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Abstract
The plastic hinge lengths of beams and columns are a critical demand parameter in the nonlinear analysis of structures using the finite element method. The numerical model of a plastic hinge plays an important role in evaluating the response and damage of a structure to earthquakes or other loads causing the formation of plastic hinges. Previous research demonstrates that the plastic hinge length of reinforced concrete (RC) columns is closely related to section size, reinforcement ratio, reinforcement strength, concrete strength, axial compression ratio, and so on. However, because of the limitations of testing facilities, there is a lack of experimental data on columns with large section sizes and high axial compression ratios. In this work, we conducted a series of quasi-static tests for columns with large section sizes (up to 700 mm) and high axial compression ratios (up to 0.6) to explore the propagation of plastic hinge length during the whole loading process. The experimental results show that besides these parameters mentioned in previous work, the plastic hinge of RC columns is also affected by loading amplitude and size effect. Therefore, an approach toward considering the effect of these two parameters is discussed in this work.

Key Words
reinforced concrete column; axial compression ratio; plastic hinge length; loading amplitude; size effect

Address
Zhenyun Tang, Hua Ma, Jun Guo, Yongping Xie and Zhenbao Li: The Key Laboratory of Urban Security and Disaster Engineering, Ministry of Education, Beijing University of Technology. Beijing, 100124, China Yongping Xie: College of Exploration Technology and Engineering ,Shijiazhuang University of Economics, Shijiazhuang,050031, China

Abstract
Bridge bearings are important connection elements between bridge superstructures and substructures, whose health states directly affect the performance of the bridges. This paper systematacially presents a new method to identify the bridge bearing damage based on the neural network theory. Firstly, based on the analysis of different damage types, a description of the bearing damage is introduced, and a uniform description for all the damage types is given. Then, the feasibility and sensitivity of identifying the bearing damage with bridge vibration modes are investigated. After that, a Radial Basis Function Neural Network (RBFNN) is built, whose input and output are the beam modal information and the damage information, respectively. Finally, trained by plenty of data samples formed by the numerical method, the network is employed to identify the bearing damage. Results show that the bridge bearing damage can be clearly reflected by the modal information of the bridge beam, which validates the effectiveness of the proposed method.

Key Words
bridge bearing; damage identification; vibration mode; Radial Basis Function Neural Network; finite element model

Address
Zhaowei Chen: State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu, China Hui Fang: Electric Power Research Institute, State Grid Chongqing Electric Power Co. Chongqing, China Xinmeng Ke: Locomotive Vehicle Department, Zhengzhou Railway Vocational and Technical College, Zhengzhou, China Yiming Zeng: Locomotive and Car Research Institute, China Academy of Railway Sciences, Beijing, China

Abstract
The Groningen gas field shows exponential growth in earthquake event counts around a magnitude M1 with a doubling time of 6-9 years since 2001. This behavior is identified with dimensionless curvature in land subsidence, which has been evolving at a constant rate over the last few decades essentially uncorrelated to gas production. We demonstrate our mechanism by a tabletop crack formation experiment. The observed skewed distribution of event magnitudes is matched by that of maxima of event clusters with a normal distribution. It predicts about one event <M5 per day in 2025, pointing to increasing stress to human living conditions.

Key Words
induced earthquakes; crack formation; statistical forecasting

Address
Maurice H.P.M. van Putten: Physics and Astronomy, Sejong University, Seoul, South Korea Anton F.P. van Putten: AnMar Research Laboratories B.V., Eindhoven, The Netherlands Michael J.A.M. van Putten: Clinical Neurophysiology, Medisch Spectrum Twente and University of Twente, Enschede, The Netherlands

Abstract
Determination of earthquake-safety of existing buildings requires a rather long and challenging process both in terms of time and expertise. In order to prevent such a tedious process, rather rapid methods for evaluating buildings were developed. The purpose of these rapid methods is to determine the buildings that have priority in terms of risk and accordingly to minimize the number of buildings to be inspected. In these rapid evaluation methods detailed information and inspection are not required. Among these methods the Canadian Seismic scanning method and the first stage evaluation method included in the principles concerning the determination of risk-bearing buildings promulgated by the Ministry of Environment and Urbanization in Turkey are used in the present study. Within the scope of this study, six reinforced concrete buildings damaged in Van earthquakes in Turkey are selected. The performance scores of these buildings are calculated separately with the mentioned two methods, and then compared. The purpose of the study is to provide information on these two methods and to set forth the relation they have between them in order to manifest the international validity.

