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CONTENTS
Volume 17, Number 5, November 2019
 

Abstract
The collapses of curved bridges are mainly caused by the damaged columns, subjected to the combined loadings of axial load, shear force, flexural moment and torsional moment, under earthquakes. However, these combined loadings have not been fully investigated. This paper firstly investigated the mechanical characteristics of the bending-torsion coupling effects, based on the seismic response spectrum analysis of 24 curved bridge models. And then 9 reinforced concrete (RC) and circular column specimens were tested, by changing the bending-tortion ratio (M/T), axial compression ratio, longitudinal reinforcement ratio and spiral reinforcement ratio, respectively. The results show that the bending-torsion coupling effects of piers are more significant, along with the decrease of girder curvature and the increase of pier height. The M/T ratio ranges from 6 to 15 for common cases, and influences the crack distribution, plastic zone and hysteretic curve of piers. And these seismic characteristics are also influenced by the compression ratio, longitudinal reinforcement ratio and spiral reinforcement ratios of piers.

Key Words
curved bridge; earthquake; bending moment; torsion coupling; seismic analysis; pseudo-static test

Address
Chiyu Jiao: Advanced Innovation Center for Future Urban Design, Beijing University of Civil Engineering and Architecture, 1 Exhibition Hall Road, Beijing, China; State Key Laboratory of Disaster Prevention in Civil Engineering, Tongji University, 1239 Siping Road, Shanghai, China; Engineering Structure and New Materials Research Center of Beijing Higher Education Institutions, Beijing University of Civil Engineering and Architecture, 1 Exhibition hall Road, Beijing, China
Jianzhong Li: State Key Laboratory of Disaster Prevention in Civil Engineering, Tongji University, 1239 Siping Road, Shanghai, China
Biao Wei: School of Civil Engineering, Central South University, 22 Shaoshan South Road, Changsha, China
Peiheng Long: Advanced Innovation Center for Future Urban Design, Beijing University of Civil Engineering and Architecture, 1 Exhibition Hall Road, Beijing, China; Engineering Structure and New Materials Research Center of Beijing Higher Education Institutions, Beijing University of Civil Engineering and Architecture, 1 Exhibition hall Road, Beijing, China
Yan Xu: State Key Laboratory of Disaster Prevention in Civil Engineering, Tongji University, 1239 Siping Road, Shanghai, China

Abstract
This present paper concerned with the analytic modelling for vibration of the functionally graded (FG) plates resting on non-variable and variable two parameter elastic foundation, based on two-dimensional elasticity using higher shear deformation theory. Our present theory has four unknown, which mean that have less than other higher order and lower theory, and we denote do not require the factor of correction like the first shear deformation theory. The indeterminate integral are introduced in the fields of displacement, it is allowed to reduce the number from five unknown to only four variables. The elastic foundations are assumed a classical model of Winkler-Pasternak with uniform distribution stiffness of the Winkler coefficient (kw), or it is with variables distribution coefficient (kw). The variable\'s stiffness of elastic foundation is supposed linear, parabolic and trigonometry along the length of functionally plate. The properties of the FG plates vary according to the thickness, following a simple distribution of the power law in terms of volume fractions of the constituents of the material. The equations of motions for natural frequency of the functionally graded plates resting on variables elastic foundation are derived using Hamilton principal. The government equations are resolved, with respect boundary condition for simply supported FG plate, employing Navier series solution. The extensive validation with other works found in the literature and our results are present in this work to demonstrate the efficient and accuracy of this analytic model to predict free vibration of FG plates, with and without the effect of variables elastic foundations.

Key Words
free vibration; variables elastic foundations; Functionally graded plate; higher shear deformation theory

Address
Mokhtar Nebab: Faculty Civil Engineering and Architecture, Civil Engineering Department, University Hassiba Benbouali of Chlef, Algeria
Hassen Ait Atmane: Faculty Civil Engineering and Architecture, Civil Engineering Department, University Hassiba Benbouali of Chlef, Algeria; Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria
Riadh Bennai: Faculty Civil Engineering and Architecture, Civil Engineering Department, University Hassiba Benbouali of Chlef, Algeria
Benabdallah Tahar: Deanship of Quality and Academic Accreditation, King Abdualziz University, Jeddah, Saudi Arabia

Abstract
In this paper, a procedure to develop fragility curves of structures equipped with semi-active tuned mass dampers (SATMDs) considering multiple failure criteria has been presented while accounting for the uncertainties of the input excitation, structure and control device parameters. In this procedure, Latin hypercube sampling (LHS) method has been employed to generate 30 random SATMD-structure systems and nonlinear incremental dynamic analysis (IDA) has been conducted under 20 earthquakes to determine the structural responses, where failure probabilities in each intensity level have been evaluated using Monte Carlo simulation (MCS) method. For numerical analysis, an eight-story nonlinear shear building frame with bilinear hysteresis material behavior has been used. Fragility curves for the structure equipped with optimal SATMDs have been developed considering single and multiple failure criteria for different performance levels and compared with that of uncontrolled structure as well as structure controlled using passive tuned mass damper (TMD). Numerical analysis has shown the capability of SATMDs in significant enhancement of the seismic fragility of the nonlinear structure. Also, considering multiple failure criteria has led to increasing the fragility of the structure. Moreover, it is observed that the influence of the uncertainty of input excitation with respect to the other uncertainties is considerable.

