of the Philippines (ASEP) held its 14th ASEP Internation-al Convention on 21-22 May 2009 with the theme of "Structural Engineering: Coping with Global Crisis".

The Asian Center for Engineering Computations and Software (ACECOMS) has been actively col-laborating with and supported by the Association of Structural Engineers of the Philippines (ASEP) for the development of structural engineers and the structural engineering profession in the Philippines since 2001. To further enhance and to formalize this corporation, a Memorandum of Understand-ing (MoU) was signed between ASEP and ACE-COMS on 30 October 2009.

The purpose of MoU’s is to enable cooperation between ACECOMS and ASEP in the promotion of professional activities for mutual benefit. The activities under the scope of this MoU are software development, professional training and human re-source development, research and development and publication and member services.

Currently, ACECOMS is working on several projects in the Philippines ranging from evaluation of causes of Slab Deflection to full Performance Based De-sign Analysis and Design of 76 storey building. ACECOMS team comprising of Dr. Naveed An-war, Engr. Keerati Tunthasuwattana, Engr. Thaung Hut Aung and Engr. Deepak Rayamjhi visited Phil-

The venue of the event was the Great Eastern Ho-tel (formerly Aberdeen Court) in Quezon Avenue, Quezon City. During this event Dr. Naveed Anwar together with Engr. Thaung Hut Aung presented one technical paper in the plenary session titled "Modeling of Shear Walls for Non-Linear and Pushover Analysis of Tall Buildings." Dr. Naveed Anwar also conducted a Continuing Professional Development (CPD) Lecture. The CPD Lecture was an "Overview of Pushover Analysis of Buildings." This lecture pro-vided a consolidated theoretical background and practical knowledge on Performance Based Design and Pushover Analysis of Buildings. It also demon-strated the effective usage of modern computing tools for carrying out Performance Based Design and Pushover Analysis.

14th ASEP International ConventionAssociation of Structural Engineers of the Philippines, Inc. (ASEP)

Establishment / Designation of Collaboration ACECOMS and ASEP

Association of Structural Engineers of the Philippines, Inc. (ASEP)

ACECOMS Team visits Manila to meet with Project Clients, Developers and Consultants

Recent Training and Seminars Recent Training and Seminars

A Plaque and a certificate presented to Dr. Naveed Anwar

March 2010 43

The Philippine Institute of Civil Engineers (PICE), an organization of the Civil Engineers in the Phil-ippines organized a Continuing Professional Edu-cation (CPE) Seminar on 23 May 2009 at National Office, Port Area, Bonifacio Drive, Manila in Coop-eration with the Asian Center for Engineering Com-putations and Software (ACECOMS), Associate Center (DLSU, Manila). The CPE Seminar was con-ducted by the Director of ACECOMS Dr. Naveed Anwar with the theme "Computer-Aided Modeling, Analysis and Design of Bridges (Various Approaches)". The objectives of the seminar were to provide an overview of the theoretical and practical back-ground on analysis & design of various types of bridge structures with a special focus on RC bridges, and to introduce the use of current computing tools for the modeling, analysis, and design of bridge structures. The seminar used SAP 2000 software that provides powerful capabilities for modeling a wide range of structures, including bridges, dams, tanks, and buildings.

The 9th International Symposium on Ferrocement and Thin Reinforced Cement Composites with the theme "Green Technology for Housing and Infra-structure Construction" was held on 18-20 May 2009 in Bali, Indonesia. Dr. Naveed Anwar, Dr. Pennung Warnitchai and Engr. Keerati Tunthas-uwattana published a paper, "Finite element based analysis and design of sandwich panel structures". This paper described the evaluation and application of sandwich panels consisting of two concrete/ ferrocement surfaces, separated by a layer of fill material for a residential building. It was based on laboratory testing of components and subsystems, and a finite element based analysis using the results obtained from the testing with special focus on the seismic resistance.

The Mony Engineering Consultants Ltd. (MEC) organized a seminar on Modeling, Analysis and Design of High-Rise Building Structures. The seminar was held in Institut de Technologie du Cambodge (ITC), Phnom Penh, Cambodia on 27-28 August 2009. Fifty bachelor students from the Institute attended the seminar conducted by ACE-COMS Manager Engr. Keerati Tunthasuwattana.

9th International Symposium on Ferrocement and Thin Reinforced Cement Composites

ACECOMS Manager Engr. Keerati Tunthasuwattana with the participants.

