Day 3 :
- Track 4: Digital Structural Designs
Track 6:Safety Management in Construction
Track 7:Earthquake resistance engineering structure
Track 11:Fire Safety Engineering and Design of Structures
Location: Ballroom section 3
Chair
Sherif Mohamed
Griffith University Queensland, Australia
Session Introduction
Konstantinos Daniel Tsavdaridis
University of Leeds
UK
Title: Seismic resistant design of connections with the use of perforated beams
Time : 10:05-10:25
Biography:
Konstantinos Tsavdaridis is the Director of the research group focuses on steel and steel-concrete composite structures at the University of Leeds. He holds a MEng from City University London and an MSc (DIC) from Imperial College, London. His research expertise is in structural product development that embraces resilience and sustainability; particularly the development of innovative structural systems and members, and testing large-full scale structures. He has published more than 60 scientific articles, journal publications, technical reports and international conference papers. He is a member of ASCE, Professional Chartered Civil Engineer and registered at the European Federation of National Engineering Associations.
Abstract:
The 1994 Northridge and 1995 Kobe earthquakes had destructive effects and proved that welded steel moment frames were generally prone to premature brittle failure. Studies were conducted by FEMA and the SAC Joint Venture with reports ranging from FEMA 350 to 355F with main aim to develop reliable, practical and cost-effective design guidelines and specifications. Alternative solutions were considered (FEMA 350, EC8: Part 3) by reinforcing connections or utilizing a Reduced Beam Section (RBS). Today, it is estimated that around 35% of steel-framed buildings incorporate long spans in excess of 12m. In the 1990s the cellular beam, which replaced the castellated beam, gained prominence. Cellular beams are now estimated to have an 80% share of the long span beams in the UK market. There has been a lot of research on perforated beam webs with the geometry of the perforation ranging from circular, elongated, to elliptically-based shapes. However, very limited research has been found up to date regarding the design limitations of seismic resistant connections when such perforated beams are used. Recent research has come up with the development of a new technique, which is consisted by the engagement of the RBS and the use of perforated beams. It is concluded that the design of Reduced Web Section (RWS) connections should be based on the articulate decision of the first opening’s distance as well as the use of large isolated perforations as an effective way of improving the behavior of connections enhancing their ductility, rotational capacity and energy dissipation capacity.
Albert Owusu
Bana Consulting Engineers, Brisbane
Australia
Title: Rethinking the Application of Engineering: Structural Analysis of Economic Impact Risk Propagation in Infra_Structures
Time : 10:25-10:45
Biography:
Dr Albert Owusu is a Senior Consultant in Construction & Structures. He specialises in Construction Projects Management. He has worked as a Structural Engineer on Civil Infrastructure Projects and their Construction for several years in different countries including New Zealand and Australia. His research interests are in Structural Modeling, Risk Impact Assessment on Network of Infrastructures. More specifically, his research work has examined the Expected Impact Risk from Climate Change on Critical Infrastructures and its interdependencies, Natural and Manmade disasters and their ripple effects to interdependent National Economics
Abstract:
Engineers are not only designing structures. They are developing technologies that have the capacity to enable tremendous progress; whether it is practical structures for services, or the movement of goods, or the creation of transportation systems, to strengthening economic prosperity. Engineering fosters a plethora of methods and concepts that can be applied beyond conventional thinking. My presentation will illustrate application of two integral structural analysis methods; Moment Distribution and the Stiffness Matrix methods, to analyse the impact of risk in the economic sector. It will exhibit how Moment Distribution and the Stiffness Matrix Methods in Structural Analysis are used to analyse impact risk in a network of infra_structures. The idea originates from considering ‘infra_structures’ as a network of physical assets, all connected, similar to a skeletal framed structure. This presentation introduces the term ‘vulnerability coefficients,’ which are analogous to stiffness coefficients and used to convey the impact of risk to dependent others. An analogous comparison is made between structural parameters and economic variables in order to explain this concept. A Vulnerability Coefficient Method (VCM) computes impact risk propagation due to interdependency, and then converges to the widely cited Wassily Leontief’s Economic Model. An example showing impact risk propagation will be provided to verify and demonstrate the application. Through this concept, the inevitable ripple effects of economic turmoil can be managed. Engineers have the opportunity to impart their knowledge to benefit other disciplines. A disruption or threat to economic stability has cascading effects in the infra_structure network system and engineers have the capacity to implement fast, powerful and effective solutions. This can benefit management of disruptions on a local and global scale. There is immense promise for improvement of the economic sector embedded within engineering methods, and engineers must not continue to limit their capabilities
Khalifa S. Al-Jabri
Sultan Qaboos University
Oman
Title: Role of Composite Joints on the Performance of Steel-Framed Buildings in Fire
Time : 10:45-11:05
Biography:
Khalifa Al-Jabri obtained his PhD in structural fire engineering from Sheffield University, UK in 2000. He is currently Professor and Head of the Department of Civil and Architectural Engineering at Sultan Qaboos University, Oman. He published more than 110 papers in international Journals and Conferences. His main research interests are Behaviour of structures in fire, use of waste materials in Civil Engineering applications and Seismic Hazard Assessment. He is peer reviewer in more than 30 journals and he is member in the editorial board of several journals such as Structural Fire Engineering Journal.
