Vice President 2 Keynote speaker 3 Programme 4 Poster ... · PDF fileProgramme 4 Poster presentations 5 ... Concrete shear failure in fire 55 ... Structural interactions between cold-formed

Vice President 2Keynote speaker 3Programme 4Poster presentations 5Synopses 6

01 Alireza Ahangar-Asr - A new approach to modelling the stability behaviour of soil and rock slopes in civil and structural engineering 0602 Buan Anshari - Determination local reinforcement patterns on glulam beams pre-stressed by compressed wood using finite element modeling 0703 Shahryar Arshi - Structural behaviour and performance of skirted hybrid monopile-footing foundations for offshore oil and gas facilities 0804 Minixi Bao - Performance and failure analysis of IGUs under in-service environmental actions 0905 Caroline Butchart - Post-fracture performance of laminated glass 1006 David Byrne - The analysis of shear transfer in void form flat slab systems, including in-situ measurements from a building 1107 Alfredo Camara - Linear and nonlinear seismic response of cable-stayed bridges; dissipation and damping devices 1208 Richard Campbell - More with [home]less 1309 Seán Carroll - Pedestrian crowd-bridge interaction modelling utilising a discretely defined crowd 1410 Hiep Vu Dang - Modelling of human structure interaction using motion capture system 1511 Paula Drew - Comparative thermal mass experiments with GGBS and PC concrete 1612 Jack English - Experimental and numerical seismic analysis of steel gusset plate connections to brace members 1713 Xabier Fernandez Rodriguez - Comparative life cycle cost for cold-formed steel portal frames 1814 William Finnegan - The structural loading on vertically oscillating wave energy converters in deep seas 1915 Abdelhamed Ganaw - Rheology of grout for preplaced aggregate concrete 2016 Peter Gates - Polymeric facades: advanced composites for retrofit 2117 Declan Gavigan - Stabilised soil blocks – a cost-effective sustainable construction technology 2218 Ellen Grist - The implementation of sustainable construction materials 2319 Christopher Gross - Low carbon building using hemp-lime: optimisation of materials and constructive systems 2420 Aram Hassan - Ultra high performance fibre reinforced concrete (UHPFRC) for bridge deck applications 2521 Sam Hayhurst - Dynamic soil-structure interaction in monopile-supported offshore wind turbines 2622 Malcolm Hudson - Implementing active vibration control in floor structures 2723 Philip Isaac - Effects of blast loads on reinforced concrete columns with a view to strengthening 2824 Qian Jin - Multi-objective optimisation of high-performance façade technologies 2925 Ryan Judge - Lightweight cable supported structures subjected to blast fragmentation 3026 Kunal Kansara - An expert system for FRP-based strengthening of concrete structures 3127 Mehdi Kashani - Life span simulation approach to performance-based assessment of corroded RC bridge piers subject to seismic loading 3228 Majd Khador - The behaviour of semi-rigid through-diaphragm connection between steel I-beams and circular/ellipitcal hollow section columns under cyclic loading 3329 Shutuan Lin - Computer modelling of steel and composite structures in fire 3430 Anca Lungu - Assesment of time-frequency analysis techniques in structural dynamics applications 3531 Daniel Maskell - Contemporary structural use of unfired clay masonry 3632 Navroop Singh Matharu - Aspects of bolted connections of fibre reinforced polymer structures 3733 Maung Than Soe - Bridge condition assessment based on vibration measurements 3834 Mark McCaffrey - The use of embodied energy and carbon to assess the environmental impact of concrete structures 3935 Zainorizuan Mohd Jaini - Multi-scale simulation and fracture modelling of protective reinforced concrete slabs subjected to blast loading 4036 Colm Murphy - Structural modelling of trachea distortion of leatherback turtles during deep dives 4137 Thuy Nguyen Tien - Global buckling behavior of pultruded fiber-reinforced polymer (FRP) members 4238 Nima Noormohammadi - Semi-active control of human-induced vibration 4339 Shane O’Neill - Model-centric design of temporary works 4440 Gerard O’Reilly - The development of cost effective modular systems for rapid deployment to post earthquake disaster zones 4541 John Orr - Flexibly formed concrete structures 4642 Hannah Pearson - Connections and geometry for timber plated structures 4743 Phan Thanh Duoc - Design optimisation of cold-formed steel portal frame buildings taking into account semi-rigid joints and stressed-skin action 4844 Tom Rogers - Design of double shear steel-timber connections 4945 Suhaib Salawdeh - Seismic design of concentrically braced frames and dual systems with vertical irregularity 5046 Gennaro Senatore - Adaptive responsive building structures 5147 Ashkan Shahbazian - Fire resistance design methods for thin-walled steel structural panels for wall construction 5248 Therese Sheehan - Structural performance of concrete-filled tubular members under cyclic loading 5349 Karol Sikora - The effect of superabsorbent polymers (SAP) on freeze-thaw performance of cementitious mortars and plasters 5450 Holly McLeod Smith - Concrete shear failure in fire 5551 Jason Song - Computational mesoscale analysis of cement-based materials with dynamic load 5652 David Stephen - The behaviour of connection under extreme temperatures in resisting progressive collapse 5753 Victoria Stephenson - Investigation into the loss of structural integrity in historic wall construction systems caused by water ingress 5854 Mariati Taib - A component-based model of fin plate connections in fire 5955 Clement Thirion - The role of material-efficiency in reducing the environmental impact of building structures 6056 Junzhe Wang - Investigation of spandrel wall failure on masonry arch bridge 6157 Zhiyu Wang - Assessment of cyclic structural performance of an innovative blind bolted connection to concrete filled steel tubular column 6258 Natasha Watson - Using natural materials as part of building construction to improve the sustainability of buildings - development knowledge and guidance for increased deplyment 6359 Graham Webb - Advanced sensor monitoring of infrastructure 6460 Robert Westgate - Environmental effects on a suspension bridge’s performance 6561 Behrouz Zafari - Determination of pin-bearing strength for the design of bolted connections for fiber reinforced polymer (FRP) shapes 6662 Congxiao Zhao - Structural interactions between cold-formed sigma steel purlins and roof sheets 67

Conference sponsors 68

2 | The Institution of Structural Engineers | Young Researchers’ Conference 2011 |

Vice PresidentProfessor Tim Ibell, CEng BSc(Eng) PhD FIStructE MICE FHEA

Tim Ibell graduated with a First Class Honours degree in Civil Engineering from the University of Cape Town in 1988. After completing a PhD in prestressed concrete structures at the University of Cambridge in 1992, he acted as a civil/structural engineering consultant at a petrochemical company, SASOL, until 1994 when he returned to Cambridge for three years as a post-doctoral research fellow. In 1997, he joined the University of Bath as a Lecturer in the Department of Architecture and Civil Engineering. He was subsequently promoted through to Professor of Civil Engineering in 2003, to Head of Department in 2005, and to Associate Dean of the Faculty of Engineering and Design in 2008. He currently heads up the Graduate School in the Faculty of Engineering and Design.

He has a strong research interest in the structural behaviour and retrofit of concrete bridges and structures. For many years, Tim has been interested in the realistic structural assessment of existing concrete bridges using plasticity, on the basis that it is unacceptable to society to be earmarking bridge (and other) structures for demolition or structural strengthening when reliance on better analysis could reveal adequate capacity, in fact. If such structures are then indeed found to be wanting structurally after rigorous assessment, Tim has a team of researchers looking at the use of fibre-reinforced polymers to reinforce and/or strengthen such concrete structures. With colleagues, notably Dr Antony Darby and Dr Steve Denton, he co-authored The Concrete Society’s second edition of the guide to strengthening existing concrete structures using advanced composites (TR55), and he is presently co-authoring the latest third edition. He leads research into fabric-formed concrete structures, whereby architecturally-interesting, optimised concrete structures are possible through using cost-effective fabric moulding techniques. He is also leading a project looking into the use of polymeric façades for retrofit of existing multi-storey buildings. Blast resistance of structures (and mitigation) is a growing interest.

Tim has won three best journal-paper awards and a best conference-paper award for his research. He is a member of the EPSRC Peer Review College, and he will be a member of Sub-Panel 14 Civil and Construction Engineering in the forthcoming Research Excellence Framework. He sits on two editorial boards for journals. In 2001, he was awarded a Fulbright Commission Distinguished Scholar Award which led to a one-year sabbatical in the US in 2002.

Tim has a great passion for wishing to ensure that students are inspired to learn structural engineering. His own personal teaching interests include fundamental structural behaviour, innovative construction materials, plasticity theory and holistic design.

Within the Institution of Structural Engineers, Tim sits on the Executive Board, Council and Membership Committees. He chairs the Academic Qualifications Panel and represents the Institution on the Joint Board of Moderators. He is Chair of the Western Counties Branch of IStructE in 2011.

| The Institution of Structural Engineers | Young Researchers’ Conference 2011 | 3

John Roberts graduated from The University of Sheffield in 1969 with a BEng (Hons) in Civil and Structural Engineering, and then carried out a 3-year research project leading to a PhD, also at Sheffield, in 1972. Since that time he has pursued a career as a consulting structural engineer based in Manchester, with Allott & Lomax which joined with Babtie in 2000 and then Jacobs in 2004 where he is an Executive Director of Operations of a 700-strong multi-discipline building design team.

Although he has worked on a very large variety of building projects, he is particularly known for a long association with the design of major rides and attractions including the world’s largest rollercoaster (at Blackpool Pleasure Beach), Europe’s tallest timber ride (at Tusenfryd in Oslo, Norway) and of course the iconic London Eye.

John was President of the Institution of Structural Engineers in 1999 – 2000 and was awarded the prestigious Gold Medal in 2005. He is a well-known figure in the civil and structural engineering profession worldwide and has made a number of TV and radio appearances including Scrapheap Challenge, DriveTime and even Richard & Judy.

John has held a visiting chair in principles of Engineering Design at Manchester University for the last 10 years or so, and was awarded an honorary doctorate at the University of Sheffield in 2006 and at the University of Brighton in 2008.

Keynote speakerDr John M Roberts, FREng BEng PhD DEng DTech FIStructE FICE


09:45 Registration and coffee

10:15 Welcome by Professor Tim Ibell - Vice President of the Institution of Structural Engineers

10:25 Keynote Address by Dr John Roberts – Executive Director of Operations, Jacobs Engineering UK Limited

10:55 Session 1

10:55 Putting material in the right place Mr Clement Thirion - University College London / Expedition Engineering (Abstract No. 55)

11:10 The implementation of sustainable construction materials Miss Ellen Grist - University of Bath (Abstract No. 18)

11:25 Discussion

11:35 Coffee

11:55 Session 2

11:55 Flexibly formed concrete structures Mr John Orr - University of Bath (Abstract No. 41)

12:10 Implementing active vibration control in floor structures Mr Malcolm Hudson - Sheffield University (Abstract No. 22)

12:25 Dynamic soil-structure interaction in monopile-supported offshore wind turbines Mr Samuel Hayhurst - University of Bristol (Abstract No.21 )

12:40 Discussion

12:55 Membership matters

13:00 Lunch

13:40 Poster session

14:15 Session 3

14:15 The structural loading on vertically oscillating wave energy converters in deep seas Mr William Finnegan - National University of Ireland, Galway (Abstract No. 14)

14:30 Lightweight cable supported structures subjected to blast fragmentation Mr Ryan Judge - Liverpool University (Abstract No. 25)

14:45 Structural interactions between cold-formed sigma steel purlins and roof sheets Miss Congxiao Zhao - University of Birmingham (Abstract No. 62)

15:00 Discussion

15:15 Tea & judging

15:50 Prize giving and closing remarks

16:20 Close

Programme


Mr Buan Anshari, Liverpool UniversityDetermination local reinforcement patterns on glulam beams pre-stressed by compressed wood using finite element modeling. (Abstract No. 02)

Mr Minxi Bao, University of BirminghamPerformance and failure analysis of IGUs under in-service environmental actions. (Abstract No. 04)

Mr David Byrne, National University of IrelandThe analysis of shear transfer in void form flat slab systems, including in-situ measurements from a building. (Abstract No. 06)

Mr Seán Carroll, University of NottinghamPedestrian crowd-bridge interaction modelling utilising a discretely defined crowd. (Abstract No. 09)

Mr Abdelhamed Ganaw, University of BradfordRheology of grout for preplaced aggregate concrete. (Abstract No. 15)

Mr Peter Gates, University of BathPolymeric facades: advanced composites for retrofit. (Abstract No. 16)

Mr Christopher Gross, University of BathLow carbon building using hemp-lime: optimisation of materials and constructive systems. (Abstract No. 19)

Mr Zainorizuan Mohd Jaini, University of Wales SwanseaMulti-scale simulation and fracture modelling of protective reinforced concrete slabs subjected to blast loading. (Abstract No.34)

Mr Qian Jin, Cambridge UniversityMulti-objective optimisation of high-performance façade technologies. (Abstract No. 24)

Mr Nima Noormohammadi, Sheffield UniversitySemi-active control of human induced vibration. (Abstract No.38)

Mr Hannah Pearson, University of BathConnections and geometry for timber plated structures. (Abstract No. 42)

Mr Thomas Rogers, Coventry UniversityDesign of double shear steel-timber connections. (Abstract No. 44)

Mr Gennaro Senatore, University College LondonAdaptive responsive building structures. (Abstract No. 46)

Mr Ashkan Shahbazian, University of ManchesterFire resistance design methods for thin-walled steel structural panels for wall construction. (Abstract No. 47)

Mr Mariati Taib, Sheffield UniversityA component-based model of fin plate connections in fire. (Abstract No. 54)

Mr Robert Westgate, Sheffield UniversityEnvironmental effects of a suspension bridge’s performance. (Abstract No. 60)

Poster presentations


01 Alireza Ahangar-AsrUniversity of Exeter

Project objectives

Purpose – Analysis of stability of slopes has been the subject of many research works in the past decades. Prediction of stability of slopes is of great importance in many civil engineering structures including earth dams, retaining walls and trenches. There are several parameters that contribute to the stability of slopes. This project aims to present a new approach, based on evolutionary polynomial regression (EPR), for analysis of stability of soil and rock slopes.

Methodology – EPR is a data-driven method based on evolutionary computing, aimed to search for polynomial structures representing a system. In this technique, a combination of the genetic algorithm and the least square method is used to find feasible structures and the appropriate constants for those structures.

Findings – EPR models are developed and validated using results from sets of field data on the stability status of soil and rock slopes. The developed models are used to predict the factor of safety of slopes against failure for conditions not used in the model building process. The results show that the proposed approach is very effective and robust in modelling the behaviour of slopes and provides a unified approach to analysis of slope stability problems. It is also shown that the models can predict various aspects of behaviour of slopes correctly and accurately.

Value – In this project a new evolutionary data mining approach is presented for the analysis of stability of soil and rock slopes. The new approach overcomes the shortcomings of the traditional and artificial neural network-based methods presented in the literature for the analysis of slopes. EPR provides a viable tool to find a structured representation of the system, which allows the user to gain additional information on how the system performs.

Factor of safety prediction model for soil slopes: The parameters used for modelling the circular failure mechanism in soil slopes (Figure 1) are unit weight ( ), apparent cohesion (c), angle of internal friction ( ), slope angle ( ), height (H) and pore water pressure parameter (ru ).

Factor of safety prediction model for rock slopes: The main parameters contributing to the stability of rock slopes are considered to be the unit weight ( ), apparent cohesions (cA ) and (cB ), angles of internal friction ( ) and ( ), angle of the line of intersection of the two joint sets ( ), slope angle ( ) and height (H), where A and B refer to the two joint sets (Figure 1).

Potential for application of the results

Presenting an easier, quicker and more economically feasible designing technique for soil and rock slopes/cuts in civil and structural engineering applications compared to complex and time consuming conventional trial and error based methods.

A new approach to modelling the stability behaviour of soil and rock slopes in civil and structural engineering

Figure 1. Soil and rock slopesFigure 2. Comparison of EPR prediction results with ones from ANN and field measurements for F

S in soil slopes

3 2

23

(1)

(2)


02Buan AnshariUniversity of Liverpool

Determination local reinforcement patterns on glulam beams pre-stressed by compressed wood using finite element modeling

Poster presenter

Introduction

Reinforcement of structural wood products has been studied for more than 40 years. In the earlier stages of the research, the focus was mainly on using metallic reinforcement, including steel bars, pre-stressed stranded cables and bonded steel and aluminium plates. Recently, research on glulam beams reinforced with fibre-reinforced polymers (FRP) has been increased significantly. Wood densification by thermal transverse compression has attracted many researchers as a process to improve the strength properties of low-density wood species. Compressed wood (CW) is made of a low grade wood, which is densified in the radial direction under a specific pressure and temperature condition. The CW blocks are applied to strengthen glulam beams by inserting CW blocks into the pre-cut rectangular holes on the top part of the glulam beams. This practice was to make use of moisture-dependent swelling nature of compressed wood, which contributes to the pre-stressing.

