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Abstract
A family of the structure-dependent methods seems very promising for time integration since it can simultaneously have desired numerical properties, such as unconditional stability, second-order accuracy, explicit formulation and numerical dissipation. However, an unusual overshoot, which is essentially different from that found by Goudreau and Taylor in the transient response, has been experienced in the steady-state response of a high frequency mode. The root cause of this unusual overshoot is analytically explored and then a remedy is successfully developed to eliminate it. As a result, an improved formulation of this family method can be achieved.

Key Words
overshooting, steady-state response, local truncation error, structure-dependent integration method

Address
Shuenn-Yih Chang and Tsui-Huang Wu: Department of Civil Engineering, National Taipei University of Technology, 1, Sec. 3, Jungshiau East Road, Taipei 106-08, Taiwan

Abstract
This paper investigates the role of the masonry infills on the correlation between widely used earthquake Intensity Measures (IMs) and the damage state of 3D R/C buildings taking into account the orientation of the seismic input. For the purposes of the investigation an extensive parametric study is conducted using 60 R/C buildings with different heights, structural systems and masonry infills\' distributions. The results reveal that the correlation between the IMs and the seismic damage can be strongly affected by the masonry infills\' distribution, depending on the special characteristics of the structural system, the number of stories and the incident angle.

Key Words
reinforced concrete; masonry infills; nonlinear dynamic analysis; seismic excitation angle; seismic damage; ground motion intensity measures; correlation between IMs and seismic damage

Address
Konstantinos G. Kostinakis: Department of Civil Engineering, Aristotle University of Thessaloniki, Aristotle University Campus, 54124, Thessaloniki, Greece

Abstract
Low cyclic loading tests are conducted on the steel reinforced recycled concrete (SRRC) column-steel (S) beam composite frame joints. This research aims to evaluate the earthquake damage performance of composite frame joints by performing cyclic loading tests on eight specimens. The experimental failure process and failure modes, load-displacement hysteresis curves, characteristic loads and displacements, and ductility of the composite frame joints are presented and analyzed, which shows that the composite frame joints demonstrate good seismic performance. On the basis of this finding, seismic damage performance is examined by using the maximum displacement, energy absorbed in the hysteresis loops and Park-Ang model. However, the result of this analysis is inconsistent with the test failure process. Therefore, this paper proposes a modified Park-Ang seismic damage model that is based on maximum deformation and cumulative energy dissipation, and corrected by combination coefficient a. Meanwhile, the effects of recycled coarse aggregate (RCA) replacement percentage and axial compression ratio on the seismic damage performance are analyzed comprehensively. Moreover, lateral displacement angle is used as the quantification index of the seismic performance level of joints. Considering the experimental study, the seismic performance level of composite frame joints is divided into five classes of normal use, temporary use, repair after use, life safety and collapse prevention. On this basis, the corresponding relationships among seismic damage degrees, seismic performance level and quantitative index are also established in this paper. The conclusions can provide a reference for the seismic performance design of composite frame joints.

Key Words
steel reinforced recycle concrete columns; steel beams; joints; seismic performance level; seismic damage model

Address
Jing Dong, Hui Ma, Nina Zhang, Yunhe Liu and Zhaowei Mao: School of Civil Engineering and Architecture, Xi\'an University of Technology, Xi\'an, China

Abstract
The paper focuses on the seismic responses of a hyperbolic cooling tower resting on soil foundation represented by the three-parameter Vlasov elastic soil model. The three-parameter soil model eliminates the necessity of field testing to determine soil parameters such as reaction modulus and shear parameter. These parameters are calculated using an iterative procedure depending on the soil surface vertical deformation profile in the model. The soil and tower system are modeled in SAP2000 structural analysis program using a computing tool coded in MATLAB. The tool provides a two-way data transfer between SAP2000 and MATLAB with the help of Open Application Programming Interface (OAPI) feature of SAP2000. The response spectrum analyses of the tower system with circular V-shaped supporting columns and annular raft foundation on elastic soil are conducted thanks to the coded tool. The shell and column forces and displacements are presented for different soil conditions and fixed raft base condition to investigate the effects of soil-structure interaction. Numerical results indicate that the flexibility of soil foundation leads to an increase in displacements but a decrease in shell membrane and column forces. Therefore, it can be stated that the consideration of soil-structure interaction in the seismic response analysis of the cooling tower system provides an economical design process.