Abstract:
All structural members exposed to fire heat up, but the rate of temperature rise in each member is different. Joints in a steel-framed building tend to heat up slower than the material within the span of the beam because of the presence of additional materials (bolts, plates, angles, etc.) and due to their shielded location (i.e. usually beneath a composite floor). EN 1993-1-2:2005 suggests temperatures at joints of between 62% and 88% of that in the beam lower flange temperature at mid-span. The design guidelines presented in the current codes of practice for the design of steel-framed buildings in fire conditions are based on results of isolated member tests carried out in a laboratory that followed a prescribed standard fire curve. The laboratory testing conditions were obviously different from the real situation wherein the structure is subjected to natural fires. It has been known for many years, from observations of accidental fires, that structural members behave better in fire when they constitute part of a structural arrangement than when they are tested in isolation. These observations have been confirmed by results from experimental fire tests conducted on full-scale multi-story steel-framed buildings. It has been demonstrated that members that form part of the structure can withstand much higher temperatures than those tested singly due to the ability of the joints to resist the effect of fire and re-distribute the forces to the adjacent cold resign in the vicinity of the affected areas. Also, the restraint to thermal expansion by other connected members has significant influence on fire resistance of steel-framed buildings. This has raised doubts concerning the conservative design approaches provided by current fire engineering design codes. The attack on the twin towers of the World Trade Centre in New York on 11 September 2001 has prompted close examination of the way in which buildings can fail in fires and has brought into the public eye the hazards that fires can pose to major building structures. This paper examines the effects of fires on multi-story steel-framed buildings and the role of composite joints in enhancing their fire resistance. This provides vital knowledge of the behavior of real buildings and will allow for the construction of safer buildings in the future.
Madhar Haddad
United Arab Emirates University
UAE
Title: Finite Element Modeling of the Seismic Behavior and Fracture of Concentric Braces
Time : 11:15-11:35
Biography:
Madhar Haddad completed his Ph.D at The University of Calgary and engaged in postdoctoral studies at the Schools of Engineering at both The University of Calgary and the Ecole Polytechnique of Montreal. He is an assistant professor of structural engineering at the Architectural Engineering Department of the United Arab Emirates University. He has published several papers in refereed journals and conference proceedings.
Abstract:
In steel construction, Hollow Structural Steel (HSS) sections are frequently used as concentric bracing members in framed structures to resist seismic excitations. The prediction of the fracture life of the HSS tubes is still a concern, despite four decades of cyclic testing and numerical modeling. That work has however, led to stringent limits on the width-to-thickness ratio as in the AISC 2010 seismic provisions. High local strains develop in HSS bracing members because of the geometric nature of the local buckling at the mid-length plastic hinge that leads to severe local rotation with high cyclic strain demand. Thus, brace fracture occurs at smaller inelastic deformation for HSS members than for wide flanges when all other factors are identical. Wide flange (WF) sections could represent an attractive alternative to HSS sections as bracing members. The slight increase in cost per ton of columns and the low compressive resistance of WF braces could be justified by an improved fracture life expectancy and better control in terms of expected strength compared to HSS tubes. In addition, there is the possibility of using the WF braces in opposing pairs in frames. The high overstrength value of HSS bracing members is unfavorable and could lead to fracture in the connection if not taken into account as seen in several earthquakes. Finite element modeling is presented here to predict cracking and fracture life of bracing members under different applied cyclic loadings. It is shown that the fracture life predicted from finite element analysis agrees well with experimental results.
Peter Jiki
University of Agriculture
Nigeria
Title: Lateral Stability of Damaged Open Thin-walled Beams using Lyapunov’s Second method
Time : 11:35-11:55
Biography:
Peter Jiki studied Civil engineering in Bolton Institute of Tech (now University of Bolton),England and graduated in 1979. He later obtained his M.Sc. Structures from Cranfield Institute of Tech (now Cranfield University), England in 1983. He finally obtained his Ph.D in Civil Engineering Structures from the University of Lagos in 1997. Since 2011 he has been associate professor in Civil Engineering Structures in the University of Agriculture Makurdi in Nigeria. He has a prima facie case for promotion to full professor any time from now. He has many publications to his credit.