Institut de Technologie du Cambodge (ITC) venue of the seminar.

In InDOnESIA

Mony Engineering Consultants Ltd. (MEC)

Seminar on Modeling, Analysis and Design of high-Rise Building Structures

IN CAMBODIA

PICE CPE SeminarModeling, Analysis, and Design of Bridge Structures

A group photo of the participants of PICE Continu-ing Professional Education (CPE) Seminar

Recent Training and Seminars Recent Training and Seminars

ippines on more than one occasion to discuss the progress, issues and outcomes of the projects in progress. Meetings were held with Century Proper-ties, Inc., Ayala Land Inc., SY∆2 + Associates, Inc., R.S. Caparros & Associates, and ARUP.

March 201044

Engineering Staff College, Institute of Engineers, Bangladesh

BAnGLADESh

Bangladesh is one of the developing countries that lies on the active seismicity area. Many of the buildings that are already built may not be ad-equate to resist strong earthquake ground motions. Therefore, Bangladesh government officials and the public are interested in evaluating the seismic performance of old buildings and retrofit them in order to reduce the potential disaster due to failure of structure during a strong earthquake.

ACECOMS has conducted a three day training on the “Seismic Evaluation and Retrofitting Design of Masonry and Reinforced Concrete Structures”. The train-ing was held from 21-23 January 2010 in associa-tion with the Engineering Staff College, Dhaka Bangladesh. A team of three resource persons Dr. Pennung Warnitchai (Associate Professor at AIT), Dr. Naveed Anwar (Director of ACECOMS) and Mr. Deepak Rayamajhi (Research Associate of ACECOMS) conducted the training. Engineers from different sectors (Private, Government, and Army) participated in this training, with a large group from the Public Works Department (PWD), which is a government institution managing all the public building infrastructure in Bangladesh. More than fifty participants attended the seminar, which shows the great interest of Bangladesh engineers in this subject.

The aims of the training were to disseminate the knowledge of current state of art technology and provide enough background and skills to use this information in their future work. Dr. Pennung pre-sented the current seismic status and vulnerabil-ity of buildings present in Bangladesh, along with several measures and advanced techniques related to improving the seismic performance of vulner-able buildings. Dr. Anwar discussed the detailed methodology to perform the seismic evaluation and retrofitting, whereas Mr. Rayamajhi helped the engineers to get familiar with the tools and implementation of those tools to perform seismic evaluation and retrofitting.

TRAInInG In BAnGLADESh

Seismic Evaluation and Retrofitting Design of Masonry and Reinforced Concrete Structures

Engr. Malik Sikdan, the superintendent Engineer of the PWD, Prof. Hannan, the Rector of ESCB with the resource speakers

Dr. Pennung Warnitchai discusses during the seminar

The closing ceremony of the seminar was presided over by the President of the Institute of Engineers in Bangladesh Dr. S. M. Nazrul Islam, the Chief Engineer of Public Works Department (PWD) Engr. Dewan Md. Yamin was the special guest. The Rector of Engineering Staff College Prof. M. A. Hannan presenting ther overview of the seminar, and the resource person from ACECOMS Dr. Naveed Anwar seated next to him

A view of the participants in the classroom for the Training Course on Seismic Evaluation and Retrofitting Design of Masonry and RC Structures

Recent Training and Seminars

March 2010 45

Professor Worsak Kanok-Nukulchai, the founder of ACECOMS as well as its Director from its in-ception until 2008 has been appointed as the Vice President for Resource Development of the Asian Institute of Technology. Prior to this appointment , he was the Dean of the School of Civil Engineering and Technology for more than 5 years.

Professor Worsak Kanok-Nukulchai, obtained his bachelor degree in Engineering at Chulalongkorn University in 1971. He finished his Masters in Struc-tural Engineering in 1973 here in AIT and received the Top Student Award with a 4.0 GPA. Later, he re-ceived his Doctoral Degree in Structural Engineer-ing and Structural Mechanics in 1978 at the Univer-sity of California in Berkeley, California, USA as a Fulbright Scholar.

Prof. Worsak is a well known and recognized interna-tional expert in the development of finite elements and other fields related to computational mechan-ics. He has been the chair of organizing committees to many international conferences including IABSE 2009 and EASEC 10.

Dr. Nitin Afzulpurkar, an Associate Professor in Mechatronics and Microelectronics has been select-ed as the new Dean of the School of Engineering and Technology (SET). He has been the Associate Dean of SET from 2004-2008.

