Day 2 :
Keynote Forum
Lu Deng
Hunan University, China
Keynote: Study on rotation construction control of a hybrid-girder cable-stayed bridge with single pylon and single cable plane
Time : 09:15 to 10:00
Biography:
Lu Deng has obtained his PhD degree in Civil Engineering from Louisiana State University in 2009 and worked as a Research Engineer in the Offshore Structure Division at ExxonMobil for 3 years. He is currently a Full Professor in the College of Civil Engineering at Hunan University. He is an Associate Editor of the ASCE Journal of Bridge Engineering and Guest Editor of ASCE Journal of Aerospace Engineering. His areas of expertise include bridge safety evaluation, bridge fatigue and bridge-vehicle coupled vibration. He has published over 100 technical papers, including more than 40 peer-reviewed journal papers in English.
Abstract:
The structure of hybrid girder cable-stayed bridges with single pylon and single cable plane is very complex, which leads to the difficulty in predicting their structural behavior during construction and operation. In this study, the rotation construction process of such a bridge is analyzed. The bridge under consideration is a highway bridge that crosses the railway and has a main span of 169 m. The ZTQZ-350MN rotating system, which is the largest of its kind that has ever been adopted in the rotation construction of bridges, is adopted for this bridge to avoid the interruption of the railway operation. The structural design for the rotation construction of the bridge, the construction of the steel-concrete hybrid girder, and the mechanical behavior of the rotating parts of the bridge during rotation and its construction control are investigated. The structural behavior of the bridge during the construction process is analyzed using the commercial finite element software Midas/Civil. The displacement and the stress of the main girder are calculated, which then provide useful information for the determination of the line shape and the stress control of the bridge. The dynamic analysis model of the bridge is established and is used to investigate the stresses of the bridge during the accelerated and decelerated rotation process. Based on the analysis results, the threshold value for the acceleration/deceleration rate during the rotation process is determined. The findings from this study provide useful reference for the construction control of hybrid girder cable-stayed bridges with single pylon and single cable plane.
Keynote Forum
Feroz Alam
Public Works Authority, Qatar
Keynote: Innovative concept on structural engineering of mega tall buildings: Applied to one kilometer high concrete skyscraper and concept of concrete reduction from shear walls of tall buildings
Time : 10:AM to 11:00
Biography:
Feroz Alam has invented a structural concept for mega tall buildings which can build one kilometer tower where no additional structural supporting systems are required like belt truss, outriggers and bracings, etc. Currently he is working for Qatar Government as a Design Engineer.
Abstract:
Structural system of tall buildings have undergone dramatic changes since the demise of the conventional rigid frames in the 1960s as the predominant type of structural system for steel or concrete tall buildings. There are numerous structural lateral systems used in high-rise building design such as shear frames, frames with shear core, framed tubes, tube in tube, super frames which can construct for up to 140 stories. Later developed structural systems like outriggers and the buttress core has allowed for even higher buildings, can design for up to 160 stories. This study is intended to model an advanced structural system for tall buildings which can build taller than the tallest existing one in the world. In this innovative concept, “One Kilometer Mega Structure’’ analyzed where several parallel shear walls have been arranged in both directions and connected with beams and slabs. The shear walls are continuous down to the base to which they are rigidly attached to form vertical cantilevers. Their high in plane stiffness and strength make them well suited for bracing buildings up to about 278 stories (where drift at top 1930 mm, allowable H/500=2000 mm). Dynamic analysis of this I KM tower shows that the habitable floor is at height 723 m (Record breaking habitable height at 201 storied) besides, by introducing TMD can make the top habitable. Also it is found by research that, when this structural arrangement is applied to around 831 m tall structure with aspect ratio 8.14:1, no additional structural supporting system is required and habitable floor is at 831 m (231 stories). Whereas existing world tallest one have habitable floor at 535 m (160 stories). This shear walls arrangement is applicable for tall buildings of any height to avoid additional supports to resist the lateral forces while taking advantage of the creative approach of this concept.