Abstract:
Lateral buckling of damaged thin-walled beams of open sections is studied in this work using Lyapunov’s direct method of stability analysis. First, a damaged stiffness reduction parameter α is calculated, following which a metric and an energy type Lyapunov functional (function) are proposed for the solution of the stability problem. It is shown that without the use of deflection functions for u, v and β in the equilibrium equations, a simple manipulation of the eigen-value inequalities yields familiar expressions for the lateral buckling loads(moments) for simply supported and fixed beams. The lateral bucklibng moments obtained using this method compare well with those in the literature using deflection functions. When the damaged parameter is applied to these expressions, the reduced lateral buckling loads or moments are obtained. Numerical examples demonstrate the application of the method proposed in the present work. It is concluded that the method is accurate and when combined the proposed load reduction parameter, the extent of damage to the beam can be obtained rapidly.
Mahesan Bavan
National University of Malaysia
Malaysia
Title: Local Failure Behaviour of the Steel-Concrete Composite Beam with Web Openings in Various Shapes under Axial Tension and Uniaxial Negative Bending
Time : 11:55-12:15
Biography:
Bavan has completed his MSc. In Civil and Structural Engineering from National University of Malaysia, Malaysia. He is a Civil Engineer with twelve years of vast professional experiences in planning, designing and directing the constructions of infrastructure, utilities, geotechnical & structural projects, and currently he is enduring the research to read PhD. He has published more than 25 papers in reputed journals and international conferences.
Abstract:
The prospects of openings on the steel section of the steel-concrete composite beam under combined uniaxial negative bending and axial tension, which may undergo early failure state, have attained slight attention in the open literature such that this is the hypothesis of this study, which is herewith highlighted. A three dimensional numerical model for a composite beam under such combined loads was developed. The characteristic behaviours of material non-linearity, complicated interactions, load applications and boundary conditions were determined based on the nature of this particular case. A comparative study was performed to validate the accuracy of the computer solutions against the existing experimental analysis. The numerical model was then incorporated by a series of numerical analyses with a parametric study, which was the presence of openings on steel beam with different shapes, for examining the influences on the structure. The numerical results predicted were provided a better understanding in the fracture behaviour of the material components due to the openings with different shapes and ultimate limit behaviour of the composite beam. It was found that the shapes of openings on the steel beam can affect significantly the behaviour of the composite beam, which must be taken into account in the design models. Moreover, the techniques used in the development of numerical modelling is analysed extensively in this paper.
Kamal M Bajoria
Indian Institute of Technology Bombay
India
Title: Performance Based Design of Cold Formed Steel Structures
Time : 12:15-12:35
Biography:
Prof. K M Bajoria has completed his PhD at the age of 27 years from Cambridge University and also postdoctoral research at Cambridge University Department of Engineering. He is Professor of Civil Engineering at Indian Institute of Technology Bombay, a premier technical university in India. He has published more than 35 papers in reputed journals and more than 35 papers in international conferences and has been serving as chairman of Indian Association for Structural Rehabilitation.
Abstract:
Thin-walled cold-formed steel (CFS) section construction has gained popularity as light weight construction with high stiffness and easy erection and installation. During earthquake, vibration causes to and fro motion which brings pinching effect in CFS structures. The capacity of CFS structure to dissipate energy in elastic range is less and its dissipation capacity in inelastic range need to be considered. Performance based design is a more general design philosophy in which design criteria are expressed in terms of performance objectives, like lateral deflections, inter-storey drifts, element ductility, and element damage indices, when the structure is subjected to different levels of seismic hazard.. The purpose of this paper is to evaluate the performance of cold-formed steel (CFS) structures and based on its performance decide which type of performance is required in a particular hazard level or seismic condition and thereafter design the structure. The goal of a performance-based design procedure is to produce structures that have predictable seismic performance under multiple levels of earthquake intensity. In order to do so, it is important that the behaviour of the structures is targeted in advance, both in elastic as well as the inelastic ranges of deformation. It is very essential to understand first, the performance of CFS in seismic conditions and to evaluate the performance, various methods and analyses are required. So, different performance evaluation procedure are discussed. Performance of different CFS structures are evaluated and their suitability in different occupancy conditions are discussed. Finite element modelling is done using ABAQUS to observe the non-linear performance of CFS. Other analysis is done in SAP2000.
Lmokhtar Ikharrazne
National School of Applied Sciences, Al-Hoceima
Morocco
Title: Numerical investigation of composite materials and structures
Time : 12:35-12:55
Biography:
Lmokhtar Ikharrazne is currently professor teaching in Civil and Environmental Engineering at National School of Applied Sciences, Al-Hoceima (ENSAH) which is affiliated with the Mohammed First University of Oujda. He has Doctorate Degree in Structural Mechanics, conferred by Hassan II University of Casablanca. He is leader and educational coordinator of teaching programme of Civil Engineering. He has a total of 20 years of experience in research and education in structural and civil engineering, applied mechanical engineering.