In this study, 3-D finite element models have been developed by using commercial code ABAQUS to simulate the pre-stressing behaviour of reinforced glulam beams using compressed wood blocks. Both glulam timber and compressed wood are modelled as orthotropic linear elastic materials in tension, and as elasto-plastic materials in compression in the embedding areas. Moisture-dependent swelling of the compressed wood blocks after they are inserted into the glulam beams is simulated by implementing swelling data obtained from experimental measurements.

Project objective and goals

The project aims to optimise the performance of structural glulam beams in terms of load carrying capacity, strength and stiffness. The way to reinforce the glulam beam needs to be optimised to investigate the effective size, location and number of the CW blocks. To undertake such parametric studies purely by experimental tests will be time consuming and expensive. The better way forward is to develop numerical models and to apply them to determine local reinforcement patterns on glulam beams to be strengthened. In this way limited number of representative tests can be undertaken with a low cost.

Project description

A new approach to reinforce glulam timber beams has been developed by using compressed wood. CW blocks are inserted into pre-cut holes on the top of glulam beams to strengthen glulam beam. In order to optimise the use of CW blocks, 3-D finite element models have been developed. Parametric studies are carried out on the CW block to increase load carrying capacity, strength and stiffness of the reinforced beam. Beams with a size of 105x105x1500 in mm have been analysed through numerical modelling. Glulam beams are assumed to have a typical ambient MC of 12%, whilst MC of the CW block is conditioned as 6% which is likely to swell after absorbing moisture from the ambient in order to reach equilibrium moisture content. The final models developed have been validated against the corresponding experimental results in terms of the pre-camber deflection and the initial strains (so stresses).

Significance and potential application for result

The use of compressed wood as a reinforcing material has been approved effective. As there is no need of resin and only a small amount of CW is needed, the techniques developed are simple and purely green. It has shown a significant enhancement on strength, bending stiffness and load carrying capacity of the glulam beam reinforced.

Funding body

Authors are grateful to the Higher Education Directorate General, Ministry of National Education, Republic of Indonesia for the financial support of this project


03 Shahryar Arshi University of Brighton

Structural behaviour and performance of skirted hybrid monopile-footing foundations for offshore oil and gas facilities


To investigate the influence of combining skirted footings with monopiles on the strength of the foundation system to lateral forces.

Brief description

In the current offshore technology there is clearly scope to develop foundation systems which are more efficient, economic and satisfactory for the particular case of an offshore oil platform. One such approach is that foundation systems are developed which combine several foundation elements to create a ‘hybrid’ system. In this way it may be possible to develop a foundation system which is more efficient for the combination of vertical and lateral loads associated with the structure. This proposal concerns an investigation of the performance characteristics of skirted monopiled-footing foundation systems, consisting of a monopile with a large surface based skirted bearing plate (similar to a pile cap) as shown schematically in Figure 1.

Previous model studies have demonstrated that the lateral resistance of a monopiled foundation is significantly enhanced by the presence of the bearing plate (not skirted). This is illustrated below in Figure 2 which shows the lateral load versus lateral displacement observed in some single gravity model tests conducted in samples of uniform dense sand. However, the influence of upgrading such a design by adding a skirted element to the bearing plate has not been done before. The results of the model tests will provide insights into the effect of the various foundation elements (i.e. pile, plate, skirt) and their contribution to the overall structural performance of the foundation system.

Potential for application of results

Upgrading the existing deep foundations systems of offshore oil and gas facilities to a more efficient design

Research supported by

Ramboll Group, University of Cambridge, University of Western Ontario.

Figure 1. Schematic arrangement of a deepwater skirted monopiled-footingFigure 2. Model tests on non-skirted monopiled-footing and single pile subjected to lateral loads

Skirted bearing plate

Pile


04Minixi Bao University of Birmingham

Insulating Glass Units (IGUs) provide an effective thermal and acoustic barrier of buildings owing to their excellent insulation properties. The use of IGUs for claddings or windows has become a common practice nowadays. Most IGUs will gradually deteriorate in performance during their service life to a certain point where the failure starts. The failure state can be identified by physically measuring their performance indicators and comparing them with pre-defined threshold values. However, this exercise is usually expensive and sometimes impractical. It is necessary to develop a reliable theoretical system to define the failure criteria and estimate the service lifespan.

In this project, a numerical method has been developed to predict the service lifespan of IGUs. The structure integrity, thermal performance and condensation resistance affected by environmental factors like temperature, relative humidity, barometric pressure and wind load are studied. The research on coupled actions between these environmental conditions will be also conducted in the real service conditions. The failure criteria of IGUs in terms of maximum stress, maximum stain, minimum U-value and maximum water content will be also determined.

A field experiment program will be carried out, in which the failure causes will be explored from inspecting existing IGUs which have failed or are approaching failure. A continuous in-situ monitoring work will be conducted on units that are approaching failure. The variations of temperature, RH inside the units and stress/strain distribution on the edge sealants will be recorded. Furthermore, a novel remedial treatment will be applied on some of these IGUs and their new performances will be monitored as a comparison.

This project will benefit the building design and window and cladding industry in providing a rational method to predict the life expectancy and to explore the method to improve the durability of IGUs. It will also provide useful information to retrofitting of existing buildings.

Performance and failure analysis of IGUs under in-service environmental actions

Posrer presenter


05 Caroline ButchartUniversity of Cambridge

Post-fracture performance of laminated glass

Description of the problem

All structural systems have redundancy built into them; if not, the effect of failure of an element would be the collapse of that structural system. Glass is an extremely brittle material with no ability to re-distribute forces via plastic deformation. For this reason, upon reaching the critical strength of glass, it fractures instantaneously, and this causes complete collapse of the element. Glass has the added danger that the fractured pieces are a safety hazard especially when falling from a height. For this reason it is important to introduce a residual structural capacity into the glass elements. Laminated glass is two sheets of glass laminated together with a polymer interlayer such as Polyvinyl Butyral (PVB) this serves two purposes, firstly to adhere to the broken glass shards and prevent them falling, and secondly to provide a residual tensile strength to the element. Designers currently have no method of predicting the post-breakage capacity of a laminated glass panel, and consequently full scale destructive tests are required in all but the most conservative designs. This makes the use of glass in construction an extremely costly and time consuming process.

There is currently little knowledge about the post-fracture strength of laminated glass panels, largely because the behaviour of the interlayer is as yet, not fully quantified. PVB is a viscoelastic material and currently almost all modelling of it concentrates on the short term behaviour. This means that the few models that exist to predict the post-breakage behaviour of laminated glass only quantify the behaviour immediately after fracture [1], and not the long term behaviour of the panel. This is necessary knowledge, unless fractured glass panels are replaced immediately after fracture.

The behaviour of laminated glass post-breakage consists of the deformation of the interlayer, and the delamination of the glass from the interlayer. Currently all models group the two effects into one energy effect. This is excellent for simplicity and ease of use during a design situation, but means current models cannot be extended to other scenarios besides those used in the testing conditions. Before the model can be simplified for use in design, it first has to become more detailed, and establish the relationship between all the factors relating to post-fracture strength such as loading and support conditions, time and temperature.

Approach to the problem

Initial research would investigate the viscoelastic behaviour of PVB by comparing data from TCT tests [2] with data from dumbbell tests of PVB. The aim of this is to establish the contribution to energy dissipation of the deformation, and the delamination separately. Further work will involve continuing these tests to include other factors such as moisture, temperature, alternative interlayers, and varying strain rates.

The next stage of the research will be to use the data gathered to establish a simple generalised model that can be used during the design stage to eliminate the necessity for full scale testing. This will require the model for the simple tension test to be extended to different orientations, fracture patterns, such as a hinge, or a radial fracture pattern as is common in impact fractures, and also to different loading conditions such as blast, impact, and dynamic. It is hoped that the research would also enable a guide to be written which would advise designers on methods of improving the post-breakage performance of glass which would be especially useful in critical designs such as those involving load bearing elements.

[1] Seshadri, M. et al., 2002. Mechanical response of cracked laminated plates. Acta Materialia, 50(18), pp.4477-4490.

[2] Sha, Y., Hui, C. & Kramer, E., 1997. Analysis of adhesion and interface debonding in laminated safety glass. Journal of Adhesion, 11(1), pp.49-63.


06David ByrneNational University of Ireland

Project objectives and goals

• Offeranindependentinvestigationinto,andcontributeanoriginalideain,thedesignofvoidformflatslab systems.

• Instrumentationofabuildinganddevelopingitasastructuralteachingtool.

• Investigatesheartransferinvoidformflatslabsystemsandtoexaminewhatextentsheartransferis achieved through the use of ‘stitching’ bars in void form flat slabs.

• Todetermineifthereisabetterandmoreefficientmethodofachievingsheartransfer.

• Investigatewhatareasoftheslabsaresusceptibletofailureandwhatfailuremechanismsareinvolved.

• Clarifyanydesignissuesinrelationtovoidformflatsystems.

Brief description

Void from flat slab systems are an innovative and novel form of flat slab system. They consist of spherical void-formers, positioned in the middle of the concrete cross section to reduce the overall self weight of the slab, while maintaining the full flexural strength allowing a two-way or bi-axial load transfer. The reduction in self-weight, up to 35%, allows for savings in overall materials and permits longer spans. Void form flat slabs can be constructed by two methods; traditional in-situ or in combination with pre-cast elements. This research focuses on the use of semi-precast elements and how two-way action in the bottom steel is restricted. To ensure that two-way action is achieved between the different slab panels a series of reinforcement or ‘stitching’ bars are provided. These ‘stitching’ bars are centred on the joint between the pre-cast elements. The assumption is that these will provide sufficient bond between the slab panels to ensure transfer of load across the slab joints rendering the joints irrelevant to the completed structural performance. One of the primary aims of this project is to analyse this load transfer. Central to the project is the instrumentation of the New Engineering Building (NEB) at the National University of Ireland Galway. It is the first building in Ireland to employ the use of void form flat slab systems. One of the slab bays within the NEB has been instrumented with over 160 gauges at fifteen different sections. Sensors have been installed both in the concrete and on the reinforcement bars. The sensors are being used to monitor the geometric and material properties of the slab system during construction and throughout the buildings lifetime. They are providing valuable data as to how the slab system behaves in-situ and responds to different loadings. The research strategy will combine numerical simulation using finite element models and field measurements. The finite element models of the instrumented slab system will be validated by comparison and continual updating of data obtained from measurements on site.


The primary aim is to establish how efficient load and shear transfer is achieved within void form flat slab systems and what further measures can be taken to improve the performance of the system. It will also clarify other design issues related to void form flat slab systems. At present there are very few publications in relation to this unique slab system and their design is not specifically included within the provision of Eurocode 2. This project aims to carry out an independent investigation of the slab system and highlight a set of procedures which could be incorporated within the codes. Furthermore, the instrumentation of the NEB will form the basis for future research projects.

Funding body

Funding is being provided by the Arup Consulting Engineers and the Irish Research Council for Science, Engineering and Technology (IRCSET) through the Enterprise Partnership Scheme.

The analysis of shear transfer in void form flat slab systems, including in-situ measurements from a building

Poster presenter


07


The main objective of the research is to obtain conclusions about the role of the tower’s shape, main span length, type of cable arrangement and foundation soil in the seismic behaviour of cable-stayed bridges, and to study the improvement in such response with the incorporation of different types of seismic devices.

Brief description

Due to the special social and economic importance that is usually associated with cable-stayed bridges, it is necessary to ensure their proper seismic performance.

In order to address the problem, the research has been divided in three main parts; (1) study of the numerical methodologies for the elastic and inelastic seismic response of this structures, (2) comparation of the ductility demand in the models with different types of towers, span lengths, cable arrangements and foundation soils, and (3) study of the optimum seismic devices which avoid the plastification of the tower’s sections.

Broadly speaking there are four different calculation methodologies for the analysis of the seismic response of a structure, which in order of most to least complexity are: (1) the dynamic calculation of the history of response by direct integration (DRHA) of the coupled system of equations of dynamics, (2) nonlinear static analysis of the structure until its structural collapse (Pushover), (3) the modal dynamic calculation of the history of response (MRHA) and (4) the spectral modal analysis (MRSA). All of these numerical approximations have been considered in the present research.

Five types of towers have been considered; “H”, “inverted Y” with and without lower diamond, and “A” with and without lower diamond. The dimensions of its sections have been considered taking into account cable-stayed bridges already constructed. The seismic response of 70 models was compared and specific studies like the performance of the lower strut were performed.

It has been considered different types of seismic devices which provide; isolation, dissipation and or added damping. The position of such devices along the tower and the optimisation of their mechanical properties in order to minimise the seismic demand of the main structure have been studied.

2010 is the third year of this research, which is going to finish in 2011 with the presentation of my PhD thesis.

Alfredo CamaraPolytechnic University of Madrid (UPM)

Linear and nonlinear seismic response of cable-stayed bridges; dissipation and damping devices


08Richard CampbellUniversity of Strathclyde

Introduction

An engineering led design initiative which provides an exemplar model for regeneration and social inclusion. A simple and effective process aims to provide opportunities for homeless people to rebuild their lives, literally. This participatory approach enables the end user to be an integral part of the projects inception and construction.

The research will involve the development of new building systems which innovatively combine and adapt existing technologies and materials to make easily built construction options. A review of communication techniques will improve methods of explaining how systems are built and how individual elements fit into an overall building model. 3D computer modelling and full scale prototypes aim to help develop the way in which training is provided to allow systems to be built by non skilled workers.

Project objectives

Structural engineering research and design will be at the forefront of how this project can be a success. A design brief for a mobile exhibition space will be used to provide a context for engineering design solutions to be presented. Full scale prototypes of developed solutions will be built using a team of civil engineering students from the University of Strathclyde. This will provide them with excellent experience in the form of a summer placement whilst also being a strong test bed for the design.

The designs will combine individual elements which will be phased as part of a training programme gradually developing the skills and knowledge of those involved. Structural design will consider the following; wall/floor/roof systems, frame options, stability systems, connections, and foundations. The designs will strive to showcase strong architectural concepts and a subtle integration with building services.

The initiative will combine the collaborative design skills of engineers, architects and contractors to create buildings which can be built by homeless people for homeless people. Designs will innovatively use traditional and modern building materials, processes and technologies, utilising local workshop facilities, to provide a simple buildable exemplar model.

Potential for application and results

The systems will have the potential to be used for projects such as designing for changing needs, engineering relief and buildings in the developing world. The solution aims to provide an achievable end product, which enables people to receive the help and support required to get their lives back on track. This will also provide them with useful knowledge and skills to achieve employment, thus improving modern society.

More with [home]less


09

Poster presenter

Pedestrian crowd-bridge interaction modelling utilising a discretely defined crowd

Seán Carroll University of Nottingham

The work discussed herein, pedestrian crowd-bridge interaction modelling utilising a discretely defined crowd, is part of a wider Ph.D project investigating human-induced bridge vibration. Financial support is provided by the University of Nottingham through the Faculty of Engineering.

Crowd-induced dynamic loading of bridges has become an issue of concern as a result of the events that took place on the opening day of the London Millennium Bridge in June 2000. Since this event, much research has focused on developing models capable of predicting the onset of large amplitude lateral oscillations, termed lateral instability.

Recent work has identified the importance of modelling the pedestrian crowd as an integral part of the complex dynamic system, rather than an externally applied force. Modelling the non-linear interaction between an oscillating bridge and pedestrian crowd results in a time-evolving description of coupled bridge-crowd behaviour. Previous crowd-bridge interaction modelling has been limited by the nature of the crowd models utilised, hydrodynamic models in which the crowd is idealised as a compressible fluid. Modelling crowd behaviour (and therefore interaction behaviour) in this way requires significant limiting assumptions.

To address these limitations a novel interaction modelling framework has been developed that utilises discrete element theory (DET) to model the pedestrian crowd. DET, also known as agent-based modelling, is widely used in the simulation of pedestrian movement, particularly in cases where building evacuation is potentially problematic. Pedestrians are modelled as individual elements subject to global behavioural rules. Wider crowd behaviour emerges as the result of multiple pedestrian-pedestrian interactions. In this work an additional pedestrian stimulus is introduced that is a function of bridge lateral dynamic behaviour. The pedestrians’ relationship with the bridge as well as the pedestrians around them is thus simulated.

The lateral dynamic behaviour of the bridge is modelled as a damped single degree of freedom (SDOF) oscillator. The system excitation and added mass is determined as the sum of individual pedestrian contributions. The resulting non-linear interaction between the crowd and bridge produces emergent behaviour typical of that reported by other researchers. Under dense (critical) crowd loading the model predicts the onset of lateral instability. However under sub-critical loading conditions the model is a useful tool for the prediction of peak bridge response. The statistical post processing of simulation data allows application of a probabilistic design methodology that outputs not only the maximum expected response, but its probability of exceedance in a given return period.