Key Words
reinforced concrete; first stage; seismic screening rapid assessment

Address
Department of Civil Engineering, Faculty of Engineering and Architecture, Bitlis Eren University, TR-13100, Bitlis, Turkey

Abstract
An efficient, economical and practical strengthening method for hollow brick infill walls was proposed and investigated in the present study, experimentally and numerically. This method aims at increasing the overall lateral strength and stiffness of the structure by increasing the contribution of the infill walls and providing the non-bearing components of the structure with the capability of absorbing earthquake-induced energy to minimize structural damage during seismic excitations. A total of eleven fullscale infill walls strengthened with expanded mild steel plates were tested under diagonal monotonic loading to simulate the loading condition of the non-bearing walls during an earthquake. The contact surface between the plates and the wall was increased with the help of plaster. Thickness of the plates bonded to both faces of the wall and the spacing of the bolts were adopted as test parameters. The experiments indicated that the plates were able to carry a major portion of the tensile stresses induced by the diagonal loads and provided the walls walls with a considerable confining effect. The composite action attained by the plates and the wall until yielding of the bolts increased the load capacities, rigidities, ductilities and energyabsorption capacities of the walls, considerably.

Key Words
expanded steel plate; brick infill wall; structural strengthening; diagonal compression; seismic behavior; reinforced concrete frame

Address
Alper Cumhur, Adil Altundal: Civil Engineering Department, Sakarya Üniversity, 54187 Sakarya, Turkey Sabahattin Aykac and Bengi Aykac: Civil Engineering Department, Gazi University, 06500 Ankara, Turkey

Abstract
Several two-dimensional analytical beam column joint models with varying complexities have been proposed in quantifying joint flexibility during seismic vulnerability assessment of non-ductile reinforced concrete (RC) frames. Notable models are the single component rotational spring element and the super element joint model that can effectively capture the governing inelastic mechanisms under severe ground motions. Even though both models have been extensively calibrated and verified using quasi-static test of joint sub-assemblages, a comparative study of the inelastic seismic responses under nonlinear time history analysis (NTHA) of RC frames has not been thoroughly evaluated. This study employs three hypothetical case study RC frames subjected to increasing ground motion intensities to study their inherent variations. Results indicate that the super element joint model overestimates the transient drift ratio at the first story and becomes highly un-conservative by under-predicting the drift ratios at the roof level when compared to the single-component model and the conventional rigid joint assumption. In addition, between these story levels, a decline in the drift ratios is observed as the story level increased. However, from this limited study, there is no consistent evidence to suggest that care should be taken in selecting either a single or multi component joint model for seismic risk assessment of buildings when a global demand measure such as maximum inter-storey drift is employed in the seismic assessment framework.

Key Words
beam-column joint; reinforced concrete; super-element joint model; scissors joint model; seismic analysis

Address
Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

Abstract


Key Words


Address


Abstract
With ongoing development of earthquake engineering research and the lessons learnt from a series of strong earthquakes, the seismic design concept of "resilience" has received much attention. Resilience describes the capability of a structure or a city to recover rapidly after earthquakes or other disasters. As one of the main features of urban constructions, tall buildings have greater impact on the sustainability and resilience of major cities. Therefore, it is important and timely to quantify their seismic resilience. In this work, a quantitative comparison of the seismic resilience of two tall buildings designed according to the Chinese and US seismic design codes was conducted. The prototype building, originally designed according to the US code as part of the Tall Building Initiative (TBI) Project, was redesigned in this work according to the Chinese codes under the same design conditions. Two refined nonlinear finite element (FE) models were established for both cases and their seismic responses were evaluated at different earthquake intensities, including the service level earthquake (SLE), the design-based earthquake (DBE) and the maximum considered earthquake (MCE). In addition, the collapse fragility functions of these two building models were established through incremental dynamic analysis (IDA). Based on the numerical results, the seismic resilience of both models was quantified and compared using the new-generation seismic performance assessment method proposed by FEMA P-58. The outcomes of this study indicate that the seismic resilience of the building according to the Chinese design is slightly better than that according to the US design. The conclusions drawn from this research are expected to guide further in-depth studies on improving the seismic resilience of tall buildings.