Abstract:
The main goal of the development described in this work is to provide a numerical tool that could be used to obtain approximate solutions for composite skew plate bending. This research deals with bending problems under different loading and various support conditions. At first, it is of pivotal importance to note that despite the spread use of composite skew plates, the published literature shows an important lack of scientific works regarding these particular structures. For a better understanding of composite skew plate behavior, the present investigation was based on a simplified theoretical model, known as Kirchhoff-love model, established for thin plate analysis. The proposed numerical method uses an efficient finite difference scheme that exhibits controllable accuracy for approximations and shows excellent flexibility in handling complex geometry and boundary conditions. Particular examples of simply supported composite skew plates are discussed. Different examples involving a variety of boundary conditions are also analyzed in this paper. Highly consistent numerical solutions are obtained for skew composite plates with various skew angles. Numerical results given by our model are checked against the only existing solutions.
Yassin AL-Kour
K&A Beirut
Lebanon
Title: Steel versus steel-reinforced concrete bridges
Time : 12:55-13:15
Biography:
Yassin AL-Kour is a Senior Geotechnical Engineer in K&A Lebanon. He is the member of Professional Societies Order of Syrian Engineers (OSE), Member of the International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE), Syrian Soil of Mechanics Society (SSMS) and also Syrian Society of US Graduates (SSUSG).He has 25 years of experience in the geotechnical engineering domain.
Abstract:
The competition between steel and steel-reinforced concrete bridges can become very decisive when it comes to the specific prevailing geotechnical subsurface conditions and to the design criteria that can be adopted in designing a safely bridge foundation. Heavy concrete elements that come from a steel-reinforced concrete superstructure develop tremendous stresses which will, in turn, compress the soil underneath profoundly. This results in excessive settlement that, in most cases, the bridge superstructure cannot tolerate unless a super pile foundation design has been pursed. This paper will illustrate the real benefits of selecting light bridge superstructure for waterways and viaducts and finally highlight the sustainability and more economically efficient in the long run. Case history examples, when light weight steel bridge structures were favored over heavy steel concrete structure system, will be presented. This paper will conclude with recommendations and guidelines for structural bridge designers to use in their rules of preference when it comes to selecting the of bridge structural type for waterways and viaducts structural system.
Erfan Alavi
International Institute of Earthquake Engineering and Seismology
Iran
Title: Seismic behavior of Steel Plate Shear Walls with Different Configurations
Biography:
Erfan Alavi was born in 1970. He has completed his PhD from International Institute of Earthquake Engineering and Seismology, IIEES. He is the structural department head of SAZEH, a consulting and construction engineering organization. He has published more than 22 papers in international conferences and reputed journals as ASCE-JSE, JCSR-Elsevier, IJE, and has been serving as an editorial member of repute. He began researching on steel plate shearwalls system in 2006. He has also worked, taught, and researched on the other fields of structural engineering as base-isolated buildings, soil- structure interaction, damper devices, blast-resistant buildings, dynamic experiments, industrial structures, high-rise buildings, performance-based design, and offshore structures.
Abstract:
During the recent decades many research have been carried out on steel plate shear walls, SPSWs, and accordingly, they have been classified as a reliable lateral load resisting system in the high seismic risk zones. This has given rise to increase of attentions to SPSWs as a new and economical system in structural design of buildings and even retrofitting of existing structures. Since different philosophies have been elaborated to explain and improve nonlinear behavior of SPSWs, various configurations are deemed in the design and construction of SPSWs as stiffened, un-stiffened, with holes, with simple or rigid frames, etc. Where, the stiffened approach employs stiffeners to prevent the infill steel plate fully or partially from elastic out -of-plane buckling. The un-stiffened approach relies mainly on post-buckling strength of infill steel plate ascribed to tension field action development in the plate. Also, application of holes in the infill plates is sometimes considered for passing utilities, architectural purposes, and/or special structural reasons. In addition, the type of peripheral frames affects on nonlinear responses of the steel shear walls. This variety of the theories and applications might face structural designers with the difficulty of selection of an appropriate system in the design. Hence, in this study, seismic behaviors and structural characteristics of steel shear walls with different construction details are investigated based on the experimental and analytical results. Some aspects of advantages and areas of concerns of each type of steel plate shear walls are briefly reviewed and discussed, and some considerations are resulted and presented.
Abdurrahman Sahin
Yıldız Technical University
Turkey
Title: Current State, Advances and Future Plans for Development of Next Generation City Simulation System
Biography:
Abdurrahman Sahin gained his PhD from Karadeniz Technical University, then worked as a post-doc at Bogazici University – Kandilli Observatory and Earthquake Research Institute (KOERI), and finally came to Yıldız Technical University. He worked as a Visiting Professor at The University of Tokyo - Earthquake Research Institute (ERI). His research focuses on seismic design, soil-structure interaction, earthquake wave propagation, experimental and operational modal analysis, digital signal processing, system identification, numerical damage assessment and structural health monitoring and nondestructive evaluation. He is currently working on next generation city simulation system development about full computation of earthquake hazards and disasters for urban areas.