PROFESSOR WORSAK KAnOK-nuKuLChAI

Higher Education Commission (HEC) of Pakistan to offer scholarships for Doctoral Studies at AIT

The Higher Education Commission of Pakistan (HEC) has recently announced scholarships for students to pursue their doctoral studies in vari-ous universities around the world including AIT. At present, there are 45 HEC scholars at AIT enrolled in a special integrated 5 years Masters leading to Doctoral degree program. Dr. Naveed Anwar is ac-tively involved in coordinating efforts between AIT and HEC.

The last few months there have been many devel-opments in ACECOMS officer. The entire office has been renovated and upgraded both in terms of physical space and equipment. Three more staff members have joined ACECOMS; two of them are Research Associates and one as Administrative As-sistant. Engr. Deepak Rayamjhi who recently gradu-ated from AIT in Structural Engineering at the top of his class is now working as a Research Associate on several projects and developments. Engr. Anil Ratna Shakya rejoined ACECOMS as Research As-sociate after 2 years of working with Nichad Thani as Project Engineer. Mr. Suradej Thanakorn is now helping and supporting office activities. The ACE-COMS website is being redeveloped and updated and is expected to be launched in early 2010.

new Developments in ACECOMS

Newsand Updates

Appointed as the Vice President for Resource Development for AIT

DR. nITIn AFzuLPuRKARSelected as the new Dean of School of Engineering and Technology (SET)

March 201046

?AIT Outsources its Infrastructure Management to Sodexo

AIT has outsourced the management of all of its non-core infrastructure facilities to SODEXO which is a world leader in Food and Facilities Man-agement Services. Dr. Naveed Anwar was the chair of the committee tasked to formulate the Infra-structure Facility Management (IFM) contract and was also the member of the transition monitoring team, and the advisory committees for operation of the contract.

CPAC Roof Tile Co. Ltd., manufacturing company for roof tile and roof structures under the Siam Cement Group (SCG) has engaged the services of ACECOMS and CASE Co. Ltd. to create the soft-ware for analysis, design and detailing of their roof truss system and to verify the design reliability. To ensure the safety of the roof truss system, a full scale testing and cantilever testing of the trusses was carried out at the structural engineering laboratories at AIT. The load testing and verification was jointly supervised by Dr. Sun Sayamipuk, Senior Labora-tory Supervisor and Engr. Keerati Tunthasuwattana, ACECOMS Manager, along with representatives from CPAC Roof Tile Co. Ltd. Recommendations were made to improve the detailing of the trusses based on the test results.

Verification Test for Roof Truss System

Roof truss system for full scale testing.

Roof truss system for cantilever testing.

1) All types of unconfined concretes reach their ultimate

strengths at a strain of about 0.003.

(TRUE/FALSE)

2) The ductility of a column is always larger at the axial

load levels below the balanced failure rather than at

the axial load level above the balance failure.

(TRUE/FALSE)

3) According to the ACI-318, shear strength of concrete

is always considered in the shear design of beams

against the earthquake induced shear force.

(TRUE/FALSE)

4) Strut and tie approach always gives a unique design

solution.

(TRUE/FALSE)

5) Strut and tie model always gives lower-bound (safe)

capacity.

(TRUE/FALSE)

6) Strain at the point of rupture of high strength concretes

is larger than that of normal strength concretes.

(TRUE/FALSE)

7) What are the effects on the ductility of unconfined

concrete beam by increasing the following strength of

materials?

a. Does the ductility of the beam increase or decrease if the

yield strength of the tension steel is increased?

b. Does the ductility of the beam increase or decrease

if the compressive strength of the concrete is increased?

8. Depth of the neutral axis at balanced failure is independent

of strength of concrete.

(TRUE/FALSE)

9) Diagonal bars in the coupling beams are ineffective if

the beam depth to span ratio is small.

(TRUE/FALSE)

10) A flexural Beam theory is invalid in D-regions of beams.

(TRUE/FALSE)

QuizConcrete Mechanics ?

Answers on page 48

March 2010 47

One of the leading construction companies in Philippines has en-gaged the service of ACECOMS to carry out the Structural Per-formance Evaluation with special focus on the effect of the loca-tion of splices in the reinforced concrete columns and beams in a new office building in Metro Manila. The main objective of this project was to evaluate the applicability of the appropriate rein-forcement detailing for special moment resisting frames specified in ACI 318-02, especially related to the location of splices in col-umns and beams.