Once validated the model can be applied directly in the serviceability design of bridge structures subject to human-induced loading. There is also scope to utilise similar discrete crowd models to simulate the spatial and temporal variation of dynamic loads on other structures in which human-structure interaction may take place, such as long-span floors or grandstands.


10

Long span, slender civil engineering structures, such as footbridges, stadiums and floors, are nowadays more prone to excessive vibrations due to human-induced excitations (such as walking, running and jumping) than they were only a decade ago. This is due to somewhat inconvenient dynamic properties often encountered in modern structures made of light high-strength materials. These problematic properties are low mass and damping as well as natural frequencies being in the range of frequencies typical for human activities. While modelling structural dynamic properties is quite well established in the field of dynamics of structures, models for human-induced loading are still under development. Most debated and still not fully understood aspect of this modelling is a phenomenon called the Human-Structure Interaction (HSI), which occurs when people who dynamically excite the structure are at the same time perceiving the vibrations induced and reacting to them. The HSI usually refers to changes in both dynamic properties of the structures and in human-induced forces caused by people’s reaction to vibration perceived. Best publicly known example of HSI is excessive lateral vibration of the Millennium Bridge on the opening day in 2000. The bridge had to be closed shortly after its opening to be fitted with dampening devices that reduced vibrations to acceptable levels. A lot of research in HSI in the lateral direction have been conducted since the Millennium Bridge problem occurred, but the investigation in the vertical direction stayed almost untouched. In addition, little is known how occurrence of HSI phenomenon changes the level of synchronization between people walking in groups.

HSI occurs because the humans are intelligent dynamic systems, who are highly sensitive to vibrations. To achieve greater understanding of the phenomenon, it is necessary to better understand how the walking-induced force develops when pedestrians crossing perceptibly moving surfaces. My research will concentrate on the under-researched vertical component of the force induced during walking activity. This will be done by instrumenting a pedestrian’s body with markers that will be tracked. The kinematic data collected will then be used to reconstruct the dynamic force generated during walking over a vibrating platform. In addition, capability of two or more people to synchronise their actions will be investigated, using the state-of-the-art motion capture VICON system, available at Warwick University.

The main objective of the project is to develop a computer model of human-induced forces in the vertical direction, taking into consideration the effects of HSI. The study is expected to reveal how biomechanics of human gait changes when walking on vibrating surface. Once the force model is established, the verification of the model will be carried out using some existing (in literature) data and acquiring new vibration response data from lively footbridge structures.

Hiep Vu Dang Warwick University

Modelling of human structure interaction using motion capture system


11

Comparative thermal mass experiments with GGBS and PC concrete

Paula DrewNorthumbria University

Objectives and goals

This research aims to investigate the thermal properties of concrete to develop a low thermally conducting concrete, with enhanced sustainability credentials. This will stabilise the internal temperature profile of a building reducing heating and cooling requirements, therefore reducing the buildings whole lifecycle CO2 emissions. This will be achieved by investigating;

• theeffectofdifferentcementtypesonemissivity(E)ofconcrete

• thermalconductivity(k)oflowdensityvhighdensityconcrete

• thermalconductivity(k)ofaggregatesizeandtype

• theeffectofcementtypeandpercentageonthermalconductivity(k)

• optimumporestructure,andimpactoftransitionzonesandcapillaryactiononthermalconductivity(k)

• optimisedconcretemixdesignbasedonthefindingsfromaboveobjectives

Project description

Government targets dictate energy consumption in buildings must be reduced, already more stringent Part L 1a of the Building Regulations have been introduced effective from 1st Oct 2010 (NBS,2010).

Energy consumption from housing accounts for 28% of the worlds total CO2 emissions (Bennet,2010). Thermal mass is generally used to help reduce the need for energy intensive heating and cooling systems in buildings, however there can be problems to using a thermal mass system; thick slabs are used which encroaches floor space, orientation is paramount which may not be an option, and overheating can occur.

Developing a low thermally conducting concrete will allow for stabilisation of a building’s internal temperature profile without relying on variable factors, achieving higher building functionality.


The potential application of this research will be in the development of a concrete mix which will save energy devoted to the heating and cooling requirements of a building, for application primarily in UK housing. The developed mix by nature will have superior sustainability credentials due to its enhanced thermal properties, as well as reduced embodied energy giving further merit to its sustainability.

Bennett. D., (2010), Sustainable Concrete Architecture, London: RIBA Publishing NBS, (2010), Building Regulations: Part L1a, London: RIBA Publishing


12


To investigate the performance of gusset plate connections to brace members under earthquake loading through both physical and numerical modelling. This will lead to improved design provisions in seismic design codes, such as Eurocode 8, for gusset plate connections to brace members.

Brief description

Current design of gusset plate connections in concentrically braced frames (CBFs) is based on elastic design principles. Thus, the gusset connection to the brace member is normally classed as a non-dissipative element. The brace capacities, together with an over-strength factor, are used to size the gusset plate, connecting welds and/or bolts. Full frame actions are generally ignored in the design of gusset plates, including the effects of the opening and closing of the angle between the beam and column on account of lateral frame deformations. These rotations induce tensile or compressive forces in the connections depending on what direction the frame is drifting in relation to the brace. Conversely, the gusset plate connection can add significant rotational stiffness to the beam-column connection when connected to both the beam and column. These tests will also act as a set of complementary tests for further full-scale shake table tests on CBFs to be completed in Paris in June 2012 under the EU FP7 SERIES programme.

Potential application of results

It is proposed that proper seismic design of these gusset plates will improve the efficiency and energy dissipation capacity of the frame, where the brace together with its end connections will be classed as the dissipating member, while maintaining stability of the structural system.

Funding body

Irish Research Council for Science, Engineering and Technology (IRCSET) EU FP7 SERIES

Jack EnglishNational University of Ireland

Experimental and numerical seismic analysis of steel gusset plate connections to brace members


13


The main objectives in this project consist of:

• Optimisingthesectionsoftheframe.

• LifeCycleAssessment(LCA)andLifeCycleCosting(LCC)ofthebuildings.

• StudyingtheimprovementsonthethermalefficiencyandreductionofCO2 emissions as a result of adding insulation materials to the building envelope.

• Comparingtheinitialinvestmentwiththeoperationalenergysavingachieved.

Brief description

Portal frames account for 90% of all single storey buildings and 50% of all the constructional steel used in the UK each year. The uses of such buildings range from agricultural sheds to large warehouses. In the UK, the recent ADL2 Regulations (2010) require buildings to be more energy efficient and reduce their CO2 emissions by at least 80% by 2050, with a first target of a 34% reduction by 2020, against a 1990 baseline. For portal frame warehouses, this will require higher initial costs in the form of insulating sandwich panels, more efficient heating, cooling and lighting installations, and refined construction methods to improve the air-tightness and reduce heat-loss by thermal bridging in the connections between elements. Insulation materials can significantly reduce energy use for cooling or heating load.

An energy efficiency analysis is undertaken by computer simulation of the buildings performance. Economic comparisons are made on the LCC based on the amount of insulation used in the sandwich panels and the energy saving obtained. The LCA also compares this in terms of CO2 emission reduction achieved.


In the United Kingdom, steel portal frames are widely used for single-storey buildings. Therefore, reducing their energy consumption and carbon emissions is highly beneficial for the environment. This project also studies the compliance of this kind of buildings to the recent ADL2 legislation. The potential for application of results are very large for both construction and design companies.

Funding body

This project is sponsored by the Queen’s University Belfast.

Xabier Fernandez Rodriguez Queen’s University Belfast

Comparative life cycle cost for cold-formed steel portal frames


14


• Developananalyticalapproachforcalculatingthewaveforcesonaverticalcylinderindeepwater.

• UseComputationalfluiddynamics(CFD)toexplorethewaveforcesoncomplexgeometriesfor axisymmetric vertically oscillating wave energy converters (WEC’s)

• DevelopamethodofmatchingthefrequencyofaWECtothetothepeakfrequencyofthewavespectrum of a given location by optimising its geometry.

Brief description

The initial stage of the project involves the development of an analytical solution, for periods greater than 5 seconds, for the wave forces on a vertically oscillating axisymmetric cylinder. The heave, or vertical, motion of the body is the principle concern in this problem. Therefore, the wave excitation force, the added mass and the wave damping are the unknowns that need to be calculated. Furthermore, this solution will serve as a method of approximating the structural loading and the response of the axisymmetric vertically oscillating WEC’s with more complex geometries, thus insuring the accuracy of the CFD analysis.

A variety of complex geometries will be examined using the fluid-structure interaction aspect of CFD, as the frequency of the incoming linear deep water wave changes. In order to insure the properties of the incident wave are accurate, a study for creating an accurate and optimum model was carried out. The results of the fluid-structure interaction study will identify the optimum geometries of a vertically oscillating axisymmetric WEC over a realistic range of incident wave frequencies. In order to verify the study, a number of selected geometries will be fabricated in order to perform physical experiments in a linear wave tank. Furthermore, these are designed with a method of varying their draft.


For every sea or ocean region around the world the energy and properties of the waves is unique. Therefore, it is necessary to design a WEC depending on its expected location. The outcome of this project will enable a designer to optimise the geometry of the device by matching its natural frequency to the peak frequency of the wave spectrum of the location. This will aid to increase the frequency range of a vertically oscillating axisymmetric WEC when mechanically tuning the device to match the frequency of the incident wave, in order to force it to resonate.

Funding body

College of Engineering and Informatics Postgraduate Scholarship

William Finnegan National University of Ireland

The structural loading on vertically oscillating wave energy converters in deep seas

Oral presenter


15

Preplaced aggregate concrete (PAC) is produced by two stages technique. In the first stage, coarse aggregate (stone) is placed into the form to be concreted then, grouting the aggregate voids by cement grout in the second stage. Because of its low shrinkage, PAC has been used for many repair jobs like; tunnel lines, dams and bridge piers. Moreover, it has been used for underwater construction.

Grout has a major effect on the properties of resulted concrete. Well defined grout controls the properties of resulted concrete where grout fluidity should be defined by many variables for instance, water content, sand content, etc. It is also necessary to point out the rapid progress in concrete admixtures; their effect on concrete needs a wide investigation as their use could improve the grout characteristics. Relation between grout fluidity and concrete properties needs to be carefully investigated.

The aim of the PhD investigation is to study the effect of grout fluidity on the properties of preplaced aggregate concrete with and without admixtures. More specifically, to optimize the grout fluidity with respect to the properties of PAC using different types of fine aggregates (sands).

So far, grout workability (Rheology) by using different sands has been identified through a set of lab work at Bradford University without using concrete admixtures in the mix. Four different sand gradations have been used at different cement-sand ratios and at different water-cement ratios. Thereafter , improving the grout fluidity by adding admixture (super-plasticizers) as an admixture at low water contents and Pulverising fly ash (Pfa) as a cement replacing material to the mix and their role to optimize the grout fluidity has been investigated.

Finally, PAC has been successfully produced by compacting rounded coarse aggregate in the form, the remaining voids were injected by high fluidity cement grout. It has been observed that the grout has enough workability to penetrate the stone skeleton successfully. Then, the effect of grout workability or rheology on the properties of hardened grout and concrete has been investigated. More specific, their effect on compressive strength and absorption properties of hardened grout and concrete has been assessed.

Abdelhamed Ganaw University of Bradford

Rheology of grout for preplaced aggregate concrete

Poster presenter


16

Retrofitting of existing buildings as an activity currently makes up 50% of all building construction in the UK.

Replacing a building’s façade offers the prospect of improving the whole life performance of the building, in some instances as a favourable alternative to replacing the entire structure. This presents the opportunity to exploit the properties of advanced composite materials for maximum benefit. Addressing the shortfall in industry required design knowledge offers huge rewards. ‘Upwards and outwards’ retrofit, where extending floor slabs yields extra floor area, is permitted by a lightweight replacement façade, without the need to underpin foundations. For typical medium or high-rise office buildings, the extra let-able space obtained, and reduced heating and maintenance costs, can work to offset the expense of implementation.

The specific materials, manufacturing processes, and façade type, most appropriate for such a scheme have been determined. A unitised façade of sandwich panels with foam cores and pultruded GFRP skins forms the ‘design platform’ for this project.

Research aims to resolve how the connections in such a façade system can meet the many requirements of an integrated building envelope. Structural integrity, enhanced environmental control, sustainability attributes, fire provisions, acoustic control, ease of manufacture, tolerance control, durability, lightness in weight, cost effectiveness and aesthetics must all be addressed by any proposed design methodology.

Investigating suitable connections through prototype development and review, targets objectives under the headings of Structural Integrity, Thermal Performance, and Constructability.

Analytical review at material level has provided a greater understanding of the behaviour of GFRP elements in bending. Modelling section stiffness from first principles by stress distribution in the composite has examined the influence of several material parameters, whilst observing the extent of deviation in neutral axis position.

At element level, a means to assess existing sandwich panels has been devised. A procedure based around classical plate theory can ascertain internal actions at design ultimate loading without full knowledge of the materials used in its construction. This method works by performing a ‘calibration’ involving the Navier Solution for plate bending, and the permissible deflection limit as per original panel design.

Mechanical testing of naturally aged GFRP building panels from the demolished Seven Crossing Visitors Centre has formed a ‘composites durability study’ that does not rely on artificial aging techniques. Testing coupons from internal and external locations and whole panels from each of the four building facades examines the effect of environmental exposure.

Funding body

ARUP, EPRSC (case award)

Peter GatesUniversity of Bath

Polymeric facades: advanced composites for retrofit

Poster presenter


17


Through this research project, the development of a novel cost-effective sustainable composite building technology or product for use in a European context will be proven through extensive testing in terms of durability, strength and appearance.

Brief description

Composite materials comprising of locally sourced constitutive materials that have low impact on the environment are being developed. These materials are being formed into masonry blocks, known as stabilised soil blocks (SSBs), which are low-cost as their main component, the soil, is sourced locally, often directly from the site of construction. Further, these blocks can be produced on site, saving in transportation costs. The main stabiliser used in the manufacture of SSBs is Ordinary Portland Cement (OPC). Furthermore, OPC is the most common binder used in concrete, which is the most utilised substance in the world after water. OPC is, by far, the most expensive and energy intensive ingredient in concrete. Replacing cement with alternative waste materials and by-products from industrial and agricultural processes is a cost-effective process as their use in concrete or in soil blocks can benefit the environment, as the alternative may be to dispose of them in landfills. It has been revealed that the use of these materials in concrete or soil blocks not only reduce their cost and embodied energy, but also improve their structural performance. In summary, the successful implementation of stabilised soil blocks (SSBs), incorporating a waste material sourced locally as a cement replacement, will be confirmed for a European climate.


Through extensive experimental testing, the successful implementation of stabilised soil blocks (SSBs), incorporating a waste material sourced locally as a cement replacement, will be confirmed for a European climate. I believe that this product has a high potential for commercialisation and I believe that this research can contribute to the development of a more sustainable, green economy, in particular, focussing on the materials used in the construction sector.

Funding body

This project is being funded by the Irish Research Council for Science, Engineering & Technology (IRCSET).

Declan Gavigan National University of Ireland

Stabilised soil blocks – a cost-effective sustainable construction technology


18

The high level objective of this research programme is to develop a process for ‘de-risking’ the introduction of innovative and sustainable materials in construction.

In response to a recognised need for sustainable solutions in the built environment, there is widespread research being undertaken into the development of new ‘low-impact’ construction materials. This project focuses on the process by which these new materials move from the research laboratory into use on commercial construction projects. It takes the development of ‘limecrete’, a material with a potentially lower embodied carbon and energy to Portland cement concrete, as a case study for investigating the process.

It is appreciated that the use of any innovative technology in a commercial project environment is risky. Risks associated with the technical performance of the new product are significantly increased when it is transferred into a new environment, integrated into a new system and when it has to meet the requirements of a wider range of users. There are also significant commercial risks, with companies staking their reputation and market share on the successful implementation of new technologies. Commercialisation of innovative technologies is a highly complex activity, with numerous unknowns and a large number of stakeholders with different needs and values.

However it is recognised, that innovation in construction is both necessary, to meet the changing needs of the built environment in response to a changing climate, but also a significant opportunity for pro-active and outward looking businesses to gain a competitive edge. It is believed that companies that can be successful in recognising and taking appropriate opportunities to innovate, who appreciate the demands of the stakeholders, who can handle the complexity and who can effectively manage the risks, are well placed to become market leaders and drive for more sustainable solutions in construction.

It is envisaged that the results of this research will both further the development of limecrete, as a structural material, but also more generally be beneficial in informing the technology strategies of Ramboll, the sponsoring company, and others.

Funding body

This work is supported by the EPSRC funded Industrial Doctorate Centre in Systems, the Universities of Bath & Bristol (Grant EP/G037353/1) and Ramboll.