Abstract:
The rapid and uncontrolled growth of cities and expansion of critical infrastructure systems in seismically active regions is an important engineering problem which must be taken into account. It has been observed from the past huge earthquakes that serious tragedies have been faced when the earthquakes hit the metropolises. It is essential to develop next generation city simulation system for obtaining higher reliable estimation of earthquake hazard and disaster which could take place in growing urban areas. Developed computer technology and science enable us to carry out a large scale numerical simulation. Now, we have opportunity to simulate all part of city during a possible earthquake scenario. The all phases of an earthquake may be simulated and evaluated. The earthquake wave may be generated and propagation from source to city may be simulated. The response and damage of structures may be monitored and the human and society actions due to the earthquake damages may be observed. High performance computing and advanced graphical capabilities are necessary to develop such a comprehensive simulation system. Current state, advances and future plans for development of such a next generation city simulation system is presented.
Theodore L. Karavasilis
University of Warwick
UK
Title: Earthquake-resilient post-tensioned steel buildings: Large-scale experiments, advanced numerical models and probabilistic economic seismic loss estimation
Biography:
Theodore L. Karavasilis is Associate Professor of Structural Engineering and Director of the Resilient Steel and Steel-Concrete Composite Structures Laboratory at the School of Engineering of the University of Warwick (UK). Previously he was a Lecturer at the University of Oxford (UK; 2010-2012) and Post-Doctoral Researcher in the ATLSS Research Center of Lehigh University (USA; 2008-2010). He holds a PhD in Seismic Design of Steel Structures from the University of Patras (GR). He is author/co-author of more than 100 publications on performance-based seismic design of steel structures. He has been the Principal Investigator of various research projects funded by UK and EU funding bodies.
Abstract:
Conventional seismic-resistant steel structures are traditionally designed to sustain significant inelastic deformations in structural members under strong earthquakes. This design philosophy has well known advantages including life safety and economy but results in socio-economic losses due to repair costs and long disruption of building use and occupation. Starting from the idea of resilience-based seismic design, which has as major objective the reparability of a structural system, this presentation will show how smart structural detailing, post-tensioning, and use of rate-dependent passive dampers can be integrated to design steel buildings that return to service within an acceptable short, if not immediate, time after very strong earthquakes. A sequence of major research tasks will be presented including the design, plan and execution of a large-scale experimental program; the development of advanced nonlinear numerical models capable to simulate the dynamic response of the building up to dynamic instability; the development of practical design procedures within the framework of Eurocodes 3 and 8; and the implementation of a state-of-the-art probabilistic framework for direct economic seismic loss estimation.
Bulent Akbas
Gebze Technical University
Turkey
Title: Earthquake Resistance Engineering Structure – Seismic Loading Patterns on the Brace-Intersected Beams in Two-Story X-Braced Frames
Biography:
Bulent Akbas obtained his Ph.D. degree in Structural Engineering in 1997 from Illinois Institute of Technology, Chicago, IL, USA. He has been conducting research and teaching structural and earthquake engineering at the Department of Earthquake and Structural Engineering, Gebze Technical University, Turkey, since 1999. He has published more than 100 journals and conference papers in the area of seismic behavior and design of steel structures, performance-based earthquake resistant design and evaluation of structures, non-building structures, historical structures, structural health monitoring, and soil-structure interaction. He is a member of the seismic design of steel structures committee in Turkey.
Abstract:
Current seismic design specification in the US (AISC 341-10) requires that braced-intersected beams in special concentrically braced frames be expected to remain elastic under the design earthquake ground motion. This design criteria yields in a large unbalanced force from the difference in yielding and buckling strengths in V-type or inverted V-type braces for the brace-intersected beams. As a result, brace-intersected beams always have heavy and deep sections in V-braced or inverted V-braced frames. As an alternative, structural engineers have been using the two–story X-braced frames, having inverted V-type braces in one story and V–type braces of the same sizes above it with an intention to reduce the beam size. Many practicing engineers believe that there is no need to consider unbalanced force in the brace-intersected beams in two-story X-braced frames assuming that unbalanced forces below and above the beam would be equal, but in opposite directions. Such design practice assuming no or little unbalanced force on the brace-intersected beam in X-braced frames appears to be encouraged by some design examples in AISC Seismic Design Manual. This paper will present a study to reveal actual mechanisms and seismic loading patterns on the braced-intersected beams in two-story X-braced frames and discusses the impacts of yielding beams on critical components, such as braces and connections.