In particular, typical bays of the building were selected to investi-gate the performance of the structure and response at the lap splice

Research and Consultancy Projects

ACECOMS provides expertise and services in a vast area falling under the general category of com-putations in engineering. The main areas of expertise are design reviews, laboratory testing, investiga-tion of failures, software development, structural system development, and infrastructure design and development. Projects under these categories have been undertaken around the globe and have been successfully completed. Some of the current and completed projects are summarized below:

Structural Design Review of 42-Story Tower in Manila

Structural Performance Evaluation with Special Focus on Splice Location in a new Office Building

One major developer in Philippines has engaged the service of ACECOMS to carry out the Structural Design Review of 42-story building, with an approximate floor area of 50,000 sq.m., in Maka-ti, Philippines. The tower is a reinforced concrete building, with a primary lateral load resisting system comprised of shear walls and moment resisting frame.

locations. After that, the finite element model was created using the hinges in accordance with FEMA 356 to model the nonlinear behavior of members. The hinges in the compression lap splice regions were modified by reducing the moment capacity of FEMA hinge with different percentages. Pushover analysis was conducted to check the overall performance of selected frames and the local performance of the members at the location of lap splices.

It was found that no yielding has occurred in the hinges at the lap splice regions in both beams and columns until 30 % reduction of moment capacity, i.e. less likelihood of lap splice failure in the representative frame.

First, overall structural behavior of the building including static and dynamic responses under the gravity and lateral loads was evaluated. The natural time periods, base shear, inter-story drifts and maximum lateral deflection were checked in the initial review of the building.

Next, the structural design verification was performed in accord-ance with ACI 318-05 and UBC 97. In addition, sequential con-struction analysis was carried out and the design was also checked for the sequential construction analysis results.

It was concluded that the overall design of the building was with-in the margin of safety in accordance with the codes whereas a minority of the members were overstressed due to the differenc-es in the design assumptions, modeling techniques and analysis methods.

Answers on page 48

March 201048

Structural Design Review for Investigation of Deflected Slab

Analysis and Design of Extended Stack Structure

A developer in Philippines has engaged the service of ACECOMS to carry out the structural design review for investigation of de-flected slab in a building in Metro Manila. Based on the site survey, the deflection of the slab was 9 cm approximately.

First, the concrete core samples at the different locations of the floor slab were tested to determine the actual compressive strength of the concrete. After that, several finite element models were cre-

One of the leading engineering companies in refrigeration, food machineries and petrochemical processing, has engaged the serv-ice of ACECOMS for the analysis and design of extended stack structure for a petrochemical processing industry in Rayong, Thailand. The existing stack is 80 m high and supported with a steel guyed structure. This stack will be extended to 120 m height and supported with free steel free stand tower. Then, the existing structure will be removed after the new structure is completed.

Among the technology trends pre-dicted for next year is the advent

of mainstream broadband-enabled television, with the BBC and other U.K. play-ers participating in Project Canvas. The initiative in-volves the installation of a set-top box with an In-ternet link, establishing a means to access Web sites and their content

via the TV. Although the popularity of Twitter signals

that real-time social networks have become well-entrenched,

the challenge remains in gathering their short-form contents together

in a genuinely practical format. Twitter is saturated with people's opinions, which makes it

Technology Predictions for 2010Telegraph.co.uk (12/24/09) Richmond, Shane; Barnett, Emma; Warman, Matt; et al.

nearly impossible to present them in a manner in which their relative merits are apparent. Augmented reality also is poised to progress in 2010, having al-ready been a hit with early tech-savvy adopters in such applications as compasses and global position-ing systems in cell phones. Location-based games are expected to proliferate while navigation displays will shift from bird's-eye-view map-based schematics to arrows on the road. Meanwhile, three-dimensional (3D) TV is on the way, with both Panasonic and Sky verifying that they will release 3D TVs and Sky's an-nounced rollout of a dedicated 3D channel. The un-known factor is whether consumers will be willing to adopt the technology, and the initial cost of the 3D TVs is expected to be high. Another challenge the technology will need to overcome is consumers' resistance to wearing special glasses while watching TV, at least until next-generation TVs with screens that automatically perform 3D rendering appear.

Source: ACM TechNews (December 30, 2009 Edition)

ated with various complexities and design parameters to analyze and investigate the possible causes of the observed deflection in the slab system. Effects of moment yielding in the slab section were considered to redistribute the moment where the moment capacity was less than the demand.