Key Words
performance-based design method; seismic loss; resilience; tall building; design codes

Address
Yuan Tian, Mengke Li: Beijing Engineering Research Center of Steel and Concrete Composite Structures, Tsinghua University, Beijing P. R. China Xiao Lu: Department of Civil Engineering, Beijing Jiaotong University, Beijing, P.R. China Xinzheng Lu: Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Department of Civil Engineering, Tsinghua University, Beijing, P.R. China Hong Guan: Griffith School of Engineering, Griffith University Gold Coast Campus, Queensland 4222, Australia

Abstract
Recently, magnetorheological elastomer (MRE) material and its devices have been developed and attracted a good deal of attention for their potentials in vibration control. Among them, a highly adaptive base isolator based on MRE was designed, fabricated and tested for real-time adaptive control of base isolated structures against a suite of earthquakes. To perfectly take advantage of this new device, an accurate and robust model should be built to characterize its nonlinearity and hysteresis for its application in structural control. This paper first proposes a novel hysteresis model, in which a nonlinear hyperbolic sine function spring is used to portray the strain stiffening phenomenon and a Voigt component is incorporated in parallel to describe the solid-material behaviours. Then the fruit fly optimization algorithm (FFOA) is employed for model parameter identification using testing data of shear force, displacement and velocity obtained from different loading conditions. The relationships between model parameters and applied current are also explored to obtain a current-dependent generalized model for the control application. Based on the proposed model of MRE base isolator, a second-order sliding mode controller is designed and applied to the device to provide a real-time feedback control of smart structures. The performance of the proposed technique is evaluated in simulation through utilizing a three-storey benchmark building model under four benchmark earthquake excitations. The results verify the effectiveness of the proposed current-dependent model and corresponding controller for semi-active control of MRE base isolator incorporated smart structures.

Key Words
magnetorheological elastomer (MRE) base isolator; earthquake mitigation; sliding mode control

Address
Yang Yu, Jianchun Li, Yancheng Li: School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia Sayed Royel, Quang Ha: School of Electrical Mechanical and Mechatronic Systems, University of Technology Sydney, Ultimo, NSW 2007, Australia

Abstract
Current codes design the buildings based on life safety criteria. In a performance-based design (PBD) approach, decisions are made based on demands, such as target displacement and performance of structure in use. This type of design prevents loss of life but does not limit damages or maintain functionality. As a newly developed method, resilience-based design (RBD) aims to maintain functionality of buildings and provide liveable conditions after strong ground movement. In this paper, the seismic performance of plain and strengthened RC frames (an eight-story and two low-rise) is evaluated. In order to evaluate earthquake performance of the frames, the performance points of the frames are calculated by the capacity spectrum method (CSM) of ATC-40. This method estimates earthquake-induced deformation of an inelastic system using a reduced response spectrum. Finally, the seismic performances of the frames are evaluated and the results are compared with a resilience-based design criterion.

Key Words
buildings; rehabilitation; resilience; performance; earthquake

Address
S. Ali Hadigheh: School of Civil Engineering, The University of Sydney, NSW, Australia S. Saeed Mahini: Discipline of Civil and Environmental Engineering, University of New England, NSW, Australia Sujeeva Setunge: Department of Civil Engineering, School of Engineering, RMIT University, VIC, Australia Stephen A. Mahin: Department of Civil and Environmental Engineering, University of California, Berkeley, USA

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