D.Vlachakis
European Centre for Training and Research in Earthquake Engineering
Italy
Title: Seismic response of deep tunnels: comparison of different existing methods
Biography:
D.Vlachakis is working in European Centre for Training and Research in Earthquake Engineering, Italy
Abstract:
The task at the present study was the verification of the current methods used in a conventional manner so as to estimate the behaviour of a tunnel against ground motion but also the investigation and suggestion of additional methods. To accomplish this objective, the study analyzes a real project that had been designed by the engineering team of Geodata. Moreover there is a review of what has already been applied to the case (pseudo-static methods) and in parallel there is a consideration of various other existent procedures: analytical, dynamic time-history and a different numerical model again in pseudo-static condition. The time-history method is highlighted in particular as it is a rigorous scheme that needs prudent consideration. In the end, the comparison brought out both advantages and drawbacks but as well as the contrasts of the distinct proceedings and made the associated proposal for future performance issues. Creating a model for a pseudo-static approach has a simplicity that makes it advisable as the primary way to characterize the situation. On the other hand it is the only way among all those that were described at the study and can exist on its own. The model itself is capable of enclosing sufficient results provided that the configuration guarantees a reliable representation of the surrounding mass conditions (in the present case, the project adopted pure material homogeneity and a detailed grid around the tunnel). Shear deformation is the dominant value that plays the role to define the level of the response and therefore the dynamic analysis was also a tool to detect the relative strain levels. Even so, a thorough search among past ground motion scenarios brings the suitable records (the key parameter here is the PGA of the region) that can more or less set the stress-strain framework to strengthen the reliability of the numerical model. The use of time-history (dynamic) analysis requires a suitable record selection (three or more) and a number of accompanying checks. The record time-histories must be compatible to the site response spectrum and were scaled to the relevant PGA. Further checks have to do with the frequency propagation ability offered by the model but also with the energy content of the input. Even the damping issue is considered in more than one ways. Consequently, this method turns out to be a useful, representative and exceptional tool as it is the only one that inserts dynamic loading. The basic topic is the interaction and the coexistence of the dynamic analysis with any simplified numerical approach. Such a combination is to be further examined at a large group of deep elements. This study demonstrates that, the two methods, if put together, can set the analyses to the same strain levels and consequently the correlation between them will be considered much more valid so as to evaluate the seismic response of the structure.
Reza Karami Mohammadi
K.N.Toosi University of Technology
Iran
Title: A New Approach in Optimal Semi-Active Control of Structures
Biography:
Reza Karami Mohammadi received the B.Sc. degree in civil engineering and the M.Sc. and Ph.D. degrees in earthquake engineering from Sharif University of Technology, Tehran, Iran, in 1983, 1989, and 2001, respectively. He is a faculty member with the Department of Civil Engineering, K.N. Toosi University of Technology, Tehran, since 2008. He is an experienced Civil Engineer with specializations in structural dynamics and earthquake engineering. He studied the effects of earthquakes on many residential, official, and industrial buildings since 1996. He has more than 16 years of experience in seismic analysis and design of structures. He is a Registered Professional Engineer in Tehran, Iran.
Abstract:
Magneto rheological (MR) dampers, as one of the most promising semi-active control devices, have received significant attention in recent years. Up to now, researchers have proposed various semi-active control algorithms for optimal control of buildings equipped with MR dampers. Optimization based on uniform deformation theory (UDT) was first proposed as a novel method in field of optimum design of structures. In this paper, efficiency of uniform deformation theory has been evaluated in field of semi-active control of buildings equipped with MR dampers, and the effect of applying this theory on structural response mitigations has been investigated. A method has been proposed in this research, by using polynomial controller, for determining optimum control voltage of MR damper with the goal of uniform distribution of maximum inter-story drifts of structure. In order to evaluate the performance of the proposed method, this controller has been applied to control of a six-story nonlinear shear frame. Particle Swarm Optimization (PSO) algorithm is utilized to find optimal coefficients of the polynomial controller by minimizing the standard deviation of maximum inter-story drifts of the structure for a set of three different earthquakes. The obtained results show that the proposed method has a successful performance in uniform distribution of maximum inter-story drifts. Moreover, the capability of the proposed controller has been compared with passive control in terms of reduction in the maximum inter-story drifts, displacements, absolute accelerations and control forces. The results indicate that the controller based on UDT has a better performance in structural response reductions, especially maximum inter-story drifts.
- Young Researchers Forum
Location: Ballroom section 3
Chair
Sherif Mohamed
Griffith University Queensland, Australia
Session Introduction
Md. Imran Kabir
Concordia University
Canada
Title: Finite Element Modeling to Evaluate the Existing Lateral Torsional Buckling Equations for Welded Wide Flange Shape
Biography:
Md. Imran Kabir has completed his B.Sc. from Bangladesh University of Engineering & Technology (BUET) and currently doing M.A.Sc. at Concordia University, Canada. Md. Imran Kabir has published 2 papers in reputed journals and 1 paper in conference.