Key Words
hyperbolic cooling tower; response spectrum analysis; open application programming interface; finite element analysis; three-parameter foundation model

Address
Ali I. Karakas, Korhan Ozgan and Ayse T. Daloglu: Department of Civil Engineering, Karadeniz Technical University, Trabzon, 61080, Turkey

Abstract
Seismic fragility curves of concrete cylindrical tanks are determined using the finite element method. Vulnerabilities including sloshing of contents, tensile cracking and compression failure of the tank wall due to bending are accounted for. Effects of wall flexibility, fixity at the base, and height-diameter ratio on the response are investigated. Tall, medium and squat tanks are considered. The dynamic analysis is implemented using the horizontal components of consistent earthquakes. The study shows that generally taller tanks are more vulnerable to all of the failure modes considered. Among the modes of failure, the bending capacity of wall was shown to be the critical design parameter.

Key Words
earthquake; concrete cylindrical tank; fragility curve; finite element method; vulnerability

Address
Mohammad Yazdabad, Farhad Behnamfar and Abdolreza K. Samani: Department of Civil Engineering, Isfahan University of Technology, Esfahan 8415683111, Iran

Abstract
In this work, a simple but accurate hyperbolic plate theory for the free vibration analysis of functionally graded material (FGM) sandwich plates is developed. The significant feature of this formulation is that, in addition to including the shear deformation effect, it deals with only 3 unknowns as the classical plate theory (CPT), instead of 5 as in the well-known first shear deformation theory (FSDT) and higher-order shear deformation theory (HSDT). A shear correction factor is, therefore, not required. Two common types of FGM sandwich plates are considered, namely, the sandwich with the FGM face sheet and the homogeneous core and the sandwich with the homogeneous face sheet and the FGM core. The equation of motion for the FGM sandwich plates is obtained based on Hamilton‟s principle. The closed form solutions are obtained by using the Navier technique. The fundamental frequencies are found by solving the eigenvalue problems. Numerical results of the present theory are compared with the CPT, FSDT, order shear deformation theories (HSDTs), and 3D solutions. Verification studies show that the proposed theory is not only accurate and simple in solving the free vibration behaviour of FGM sandwich plates, but also comparable with the higher-order shear deformation theories which contain more number of unknowns.

Key Words
sandwich plate; functionally graded material; a simple 3-unknown theory

Address
Zakaria Belabed: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Department of Technology, Institute of Science and Technology, Center University of Naama, Algeria Abdelmoumen Anis Bousahla: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Laboratoire de Modélisation et Simulation Multi-échelle, Département de Physique, Faculté des Sciences Exactes, Département de Physique, Université de Sidi Bel Abbés, Algeria; Département de Génie Civil, Centre Universitaire de Relizane, Algeria Mohammed Sid Ahmed Houari: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Department of Civil Engineering, Université Mustapha Stambouli de Mascara, Mascara, Algeria Abdelouahed Tounsi: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia S.R. Mahmoud: Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia

Abstract
In this research work, free vibrations of simply supported functionally graded plate resting on a Winkler-Pasternak elastic foundation are investigated by a new shear deformation theory. The influence of alternative micromechanical models on the macroscopic behavior of a functionally graded plate based on shear-deformation plate theories is examined. Several micromechanical models are tested to obtain the effective material properties of a two-phase particle composite as a function of the volume fraction of particles which continuously varies through the thickness of a functionally graded plate. Present theory exactly satisfies stress boundary conditions on the top and the bottom of the plate. The energy functional of the system is obtained using Hamilton\'s principle. The closed form solutions are obtained by using Navier technique, and then fundamental frequencies are found by solving the results of eigenvalue problems. Finally, the numerical results are provided to reveal the effect of explicit micromechanical models on natural fundamental frequencies.