Ellen Grist University of Bath

The implementation of sustainable construction materials

Oral presenter


19

Low carbon building using hemp-lime: optimisation of materials and constructive systemsChristopher Gross University of Bath

Hemp-lime (HL) is a novel composite building material that combines renewable plant based aggregates (fast growing hemp shiv) with a lime based binder. Hemp-lime offers a combination of negative embodied carbon and high quality thermal performance during the life cycle of the building. As an insulating material hemp-lime’s thermal performance is enhanced by the material’s hygro-thermal properties, in which latent heat energy is absorbed and released as water vapour is released and absorbed, giving the material much greater apparent thermal mass. As a lightweight composite, hemp-lime is ideally suited to solid walls, as part of framed buildings, as well as for roof and under-floor insulation. Presently it is mainly an in-situ technique, either sprayed or cast.

Although hemp-lime is used together compositely with other materials and structural elements, the structural contribution of hemp-lime is currently ignored, as the strength ( comp = 0.1 – 0.3N/mm2) and stiffness (E = 10 – 20N/mm2) of the material is low. However, in framed building hemp-lime encapsulates the frame elements, potentially increasing capacity of studs by reducing tendency to buckle under compression loading. Hemp-lime also has the potential to make similar contributions to racking shear resistance. In addition hemp-lime must develop sufficient flexural strength in external walls to resist external actions, such as wind loading. The structural performance of hemp-lime and its composite interaction with other elements is not well understood, as a result design and construction is not being optimised in performance or use of resources.

The overall aim of the research project is to improve fundamental understanding of structural behaviour of hemp-lime composite timber framed construction, enabling improvements in material performance and use of resources which may lead to improvements in constructive systems. The research is being undertaken using a combination of material and structural component testing and development of analytical models. The research concentrates on three key loading cases; resistance to vertical loads; in plane racking and out of plane loading. The project focuses on light weight hemp-lime (density of 275kg/m3) used with timber studwork framing.

To date compressive and bending test have been undertaken on hemp-lime in order to establish the material properties. Several full scale vertical compressive loading tests have been undertaken on studwork frames both with and without hemp-lime encapsulation. Full scale in plane racking and out of plane bending tests have also been carried out. Currently results from the vertical compression tests show that low density hemp-lime provides restraint against stud buckling and significantly increases the structural capacity of the stud.

Outcomes from this research will include a greater understanding of the composite behaviour of studwork framing with hemp-lime and design guidance on composite hemp-lime wall systems. The results from this project have the potential to be applied to any timber studwork framed and hemp-lime construction, particularly house construction. Currently the percentage of new home constructed from hemp-lime is very small, but as this increases the potential application for the results from this research will also increase.

Poster presenter


20


• Determinationofthemechanicalpropertiesofthematerialusingbothstaticandultrasonicdynamic techniques.

• Examinethestrengthgaincharacteristicsofthematerialunderconditionsrepresentativeofsiteconditions

• ToapplytheresultingmaterialpropertiestoanappropriatematerialmodelforuseinFEmodellingthatcan be used to predict the structural behaviour of thin UHPFRC slabs under bending and punching shear failure

• Adaptandapplytheresultofsmalllaboratoryslabstolargerbridgedeckapplications

• Finally,determinepracticalproposalsforthedesignofUHPFRCtosupportthedevelopmentofrational bridge designs.

Brief description

UHPFRC is a combination of high strength concrete and steel fibre reinforcement first developed in France in the mid 1990’s. This advanced cementitious material is characterised by significantly improved mechanical and durability properties compared to existing concrete materials. One of the potential applications of this advanced construction material has been identified as a promising way to design slenderer, lighter and more durable bridge structures. Despite its vastly improved material properties, the structural application of UHPFRC is still not widespread due to: (i) reluctance to adopt a new material whose properties is perceived not to be fully understood, (ii) the lack of recognised design standards and (iii) high cost.

Research method

Test methods have been developed to determine the mechanical properties as previously described and the result will be used in the finite element method of analysis, using the SIMULIA software package, to predict structural behavior of thin slabs, which will be validated against the results of laboratory tests.


In industry, the owners of the most large structures have been reluctant to use this material due to the risks associated with being first to use a new type of construction material where its structural behaviour is not fully understood. Therefore, studying the structural behaviour based on experimental and theoretical analysis will provide more rational understanding of UHPFRC for highway bridge applications and other structures where strength, durability and low maintenance are required. Eventually, this could shift it from a research phase to a marketing phase and make it a more attractive material in construction. The outcomes of this study is to provide further understanding of UHPFRC’s structural behaviour in bending and shear failure, specifically when it is used in thin slab sections for highway bridge decks. This may give improved reassurance against the doubts and reservations that have limited the application of this material and promote its use in highway bridge design.

Funding body

EPSRC

Aram Hassan University of Liverpool

Ultra high performance fibre reinforced concrete (UHPFRC) for bridge deck applications


21

Oral presenter

Dynamic soil-structure interaction in monopile-supported offshore wind turbines

Sam Hayhurst University of Bristol

Project aim

This project aims to investigate the influence of foundation stiffness upon the dynamic properties of a wind turbine system in the long-term.

Problem description

Wind turbines are light, slender and top-heavy structures exposed to large lateral environmental loads with a significant dynamic component. These structural properties lead to a low global resonant frequency, within a similar range to the forcing frequencies of these environmental loads. This means that dynamic amplification of loading is a key concern in the design of the tower structure for the turbine; the structure must be tuned to resonate at a frequency which does not coincide with the typical range of forcing frequencies.

Since the stiffness of the system is a key parameter in determining the resonant frequency, the stiffness of the foundation has a significant impact. This contribution is normally characterised during design as being similar to that of a linear elastic spring in both the lateral and rotational dimensions. However, over the design life of the structure (normally 25 years) the soil around the foundation will undergo many cycles of stress and is likely to change in stiffness. This will result in a change in the resonant frequency of the system over with time. If this is not considered during design, it is possible that the effect of dynamic amplification of the structure will be miscalculated, leading to resonant behaviour or reduced fatigue life.

Whilst work has been carried out on cyclic loading of piles in relation to the design of offshore oil platforms, this has largely focussed upon the accumulation of displacements rather than changes in dynamic behaviour. This is a reflection of the fact that dynamic effects are not normally important in oil platforms. Furthermore, the dominant design method for laterally loaded piles (API-recommended p-y springs) was developed empirically to model the behaviour of the more slender small-diameter piles used in the oil and gas industry. It has been suggested that the behaviour of the large-diameter, stiff monopiles used in wind turbines will exhibit notably different stiffness characteristics under both static and cyclic loading.

Investigative approach

The problem is being investigated through a combination of small-scale model testing at 1g and numerical modelling. A large diameter (600mm) consolidation chamber has been developed in order to facilitate the model tests in clay. Model piles are subjected to large numbers of cycles of load through an actuator, and the natural frequency and damping of the system measured throughout the test using accelerometers. The pore pressure at the pile face will also be monitored to assess drainage conditions and the likelihood of pore pressure build-up.

Application of results

It is hoped that the results of this work may be applied in checking of and possible recommendations of revisions to to current design practices recommended in standards such as those published by the API, which are currently dominant in design practice.

Funding body

DTA Grant from EPSRC


22

Brief description

In recent years, the problem of floor vibrations causing annoyance and disturbance has been noted in a range of newly built structures, especially office buildings. This is due to advances in design methods which have led to the use of more slender beams and floors in construction and a shift in the division of office space from compartmentalised to open plan.

At present, when a structural design fails to meet the desired level of vibration performance, the primary option considered by most design engineers is to modify the structure in some way, such as: adding extra mass; increasing the stiffness of members; or reducing the span between columns. However, these options can detract from the architectural design and potentially increase costs significantly.

An attractive alternative as demonstrated in on-going research is to use an active vibration control (AVC) system. These systems reduce the response of the structure to the dynamic load through the application of a control force that is generated in real-time as a function of the measured response of the structure. However, there is a notable lack of guidance available for design engineers to incorporate AVC technology into new structures, without which the many advantages that AVC systems can bring to a structural floor will not be realised.

Objectives

The main objectives of this project are: firstly, to develop tools and recommendations to assist in the design of buildings that include AVC systems. This should address issues such as what potential reduction in response could be achieved, what control law should be used and how many actuators should be used to apply the control force? Secondly, the economic and environmental benefits of including AVC systems at the design stage of a floor structure will be investigated to enable an informed decision about the suitability of incorporating AVC to be made. This second objective is crucial for the commercial acceptance of AVC technology.

Potential application for results

Long-span structures built in the UK are increasingly limited in slenderness by the vibration limit state. The results from this project will work towards developing design guidance so that design engineers can incorporate AVC immediately into new buildings and realise the potential slenderness benefits that are available. Furthermore, this work will also facilitate the retrofitting of AVC into existing buildings with known vibration problems.

Funding bodies

EPSRC, WSP Buildings

Malcolm Hudson Sheffield University

Implementing active vibration control in floor structures

Oral presenter


23

Objectives

• Provideasuitableandaccurateanalysistechniquetopredictthebehaviourofreinforcedconcrete(RC) columns

• ComparethebehaviourofRCcolumnswrappedwithfibrereinforcedpolymers(FRP)andthosenot wrapped

• Developdesignprinciplesthatallowengineerstodesignretrofitsystemstoimproveastructuresresponse to blast loads

Description

In recent years the threat of terrorism has increased and many examples exist where significant damage and fatalities have resulted from building collapse caused by explosions. It was estimated that of the 168 people who lost their lives in the Oklahoma City bombing, 87% were in the collapsed portion of the structure. It is therefore apparent that engineers have an important role to play in protecting the inhabitants of buildings from these events. In recent years FRP materials have come to the fore as a possible method for achieving this.

The current research project looks at methods for analysing the behaviour of FRP wrapped reinforced concrete columns subjected to blast loads. The interaction between a blast load and a column can be extremely complicated and concerns over the accuracy of the most common method of analysis (the equivalent single degree of freedom method) have been raised. The current alternative to this is finite element models but these tend to be time consuming to develop and often unreliable when little is properly understood regarding the fundamentals of the problem.

In response to this, a new method of analysis has been developed in the current research project. This method is based on plasticity theory and energy considerations and has been developed for columns deforming flexurally. The new method allows the complicated nature of the response of the structure to be effectively analysed in a relatively simplified manner. This includes accurately assessing and incorporating the effects of the high rates of straining, which have been shown to have a significant effect on the strength of the materials and the response of a member.

The method has so far demonstrated promising results in analysing the behaviour of FRP wrapped RC columns subjected to blast. It has also been extended to analyse the behaviour of both FRP wrapped and unwrapped columns subjected to impact loads and has displayed encouraging results.

Application

The research aims at improving the understanding of the complicated phenomena of the response of RC columns to extreme dynamic loads. Through understanding this complex situation and developing suitable methods for analysing the behaviour of RC columns, appropriate retrofit systems can be designed to improve the response of the structure and safeguard it from attack.

Funding body

University of Bath

Philip IsaacUniversity of Bath

Effects of blast loads on reinforced concrete columns with a view to strengthening


24

Façade engineering design is attracting an increasing amount of attention on account of the growing importance of building envelopes. The demands for energy efficient buildings and occupant comfort often result in conflicting performance requirements, which are being addressed by bespoke high-performance facades with high complexity and cost. A façade can constitute up to 25% of the total capital building cost, and the operating costs might be even higher, it is therefore desirable for façade designers, manufacturers, and building owners to identify the façade systems that provide an optimal balance of performance, sustainability, and economy.

Glazed openings are primary components for façade design due to their multi-functionality. Consequently they introduce conflicts into a design process. For example, window frames improve the structural performance, but often create thermal bridges leading to unwanted heat loss. Moreover, since the outdoor environment is transient, traditional windows of fixed properties are unlikely to make the best of natural resources, thereby failing to minimise energy consumption. All these facts lead to one question: how much could windows contribute in terms of seeking the optimum balance of aspirations and requirements?

High-performance glazed facades, based on new materials and novel technologies, such as actively controlled glazing and vacuum insulation glazing, have been developed during the recent decades. They provide a timely opportunity for the promotion of actively controlled facades with switchable properties, which intelligently interact with outdoor environment and occupants to satisfy the performance requirements with the least environmental impact. Research in such materials and technologies have been carried out in a fragmented manner, which results in several high-performance technologies with little or no regard to how these technologies interact when they are brought together in a real-world façade. A further barrier to implementing these novel high-performance technologies is that there is a lack of data on their relative whole-life value, i.e., social values, economic value, and environmental value, thereby making it difficult to select one technology over another.

In order to address these issues, we propose to develop a comprehensive multi-objective selection system that will integrate accurate simulation, systematic parametric analysis and design optimisation. This will eventually lead to a whole-life value based multi-objective selection and design optimisation tool for high-performance façade design. Three main outcomes shall be achieved by the end of the project:

• Validatedsimulationmodelsthataccuratelyevaluatethesocialvalue,economicvalue,andenvironmental value of high-performance glazed facades;

• Amulti-objectiveoptimisationmodelthatintegratesthewhole-lifevaluedesigncriteriawithplentyof flexibility;

• Auser-friendlyrepresentationfortherelativewhole-lifevalueforexistingandfuturehigh-performanceglazed facade technologies.

Funding body

Cambridge Overseas Trust

Qian Jin University of Cambridge

Multi-objective optimisation of high-performance façade technologies

Poster presenter


25

Brief description

Lightweight cable-supported structural systems are widely used in the design and construction of sports stadia and bridges but their robustness and resilience against explosively formed fragment impact remains largely unknown. Very little research has been carried out to study the effects such an impact has on the cables, cable terminations and surrounding structure. Recent studies carried out in the US to assess the vulnerability of typical cable types used on cable stay and cable suspension bridges highlighted the potential mechanisms capable of inducing abrupt cable loss, one of which was the impact of explosively formed fragments traveling at high velocity from an accidental or malicious explosion.


• Determinetheperforationandpenetrationresistanceoftypicalspiral-strandcablesandestimateresidual breaking loads in the event of damage without loss.

• Determinetheoptimumperforationandpenetrationfragmentvelocityrangesandback-calculatecritical stand-off distances.

• Determinecriticalfragmentcharacteristicsintermsofsizeandshapeeffects.

• Investigatetheglobaleffectsonthesurroundingstructureintheeventofcabledamageand/orloss.

• Determineoptimummitigationmethods.

Research method

Advanced numerical modeling using LS-DYNA coupled with validation testing at Shrivenham Defense Academy.


Due to the lack of knowledge and understanding in this area cable supported structural systems have been designed with a certain degree of redundancy when such highly transient loadings conditions have to be considered in design. The findings of this research and further studies in this area could potentially lead to the development of design guidance, published papers, and a key understanding of the design measures required to achieve robustness and resilience against such loading conditions when adopting lightweight cable supported structural systems, which may in return add-value to a specific project by negating the level of redundancy.

Funding Bodies

Arup and EPSRC

Ryan Judge University of Liverpool

Lightweight cable supported structures subjected to blast fragmentation

Oral presenter


26

The global infrastructure crisis

Structural concrete, constituting a major share of global infrastructure, is perhaps the most successful man-made structural material. However, ageing and deterioration on one hand and ever increasing load demands on the other, lead to the reduction in performance and service-life of concrete structures. To have safe and serviceable structures under stringent economic and sustainability constraints comprises what is known as the Global Infrastructure Crisis that the world is facing in the present time.

Fibre reinforced polymer (FRP) composites for structural strengthening

Fibre Reinforced Polymer (FRP) composites have emerged as promising materials offering superior properties compared to steel including high strength-to-weight ratio and structural efficiency, ease in handling, significantly less corrosion potential and adaptability to suit almost any geometry and shapes. Since strengthening an existing under-performing structure is generally a greener and more economical option compared to replacement with a new structure, the use of FRP composites for structural strengthening presents an excellent sustainable and economical solution to the global infrastructure crisis.

Expert system for FRP-based strengthening

Adding FRP as an externally bonded reinforcement has proved to be an effective technique to impart additional flexural and shear strength and confinement to the existing concrete sections. However, due to the relatively short history of use of FRP within the construction industry, engineers are less confident in their applicability. For this reason, the design guidelines for FRP-based strengthening tend to be more conservative than usual by specifying higher factors of safety on FRP material properties. While such an approach is justifiable for conventional steel reinforced concrete (RC) structures, it doesn’t necessarily result into more conservative design solutions for the externally bonded FRP, which involve multiple possible failure modes (e.g. debonding and rupture). This results in an unknown or reduced conservativeness being attached to a design solution than the designers believe. Thus, typical RC design mind-set doesn’t serve directly for externally bonded FRP. In spite of the acute need, most Universities worldwide do not offer training to engineers for this, resulting in a fewer trained engineers available to cater the global infrastructure crisis. These factors warrant a smart tool useable even to trainee designers in making important decisions required for typical strengthening designs.