Abstract:
Lateral Torsional Buckling (LTB) can be defined as a combination of lateral displacement and twisting due to an application of load on an unsupported beam. Design specifications in North America (AISC 2010 and CSA S16-09) provide solutions for LTB of welded and rolled beams that were derived for constant moment situation. Same equations have been used over the years for design of rolled and welded shape beams. A recent study has shown that the current code equations might overestimate the capacity of the welded wide shape beams, which make them unsafe to use. Thus a detailed study is required to evaluate the existing LTB equations for welded wide flange shapes. This paper evaluates the performance of current equations in providing LTB capacities of WWF shape beams. A nonlinear finite element model is developed using the commercial finite element software ABAQUS. In total of 15 WWF shape beams are analyzed. For the FE analysis, the beams are considered simply supported beams with uniform moments applied at the ends. Initial residual stresses in the WWF shapes that are reported in the literature are also included in the FE model.
Wei Gong
Huazhong University of Science and Technology
China
Title: A comparative assessment of probabilistic seismic hazard for pseudo-negative stiffness control of a steel base-isolated building
Time : 13:50-14:00
Biography:
Wei Gong is a doctoral researcher from China applying for my doctor degree from Huazhong University of Science and Technology. She has published 2 papers in chineses journals and several papers are about to publise. She is a younger researcher and her major research direction is seismic control of base-isolated structure.
Abstract:
Pseudo-negative stiffness (PNS) control is a semi-active control scheme that is aimed to track a negative-stiffness hysteretic loop. It is regarded as one of the most promising control schemes for vibration reduction. However, its effectiveness was demonstrated only by a few individual seismic records. In view of the variability of seismic characteristics, a more systematic investigation is needed for it. Using the methodology of probabilistic seismic hazard assessment (PSHA), the effects of PNS control on benchmark base-isolated building is studied. Comparisons are made between PNS control scheme and bilinear isolated scheme. The advantage of PSHA employed herein is that it allows for the consideration of effects of PNS control over various ground motions with different frequency contents or intensities. Moreover, the description of seismic responses in probabilistic format with PSHA is more explicit and scientifically complete. The spectral acceleration is selected as the seismic intensity measure and three response parameters (i.e. inter-storey drift ratio, isolation bearing deformation and floor acceleration) are considered to describe the damage associated with structure safety and structure functionality. For the particular controlled systems with nonlinear properties and thus with potential variable dynamic characteristics under different ground motions, an optimal period searching procedure is developed for the spectral acceleration calculation and hence leading to a more effective probabilistic estimation. The results of PSHA show that the PNS control scheme can achieve better performance with respect to structure safety and structure functionality than bilinear isolated scheme.
Omnia AbouEl-Hamd
United Arab Emirates University
UAE
Title: Experimental Investigation of the Fastening Parameters Influencing the Interfacial Behavior of Composite-Steel Anchored Lap Connections
Time : 14:00-14:10
Biography:
Eng. Omnia AbouEl-Hamd is a Graduate Teaching Assistant at the Department of Civil and Environmental Engineering at the UAE University. She completed her B.Sc. degree in Civil Engineering from UAE University in 2013 with distinction (honors degree). She is currently involved in the structural engineering research area for the fulfillment of her M.Sc. degree.
Abstract:
Fiber reinforced polymers (FRPs) are extensively used in several engineering fields due to their superior properties. In structural engineering applications, fiber polymers have been recently used for retrofitting and strengthening of existing structures. Bonded FRP-steel systems are widely used for rehabilitation purposes. However, the brittle failure at the composite-steel interface weakens those systems. This paper reports on recent experimental outcomes of an on-going multiphase research project that is being conducted at the United Arab Emirates University (UAEU). The project aims for investigating the effectiveness and performance of mechanically fastened composite FRP-steel systems. The current paper investigates the response of hybrid FRP-steel lap connections along with the associated interfacial behavior under different fastening parameters. The experimental program includes testing of 24 specimens to explore the influence of clamping torque, number of washers' thickness, and clearance between bolt and FRP hole on the load carrying capacity and ductility of the assembly. Experimental results show insignificant increase in the ultimate load of the connection associated with increasing the clamping torque. The presence of washers affects the failure mode of the connection and has significant effect on the load carrying capacity of the assembly. However, economical evaluation for the optimal number of washers-per-bolt is necessary for practical applications. Experimental outcomes reveal also that bolt-hole clearance influences both the stiffness and failure mechanism of the composite FRP-steel connections.
Mahesan Bavan
National University of Malaysia
Malaysia
Title: Typical Fracture Behaviour of the Steel-Concrete Composite Beam with Web Openings in Various Sizes under Axial Tension and Uniaxial Negative Bending
Time : 14:10-14:20
Biography:
Bavan has completed his MSc. In Civil and Structural Engineering from National University of Malaysia, Malaysia. He is a Civil Engineer with twelve years of vast professional experiences in planning, designing and directing the constructions of infrastructure, utilities, geotechnical & structural projects, and currently he is enduring the research to read PhD. He has published more than 25 papers in reputed journals and international conferences.