Keynote Forum
Airong Liu
Guangzhou University, China
Keynote: Experimental research on stable ultimate bearing capacity of leaning-type arch rib systems
Time : 11:15 to 12.00
Biography:
Airong Liu has received her PhD degree in Solid Mechanics from Southwest Jiaotong University and has worked in Guangzhou University for over 16 years. Currently she is mainly engaged in structural vibration and stability research of large span bridge and is the Vice Director of China International Science and Technology Cooperation Base and the Council Member of The Chinese Society of Theoretical and Applied Mechanics on Civil Engineering. She is also the Reviewer of Journal of Bridge Engineering and International of Structural Stability and Vibration.
Abstract:
The stability of a leaning arch structural system was investigated experimentally in this study. Scaled models of five structural systems including a single arch, a parallel arch, and leaning arch systems with a 10, 20, and 30 degree inclined angles between the main and the stabilizing arches were constructed. Each of these models was tested under five point loads spaced equally along the arch. Results show that adding stabilizing arches increased arch’s lateral stability as well as its ultimate bearing capacity. Comparing against the single arch the parallel arch, 10 degree, 20 degree and 30 degree arch system had 14.3%, 15.6%, 13.7%, and 12.9% increase in ultimate bearing capacity, respectively. As the inclined angle of the leaning arch increased, the failure mode changed from out-of-plane buckling to in-plane buckling. Out-of-plane buckling failure was observed in the single arch, parallel arch, and 10 degree arch system, while in-plane buckling failure was observed in the 20 degree and 30 degree arch rib system. Among the five models tested, the 10 degree leaning arch system had the highest ultimate bearing capacity.
Keynote Forum
Meheddene M Machaka
Beirut Arab University, Lebanon
Keynote: Composite shear walls: An efficient seismic resistant system for multi-story buildings
Time : 12.00 to 13.00
Biography:
Meheddene M Mashaka is an Adjunct Professor in the Department of Civil and Environmental Engineering at Beirut Arab University and Rafik Hariri University in the field of structural analysis and construction materials. He has received his Bachelor of Science in Civil Engineering in 1992 at BAU, MSc in Structural Engineering in 2005 and PhD degree in 2015 at Beirut Arab University, Lebanon. He is the Technical Manager for United Engineers Office at Beirut city from 1994 to till date and a Faculty Member in the Department of Civil Engineering.
Abstract:
Steel-concrete composite systems have seen widespread use in recent decades because of the benefits achieved by merging the two materials. Due to their high stiffness and lateral load resistance, reinforced-concrete shear walls (RCSW) and steel-plate shear walls (SPSW) are considered ideal for resisting earthquake lateral loads in moderate and high-rise buildings. Recently, various schemes of composite shear walls (CSW) have been the focus of recent research. The objective of this paper is to investigate analytically the behavior of composite shear walls as a lateral-load resisting system in comparison to RCSW. The investigation is performed on buildings with variable heights provided with either (RCSW) or (CSW). Three dimensional models for the case-study buildings are assembled using ETABS, computer software based on the finite element method. The buildings are analyzed for static lateral forces computed by the equivalent static load method (UBC-1997), response spectra dynamic analyses and dynamic time-history linear analyses using IZMIT earthquake record. Results are compared and interpreted so as the major findings include: First, to highlight on the structural characteristics and behavior of composite shear walls as a seismic resistant system. Secondly, to compare between the structural behavior of RCSW and CSW concerning their drifts, base shear and strength.
Keynote Forum
Hieng Ho Lau
Curtin University Sarawak, Malaysia
Keynote: Non-linear behavior of back-to-back built-up cold-formed steel columns under compression: Finite element modeling and parametric study
Time : 14:00 to 14:45
Biography:
Hieng Ho Lau is currently the Dean of Faculty of Engineering and Science, Curtin University Malaysia. He is a Member of Curtin University Malaysia Campus Community where he has accumulated over 14 years of teaching experience in the field of civil engineering. He is a Professional Engineer with Practicing Certificate registered with Board of Engineers Malaysia (BEM) and also Chartered Professional Engineer with Engineers Australia.