Objectives and impact of this research

This project has a wide spectrum of applications through developing an interactive Expert System (ES) for holistic FRP-based strengthening process. The specific objectives include: (1) to identify various sources of conservativeness within the strengthening design criteria, (2) to develop generalized evaluation and design protocols, and (3) to develop a robust inference mechanism for strengthening design process. The ES will help in the decision making process and will serve as a design tool for practicing engineers and for the education of the trainee engineers. Moreover, it will be possible to identify propagation of variously introduced conservativeness within the design process resulting in a more transparent and confident design process. The relative merits of the design solutions obtained through following different international guidelines with identical FRP materials will be of great use in fine-tuning and calibrating these guidelines thereby adding significant gravity to the outreach of this project.

Funding body

Through an ORS Award by the HEFCE and a Research Award from the University of Bath.

Kunal Kansara University of Bath

An expert system for FRP-based strengthening of concrete structures


27

Research problem

For sustainable development of the urban environment where people and nature reside together, infrastructures are required to retain their performance over the long-term. In order to provide a durable and reliable solution, functionality, safety and the service life of infrastructures must be estimated based on scientific and engineering knowledge. Therefore for existing deteriorated infrastructures a rational maintenance plan should be employed in accordance with their current condition.

Over the life cycle of any reinforced concrete (RC) structure, environmental and manmade actions such as thermal effects, chloride induced corrosion of reinforcement due to using de-icing salt in winter and earthquakes etc. are more or less unavoidable. Of those corrosion of reinforcing steel is one of the primary sources of durability problems. This leads to loss of steel cross section and weakening of the bond and anchorage between concrete and reinforcement, which directly affects the serviceability and ultimate strength of concrete elements within a structure. Furthermore, in areas subject to earthquakes, a very important design/assessment consideration is the ductility of the structure when subjected to seismic-type loading. This is because the seismic design philosophy relies on energy absorption and dissipation by post-elastic deformation for survival in major earthquakes. Therefore seismic performance of corroded structures will also be affected by any corrosion in the section and change in ductile behaviour. Currently there is a gap in our knowledge that how this long-term material deterioration over the life span will affect the non-linear behaviour of RC bridges subject to seismic loading.

Research objective and goals

The aim of this research is the investigation of the effect of different degrees of corrosion on ultimate strength, ductility and failure mode of RC bridge piers subject to dynamic/cyclic loading. Accordingly new material and constitutive models for confined concrete, reinforcing steel in tension and compression (including buckling) and bond-slip behaviour of column at base connection are being developed to take into account the effect of long-term material deterioration. These material models will then be used in numerical simulation of experimental tests.

Brief description

In order to investigate the behaviour and response of RC bridge piers subject to earthquake loading, some medium scale experimental studies on bridge piers are being done in Earthquake Laboratory at the University of Bristol. Test specimens are first subjected to a process of electrochemically accelerated corrosion and then a dynamic/cyclic loading test is carried out on the corroded specimens. Along with the experimental study a new advanced finite element formulation is under development using MATLAB code. The model is a multi-mechanical fibre-element technique with new constitutive material models. The new analytical and numerical formulations will be verified and calibrated using the results of the experimental testing.


The outcome of this research will be some new material and performance models that can be used in Displacement-Based Assessment (DBA) of existing RC bridges suffering from corrosion of steel reinforcement. This will improve the existing DBA approach and also help practicing structural engineers, bridge managers and owners to use a safer method of assessment and allow them to adopt an optimised long term maintenance/repair strategy for bridge stock.

Funding body

This research is partly funded by URS/Scott Wilson.

Mehdi KashaniUniversity of Bristol

Life span simulation approach to performance-based assessment of corroded RC bridge piers subject to seismic loading


28

In steel-framed buildings, open I-sections are the most common and efficient horizontal members to support the flooring system. The vertical members can either be open H-sections or tubular (structural hollow) sections. The latter has shown an increasing popularity due to its structural efficiency including high strength to weight ratio, high torsional stiffness and pleasant appearance. In particular, circular and elliptical hollow sections possess inherent curvatures which allow architects to express the steel-framed buildings in a creative and exciting architecture in the built-environment.

However, these advantages are often under-exploited due to the perceived difficulties on cost effective connections between I-beams and tubular columns. There is also a relative lack of design guidance and of experimental data related with the cyclic inelastic behaviour of semi-rigid connections. This project investigates the structural response of a novel semi-rigid through-diaphragm connection between steel I-beam and tubular columns. The research is based primarily upon laboratory testing and parallel numerical studies. Laboratory tests have been carried out to provide scientific data that is essential to characterize the connection behaviour including stiffness, strength, rotational ductility and hysteretic patterns. The generated structural performance data have been exploited to verify proposed component models; these have been developed in harmony with Eurocode 3 Part 1-8 for ease of future incorporation in the design code.

Funding body

Syrian Embassy in London

Majd Khador University of Warwick

The behaviour of semi-rigid through-diaphragm connection between steel I-beams and circular/ellipitcal hollow section columns under cyclic loading


29

Structural engineers and architects have a responsibility for incorporating fire safety into their building designs in order to minimise loss of life and property. One aspect of this is to ensure that structural stability is maintained if a fire develops. For last two decades, extensive research has been carried out on the behaviour of steel-framed buildings under fire conditions. In real buildings structural elements form part of a continuous assembly, and building fires often remain localised, with the fire-affected structure receiving significant restraint from cooler areas surrounding it. If such interactions are to be used by designers in specifying fire protection strategies as part of a performance-based structural design approach, then this cannot practically be based on large-scale testing because of the extremely high implicit costs. It is therefore becoming increasingly important that software models be developed to enable the behaviour of such structures to be predicted with sufficient accuracy under fire conditions. It is well known that robustness of steel connection is vital important to the fire resistance of steel-framed composite buildings. The development of effective connection models is a key issue in this research field. Hence, the main objective of this project is to develop a robust 2-noded connection element for modelling the connections between steel beam and column at elevated temperatures. The model developed in this research will be implemented into the commercial version of the program VULCAN developed in this department in order to benefit the structural fire resistance design of steel and composite buildings. After the new development, a series of comprehensive parametric studies will be conducted to deeply understand the influence of the connection on the fire resistance of steel and composite structures. Based on the results achieved in this research some constructive design recommendations will be proposed.

Shuyuan Lin University of Sheffield

Computer modelling of steel and composite structures in fire


30

Introduction/motivation

Most of the structures are expected to experience a number of extreme dynamic loads during their life-service, induced by manmade activities or extreme natural phenomena (winds, sea-waves, earthquakes, explosions, traffic etc). These loads are characterised by a time-varying intensity and frequency content, with inherently uncertain evolution patterns.

In recent years, certain time-frequency representation techniques have been proposed to extract the evolutionary patterns of signal’s energy and frequency composition of deterministic non-stationary signals. The wavelet transform is arguably one of the most extensively used in various structural dynamics applications. Other powerful adaptive parametric (e.g. the chirplet transform, the S-transform e.t.c) and nonparametric techniques (e.g. the empirical mode decomposition/Hilbert transform) for signal time-frequency analysis also exist and circumvent to some extent certain limitations of the wavelet transform.

Objectives and goals

The proposed research work has the following main objectives:

•Toevaluatetheapplicabilityofvariousnoveltime-frequencyrepresentationtechniquesof

representing/estimating evolutionary power spectra characterizing certain non-stationary stochastic processes.

•Toassessthenecessarylevelofsophisticationoftheconsideredtime-frequencyrepresentationtechniquestocapture the non-stationary attributes of various dynamic loads imposed to structured facilities in a deterministic and in a stochastic context.

•Toevaluatethepotentialoftheconsideredtime-frequencytechniquestomonitorcertainquantitiesofinterest for damage detection/system identification purposes by processing inelastic response time-histories of structures exposed to extreme transient dynamic loads represented both in a deterministic and in a stochastic framework.

•Todevelopinput/outputrelationshipsfornonlinearstructuressubjecttonon-stationarystochasticexcitationsrepresented on the time-frequency plane.

Description and potential applications

The measured or simulated inelastic structural responses of yielding structures exposed to extreme events modelled stochastically can be treated as non-stationary signals. These signals carry certain information about the inelastic behaviour of the structures and are commonly used by the structural engineering community for damage detection and system identification purposes. In this regard, certain benchmark structures models will be modelled using a state-of-the-art finite element computer code and will be exposed to simulated and recorded data to obtain inelastic structural responses. These responses will be then processed by various time-frequency representation techniques to draw conclusions on the potential of these techniques to detect damage and consequently to be used for structural health monitoring.

Funding body

Funded by the School of Engineering and Mathematical Sciences, City University London.

Anca Lungu City University London

Assessment of time- frequency analysis techniques in structural dynamics applications


31

The use of unfired clay masonry in contemporary construction can have significant environmental, economic and social impact.

Earth construction is one of the oldest building materials and one half of the world’s population live or work in buildings constructed from earth. Within the UK, earth construction has been used minimally due to the use of industrialised building materials and techniques. However there is a resurgence of the use of earth as a structural material.

There is significant commercial potential of modern earth masonry and this has been recognised by the UK fired brick industry. It is within this industry that the earth masonry can be manufactured on a large scale that also meets the required quality standards. Following similar techniques to the current production of the fired bricks, manufacturing plants can be used produced extruded unfired clay bricks. There has been a decline in the production of common bricks due to the rise in popularity of using lightweight concrete blocks.

Unfired clay bricks have a number of advantages over conventional fired bricks and concrete blocks. There is significantly lower embodied energy than comparable products, with unfired clay bricks having 14% of the energy of fired bricks and 25% of concrete blocks. Earth construction is able to provide passive environmental controls. This includes thermal mass to regulate temperature as well as the ability of the clay mineralogy to absorb water vapour leading to a regulation of humidity control.

There is significant scope for the development of unfired clay masonry for use in the UK. The compositions of the bricks, mortars and plasters have the scope for improvement and refinement. This can be achieved through adjusting the constitutional parts of each element of the wall system, or with the addition of additives that can further enhance the properties. The separate elements can be use to provide a structural system.

It has been identified that the thin walled unfired clay masonry has an inherent susceptibility to high moisture content. High moisture content is likely to occur within domestic environment due to accidental mechanical wetting. This can lead to localised damage within the earthen wall and ultimately cause disproportionate collapse. This is a severe limitation to the used of thin walled unfired clay masonry that has to be addressed.

The intention of this study is to investigate the structural performance of extruded unfired clay masonry. This will include research into the characteristics of the material, and the possible improvement of these properties. From this fundamental understanding of the materials involved the performance of complete walls can be investigated. This would involve experimental and analytical work into the development and use of unfired clay masonry.

This work would ultimately targeted at the use of unfired clay within the domestic sector as a more environmentally beneficial structural alternative to the use of the lightweight concrete blocks and fired bricks.

Daniel MaskellUniversity of Bath

Contemporary structural use of unfired clay masonry


32

Aims and objectives

The review of background information allowed the following objectives to be identified:

• Todevelopatestmethodologyforthedeterminationofpin‐bearingstrength,andtocharacterisethiskey strength property required for the design of bolted connections with FRP shapes

• Tocompleteaseriesofplate‐to‐plateteststhatcharacterisetheresistanceofboltedconnectionsof Pultruded material, which shall lead to the proposal of new or improved design guidance

• Touseacriticalevaluationofthetargetedtestresultstoeitherreviseormodifycurrentdesignprovisionsso that the risk of structural failure is minimised

Project description

The research project will involve extensive laboratory testing to scope known gaps in knowledge for the preparation of scientifically-founded provisions for the design of bolted connections for Fibre Reinforced Polymer (FRP) structures in the built environment. There are two work packages for this PhD which address pin bearing strengths of FRP material and plate-to-plate connection tests.


Dissemination of the results and findings from an evaluation of the test series will have a major impact on structural engineering research and will assist a growing industry by way of the preparation of recognised design rules, such as to be found in the new-build parts to the future structural Eurocode for fibre reinforced polymer materials. Design standardisation for the structural material of FRP will provide the confidence for wealth creation and future innovation towards buildings and bridges that have an overall performance to satisfy the drivers for sustainability and a green economy.

Funding body

This project is funded by EPRSC and forms a part of the larger research project for Connections and Joints for Buildings and Bridges of Fibre Reinforced Polymer.

Navroop Singh Matharu University of Warwick

Aspects of bolted connections of fibre reinforced polymer structures


33

Aims and objectives

The main aim of the research project is to develop an integrated procedure for life expectancy of bridges using vibration measuring sensors and a developed probabilistic risk analysis based model. The specific objectives of the project are,

• Todevelopastrategyforoptimumnetworkedsensorarrays,requiringlimitednumberofsensorsbut providing sufficient and necessary measured data for correct condition assessment.

• Todeveloptoolsofdataanalysis,interpretationandvisualisationinlightofphysics-basedmodelsfor real-time data measured from the installed sensor arrays.

• Toapplytechniquesinmodeltesting,modelupdatinganddamagedetectiontothereal-timeaswell as long-term safety and condition assessment for existing bridges.

• Todevelopacomputationalprocedurefordecision-makingtheorytopredicttheremaininglifeof existing bridges based on continuous structural health monitoring and updated structural model.

Proposed plan of work

•. Developmentofoptimumsensorarrangementandadvanceddataanalysisandinterpretation.

• Investigationonnumericalsimulationofactualbridgesandpracticaldamagedetectionapproaches.

• Probabilisticriskanalysis,conditionassessmentandpredictionofremainingservicelife.

Project summary

Any failure in bridge and highway maintenance is likely to lead to increase deterioration with unknown consequences. Structural health monitoring applications based on smart sensors and real-time monitoring for existing bridges which may exhibit premature aging, distress and performance problems and/or bridges that have aged beyond their anticipated design life cycles offer the potential for exceptional payoff. The principal objective of health monitoring is tracking any aspect of performance or condition of a bridge in a proactive manner, using measured data and analytical simulations in conjunction with heuristic experience to correctly assess the current condition and accurately predict the remaining service life of the bridge.

Maung Than Soe University of Greenwich at Medway

Bridge condition assessment based on vibration measurements


34


This project uses embodied energy (EE) and embodied carbon (EC) as indicators of the environmental impact of reinforced concrete (RC). Accuracy and completeness of EE/EC analysis is dependent on the method used. This paper demonstrates that by understanding how energy is consumed in the production of each constituent part and in the manufacture of RC, designers can significantly reduce the overall EE and EC of structures. Both EE and EC of products can vary from country to country. Therefore, to accurately calculate these for RC structures, data specific to the country where they are being constructed must be used. This project demonstrates an assessment of EE and EC in typical RC structures in Ireland. A case study is presented where it is shown that by replacing ordinary portland cement (OPC) with ground granulated blastfurnace slag (GGBS), EE and EC savings are achievable in the construction of a multi-megawatt wind turbine in Ireland.

Brief description

The use of natural energy resources has become intrinsic to human behaviour. Today the built environment is responsible for more than 40% of European energy consumption. In recent years there has been a change in public perception as the implications of irresponsible energy usage and resulting climate change have become more evident. However, perceptions and awareness alone are not sufficient factors to convince businesses and industry, who are the main contributors, that a move towards more sustainable use of our resources is required. “Energy” and “Carbon” are two key words which are often used, sometimes interchangeably, in reference to the consumption of available resources. These words are closely linked as the use of energy will have a certain amount of carbon associated with it and is dependent, for example, on whether the source of energy is renewable or not. Studies carried out to date have measured either energy or carbon or both energy and carbon. It is important that both are taken into account.

¬In the aftermath of the Kyoto protocol the ‘Carbon Market’ has incentivised industries to become more sustainable and change their outlook. Currently little attention is being paid to reducing embodied energy (EE) and embodied carbon (EC). These refer to the energy required and carbon emitted during raw material extraction, transport, manufacture, assembly, installation, disassembly, deconstruction and/or decomposition for any product or system. If a drive towards true sustainable use of our resources is to be achieved it is critical that both EE and EC are addressed.

EE and EC analysis enables informed decision making in relation to the processing methods used and the products purchased in the manufacture and supply of any product or system. This project outlines how both the EE and EC of reinforced concrete (RC) structures can be significantly reduced at potentially little or no extra cost.

Mark McCaffrey National University of Ireland

The use of embodied energy and carbon to assess the environmental impact of concrete structures


35 Zainorizuan Mohd JainiSwansea University

Blast loading with high pressure intensity propagates within a fraction of second after an explosion. Depending on the amount of energy and wave velocity released, blast loading is highly likely to cause damage which can lead to failure. Taking into account various interests and requirements in the protective structure under blast loading, the investigation of structural behaviour due to this extreme conditions is therefore vital.