Abstract:
The effects of openings on the web of steel section of the steel-concrete composite beam under combined uniaxial negative bending and axial tension were examined herein by utilising Finite Element (FE) analysis. This emerging area of research, which was a composite beam with openings subjected to biaxial loads is not even inherently existed. The development of the FE analysis for a composite beam by realistic geometries of material components with accurate nonlinear material models, which was with assembling by complicated interactions, load applications and boundary conditions, was studied. In order to validate the FE model, the FE model was included by a comparative study with the existing experimental analysis and it was confirmed that the FE model and experimental results were in an acceptable manner by means of failure mode and limit state of the composite beam. The FE model validated was consisted of a series of web openings in ratio, each of which represented the formation of effective area on the web. In order to obtain the failure mode, the both axial loads were increased simultaneously and stress-strain values of each material component were studied thoroughly throughout the analysis, such that the limiting strees and strain of material components leading to the best estimate of failure mode will lead to the failure mechanism, which was the concept of the failure state prediction. It was predicted that the presence of openings with its provision ratio noticeably reduces the plastic moment capacity of the composite beam such that the phenomenon whereby the ratio increases leads the early failure state concurrently. Furthermore, important failure behaviour of the material components that influence on limit state is extensively discussed in this paper.
Dinesh Kumar
Indian Institute of Technology Kharagpur
India
Title: Structural changes study in High manganese steels and its effect on mechanical properties
Biography:
Dinesh Kumar is a PhD Student in Metallurgical and materials Engineering department, Indian Institute of Technology (IIT) Kharagpur, West Bengal, India. He received his M.Tech degree in Industrial Metallurgy from Indian Institute of Technology (IIT) Roorkee, Uttrakhand, India in 2009 and B.Tech degree in Mechanical Engineering from College of Engineering Roorkee in 2007. He has published 5 papers in international journals and 10 papers in reputated conferences. He has presented more than 15 technical papers in well known conferences. Currently he is preparing to submit thesis and looking for post doctoral position in well known universities of world in steel research. He has worked on friction stir processing in Aluminum alloys. His current research interest is in the field of High manganese steels which covers Effect of alloying element on austenite stability, Phase Transformation, formation of thermal induced and deformation induced ε and α’ martensite, Recrystallization behaviour, Effect of Martensite and Twinning on mechanical properties, EBSD and Texture analysis in deformed, recrystallized TWIP steel and martensite formed steels
Abstract:
High manganese steels are widely used in automobile industry and structural applications because of having outstanding mechanical properties. In high manganese category, TWIP Steel with high manganese content offers excellent strength ductility combination for automobile industry while High manganese TRIP steel and Hadfield steel offers higher strength with lower elongation as compared with TWIP steel. In this work different compositions of high manganese steels with carbon range (0.15-0.5 wt %) has been selected and subjected to quenching test and tensile test. Microstructure analysis has been done through optical microscopy and Scanning electron microscopy. XRD analysis has been done for identification and phase fraction calculation of austenite and martensite phases during quenching and tensile test. Stacking fault energy and stacking fault probability was calculated to show the effect of it on different phase formations. Formation of Twinning was observed in high carbon steel (TWIP) during tensile test while ε and α' martensite was found to be formed in low carbon high manganese steel during quenching test and tensile test. Stacking faults and stacking fault probability increases with increase in grain size without large variation. Mechanical properties of the steels were varying with the presence of twinning and martensite. Twinning offers a tensile strength of 940MPa and 62% elongation in steel with carbon 0.5 wt % while presence of martensite in low carbon steels (0.15-0.35 wt%) steels offers a tensile strength of 620 to 808 MPa and elongation of 22 to 42%.
Samadhan G. Morkhade
Visvesvaraya National Institute of Technology, Nagpur
India
Title: Optimisation of spacing to diameter ratio of openings in to steel beams with web openings
Biography:
Samadhan G. Morkhade is a Research Scholar in Structural Engineering, Dept. of Applied Mechanics, Visvesvaraya National Institute of Technology, Nagpur, Maharashtra, India. Completed his B.E (Civil Engg.) in 2008 from Sant Gadge Baba Amravati University, Amravati and M. Tech. (Structural Dynamics & Earthquake Engg.) from VNIT, Nagpur in 2011. His research area is steel structures.
Abstract:
To make the use of steel beams with openings in the web for construction of industrial buildings, high rise building, has turn out to be extensive in modern times. There are numerous reasons for which openings are kept. Various popular openings shapes are, hexagonal, circular and rectangular. Due to openings in the web the behaviour of such beam is different than that of plain-webbed beams. The various parameters which influence the behaviour of such special type of beams are shape of openings, size of openings, spacing of openings, aspect ratio, various numbers of openings and reinforcement (stiffeners). Therefore this paper presents the detailed experimental and finite element investigation on optimisation of spacing to diameter ratio of steel beams with web openings. Five models have been tested having different spacing to diameter ratio of openings for direct comparison. Spacing to diameter ratio of openings in the range of 1.33-1.6 found to very effective.