Abstract:
This paper presents a numerical investigation on the behavior and design of back-to-back built-up cold-formed steel channel columns subjected to axial compression. Numerical models were developed using general purpose ï¬nite element (FE) package ABAQUS and have been veriï¬ed using experimental data reported by the authors recently (ting. et. al (2017). Developed finite element models included material nonlinearities as well as initial geo- metric imperfections. Axial strength of columns, failure modes, deformed shapes at failure, load-displacements were predicted from the finite element analyses and obtained comparisons with test results showed considerable match. A comprehensive parametric study has been carried out covering a wide range of slenderness for the considered back-to-back built-up columns. Axial capacities obtained from the numerical study were used to assess the performance of the current North American standards(NAS) and Australian and New Zealand Standards when applied for cold-formed back-to-back built up columns; obtained comparisons showed that NAS and the Australian and New Zealand Standards are un-conservative for stub and short columns sections which were failed by local buckling whereas standards were over-conservative for the strength of columns which were failed mainly by overall member buckling.
- Bridge Engineering | Prestressed Structures | Steel Concrete Composite Structures | Structural Stability | Foundation Engineering | Advanced Structural Analysis
Location: Seletar Room 1 , Level 3
Chair
Airong Liu
Guangzhou University, China
Co-Chair
Alnuaimi Ali
Sultan Qaboos University, Oman
Session Introduction
Olivia Mirza
Western Sydney University, Australia
Title: Experimental investigation of an existing and new retrofitted steel bridge girder due to fatigue failure
Biography:
Olivia Mirza was a Golden Jubilee Scholarship holder at University of New South Wales in 2000. She has graduated in Bachelors (Civil and Environmental) in 2002. She has worked as a Structural Engineer for 8 years before pursuing her academic career. She has worked for Leighton Contractors, Australia Consulting Engineers and Cardno Group. She is currently a Senior Lecturer in School of Computing, Engineering and Mathematics. She is also Academic Course Advisor for Postgraduate Fire Safety Engineering Program. She has published more than 25 papers in reputed journals and has been serving as an Editorial Board Member of repute.
Abstract:
This research paper investigates an innovative retrofitting technique when an existing steel bridge girder is subjected to fatigue failure. This is an alternative method other than replacing the failed existing bridge structures. The experimental study is focused on rehabilitating steel bridge girders through retrofitting to their original design capacities that have incurred fatigue cracking within the bottom flange. Fatigue is an increasing issue as many steel structures reach the end of their design life each year. Steel structures reaching the end of their design life each year coupled with increased loadings, deterioration due to weathering, climate change and human error also negatively impact the design life. Hence a solution to rehabilitation of the existing steel bridge girders is required to provide a sustainable future. This paper focuses on retrofitting steel bridge girders to further extend their service life. Experimental studies have been conducted on a 120-year-old girder and a new 610UB113 equivalent girder. The results from the experimental test showed that if steel bridge girders have experienced fatigue cracking within the bottom flange, they can be retrofitted with the designed retrofit rehabilitating the girders to their original design loading capacities. Overall it was determined that steel bridge girders can be rehabilitated with the innovative retrofitting technique. Furthermore, this innovative technique enforces that the existing structures do not need to be replaced, instead of using a simple retrofitting technique is sufficient in restoring the existing steel bridge girders to increase their service life to provide a sustainable future.
P K Gupta
Indian Institute of Technology Roorkee, India
Title: Behavior of concrete filled rectangular steel tubes subjected to flexural loading
Biography:
P K Gupta is currently working as a Professor of Structural Engineering in the Department of Civil Engineering of Indian Institute of Technology Roorkee, India. He has obtained his Doctoral degree in 2001 from Indian Institute of Technology Delhi, India in the area of Structural Mechanics. His areas of research are: Structural mechanics, finite element analysis, parallel computing, steel-concrete composite and large deformations. He has published more than 130 research papers in international and national journals, conferences. He has experience of organizing short term courses, seminars, workshops and conferences as organizing secretary. Recently, he was awarded with the Endeavour awards of Australian Government.