Key Words
fragility curves; semi-active tuned mass damper; multiple failure criteria; structural uncertainty; SATMD uncertainty

Address
Sina Bakhshinezhad and Mohtasham Mohebbi: Faculty of Engineering, University of Mohaghegh Ardabili, 56199-11367, Ardabil, Iran

Abstract
Understanding the behavior of skew bridges under the action of earthquakes is quite challenging due to the combined transverse and longitudinal responses even under unidirectional hit. The main goal of this research is to assess the response of skew bridges when subjected to longitudinal and transversal earthquake loading. The effect of skew on the response considering two- and three- span bridges with skew angles varying from 0 to 60 degrees is illustrated. Various pier fixities (and hence stiffness) and cross-section shapes, as well as different abutment

Key Words
Skew Bridge; seismic effects; finite element; design response spectrum; time history; modal analysis; earthquakes

Address
Mina F. Fakhry, Mostafa M. ElSayed and Sameh S.F. Mehanny: Structural Engineering Department, Cairo University, Giza, 12613, Egypt

Abstract
Elastic-plastic behavior of nuclear power plant elbow piping under seismic loads has been conducted in this study. Finite element analyses are performed using classical Bilinear kinematic hardening model (BKIN) and Multilinear kinematic hardening model (MKIN) as well as a nonlinear kinematic hardening model (Chaboche model). The influence of internal pressure and seismic loading on ratcheting strain of elbow pipe is studied by means of the three models. The results found that the predicted results of Chaboche model is maximum, closely followed by the predicted results of MKIN model, and the minimum is the predicted results of BKIN model. Moreover, comparisons of analysis results for each plasticity model against predicted results for a equivalent cyclic loading elbow component and for a simplified piping system seismic test are presented in the paper.

Key Words
pressurized pipe; seismic loading; finite element analysis; constitutive model; ratcheting strain

Address
Xiaohui Chen: School of Control Engineering, Northeastern University, Qinhuangdao, 066004, China; School of Mechanical Engineering, Yanshan University, Qinhuangdao, 066004, China
Kaicheng Huang, Sheng Ye: School of Control Engineering, Northeastern University, Qinhuangdao, 066004, China
Yuchen Fan: School of Control Engineering, Northeastern University, Qinhuangdao, 066004, China; College of Energy Engineering, Zhejiang University, Zhejiang, 310058, China
Zifeng Li: School of Mechanical Engineering, Yanshan University, Qinhuangdao, 066004, China

Abstract
In the study, an experimental and numerical study is performed to investigate the efficiency of diagonal shear reinforcement (DSR) on reinforced concrete (RC) short beams. For this purpose, 7 RC short beam specimens were tested under a 4-point loading, and a numerical study is conducted by using finite element method. Additionally, the efficiency of addition of DSR to specimens is observed in the experimental study together with the increase in stirrup spacing. Analysis results are compared in terms of load-displacement behavior and failure modes. As a result of the study, a significant improvement both in shear and displacement capacities of the RC short beams are achieved along with addition of DSR in short beams. Moreover, it is deduced from the numerical results that increasing both the diameter and yield strength of DSR makes a significant contribution to the shear capacity and ductility of shear critical RC members.

Key Words
reinforced concrete; shear; beams; finite element method; numerical simulation

Address
Hakan Ozturk, Naci Caglar and Aydin Demir: Department of Civil Engineering, Engineering Faculty, Sakarya University, Sakarya, Turkey

Abstract
The concrete gravity dam is one of the most important parts of the nation

Key Words
cumulative absolute velocity; fragility curve; response surface methodology; system identification; structural health monitoring; risk analysis

Address
Anh-Tuan Cao: Department of Civil Engineering, Kunsan National University, Republic of Korea
Tahmina Tasnim Nahar: Department of Civil Engineering, Kunsan National University, Republic of Korea; Department of Civil Engineering, Pabna University of Science and Technology, Bangladesh
Dookie Kim: Department of Civil Engineering, Kunsan National University, Republic of Korea
Byounghan Choi: Rural Research Institute, 870, Haean-ro Sangnok-gu, Ansan-si Gyeonggi-do, 15634, Republic of Korea

Abstract
This paper describes the construction of a laminar box for simulating the earthquake response of soil and structures. The confinement of soil in the transverse direction does not rely on the laminar frame but is instead achieved by two acrylic glass walls. These walls allow the behaviour of soil during an earthquake to be directly observed in future study. The laminar box was used to study the response of soil with structure-footing-soil interaction (SFSI). A single degree-of-freedom (SDOF) structure and a rigid structure, both free standing on the soil, were utilised. The total mass and footing size of the SDOF and rigid structures were the same. The results show that SFSI considering the SDOF structure can affect the soil surface movements and acceleration of the soil at different depths. The acceleration developed at the footing of the SDOF structure is also different from the surface acceleration of free-field soil.

Key Words
laminar box; dynamic soil response; shake table test; structure-footing-soil interaction; soil boundary condition

Address
X. Qin, W.M. Cheung and N. Chouw: Department of Civil and Environmental Engineering. The University of Auckland, Auckland Mail Centre, Private Bag 92019, Auckland 1142, New Zealand


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