The main objective of the present research is to numerically investigate the fracture behaviour of reinforced concrete slabs under blast loading with and without protection of a ceramic armour layer. The scabbing, spalling and concrete plugs are of particular interest, with special attention paid to the fracture fragmentation in conjunction with wave velocity.

Brief description

There are three major aspects considered, in term of fracture modelling, blast modelling and materials criteria.

In the present research, the computational modelling is generalised based on an experimental study conducted in the University of Western Australia. The interaction between non-uniform blast loading and a reinforced concrete slab is modelled using the 3D ELFEN program. The finite element method is incorporated with a crack rotating approach and discrete element to model the fracture onset and propagation, and the post-failure dynamics of the fragmentations. In the modelling, a mapping method has been employed to define blast loading due to incompatibility of the Jones-Wilkins-Lee method with all compression criterion models. The blast is determined based on cumulative pressure composed of the incident overpressure, the reflected overpressure and the dynamic wind blast. The calculated blast loading is compared with that obtained from the US Army standard, TM5-1300 and ATBlast software.

The Mohr-Coulomb and Von-Mises criteria are applied for material properties of the concrete and steel reinforcement respectively. Because the Mohr-Coulomb criterion in concrete can only produce continuum failure which are based upon cohesion and friction dilation, the Rankine with fracture model is introduced to control tensile fracture failure. A multi-scale simulation is applied to overcome the lack of constitutive material model for the ceramic armour layer. The multi-scale simulation is based on the periodic boundary displacement fluctuations condition, employing a unit cell of ceramic armour with uniaxial loading and a nonlinear anisotropic brittle model.


This research hopes to gain a better understanding about the facture behaviour in order to optimize the accurate design of the protective layer. Besides that, the development of rational procedure for blast analysis and the modelling method will lead to the easy structural analysis, both for military and public purposes

Funding body

This research is fully supported under SLAI scholarship, Ministry of Higher Education (MOHE) and University Tun Hussein Onn, Malaysia.

Multi-scale simulation and fracture modelling of protective reinforced concrete slabs subjected to blast loading

Poster presenter


36

Brief description

The structural composition and the deformational response of the trachea are important factors in determining the maximum diving aptitude of air-breathing animals. In the majority of terrestrial mammals the trachea is composed of a series of incomplete (c-shaped) hyaline cartilage rings that are connected to each another by connective tissue. Most of these mammals, including man, are very restricted in their diving capabilities. However, there exist some oceanic mammals and reptiles that are naturally capable of diving to very deep depths (>300m). The structural arrangements of these tracheae differ remarkably from terrestrial mammals. One such reptilian species, the critically endangered leatherback turtle (Dermochelys coriacea) regularly undertakes very deep dives and has been recorded attaining depths exceeding 1,200m. The leatherback trachea differs from those of land-based mammals in that it consists of a near-continuous elliptical tube of uncalcified hyaline cartilage with minimal connective tissue between the cartilage rings. The material properties of the tracheal cartilage are unknown as are the patterns of distortion the trachea undergoes during a typical deep dive.


The primary aim of this research is to model the response of the complete trachea of the leatherback turtle during a typical deep dive. In order to do this knowledge of the constitutive material properties of the tracheal cartilage is needed first. An inverse methodology has been proposed to determine these parameters. Namely, experimental load-deformation history (samples provided by an embalmed cadaver of an adult leatherback) is compared with that of a corresponding 2-D plane strain finite element (FE) analysis. Using constrained optimisation the material properties in the FE model are varied until a predefined objective function that measures the difference between the experimental and FE data is minimised. There are thus three main objectives to this research:

• Materialtestingtoascertaintrachealcartilagematerialproperties

• 2-Dplanestrainmodellingofacentrallylocatedtrachealringtoinvestigateitsresponseatallstagesofa typical dive

• 3-Dstructuralanalysistoexaminetheresponseoftheentiretracheawhensubjectedtoincreasedpressure due to dives


Knowledge of the material properties of the leatherback trachea will provide insights into how exactly the trachea deforms when subjected to extreme hydrostatic pressures, allowing for a complete understanding of the leatherback’s ability to dive to depths greater than 1,000m (where pressures exceed 100 atmospheres). These results may even also inform the research of deep diving in mammals, including man, whose competitive free diving has been increased to beyond 200 metres in recent years.

Funding body

Irish Research Council for Science, Engineering and Technology (IRCSET)

Colm Murphy University College Cork

Structural modelling of trachea distortion of leatherback turtles during deep dives


37

Overview

Pultruded Fibre-reinforced polymers (FRP) are widely applied in construction in recent years. This is due to the advantageous properties of FRP materials such as high strength-to-weight ratio, electromagnetic transparency, resistance to corrosion, etc.

However, the literature on design guide as well as the standard for structural engineering applications is limited. To date the only standard specification for pultruded FRP in Europe is EN 13706 which mainly discuss the material test methods. The forthcoming standard of pultruded FRP profiles of American Society of Civil Engineer (ASCE) is supported by limited test results. An in-depth understanding about the behaviour of pultruded FRP is needed to facilitate the wider use of pultruded FRP profiles in construction.

Besides, the relatively low elastic modulus of pultruded FRP may result in designs being governed by deflection and buckling limitations, rather than by strength limitations (Chambers 1997). Several researchers have studied Lateral-torsional buckling behaviour of doubly symmetric pultruded FRP member (Mottram, 1992; Turvey 1996; Davalos and Qiao, 1997). But for single symmetric sections such as channels and angles, few experimental data are available for pultruded profiles. In addition, few test data are available for pultruded beam-columns profiles (Barbero and Turk, 2000; Mottram et al., 2003). In order to promote the efficient use of pultruded FRP profiles for new structures, further experimental work is needed to develop more understanding into the global buckling response of beams and columns.

Objective

This research aims to investigate the global buckling response of pultruded FRP member through non-linear numerical (FE) simulations and experimental works. The general structural performance data obtained from tests and FE modelling will then be utilized to derive design rules in accordance to Eurocodes.

Methodology

The global buckling analysis of FRP will be carried out in three approaches. Theoretical analysis will be made on the behaviour of the structural members through fundamental mechanics and analysis methods. Numerical will be created via the use of a finite element software package such as ABAQUS to determine the structural behaviour. This will then need to be verified and calibrated through a series of experimental tests. Tests will be carried out on materials, cross-sections and structural members. The numerical and laboratory test results will then be processed and analysed to obtain a thorough understanding of global buckling behaviour of pultruded FRP member.

Thuy Nguyen Tien University of Warwick

Global buckling behaviour of pultruded fiber-reinforced polymer (FRP) members


38

Brief description

Currently, advanced materials technology and developed building design codes often lead to more slender structures with lower fundamental natural frequencies. These structures, for example grandstands and concert arenas, are sometimes susceptible to human movements such as bobbing and jumping, particularly when humans’ jumping and walking frequencies are close to a structural natural frequency. The feeling of fear and discomfort in building occupants due to high levels of vibration is an important consideration for vibration serviceability and safety.

Different vibration control techniques have been introduced and applied to improve structural vibration performance. As a novel technique, semi-active control can be considered as a passive system where the damping and/or stiffness can be changed in real time, without introducing additional energy to the controlled structure.

Semi-active controllers have many advantages. They are relatively cheap, require low power and are simple devices without too many mechanical components. Hence they are reliable and stable. An important advantage for semi-active systems is their ability to work as purely passive system in case of external power failure.

However, there are some problems with semi-active controllers. One of the most important issues is the highly complex nonlinear nature of the control algorithms that are used. This means it is difficult to formulate the link between damping force and the response of the structure. Nevertheless, applying intelligent control algorithms in addition to conventional procedures, such as Linear Quadratic method are a resolution to this problem.

Objectives

The main aim of the project is to investigate the use of semi-active to mitigate human induced vibration in civil structures.

Following specific objectives have been specified:

• ReviewpastuseofSATMDs

• EvaluatethepotentialbeneficialeffectsofSATMDsthroughsimulations

• HybridtestsofSATMDinordertoevaluatepropertiesofcontroldevicesandcheckcomputersimulations

• Lookatoff-tuningproblemsinTMDsandachieveasolutionbyusingSATMD


Cases of annoying vibration in grandstands with long cantilevers and slender food bridges have been reported in recent years. Using semi-active tuned mass dampers in such structures could reduce the amount of vibration with low cost and without requiring changes to their architectural characteristics.

Semi-active control of human-induced vibration

Nima Noormohammadi University of Sheffield

Poster presenter


39

As a part of a Knowledge Transfer Partnership between Edinburgh Napier University and Action Scaffolding Contracts Ltd. a software tool is being developed to automate the design and drawing procedures for scaffolding structures. Current regulations in the UK require that engineering design calculations and working drawings are produced for non-standard scaffold configurations. Scaffolding design in the UK is mainly carried out using manual load calculations and the effective length method with some use of 2-D beam analysis software. Using three-dimensional analysis and design software the time taken for scaffold design calculations can be greatly reduced while increasing the accuracy of the calculations and standardisation of associated documentation.

The software is being developed in C++ to customise and extend AutoCAD. This leverages the excellent visualization and computer aided drawing capability of the AutoCAD platform. Also the software integrates with the open source finite element analysis code OpenSees as the analysis engine for the software. Analysing scaffolding structures using a three-dimensional analysis tool has been proven to offer many advantages. However more research will be required to accurately model complex behaviour such as semi-rigid connections.

Shane O’Neill Edinburgh Napier University

Model-centric design of temporary works


40


The aim of this project is to develop a sustainable system of construction that can be rapidly deployed and assembled in post earthquake disaster zones to form permanent or semi-permanent modular structures that are resistant to future seismic actions. The goals of this project are to improve the standard of construction in post earthquake disaster recovery and to reduce the risk of future loss due to the reoccurrence of earthquakes.

Brief description

There have been over 1.1 million people killed, 1.5 million people injured and 14 million people left homeless in developing countries, as a result of the most devastating earthquakes that have occurred since 1970. In many of these regions, there is a fundamental lack of understanding of seismic design or provisions for buildings before and after earthquakes. Post earthquake disaster reconstruction to date consist of three stages: emergency, temporary and permanent housing. The aim of this research is to combine the latter two phases of reconstruction into one phase by developing a cost-effective sustainable system that is rapidly deployable to the affected area, which serves as temporary housing and eventually permanent housing. This will be achieved by developing a system of modular construction that can be easily assembled into semi-permanent housing for the immediate aftermath of an earthquake, and be expandable into a more permanent fixture in the future. These systems will have adequate seismic provisions in the design when prefabricated off-site to inhibit the possibility of previous problems reoccurring. The concept of disaster resilience will be used to show how by using these systems, the overall disaster resilience of a community is improved compared to alternative solutions. The outcome of this research is to develop a product that can be readily deployed to a post earthquake disaster zone and assembled for permanent use.


Potential for applications for this product are vast as the world has witnessed over 300,000 people killed and 6.7 million people left homeless by earthquakes since the Sichuan earthquake in China, 2008. The outcome of this research directly addresses the need for sustainable systems that are adequate for the recovery and for the future of the affected countries. Throughout the recovery process for an affected country, millions of Euros are spent on ensuring that the affected area quickly recovers after the disaster, and is adequately equipped to sustain future seismic loadings, at a price that is realistic for the limited funds available for a disaster recovery. This research addresses these issues directly and the outcome will be a system of construction that can be used by aid agencies around the world for effective post disaster recovery.

Funding body

Irish Research Council for Science, Engineering and Technology (IRCSET).

Gerard O’ReillyNational University of Ireland

The development of cost effective modular systems for rapid deployment to post earthquake disaster zones


41

Oral presenter

Cement, 2.8x109t of which was produced worldwide in 2007, results in a global concrete usage approaching 1.5m3 per person per year, making concrete our most widely used man made material. Whilst its constituent raw materials are widely available and easily extracted, cement has high embodied energy and its manufacture is estimated to account for some 5% of global CO2 emissions.

This all suggests that concrete should be cast in optimised structures that minimise material use and capitalise on the mouldability of concrete. The fluidity of concrete is rarely exploited and today it tends to be cast into rigid, material intensive formwork systems. The optimisation of concrete structures such that they use less material, are structurally efficient and easy to construct will bring real innovation.

Using fabric formwork, it is possible to cast architecturally interesting, structurally optimised shapes based on simple design rules that are analogous to the growth of bone. When a bone is overstressed, it grows; when it is understressed, it atrophies. Fabric formwork can be used in the construction of optimised concrete beams to place material only where it is required, and research has shown that this is both a predictable and practical approach that can achieve material reductions of up to 40% when compared to an equivalent orthogonally cast beam. The principal advantage of fabric formwork lies in its simplicity, allowing the casting of unique structures using readily available, inexpensive materials.

Previous work in this field has focused predominantly on the architectural applications of fabric formwork, and few structural tests have been carried out. The main objectives of this project are to develop, test and verify the design, optimisation and construction methods required for the fabrication of variable section reinforced concrete beams. Results obtained to date are highly encouraging and will help to facilitate the future design of fabric formed concrete structures in industry. Furthermore, by considering variable section elements broader conclusions surrounding the understanding and teaching of reinforced concrete behaviour may be drawn.

Funding body

EPSRC CASE Award with Atkins Ltd.

John Orr University of Bath

Flexibly formed concrete structures

Unique, optimised T-Beams using fabric formwork


42


Timber plate structures are increasing in popularity through their benefits in terms of sustainability, advantages in construction and aesthetic potential. Cross Laminated Timber (KLH/CLT) is a relatively new material and has been an influence in the increased number of timber plate structures.

The principles of origami have been used to develop folded structures which allow a sheet of a material to be folded to create lightweight, stiffer structures with minimum waste as well as being able to define interesting structural forms.

This research aims to consider the actions upon the connections in timber plated structures and develop a method of mechanical shear and moment resistant connection for the various angled plates to improve the strength of the connections and increase the potential for folded timber structures.

Brief description of methodology

Embedded rods are widely used for timber connections and this research considers the existing connection theories and will develop this connection method analytically and experimentally to consider angled plate connections.

The analytical work will consider the problems of connecting at various inclinations such as the angle of the rods and embedment depth as well as other issues of material, method of embedment and size of the rods. The proposed connection method will be validated experimentally.

Within the context of folded plate structures a greater understanding of the actions on the plates and connections in the structure is required. This will be researched simultaneously with developing a connection and will consider plate theory and Finite Element analysis. The results from these will be able to be applied into the design and development of the connection system as a parameter driving the design of the structure.


The results from this research have application in structural engineering through the development of a moment resistant connection method for timber plated structures. The specific application for this research is within folded timber structures but is additionally relevant for timber multi-story connection and other plated structures.

Funding body

University of Bath

Hannah Pearson University of Bath

Connections and geometry for timber plated structures

Poster presenter


43

Design optimisation of cold-formed steel portal frame buildings taking into account semi-rigid joints and stressed-skin actionPhan Thanh Duoc Queen’s University Belfast


The main objectives in this project consist of:

• Consideringtheeffectsofsemi-rigidjointsandstressed-skinactionon3-Dmodelofportalframebuilding.

• Usingcomputationalfluiddynamics(CFD)techniquestogeneratethewindloadssubjectedtofull-scale3-D model of portal frame buildings.

• Designoptimisationwithdesignvariablesbeingcross-sectionsizesofstructuralmembersandtopography of the building.

The primary goal of this project is to provide to civil engineers an exact model of portal frame building that takes into account the real structural responses in 3-D model. In addition, wind loads generated based on CFD simulation will create a complementary win loads data instead of using codified design rules as in the practical portal frame design application. Finally, design optimisation will produce a most economical design that considers minimum weight or minimum cost being the objective function.

Brief description

Semi-rigid joints are simple bolted connections formed by using brackets bolted to the webs of the sections. It has been demonstrated that stiffness of these semi-rigid joints depends much on the initial bolt-hole elongation stiffness. Rotational stiffness of these joints was computed based on the simple beam idealisation. This project will consider the effect of these semi-rigid joints in 3-D model of cold-formed steel portal frame building. In addition, stressed-skin action on the portal frame building will also be considered by simulating the equivalent prismatic bracing members connecting the two opposite corners of two adjacent frames. The stiffness of equivalent prismatic bracing members is based on the shear stiffness values of claddings from full-scale shear tests. The structural solver will be set up in ANSYS STRUCTURE. Wind loads subjected to building’s envelope will be generated using ANSYS FLUENT. The model of building will be created and meshed in pre-processor GAMBIT to be exported into ANSYS FLUENT. Finally, analysis codes will be programmed in MATLAB for both optimizing and calling ANSYS in the optimizing loop.


In the United Kingdom, steel portal frames are commonly used for single-storey buildings. Therefore, considering the exact behaviour of portal frame buildings is very necessary for its application. This project not only increases the reliability of portal frame design before constructing but also produces the most economical design. It means that the potential for application of results are very large for both construction companies and software design companies.

Funding body

This project is sponsored by the Queen’s University Belfast.