Key Words
FG plates; micromechanical models; Winkler-Pasternak elastic foundation; a new shear deformation theory; free vibration

Address
Abdelkader Mahmoudi, Samir Benyoucef, Abdelkader Benachour and El Abbas Adda Bedia: Department of Civil Engineering, Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Algeria Abdelouahed Tounsi: Department of Civil Engineering, Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Algeria; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
The current paper introduces a new approach for development of damage index to obtain the maximum damage in the reinforced concrete frames caused by as-recorded single and consecutive earthquakes. To do so, two sets of strong ground motions are selected based on maximum and approximately maximum peak ground acceleration (PGA) from \"PEER\" and \"USGS\" centers. Consecutive earthquakes in the first and second groups, not only occurred in similar directions and same stations, but also their real time gaps between successive shocks are less than 10 minutes and 10 days, respectively. In the following, a suite of six concrete moment resisting frames, including 3, 5, 7, 10, 12 and 15 stories, are designed in OpenSees software and analyzed for more than 850 times under two groups of as-recorded strong ground motion records with/without seismic sequences phenomena. The idealized multilayer artificial neural networks, with the least value of Mean Square Error (MSE) and maximum value of regression (R) between outputs and targets were then employed to generate the empirical charts and several correction equations for design utilization. To investigate the effectiveness of the proposed damage index, calibration of the new approach to existing real data (the result of Park-Ang damage index 1985), were conducted. The obtained results show good precision of the developed ANNs-based model in predicting the maximum damage of regular reinforced concrete frames.

Key Words
seismic sequence; damage index; reinforced concrete frames; empirical charts; artificial neural networks

Address
Gholamreza Ghodrati Amiri and Elham Rajabi: Center of Excellence for Fundamental Studies in Structural Engineering, School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran

Abstract
Correlation among different factors must be considered for selection of influencing factors in safety monitoring of high dam including positive correlation of variables. Therefore, a new factor selection method was constructed based on Copula entropy and mutual information theory, which was deduced and optimized. Considering the small sample size in high dam monitoring and distribution of daily monitoring samples, a computing method that avoids causality of structure as much as possible is needed. The two-dimensional normal information diffusion and fuzzy reasoning of pattern recognition field are based on the weight theory, which avoids complicated causes of the studying structure. Hence, it is used to dam safety monitoring field and simplified, which increases sample information appropriately. Next, a complete system integrating high dam monitoring and uncertainty prediction method was established by combining Copula entropy theory and information diffusion theory. Finally, the proposed method was applied in seepage monitoring of Nuozhadu clay core-wall rockfill dam. Its selection of influencing factors and processing of sample data were compared with different models. Results demonstrated that the proposed method increases the prediction accuracy to some extent.

Key Words
high dam monitoring; composite uncertain information; Copula entropy; information diffusion; fuzzy reasoning

Address
Dongjian Zheng, Xiaoqi Li, Meng Yang, Huaizhi Su and Chongshi Gu: State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, 210098, China; College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China; National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Hohai University, Nanjing 210098, China

Abstract
Methods based on nonlinear static analysis as simple tools could be used for the seismic analysis and assessment of structures. In the present study, capability of the N2 method as a well-known nonlinear analysis procedure examines for the estimation of the damage index of multi-storey reinforced concrete frames. In the implemented framework, equivalent singledegree-of-freedom (SDOF) models are utilized for the global damage estimation of multi-degree-of-freedom (MDOF) systems. This method does not require high computational analysis and subsequently decreases the required time of seismic design and assessment process. To develop the methodology, RC frames with period range from 0.4 to 2.0 s under 40 records are studied. The effectiveness of proposed technique is evaluated through numerical study under near- and far-field earthquake ground motions. Finally, the results of developed models are compared with two other simplified schemes along with nonlinear time history analysis results of multi-storey frames. To improve the accuracy of damage estimation, a modified relation is presented based on the N2 method results for near- and far-field earthquakes.

Key Words
damage index; equivalent SDOF system; MDOF system; N2 method; near and far-field records

Address
Saman Yaghmaei-Sabegh, Sadaf Zafarvand and Sahar Makaremi: Department of Civil Engineering, University of Tabriz, Tabriz, Iran

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