Abstract:
A nonlinear fiber element analysis method has been presented for predicting the flexural strength of concrete filled steel tubes (CFST). The validation of the method has been done by comparing the results with the actual tested specimens. The fiber element analysis program was developed in Oracle software. Master form has master blocks and a table. Master blocks are used for the input data as well as for calculation work. Table in master form is used to show all required information about each fiber like centroidal distance from neutral axis, strain, stress, force and bending moment of each fiber. The master block section is divided into three parts namely: (1) Input data, (2) Calculation and (3) Results. The input section contains master blocks for material properties, dimensions of the specimen (like length, breadth and depth), steel tube thickness (all four sides) dimensions of concrete core section and the curvature for which results are obtained. To create the fibers, section of the beam is divided into parts as per requirement. Calculation section contains the calculation of centroidal distance of each fiber and other parameters which includes material stress-strain relationship to find neutral axis. Results section provides the printout for centroidal distance from neutral axis, strain, stress, force, bending moment in each fiber. Two rectangular steel hollow tubes having width 120 mm and wall thickness 1.58 mm and depths 140 and 150 mm were filled with concrete having compressive strength 60 MPa and 80 MPa. Both specimens having 1000 mm span were tested under pure bending with four point loading arrangement. A good ductility was observed in the tests. Accuracy of fiber element analysis program is verified by comparing its findings with the counterpart experimental results of both tested specimens and four specimens from literature. It is found that the fiber element analysis technique predicted results within acceptable degree of accuracy.
Youqin Huang
Guangzhou University, China
Title: Investigation on dynamic instability of concrete-filled steel tubular column
Biography:
Youqin Huang has his expertise in evaluating the dynamic stability of structures. He has constructed a fresh method to investigate the stability of structure subject to arbitrary parametric excitation. He has also studied the stability of long span wind-sensitive roofs under stochastic wind loads or joint actions of wind and snow, and proposed a method to calculate the equivalent static wind load for the stability design in practical engineering.
Abstract:
A new method for evaluating the dynamic instability of concrete-filled steel tubular (CFST) column under axial periodic excitation is proposed. The unified equations of dynamic instability of CFST column are explicitly derived based on the differential equations of lateral vibration and the Galerkin method. By employing the theory of Bolotin, the equations of boundary frequencies can be formulated in the format of eigenvalue problem. Subsequently, the regions of dynamic failure can be rigorously constructed by solving the eigenvalue problem. Numerical investigations have been conducted to investigate the applicability and effectiveness of the proposed approach. It is demonstrated that the CFST column, especially those with high slenderness ratios, would become dynamically unstable when the magnitude of the excitation is well below the static buckling load of the column.
Jaewook Jeong
SEN Engineering Group , Singapore
Title: Case studies of innovative composite structural system applied to Singapore and South Korea
Biography:
Jaewook Jeong is Country Manager of Singapore at SEN Engineering Group. He has received his PhD from Architectural Engineering at Yonsei University. As a Professional Engineer, he had worked for Kolon Global Corporation in South Korea and he, as a Researcher, also have published several SCI(E) papers about productivity and sustainability on construction industry.
Abstract:
Off-site construction methods such as prefabrication method have been developed to improve productivity in construction and to reduce cost. SEN Engineering Group, a Korea-based structural productivity solution provider, introduces new productivity enhancing construction methodologies, including the Form Prefab Steel Reinforced Concrete (F-PSRC) column and Thin Steel Concrete beam system. This system can dramatically augment on-site productivity by reducing or eliminating the usage of temporary scaffolding works and form-works. The F-PSRC column and TSC beam system has been successfully applied in more than 50 projects in Korea, especially in those involving super-fast-track IT industry factories and offices. In terms of productivity, it was identified through the previous study that F-PSRC columns technology was 42.45% more productive than the conventional SRC columns without increasing of overall cost including fabrication and on-site construction. And now this system is about to be introduced in Singapore through a large-scale inland container deposit project. This system focuses to enhance productivity on site by reducing temporary on-site works and pursuing factory prefabrication. Hence, it is imperative that those in the industry learn about how the F-PSRC column and TSC beam system practices and design are able to shorten the construction periods of projects.