44

The design of dowelled timber connections is discussed within this thesis. It is highlighted that the present method adopted by Eurocode 5 (EC5) suffers from a series of limitations, these being related to splitting, premature failure and lack of design guidance.

Research has been carried out to try to determine whether more recent developments can aid or improve the design process stipulated in the standard. It is demonstrated that strength class is of little importance to the present design methods, since the overall influence of this parameter is small. In addition the use of higher dowel grades despite achieving high load capacities has a detrimental effect on the design since it leads to premature failure through splitting.

With respect to splitting, a method by Ballerini, based on the approach in EC5 but developed to include the geometry of the dowel arrangement appears to give enhanced results. However as timber density is not considered it is questionable whether this is a definite improvement on the original EC5 formula. Laboratory testing is required to give a definite result.

It has been determined that the dowel diameter and timber thickness are the most influential aspects of the design since they impact on a number of aspects of the design, such as slenderness ratio, load eccentricity, splitting capacity, failure mode, etc. It is suggested that a minimum thickness of timber be calculated prior to commencing the design of the connection, since this helps to ensure a ductile failure mode occurs.

Dowels can be categorised as either rigid or slender, with load capacities associated with rigid dowels being overestimated, it is proposed that the design of the connection should make use of slender dowels; this gives a more realistic load capacity and improves the ductility in the connection.

To improve the overall design process, design guidance has been developed to aid the engineer when completing a connection design. It is intended that the guidance be used to create a connection that fails in a ductile manner and is therefore worded with this in mind.

Finally to aid the design process a software package has been produced based on the Johansen’s formulae. This package generates an output for a number of timber thicknesses and dowel diameters. It is possible to determine the load capacity, timber thickness or dowel diameter from the software, providing two input parameters are known. Results from the software have been compared to hand calculations, with only a 1% difference.

Design of double shear steel-timber connections

Tom Rogers Coventry University

Poster presenter


45


1. Study and validate the seismic design of concentrically braced steel frames (CBFs) with rectangular hollow sections.

2. Develop a direct displacement based design procedure for dual system structures with vertical irregularity located in regions of high seismicity.

Brief description

First part of the work is to develop a robust analytical model that represents real behaviour of concentrically braced frame (CBF). This model is calibrated using data from experimental physical tests on cold formed rectangular hollow section brace members. It is then validated using single story CBF subjected to earthquake excitations through shake table tests. This analytical model is implemented for multi-story structures. Then a seismic design procedure will be presented for the concentrically braced frame systems, which are economical and practical to be used as a lateral resistant system.

Second part of the work is to develop a direct displacement based design procedure for vertical irregular dual systems. Three types of structures is investigated: irregular steel moment resisting frame with concentrically braced frame core, irregular steel moment resisting frame with concrete core wall, irregular concrete moment resisting frame with concrete core wall.


This work can be used for the following:

• Designingmanytypesofbuildingsthatcanresistseismicactions.

• Willbeaddedtothedesigncodeinprogressfordirectdisplacementbaseddesignprocedure.

Funding body

The College of Engineering and Informatics, NUI Galway.

Suhaib Salawdeh National University of Ireland

Seismic design of concentrically braced frames and dual systems with vertical irregularity


46

Abstract

Building structures could be responsive rather than relying only on load-bearing capacity. A “responsive structural system” relies on a number of actuators strategically located to actively manipulate the internal flow of forces and control the dynamic and/or static behavior of the system: deflections, vibrations, etc. This is different from a conventional passive system that relies on geometry and mass of the structure. The main benefits of such systems are the reduction of structural mass and its maximum deflection as demonstrated in recent studies at the Institute of Lightweight Structure in Stuttgart. Appropriate substitution of some of the elements of a truss structure with active members, can lead to considerable weight reductions and virtually zero deflections. Having said that, how do such systems perform on cost, reliability, operation and maintenance, whole-life energy? What are the best available technologies at hand to implement them on construction projects?

This case study aims at addressing those questions and specifically:

• Quantifyfurtherthepotentialforreductionofthemassofthestructuralsystem;

• Developamethodologyandtoolsforthedesignofadaptivestructures;

• Understandthebarriersandpreliminaryassessmentofthedrawbacks,andlookathowtheycanbe overcome in practice.

The development of such design methodology will form the basis for future investigations on more complex structural systems particularly looking at the other branch of adaptive technologies: Shape Morphing Control. Shape morphing deals with adaptation of the geometry and topology of the structure to control shape dependent forces or phenomena. This gives the chance to look beyond structural systems to include control of ambient conditions by means of natural ventilation and self-shading.

Adaptive responsive building structures

Gennaro Senatore University College London

Poster presenter


47


1. To develop a simplified calculation method to obtain non-uniform temperature distributions in thin-walled steel sections.

2. To extend the Direct Strength Method (DSM) to thin-walled columns with non-uniform temperature distributions in the steel sections.

Brief description

Cold-formed thin-walled steel sections are widely used as load bearing members in low-rise housing construction, for which both ambient temperature ultimate strength and fire resistance are important considerations. For ambient temperature design calculations, the traditional approach is the effective width method. There is now a growing movement to replace the effective width method by the Direct Strength Method. Using DSM, the elastic buckling resistance of a thin-walled column, either in local buckling, distortional buckling or global buckling, is combined with the cross-sectional resistance to obtain the design resistance, in a similar way to normal column design. Making use of validated computer programs, the elastic buckling resistance can be easily calculated. DSM eliminates the tedious procedure of calculating effective widths, which is particularly useful for thin-walled sections with stiffeners. For fire resistance calculations, non-uniform temperature distribution in the cross-section requires the cross-section to be divided into a large number of strips of similar temperature, equivalent to a cross-section with many segments of different properties. This makes the Direct Strength Method particularly attractive compared to the effective width method.

The Direct Strength Method has been developed and validated for ambient temperature column design under pure axial load. This research will develop DSM to enable it to be used under combined axial compression and bending moment induced as a result of thermal bowing deflection and non-uniform material properties.

Fire resistance design methods for thin-walled steel structural panels for wall construction

Ashkan Shahbazian University of Manchester

Poster presenter


48


The purpose of this research project is to assess the behaviour of concrete-filled steel tubes under monotonic and cyclic axial loading. These members exhibit a significant enhancement in strength and ductility compared with hollow steel tubes or conventional reinforced concrete members. Hence, they are frequently employed in seismic buildings for their energy dissipation capabilities. The performance of these varies depending on the shape and thickness of the outer steel tube. The aim of this research project is to compare the behaviour of various tube shapes and examine the current design provisions through a series of laboratory tests and numerical models.

Description

Concrete-filled tubular specimens will be subjected to cyclic axial loading in the laboratory. Circular, rectangular and elliptical sections will be used, selecting specimen lengths which correlate to member slenderness guidelines in Eurocodes 3 and 4. Certain parameters will be monitored throughout the experiments, such as the load, axial displacement, longitudinal and circumferential strains, etc. In addition to this, observations will be made of any local buckling which occurs during testing and the final failure mode.

In parallel to this, numerical models will be created using the finite element software package, ABAQUS. The accuracy of the finite element models will be validated using the experimental results, and input such as the assumed material model and steel-concrete interface will be assessed. The results of the experiments and numerical models will be used to compare the degree of confinement provided to the concrete core by different tubular shapes. Furthermore, the total amount of energy dissipated by each of the specimens will be calculated, producing hysteresis curves.

Application of results

The test results will be used to assess the existing design provisions for circular and rectangular concrete-filled tubes, and develop any necessary modifications to account for elliptical shapes.

Funding body

This research is funded by the University of Warwick and Tata Steel Tubes.

Structural performance of concrete-filled tubular members under cyclic loading

Therese Sheehan University of Warwick


49

The study intends to reveal a relationship between the alteration of cement paste morphology caused by the superabsorbent polymers and the progressive deterioration induced by freeze/thaw cycles. It is proposed to determine the effect of superabsorbent polymers (SAP) on immature and mature mortars subjected to freeze/thaw cycles and the effect of number of cycles on the efficiency of SAP protection. It is intended therefore:

• IdentifytheeffectsofSAPonmicrostructureofporousmatricesofcement-basedmortarsaccountablefor deterioration under severe service conditions and assess the efficiency of SAP “protection”

• Revealrelationshipbetweenthemorphologyofcementpasteandtheprogressivedeteriorationinducedby ice formation

• IdentifytheeffectofSAPontherheologyofmortars

• IdentifytheeffectofSAPonthemechanicalandphysicalpropertiesofhardenedcementmortarssubjected to freeze/thaw cycles in comparison to mortars curing in lab conditions

From wide range of techniques facilitating analysis of physical or thermal properties of porous materials, rheology of fresh mortar and material characterisation, the following methods have been chosen to investigate the behaviour of cement-based material:

• Identificationoftherheologyofmortars

• IdentifytheeffectofSAPonthemechanicalpropertiesofhardenedcementmortars

• IdentificationoftheeffectsofSAPonmicrostructureandrelationshipbetweenthemorphologyofcement paste and the deterioration induced by ice formation (Mercury Intrusion Porosimetry, Scanning Electron Microscopy)

More and more often construction materials are expected to comply with requirements reaching far beyond a general-utility market. New high-performance materials are required not only to be more durable and exhibit longer life time, even under severe environmental conditions but having consumed less energy during their life cycle when compared with ordinary materials, they have to be more ecologically friendly and follow sustainability trends.

It is expected that SAP can offset the effects of freezing and thawing by continuous release of water during hydration and prevention of self-desiccation. Additionally after drying out, in the collapsed stage SAP creates air-filled pores, which can act similarly to air-entrained pores. Some reports indicate that SAP may interrupt the capillary pores and therefore influence the transport properties. All these phenomena may have a strong implication on durability in general. A comprehensive research program is therefore essential to verify available data and enable formulation of deterioration model.

Funding body

The PhD project is funded by School of the Built and Natural Environment Glasgow Caledonian University and jointly supervised by the BNE (Glasgow Caledonian University) and Ecole Spéciale des Travaux Publics (Paris).

The effect of superabsorbent polymers (SAP) on freeze-thaw performance of cementitious mortars and plasters Karol Sikora Glasgow Caledonian University


50


Establish when and how concrete shear failure occurs in building structures during a fire, and hence how to avoid catastrophic shear collapse.

Brief description

Concrete structures at ambient temperatures are designed for shear and flexural failure. The fire performance design of structures only considers flexural failure for horizontal elements and buckling, crushing and flexural failure for columns. Shear failure, however, has contributed to a number of recent failures of concrete structures in fire (for example, Gretzenbach car park, T.U. Delft’s architecture department, etc.). Shear failure in concrete structures under fire is not generally designed for, not understood and has had limited research.

One of the reasons that concrete shear failure in fire has not previously been investigated is the complexity of the topic. The loads carried within a building structure during a fire can be very different to the gravity loads for which it was designed; for example, thermal expansion can place very high shear loads on columns. Shear failure could potentially occur either in the columns (shear friction), in beams (flexure-shear) or slabs (punching shear).

After approximately 100 years of research, shear in concrete at ambient temperatures is still not fully understood. The project will investigate new constitutive models for the material-level behaviour of concrete subjected to shear in fire.

Recent developments in digital image analysis techniques will allow a far better definition of the strains across the concrete than has previously been possible with traditional, localized instrumentation.


Design guidance for shear in fire will be proposed and validated using experimental results. Understanding of the interaction between shear and fire in concrete will be improved.

Funding body

Engineering and Physical Science Research Council (EPSRC)

Concrete shear failure in fire

Holly McLeod Smith University of Edinburgh

Indicative test arrangement

Field of view for digital image

HeatBeam

shear test

Load


51


Three scale levels are generally recognised in the analysis of the mechanical behaviour of composites, namely, macroscale, mesoscale, and nano- or microscale.

This project aims to develop effective and efficient mesoscale models for cement-based composites, especially concrete. These models are subsequently applied to investigate the intrinsic mechanisms governing the behaviour of this type of composite materials under complex and high rate loadings, such as those induced by shock, impact and blast.

Brief description

To cater to the needs of dynamic analysis under complex stress conditions, a robust mesoscale modelling framework is being developed in this research group. This framework integrates the capabilities of MATLAB programming for the generation of the mesoscale geometric structure, a general-purpose CAE for the finite element mesh generation, and a hydrocode (LS-DYNA) for solving the dynamic response of the model. With a successful implementation of the above mesoscale modelling framework for 2-dimensional analysis of concrete material, the current study focuses on the 3-D model development so that the crucial inertial confinement effect during the transient dynamic response can be realistically represented. A novel pseudo-3D mesoscale model has been established, and a basic form of the highly complex true 3-D mesoscale model has been put forward.

Both the 2D and pseudo-3D mesoscale models are applied to study the dynamic behaviour of concrete under high strain rate loading. Experimental data on dynamic strength of concrete are usually obtained from the Split Hopkinson Pressure Bar (SHPB) tests. Simulations with different loading schemes, namely a full replication of the SHPB apparatus and a simplified approach by applying specially chosen velocity boundary conditions, are examined. Comparisons with the dynamic experimental data are carried out, with a particular emphasis on providing a mesoscopic perspective of the damage evolution, the wave and dynamic structural effects, and the implication of such effects in the interpretation of the test results. A parametric evaluation is also conducted on the dynamic increase factor (DIF) in the concrete strength, taking into account the multi-phase composite characteristics. The mechanisms underlying the different variation trends at different strain rate regimes are examined, and the contribution of the material heterogeneity is identified.

Potential for application

The mesoscale model developed in the current framework is well suited for complex and dynamic loading analysis, and is compatible with advanced general purpose computing platforms. Thus, it can be used in a variety of applications including material investigation as well as analysis of reinforced concrete components under extreme loading. It also facilitates a mesoscopic probe into such classical problems as the effect of confining reinforcement, shear cracking and aggregates interlocking. The mesoscale model can also assist in the optimized design of cementituous composites, as well as effective strengthening and retrofitting for desired dynamic resistance. The mesoscopic evaluation of the mechanisms governing the high strain-rate behaviour of the material paves a way for more rational consideration of such effect in the design of concrete structures against impact and blast loads.

Computational mesoscale analysis of cement-based materials with dynamic load

Jason Song University of Edinburgh


52David StephenUniversity of Leeds

The behaviour of connection under extreme temperatures in resisting progressive collapse


The aim of this assessment is to investigate the performance of connections under abnormal loading conditions (high temperatures) which may trigger progressive collapse. Connection is the most important aspect that deserves special consideration in the design of high rise steel structures. The failure of a critical connection could result to partial or total collapse of the structure.

Brief description

The potential threat to tall buildings has become a major concern to the engineering community and the world. The traditional method of design of high rise structures introduces factors of safety to account for minimal human errors and variation in material properties. However, the collapse of Ronan Point Building in 1968 in London, Alfred Murray building in 1995 and the World Trade Centre in 2001 in the United States changed the focus of research, design and construction of high rise buildings to account for abnormal loads. For instance, bomb detonation, gas explosion, vehicular or aircraft impact on buildings, gross fire and natural disasters constitute what is referred to as abnormal loads. These forms of loading can result to transmission of failure from one structural member to the other through connections.

Connections play an important role in ensuring the redistribution of forces within a structural system linking structural members. The structure was designed based on the provision of Eurocode 3, 2005 using SAP 2000 structural analysis program. The moment and shear forces obtained from the analysis was used in the design of the connection which was modelled in ABAQUS; a multipurpose finite element package. The behaviour of the connection under high temperatures and normal loading conditions was assessed. The moment rotation relationship was used as a criterion in assessing the performance of the connection in resisting progressive collapse under extreme temperatures.


The results will create awareness in understanding connection behaviour under abnormal loading conditions and add to existing literatures.

Funding body

Petroleum Technology Development Fund Abuja, Nigeria


53 Victoria StephensonUniversity of Bath


The aim of the research is to define the effects of wind driven rain and flooding on the structural integrity of historic buildings. In doing so it is intended that a procedure can be designed that will allow for standardised testing of historic wall constructions, and their vulnerability to wetting from wind driven rain and flooding. An additional goal is the specification of necessary adaptation measures to mitigate the identified structural effects.

Brief description

The work is to be focussed around five case study sites based in the south of England. Prior to the commencement of the laboratory analysis, field survey assessment of these sites will cover typology identification of the historic building stock in each site, and of the climatic hazards present. Analysis of the exposure of the building stock to these hazards will allow for quantification of the risks to historic wall constructions at the sites, this will inform the choice of materials and construction systems used in laboratory analysis.

The novelty of the work lies in the quantification of the mechanical implications for historic construction systems of excessive wetting and moisture ingress through exposure to wind driven rain and flooding. The testing associated with this research will take place at the BRE facilities in Watford, and make use of their driving rain and wind tunnel test apparatus. Observation and monitoring of the wall during testing will allow for continuous appraisal of the degradation of the construction system, and testing of the wall in compression post-wetting will allow for calculation of the reduction in strength, measured against the original strength characteristics obtained through material analysis.