Through a parametric study, it was found that one of the pos-sible reasons for the observed deflection in site was the casting of slab with the thickness and concrete strength which were less than the design specifications. Another possible reason was the concrete cover in slab which was larger than the design specifica-tion, with an additional load from concrete toping used for floor leveling.

1. FALSE 2. TRUE 3. FALSE 4. FALSE 5. TRUE 6. FALSE

7. a. decreases, b. increases 8. TRUE 9. TRUE 10. TRUE

Answers from page 46

March 2010 49

weakening cyclone moved through Thailand, widespread heavy rainfall and flash flooding were reported in 40 provinces. The heavy rainfall also helped to fill up natural reservoirs within the country. The depression partially damaged 4,680 houses, destroyed 44 houses as well as 820,000 acres (330, 000 hectares) of agricultural land. Ketsana also injured a person and caused the deaths of two people before moving out of the country as an area of low pressure, and dissipating on October 3 over the Andaman sea. Three dams in Chai-ya-poom were damaged by the heavy rainfall, whilst in Pattaya; nine boats sunk after waves of over two meters were reported.

The weakening typhoon also strucked north-eastern Cambodia with the worst damage in Kampong Thom province in central Cambo-dia. Death tolls from the storm, one of the most severe ever to lash Cambodia, reached 43 people. Also more than 66,000 families were forced from their homes by floodwa-ters.

Telegraph.co.uk (12/24/09) Richmond, Shane; Barnett, Emma; Warman, Matt; et al.

Natural Disasters2009

The 2009 Natural Disasters affects the environment, and leads to financial, environmental and/or human losses. "Disasters occur when hazards meet vulnerability."To give us some glimpsed from the recent natural disasters from different parts of the globe:

The 2009 Samoa earthquake was an 8.0 magnitude submarine earthquake that took place in the Samoan Islands region at 06:48:11 local time on 29 September 2009 (17:48:11 UTC, September 29). It is the largest earthquake so far in 2009.

A tsunami was generated which caused sub-stantial damage and loss of life in Samoa, American Samoa, and Tonga. The Pacific Tsunami Warning Center recorded a 3-inch (76 mm) rise in sea levels near the epicenter. The quake occurred on the outer rise of the Kermadec-Tonga Subduction Zone. This is part of the Pacific Ring of Fire, where tec-tonic plates in the earth's lithosphere meet and earthquakes and volcanic activity are common.

Countries affected by the tsunami in the areas that were hit are American Samoa, Samoa and Tonga where more than 189 people have been killed, most of them in Samoa. Large waves with no major dam-age were reported on the coasts of Fiji, the northern coast of New Zealand and Raro-tonga in the Cook Islands as well.

2009 SAMOA EARThquAKE

Ref: http://en.wikipedia.org/wiki/File:Tsunami_2009_Pago_Pago.jpg

The September 2009 Sumatra earthquake occurred just off the southern coast of Sumatra, Indonesia The major shock hit at 17:16:10 local time on September 30, 2009 (10:16:10 UTC) and had a mo-ment magnitude of 7.6. The epicenter was 45 kilometers (28 mi) west-northwest of Padang , Sumatra, and 220 kilometers (140 mi) southwest of Pekanbaru , Su-matra. Early death-toll estimates extended beyond 1,300.

The quake toppled buildings and started many landslides, smashing homes and swal-lowing up entire villages. As rescue workers arrived and residents tried their best to dig out and help the survivors, another unre-lated quake with a magnitude of 6.6 struck less than 1,000 km south of the original epi-center. Each of the two quakes had at least one aftershock greater than 5.0 as well.

2009 SuMATRA EARThquAKE (InDOnESIA)

TYPhOOn KETSAnA hITS SOuTh EAST ASIA, EAST ASIA (PhILIPPInES, VIETnAM, LAOS, ThAILAnD AnD CAMBODIA)

Typhoon Ketsana formed early on Septem-ber 26, 2009, about 860 km (535 mi) to the northwest of Palau.