Mahesan Bhavan
Member of American Society Civil Engineers, Singapore
Title: Local web buckling failure criteria of the steel-concrete composite beam with openings subjected to combined negative bending and axial compression
Biography:
Mahesan Bavan has completed his MSc in Civil and Structural Engineering from National University of Malaysia, Malaysia. He is a Civil Engineer with 12 years of vast professional experiences in planning, designing and directing the constructions of infrastructure, utilities, geotechnical and structural projects and currently he is enduring the research to read PhD. He has published more than 40 papers in reputed journals and international conferences.
Abstract:
An investigation of the buckling behavior of webs in castellated beams of steel-concrete composite beam subjected to combined in-plane negative bending and axial compression is conducted. A Finite Element (FE) model was developed for a steel-concrete composite beam subjected to combined negative bending and axial compression and validated against global and local failure behaviors using experimental analysis in the existing literatures such that the developed FE model can be used for further parametric studies. Subsequently, castellated web panels were modeled in two forms such as square and circle patterns, while the boundary condition and load application of the composite beam were remained same and further investigations have been done on failure behaviors by applying a series of numerical analyses using the three-dimensional finite element modeling. Failure modes in two areas such as local buckling in the web and flanges of castellated steel beam were adopted to predict the ultimate strength of the composite beam, which the predicted ultimate strengths were found earlier with reduction in comparison. Due to the influences of axial compression on mechanical shear connectors, excessive stresses will be induced, which will affect the transmitting shear and accordingly, complexities of interaction analysis techniques should be adopted such that the assessment of existing composite beams and bridge girders in the castellated beams is conservative. It can be concluded in the comparison with the assessment of existing composite beams and bridge girders that this conservative approach may not be warranted as it is often necessary to extract the accurate capacity and stiffness of the beam. This study proposes combined axial loads to predict the failure behavior of steel castellated section composite beam, which is a significant new concept that allows engineers to develop more accurate procedures for determining the strength and endurance of existing composite beams and bridge girders.
- Earthquake Engineering | Strength of materials | Geotechnical aspects | Green Building | Fabrication of Structures | Construction Engineering
Location: Seletar Room 1 , Level 3
Chair
Xuechun Liu
Beijing University of Technology, China
Co-Chair
Hieng Ho Lau
Curtin University Sarawak, Malaysia
Session Introduction
Alnuaimi Ali
Sultan Qaboos University, Oman
Title: Basic wind speed map for Oman
Biography:
Alnuaimi Ali is an Associate Professor in Civil and Architecture Engineering Department, Sultan Qaboos University, Oman. His research expertise focuses on structural design and analysis, estimating construction cost and administration of contracts. He has published more than 42 refereed journal papers and 33 conference papers. He has carried out tens of consultancy works for different agents in the field of civil engineering.
Abstract:
Oman is not considered a potential earthquake zone, and therefore, the effect of wind loads on structures are considered the dominant factor when determining lateral loads on edifices such as buildings, chimneys, and power or satellite communication transmission towers. The aim of this research was to develop the first basic wind speed map for Oman. Hourly-mean wind speed records from 40 metrological stations were used in the calculation. The period of continuous records ranged from 4-37 years. The maximum monthly hourly-mean and the maxima annual hourly-mean wind speed data were analyzed using Gumbel and Gringorten methods. Both methods gave close results in determining basic wind speeds, with the Gumbel method giving slightly higher values. The maximum and minimum differences between the two method values were 2.97 and 0.31%, respectively in the case of monthly maximum hourly-mean and 7.58 and 1.85%, respectively in the case of annual maxima. Due to lack of long-term records in some regions of Oman, basic wind speeds were extrapolated for some stations with short-term records, which were defined as those with only 4-8 years of continuous records; in these cases, monthly maxima were used to predict the long-term basic wind speeds. Accordingly, a basic wind speed map was developed for a 50-year return period. This map was based on basic wind speeds calculated from actual annual maxima records of 29 stations with at least 9 continuous years of records as well as predicted annual maxima wind speeds for 11 short-term record stations. The basic wind speed values ranged from 16 m/s to 31 m/s. The basic wind speed map developed in this research is recommended for use as a guide for the structural design in Oman.