The test results will be analysed to allow for detailed quantification of the degradation processes and this will in turn inform the mitigation procedures necessary to alleviate decay and protect historic buildings. Dissemination of the findings of this research will inform the conservation and repair work undertaken by practitioners in the UK, and contribute towards the body of work currently accumulating that assesses the impact of potential changes in the UK climate on the heritage of this country.

Funding body

Arts and Humanities Research Council and Engineering and Physical Sciences Research Council.

Investigation into the loss of structural integrity in historic wall construction systems caused by water ingress


54Mariati TaibUniversity of Sheffield

A component-based model for fin-plate connections has been developed to study the robustness of simple beam-to-column connections at elevated temperatures. The new model represents the realistic behaviour of such connections under the influence of combined forces, together with the high rotations which can occur at the ends of beams, during building fires. The key aspect of the component method relates to the characterisation of the force-displacement properties, at any temperature, of each active component, represented by a non-linear “spring”. The temperature-dependent characteristics of each individual component in each bolt row are defined, including the failure mechanism of the weakest component, where relevant, based on experimental and analytical findings. Primary failure modes adopted for fin plate connections are bearing/block shear of the plates and bolt shearing. A major additional complication is force reversal in components, which may occur simply because of temperature change without any physical reversal of displacement. The Massing Rule has been adopted to incorporate the effect of permanent deformations at any temperature when force reversal occurs. To account for the bolt slip phases, force transitions between tensile and compressive quadrants take place only when positive contact between a bolt and the edge of its bolt hole is re-established.

The results of high-temperature tests on connections have been used for verification of the model for isolated joints. The component-based connection model has been used to study joint behaviour in structural sub-frame analyses. Incorporating the component-based connection element into the non-linear finite element software VULCAN enables engineers to generate the global structural interactions for steel and composite structures in fire scenarios. This approach will enable more valid performance-based assessment of the overall structural response to fires, making use of the rotational and normal characteristics of connections, during both the growth and decay phases of a fire scenario.

A component-based model of fin plate connections in fire

Poster presenter


55 Clement ThirionUCL – Expedition Engineering

Background

The built environment is the largest contributor to greenhouse gas emissions (GHG) both worldwide and in the UK where it is responsible for around 45% of the total impact (UNEP 2007). In the context of reducing these emissions, building regulations in most countries have focused on ‘operational’ carbon. ‘Embodied’ carbon, associated with the making of the building through the extraction of raw materials, the manufacture of building components etc., has largely been left unaddressed and has consequently received far less attention from building designers.

However, with around 10% of the UK GHG emissions associated with the manufacture of materials (Anderson 2009) and with new energy-efficient buildings concentrating as much as 40% of their whole-life carbon in their constitutive materials (Thormark 2002), tackling embodied carbon becomes an increasingly relevant issue and as demonstrated by the study of the repartition of the carbon embodied in a new office building in London (dCarbon8 2008), structural engineers have an important role to play.

This research project focuses on the potential role of greater material-efficiency to reduce the carbon embodied in building structures.


We can think of a variety of alternatives to reduce the quantities of material used in our building structures while keeping their performance unchanged: reassessing the design criteria used, optimising the shape of structural elements, etc. The aim of this project is to investigate the respective potential impacts of the main of those measures.

Brief description

The potential impact of two particular measures on material-efficiency of structures will be investigated and presented at the conference. The idea of the first investigation comes from the assumption that the lack of incentive on structural engineers to reduce embodied carbon leads to structures being designed and built using far more material than strictly needed, a view widely shared in the industry but lacking tangible evidence. Results obtained from the study of an actual building structure designed in 2007 and completed since then will be presented.

The second study springs from the realization that the shapes of most building structural elements are driven by a desire to simplify their fabrication rather than to minimise the quantities of material used what also leads to material wastages. Initial results on shape optimisation will be presented.


Aiming at assessing the relative merits of each possible measure towards greater material-efficiency in building structures, this project will give a valuable insight into the relative effect of each of the measures identified. Comparing their relative effects on embodied carbon to their respective costs or difficulty of implementation will yield valuable information regarding the order of priority in which they should be sought to be implemented.

Funding body

EPSRC

Putting the material in the right place:the role of material-efficiency in reducing the environmental impact of building structures

Oral presenter


56Junzhe WangUniversity of Bath


(a) Improve knowledge of the underlying mechanism(s) that can lead to the failure of spandrel walls

(b) Develop a method identifying the precursors to spandrel wall failures.

Brief description

Network Rail is undertaking a programme of work to improve its management of spandrel walls to masonry arch railway bridges. As part of this programme, the proposed research will investigate behaviour of spandrel walls to masonry arch railway bridges. Work will include: 1 Complete a literature review of (a) the failure of spandrel walls and masonry arch bridges, (b) full-scale tests undertaken on such structures, and (c) methods used to analyse the behaviour of such structures. 2 Analyse the results of monitoring in-service spandrel walls on the rail network. 3 Develop (a) a model of the behaviour of spandrel walls under loading, and (b) a method for identifying the precursors to the collapse of such walls. 4 Develop a system for risk ranking spandrel walls; such a system shall be based on simple physical parameters - such as the geometry of the arch, and the ratio of the live and dead loads.


The results of research will lead to better understand the failures of masonry arch bridges with and without spandrel walls, and it could develop a simple quantative method of assessment for such structures. It can also help to identify good and bad practice on current masonry arch bridges and categorise the underlying causes of failure.

Investigation of spandrel wall failure on masonry arch bridge


57 Zhiyu Wang University of Nottingham

Blind bolting technology provides a better use of bolted connections to hollow section members without accessing inside the closed section member for tightening. Problems related to the strength, stiffness and ductility are all introduced through the use of distinct components of blind bolted connection system. To satisfy its use as a type of moment connection to concrete filled steel tubular (CFT) column, an innovative blind bolted connection has been developed to offer better structural strength and initial stiffness. The knowledge of the cyclic performance of this connection system is very limited. The available physical experiment and numerical analysis are still lacking to form a sufficient analytical assessment for design.

The objective of this research program is to develop an analytical assessment of this innovative blind bolted connection with insights into the hysteretic moment-rotation relationship, available ductility, and progressive damage models. The research into the deformability of analytical sub-models is drawn upon to develop a global mechanical model of the connection. The ultimate goal of this research is to contribute to a better understanding the cyclic characteristics of this innovative blind bolted connection to CFT column and its practical applicability for seismic design.

The connection in this study considers the initial anchorage of the blind bolt in CFT column. Upon tensile force on the connection, the blind bolts gradually lose concrete anchorage. The blind bolt deforms accordingly in tension together with CFT column face in flexural bending. The developments of three different failure modes under cyclic loading are considered associated with the connecting components of the blind bolt and CFT column face. The full-scale experiments provide insights into the cyclic response of the connection. Preliminary test results are promising, showing that this connection system exhibits high strength and good ductility. However, further experimental study is required. The ductility classification introduced by Eurocode 8 will be used to evaluate the connection. The cyclic characteristics of the connection will be investigated including resistance ratio, strength hardening and deterioration ratio, partial ductility ratio, full ductility ratio, stiffness deterioration ratio, and absorbed energy ratio. The damage accumulation of the connections will be investigated and compared using damage index in current literature.

The development of mechanical model to trace the cyclic moment-rotation response of the connection includes two parts of work. The first is the sub-model study for deformable sources of the blind bolted connection, including the use of conical shell theory (for the flaring sleeves of the blind bolt in tension) and matrix stiffness method (for the CFT column face in bending). The second relates to the global model study based on the component method. The contributions made by individual components are idealized as extensional springs and properly assembled in the mechanical model. The mechanical model provides satisfactory comparison for tested results with initial stiffness, yield strength and ductility characteristics.

The finite element analysis will be performed as a supplement for the experimental work. This analytical means provides a better evaluation of load transfer mechanism, which may not be accurately traced by experiment due to the lack of access for instrumentation. The advanced modelling techniques including sub-structuring and element birth and death will be used in the development of the finite element model. This relieves high computational costs and better the accuracy of the finite element analysis. A comparison with experimental results and mechanical model will be made, and the suggestions for further improvement of proposed analytical model will be outlined. It is expected that both experimental analysis and finite element analysis would contribute to the development of seismic design recommendations of this innovative blind bolted connection to CFT column.

Funding body

University of Nottingham, UK/China Scholarship for Excellence scheme

Assessment of cyclic structural performance of an innovative blind bolted connection to concrete filled steel tubular column


Natasha WatsonUniversity of Bath

Project description

The main fields of interest covered by this topic are structural engineering, materials science and sustainable design.

The aim of the project is to develop the following using a combination of case studies, desktop research, and materials testing:

• Athoroughunderstandingofthebarrierstoentryandtheparametersdeterminingwhennaturalmaterial options are most effective in helping to deliver a sustainable building design, in comparison with traditional approaches.

• Adatabaseofinformationonnaturalmaterialsthatcanenabledesignanddecisionmaking.

• Athoroughunderstandingofthepracticalimplicationsofemployingnaturalmaterialssuccessfullyinto construction projects that may lead to the development of innovative design solutions and testing of materials.

• Amethodforcomparingmaterialsoptionsinaholisticway,relatingtothebroaderneedsofsustainable construction, including the availability of local materials, macro and micro economics, and the social and environmental impacts of materials production and use. This comparison tool development process may include:

- Analysis of the embodied carbon breakdown of different building types to investigate which aspects of construction have the largest adverse impact.

- Assessment of the role that currently available natural materials and material composites can have in replacing current materials and the benefits (bring out ideas for altering the properties of natural materials to improve performance) and highlight the key opportunities for making the biggest difference.

- Application of structural engineering and façade modelling techniques to design for optimum performance.

- Comparison of capital cost, buildability, skill requirements and whole life performance.

- Evaluation techniques such as Life Cycle Assessment and Whole Life Costing.

- Consideration of sustainable construction in its broadest form including considerations of embodied energy, water saving, ecology provision and operational energy benefits.

- Data collection in the form of post occupancy evaluation to verify the actual impact of natural material options.

Funding bodies

University of Bath, University of Bristol and Buro Happold

Using natural materials as part of building construction to improve the sustainability of buildings – development knowledge and guidance for increased deployment 58


59 Graham WebbCambridge University

Deterioration of bridges is a major concern since failure can cause huge disruption, loss of life and be very costly to repair. Most bridges are inspected visually on a regular basis however problems can easily be missed or only detected once the structure has deteriorated beyond an acceptable level. Various Structural Health Monitoring systems have been trialled, however in many cases the data is not easy to relate back to the health of the structure. This project aims to determine the most effective means of monitoring bridges so that useful conclusions can be drawn about their health and any problems which may be developing. It will be necessary to determine what parameters need to be measured, how they can be measured and crucially, how those measurements can be related back to an understanding of the structural behaviour.

Initial work will include investigating Structural Health Monitoring systems which have been deployed around the world and determining what, if any, useful data is being collected, with a particular focus on recent major brides. Research will also be undertaken to determine the range of parameters which can be measured with available sensors, and those for which new sensors need to be developed.

The long term aims for this area of research are to improve the standard of monitoring of bridges, by reducing the amount of irrelevant data being collected. This will provide bridge owners with useful information allowing them to implement cost effective maintenance strategies, to ensure the safety of their structures.

Funding body

EPSRC Doctoral Training Award

Advanced sensor monitoring of infrastructure


60Robert WestgateUniversity of Sheffield

Problem description

Long term monitoring of large structures has had increasing application in recent years, in particular for the maintenance of bridges. Its purpose is to gather data of the loading and responses of the structure to ascertain the bridge’s performance. Structural Health Monitoring (SHM) in particular has focused on using dynamic data for damage detection, where a change in frequency or mode shape may indicate a fault. SHM is a substitute for human inspection, which in comparison would be a periodic, lengthy and possibly expensive process.

Data collected from suspension bridges has shown that their performance is dependent on the environmental conditions to which they are subjected. Temperature, wind and traffic mass appear to influence on the static and dynamic behaviour of the bridge, along with other parameters. Unfortunately, these conditions are also linked with each other; for example a heavy flow of traffic will be during daylight hours, which is also when the bridge experiences higher temperatures.

Project objectives

The main aim of the research is to identify the primary environmental parameters that cause a change in the static and dynamic responses, which may occur in daily and seasonal cycles. This is achieved by observing monitored data from several suspension bridges, as well as via analytical data, such as detailed finite element methods.

Alongside this, a bridge’s response to a specific environmental condition is analysed, together with observations of the behaviour of the cable elements.

Potential applications

The research is intended to be used alongside SHM equipment, to determine whether a change in response may be responsible either from the environment, damage caused to the structure or monitoring equipment, or other factors. It is also hoped that the identified behaviour from long term monitoring of analysed suspension bridges in our research may be reapplied to the monitoring and research of other suspension bridges.

Environmental effects on a suspension bridge’s performance

Poster presenter


61 Behrouz ZafariUniversity of Warwick

Project objectives

1. Characterisation of the pin-bearing strength of Pultruded FRP material using the so-called Warwick University (WU) test method.

2. Strength variation with pin diameter and orientation of connection force with respect to the direction of pultrusion.

3. Effects of hot–wet conditions on strength.

Brief description

The design of connections is one of the most critical aspects when establishing that a structure, of any construction material, is safe. To avoid a catastrophic failure, and support confidence for increased demand there is a need for the FRP industry to have standards that can assist professional engineers with their designs. The American pultrusion industry has funded a project to write a pre-standard for the Load and Resistance Factor Design of Pultruded FRP Structures. My supervisor (Dr. Mottram) is the lead writer of the chapter for bolted connections. One of the distinct modes of connection failure to be designed against is bolt bearing, and its resistance formula requires knowledge of the pin-bearing strength. This strength is the stress that causes the FRP material to failure when there is a clearance hole, no lateral restraint and the steel bolting has no thread over the bearing surface. A series of pin-bearing strength tests have been conducted using a pultruded FRP material reinforced with E-glass fibre and having polyester based matrix. To do this the author used a new test method that has been specifically developed by Warwick University. Presented in this paper are variations of the pin-bearing strength measured at room temperature with three material orientations and for four different pin diameters. A comparison is made with a second series of test results after the equivalent specimens had received hot-wet conditioning to simulate a number of service years. A main finding from the comparison is that the average reduction in characteristic strength (from 100 to 120 N/mm2) following the ‘ageing’ process is in the range of 21 to 27%.


The results of this research are aimed at establishing a methodology to determine characteristic values of pin-bearing strengths that can be reliably used with the strength formula to design a bolted connection against failing in the bearing mode. It is an aspiration of the research that the Warwick University test method be developed into a recognised standard test method; one of its key advantages is that it can be used with structural shapes because it requires ‘small’ specimens.

Funding body

Technology Strategy Board (Low Impact Building Programme)

Determination of pin-bearing strength for the design of bolted connections for fibre reinforced polymer (FRP) shapes


Congxiao ZhaoUniversity of Birmingham

Cold-formed steel sections have been widely used in the building construction due to their positive features such as high strength-to-weight ratio. Alongside with other sections such as C and Z, Sigma sections offer several more advantages associated with the presence of web stiffeners. For instance, as the shear centre is closer to the web, the applied loads introduce smaller torsional moment; local buckling resistance in web is enhanced. However, the nature of the cold-formed thin-walled cross-section leads to a high susceptibility to various types of buckling failure, e.g., local and laterals torsional buckling. The roof sheets, once been installed, will provide purlins with restraints against lateral torsional buckling. It is necessary to characterise the effect of these rotation restrains on the bending resistance of purlins.

To date, very few published works have reported the method to assess this effect. This study was aimed to fill up the gap by studying the interactive behaviour between purlins and roof sheets under both downward and upward load conditions. Full scale laboratory tests have been conducted (Fig 1) to measure the buckling and failure loads, from which the buckling and post-failure behaviors were obtained. In addition, extensive range of tests on torsionally restrained purlins has been carried out in order to find the rotational stiffness. The non-linear relationship between applied moment and the resulting rotation has been analysed and results were compared with calculated predictions by using guidance in EC3. It is anticipated that the values of rotational restrain will be fed into a simplified FEA numerical model, which simulates the interaction of roof-sheeting system by introducing a number of rotational springs. This simplified model will then be further extended to a 3-D comprehensive numerical modeling including sheets and connections. The comparison between two will establish the applicability and limitation of the simplified model.

Funding body

EPRSC/Albion

Structural interactions between cold-formed sigma steel purlins and roof sheets

Fig 1 Full scale bending test on Sigma purlin-sheeting system

Oral presenter

62


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Documents

Vice President 2 Keynote speaker 3 Programme 4 Poster ... · PDF fileProgramme 4 Poster presentations 5 ... Concrete shear failure in fire 55 ... Structural interactions between cold-formed