Ref: http://en.wikipedia.org/wiki/Typhoon_Ketsana http://daveslandslideblog.blogspot.com/2009/12/munich-res-list-of-largest-disasters-of.html

On 26 September 2009 Ketsana brought the worst rainfall to Metro Manila and nearby provinces in Luzon, Philippines resulting landslide and severe flooding which left at least 246 people dead and 38 others miss-ing. Public and private roads were clogged by vehicles stuck in floodwater. Thousands of motorists and more than 500 passen-gers were stranded at the North Luzon Ex-pressway (NLEx). Ketsana also caused the shutting down of flights and operations at the Ninoy Aquino International Airport (NAIA) for almost a day. The damage to property was estimated to be approximately U$238 million including damage to infra-structure, damage to schools and damage to agriculture.

While, On 29 September 2009 Ketsana made its landfall in Vietnam at mid-afternoon, at about 37 miles south of Da Nang, Quang Nam. Ketsana's maximum winds were re-ported at 167 km/h (104 mph) with gusts as strong as 204 km/h (127 mph) as it crossed over the South China Sea and approached land. Vietnamese government evacuated some 170,000 people as floodwater rose high to the country's six central provinces. Airports, schools, communications and power lines in the affected area were shut down. Strong winds also destroyed parts of the North-South high voltage power line, the backbone of Vietnam's electricity grid. The typhoon killed 23 people during the first hours after landfall and has claimed at least 163 lives in Vietnam, 17 people missing and 616 people were injured. Total damage of Ketsana is estimate at $785 million.[

At the evening of the same day, Ketsana moved towards Laos. Currently there is ma-jor flooding in Southern and Central Prov-inces. The water height is up to knee height in the province of Saravane, at least 26 peo-ple died. Famine is possible later on as the typhoon moves through the country. The floods devastated rice fields and homes. At-tapeu is the worst effected where nearly 90% of the province was affected.

Ketsana moved into Thailand as a tropical depression early On September 30 as the

Ref: http://en.wikipedia.org/wiki/2009_Samoa_earth-quake

Tsunami 2009, Pago Pago

March 201050

2009 MESSInA FLOODS AnD MuDSLIDES (ITALY)

Ref: http://www.upi.com/Top News/2009/10/05/Russian-volcanos-eruptions-intensifying/UPI-53481254759237/

TROPICAL STORM GRACE BRInGS ACTIVITY TO ATLAnTIC huRRICAnE BASIn

It has been a quiet hurricane season in the Atlantic on 5 Oct. 2009 Tropical Storm Grace has arrived. The storm has weakened slightly but still has sustained winds of 65 mph. Located 575 miles southwest of Cork, Ireland, Grace is moving toward the north-northeast at 31 mph. tropical storm-force winds; however, no damage was reported.

Tropical Storm Grace satellite photo. (Stormpulse)

Russia’s Sarychev VolcanoErupts. This NASA photo taken by astronauts aboard the International Space Station shows the Sarychev volcano in the early stages of eruption on Rus-sia’s Kuril Islands on June 12, 2009. (UPI Photo/NASA)

Ref: http://www.upi.com/Top_News/2009/10/05/Russian-volcanos-eruptions-intensifying/UPI-53481254759237/

Ref: http://www.examiner.com/x-25803-Natu-ral-Disasters-Examiner~y2009m10d5-Natural-disaster-report-for-October-5-2009

KLYuChEVSKOY VOLCAnO COMES TO LIFE

Government reports have to date confirmed 1,115 dead, 1,214 severely injured and 1,688 slightly injured. The most deaths occurred in the areas of Padang Pariaman (675), Padang (313), Agam (80) and Pariaman (37).

In addition, around 135,000 houses were se-verely damaged, 65,000 houses were moder-ately damaged and 79,000 houses were slight-ly damaged. An estimated 250,000 families (1,250,000 people) have been affected by the earthquake through the total or partial loss of their homes and livelihoods.

The 2009 Messina floods and mudslides which occurred on the night of 1–2 Octo-ber killed at least 28 people, mainly on the Ionian coast in the Province of Messina but also affected other parts of northeast-ern Sicily. The places which suffered the most damage were Giampilieri Superiore, a small frazione 10 kilometres south of the city of Messina, the comune of Scaletta Zanclea, and the frazione of Briga Supe-riore.

The heavy downpour of rain was accom-panied by strong winds and lightning, provoked devastating mudslides; which combined with the extreme nature of the weather meant people had little time to flee buildings or vehicles as mud swept

Ref: http://en.wikipedia.org/wiki/2009_Messina_floods_and_mudslides

A collapsed building in the village of Scaletta Zan-clea, near the Sicilian town of Messina, after the mudslides

Ref:http://www.dailymail.co.uk/news/worldnews/article-1217685/Thirteen-people-killed-mudslides-

Train station in Giampilieri Ref: http://upload.wikimedia.org/wikipedia/commons/d/d0/

down from the surrounding hills and cliffs clogging the streets with debris and grime, carrying away people, cars, and dwellings. It was believed that nine inches of rain fell in a space of three hours.