Zixuan Shang
Beijing University of Technology, China
Title: Seismic performance of prefabricated cable-braced steel frames
Biography:
Zixuan Shang is pursuing graduation from the College of Architecture and Civil Engineering of the Beijing University of Technology, China. Her research interests focus on prefabricated steel high-rise steel structures.
Abstract:
Given their superior performance, steel cables have been used in steel structures as braces, but the studies on this topic have not been sufficient. A new type of prefabricated cable-braced steel frame is proposed in this paper. To investigate the seismic performance of a prefabricated cable-braced steel frame, quasi-static tests and finite element analysis are performed on a pure steel frame and on four pairs of cable-braced frames. One frame exhibited no pretension and the other exhibited pretension in each pair. All of the frames were the same, while the cables included different cross-sectional areas among the four pairs. The analysis examines the hysteresis performance, bearing capacity, ductility, self-centering capabilities and failure modes of the four pairs of cable-braced frames and pure frames. The influence of cable cross-sectional areas on the cable tension, hysteresis performance, bearing capacities, ductility, self-centering capabilities and elastic-plastic development of the cable-braced frames is studied relative to the pure frame. The results of the tests and finite element analysis (FEA) are nearly uniform. The results indicate that cable-braced frames exhibit reasonable levels of hysteresis performance, energy dissipation and self-centering. A larger cable cross-sectional area enables superior self-centering capabilities and more pronounced levels of rigidity degradation. The energy dissipation capacity and displacement ductility initially increase followed by a subsequent decrease with increasing cable cross-sectional area. The influencing factors of lateral stiffness and the load-bearing mechanisms of cable-braced frames are revealed from a theoretical formula of lateral stiffness and from an analysis of bearing capacity and the influence of pretension on cable-braced frames are obtained.
T L Pradeep
The Open University of Sri Lanka, Sri Lanka
Title: Steel structure optimization through the performance based design: Case study using push over analysis
Biography:
T L Pradeep has more than 10 years research experience and comprehensive industrial commitment in engineering discipline. He has completed his PhD in Structural Engineering at University of Basilicata, Italy under the European Commission Merit Scholarship Program (EUNICE) and Master of Science, Bachelor of Science in University of Perdeniaya, Sri Lanka and University of Ruhuna, Sri Lanka, respectively. He is pioneer in structural engineering, seismic engineering, sustainable material and green construction, dynamic analysis and design, high rise building design and renewable sector.
Abstract:
Steel structures became fastest and attractive construction strategy for the industrial building all over the world form the two decades ago. However, the many countries followed their own codes to design the steel structures based on experience. However, most of the design has been done based on the local design philosophy and country accepted codal provision given. In this research it has been discussed the performance based design of steel building to predict the global behavior in order to optimize the steel structures over the global behavior. The two case studies have been done to evaluate the structural performance of the steel structures. The both studies have been carried out under the same loading (lateral) and output compared by using push over analysis. Elastic spectrums have been derived and it has compared with demand curve produced. However, local structural elements also be evaluated based on the codal provision given in order to make sure the ultimate and serviceability limit state. It clearly show that convectional design proceedings for the steel structures has been shown less performance compare to performance based design. The performance based analysis were compared and show significant impact on the design phase where the critical analysis of the structure became the lateral loading condition. The plastic hinge formation of structure used to predict the overall structural performance. Finally, it has been compared foundation, super structural element separately for the purpose of doing the cost comparison. In Sri Lanka, the most of the construction are focus to reinforced concrete and however most of the client brings realizing the advantages of steel structure. Only challenge is the structural stability over the ductility which earns more on concrete. But, it has been addressed over this design for moderate condition where the Euro code 8 specified respect to the Ecurocode 3 (steel design). The loading combinations of each structure have been considered as per the BS 6399 and it is more conventional to have lateral loading condition.
Piero Colajanni
University of Palermo, Italy
Title: Structure dependent selection criterion of natural accelerogram sets for non-linear time history analysis
Biography:
Piero Colajanni is an Associate Professor of Structural Engineering at the DICAM, University of Palermo, Italy. He has completed his MSc in Civil Engineering (1990) and PhD in Structural Engineering (1995) at Palermo University. In 1996, he was Visiting Assistant Professor at Florida Atlantic University, Department of Mechanical Engineering, Researcher of Engineering and Solid Mechanics in 1997 and Associate Professor of Structural Engineering in 2001 at University of Messina. In 2013 he moved to University of Palermo, where nowadays teaches building structural analysis and design and seismic design of buildings. Since 1991, he is a Member of Italian National Association of Earthquake Engineering and was Promoter and President of the Scientific Committee of Masters in Seismic Engineering at University of Messina in 2003 and 2006. He has authored more than 150 papers on international and national journals and conference proceedings.
Abstract:
Non-linear response history analysis (NRHA) represents nowadays the more accurate method for prediction of the seismic response of structures because it incorporates in the analysis model the non-linear material and geometry behavior. In NRHA a key issue is the input modeling. A research aiming to find out a selection criterion for different sets of accelerograms, all of them satisfying the spectrum compatibility criteria imposed by the code, that enable a reliable assessment of the seismic demand is performed. The analysis is based on a preliminary evaluation of correlation among parameters for ground motion intensity measure (IM) and cinematic, energetic and damage parameters describing structure nonlinear responses. To this aim, a modified expression of the effective peak acceleration (EPA) is proposed, defined over the range of structure fundamental period referring to undamaged and damaged model would help this recognition. Subsequently, a method of selecting accelerograms has been proposed, able to take into account the two components of each seismic accelerations capable of providing sets of accelerometers compatible with a predetermined response spectrum and which effects on the analyzed structure are individually consistent with the seismic intensity presented by the spectrum. The selection criterion for accelerogram sets is based on the minimum value of the coefficient of variation (CoV) of the EPA. It reduces the dispersion of the effects of each accelerograms on the structure that has to analyze or designed, that is one of the most relevant drawbacks of the selection criterion available in literature. Validation of the criterion is carried out analyzing the response of the three plane multi-stored moment resisting frames (MRFs) to a set of 60 different accelerograms and analyzing the value of the correlation coefficient between input intensity measure and structure response parameters. The effectiveness of a selection criterion is proved by evaluation of average values and COV of NRHA response parameters of MRFs.
Konstantinos Daniel Tsavdaridis
University of Leeds, UK
Title: Perforated steel beams and their use for seismic-resistant design of connections
Biography:
Konstantinos Daniel Tsavdaridis is an Associate Professor and the Director of the research group focuses on steel and steel-concrete composite structures in the School of Civil Engineering at the University of Leeds, UK. He holds MEng degree from City, University of 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 seismic-resistant structural members and systems, and testing large and full scale specimens. He has published some 100 scientific articles, journal publications, technical reports and international conference papers. He is also an inventor and he has filed a few patents on resilient, lightweight and sustainable structural systems.
Abstract:
Today, it is estimated that more than 35% of steel-framed buildings incorporate long spans in excess of 12 m. In the 1990s the cellular beam, which replaced the castellated beam, gained prominence. Cellular beams are now estimated to have increased from 40% to 92% share of the steel beams in the UK market according to the new steel construction (NSC) magazine. There has been a lot of research on perforated beam webs with the geometry of the perforation ranging from circular, elongated, to non-standard shapes. However, very limited research has been found with regards the design limitations of seismic resistant connections when such perforated beams are used. Studies were conducted by FEMA and the SAC Joint Venture with reports ranging from FEMA-350 to 355F aim to develop reliable, practical and cost-effective design guidelines and specifications of reduced web opening (RBS) connections while do not include substantial reference to connections with the use of lightweight perforated beams (the so-called Reduced Web Section – RWS connections) with closely or widely spaced web openings. However, increased demand using lightweight structural members from seismic active regions has been recently recorded and the use of perforated beams in such areas deems further research. The presentation will discuss the up-to-date research work and propose design recommendations for RWS connections. The use of large isolated and periodically spaced perforations will be presented as an effective way of improving the seismic behavior of connections enhancing their ductility, rotational capacity and energy dissipation capacity.