As of 8 October 2009, seven people were still missing and at least 450 inhabitants of the comuni were left homeless by the sud-den extreme weather. It is said to be the worst landslide disaster in Italy since 1998 during which 137 people died in Sarno, near Naples.

On Russia’s Kamchatka Peninsula, 5 Oct. 2009 the Klyuchevskoy volcano was erupt-ing and could be seen by astronauts on the International Space Station. Klyuchevskoy is Eurasia’s tallest active volcano and is known to erupt about once every two years. The 15,584 mountain is not a threat to any

population however its ash emissions may threaten air travel in the region.

Typhoon Ketsana hits South East Asia,

East Asia

Messina Floods and Mudslides

Tropical Storm Grace

Samoa Earthquake

Klyuchevskoy volcano Eruption

Sumatra Earthquake

Ref: http://www.boston.com/bigpicture/2009/10/2009_sumatra_earthquakes.html

Soldiers and volunteers carry an earthquake victim from a collapsed hotel in Padang on Indonesia's Sumatra island October 1, 2009. (REUTERS/Muhammad Fitrah/Singgalang Newspaper)

Name: …………………………………………………………….……..….

ACECOMS, School of Engineering and Technology, AIT, P.O. Box 4, Klongluang, Km. 42 Paholyothin Rd., Pathumthani, 12120 THAILAND Tel: (662) 524 5539, 524 6416 Fax: (662) 524 5539 ext 105, 524 6059 Email: acecoms@ait.ac.th Website: http://www.acecoms.ait.ac.th

Membership Benefits Get free General Tools set of GEAR2003 (5 modules). Save up to 20% on regular prices of software. Get free ACECOMS Magazine-3 issues per year. Save up to 20% on regular registration fee of Training/Seminar. Membership Card and Certificate. Special download from website.

Additional Benefits

For LIFE MEMBER Get free Geometric Properties set of GEAR2003 (4 modules). Get 2 more modules of GEAR2003. Get 2 free publications.

For 3 YEARS MEMBER Get free Geometric Properties set of GEAR2003 (4 modules). Get a free publication.

Membership CategoryLife Membership US$ 140Please select two GEAR2003 modules and two publications from the list below

3 Years Membership US$ 75Please select one publication from the list below

Annual Membership US$ 35

GEAR2003 Modules

Rebar Calculator

K-Factor Calculator

Moment Magnifier

Beam Designer

Column Designer

Publications

Graded Examples in Reinforced Concrete Design

Workshop Note: Computer Applications in Structural Engineering

Article Compilation: General Topics

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Cheque or Draft Cash*Payable to Asian Institute of Technology (AIT)

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Typhoon Ketsana hits South East Asia,

East Asia

Messina Floods and Mudslides

Tropical Storm Grace

Samoa Earthquake

Klyuchevskoy volcano Eruption

Sumatra Earthquake

Professional Structural Engineering Soft wareVarious Structural Engineering softwares are available at ACECOMS to comply to your needs. These soft wares vary from simple unit con verter modules to highly so phis ti cated and in te grated state-of-the-art struc tural en gi neering appli-cations.

GEAR2003Integrated set of Programs for Assisting Routine Design Work

SAP2000 V14State-of-the-art 3D Finite Element Technology for Structural Engineering

CSICol V8.3Design of Simple and Complex Reinforced Concrete Columns

STRAND7Sophisticated Finite Element Modeling and Analysis Software

Perform 3D V4Nonlinear Analysis and Performance Assessment for 3D Structures

GRASPRapid Graphical Modeling and Analysis of Structures in 2D

Asian Center for Engineering Computations and Software (ACECOMS)School of Engineering and Technology, Asian Institute of Technology (AIT)P.O. Box 4, Klongluang, Pathumthani 12120 Thailand. .Tel: (662) 524 5539, (662) 524 6416 Fax: (662) 524 6059, (662) 524 5539 ext 105Email: acecoms@ait.ac.th Web: www.acecoms.ait.ac.th

SAFE V12.2Integrated Design of Concrete Slabs and Basemats

ETABS V9.7Integrated Building Analysis and Design Software