Description:    A novel damage detection method is applied to a 3-story frame structure, to obtain statistical quantification control criterion of the existence, location and identification of damage. The mean, standard deviation, and exponentially weighted moving average (EWMA) are applied to detect damage information according to statistical process control (SPC) theory. It is concluded that the detection is insignificant with the mean and EWMA because the structural response is not independent and is not a normal distribution. On the other hand, the damage information is detected well with the standard deviation because the influence of the data distribution is not pronounced with this parameter. A suitable moderate confidence level is explored for more significant damage location and quantification detection, and the impact of noise is investigated to illustrate the robustness of the method. Content Type Journal Article Pages 1-8 DOI 10.1007/s11803-009-8084-x Authors Weiming Li, Huazhong University of Science and Technology School of Civil Engineering and Mechanics Wuhan 430074 China Hongping Zhu, Huazhong University of Science and Technology School of Civil Engineering and Mechanics Wuhan 430074 China Hanbin Luo, Huazhong University of Science and Technology School of Civil Engineering and Mechanics Wuhan 430074 China Yong Xia, Huazhong University of Science and Technology School of Civil Engineering and Mechanics Wuhan 430074 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664

Description:    This paper describes shaking table tests of a 1:12 scale model of a special concentrically braced steel frame with pinned connections, which was fabricated according to a one-bay braced frame selected from a typical main factory building of a large thermal power plant. In order to investigate the seismic performance of this type of structure, several ground motion accelerations with different levels for seismic intensity VIII, based on the Chinese Code for Seismic Design of Buildings, were selected to excite the model. The results show that the design methods of the members and the connections are adequate and that the structural system will perform well in regions of high seismicity. In addition to the tests, numerical simulations were also conducted and the results showed good agreement with the test results. Thus, the numerical model is shown to be accurate and the beam element can be used to model this structural system. Content Type Journal Article Pages 1-13 DOI 10.1007/s11803-009-8049-0 Authors Haifeng Yu, School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Wenyuan Zhang, School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Yaochun Zhang, School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Yusong Sun, Northeast Electric Power Design Institute Changchun 130021 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664

Description:    This paper describes a shake table test study on the seismic response of low-cap pile groups and a bridge structure in liquefiable ground. The soil profile, contained in a large-scale laminar shear box, consisted of a horizontally saturated sand layer overlaid with a silty clay layer, with the simulated low-cap pile groups embedded. The container was excited in three El Centro earthquake events of different levels. Test results indicate that excessive pore pressure (EPP) during slight shaking only slightly accumulated, and the accumulation mainly occurred during strong shaking. The EPP was gradually enhanced as the amplitude and duration of the input acceleration increased. The acceleration response of the sand was remarkably influenced by soil liquefaction. As soil liquefaction occurred, the peak sand displacement gradually lagged behind the input acceleration; meanwhile, the sand displacement exhibited an increasing effect on the bending moment of the pile, and acceleration responses of the pile and the sand layer gradually changed from decreasing to increasing in the vertical direction from the bottom to the top. A jump variation of the bending moment on the pile was observed near the soil interface in all three input earthquake events. It is thought that the shake table tests could provide the groundwork for further seismic performance studies of low-cap pile groups used in bridges located on liquefiable groun. Content Type Journal Article Pages 1-12 DOI 10.1007/s11803-009-8131-7 Authors Liang Tang, School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Xianzhang Ling, School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Pengju Xu, School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Xia Gao, School of Civil Engineering Harbin Institute of Technology Harbin 150090 China Dongsheng Wang, Dalian Maritime University Research Centre of Road and Bridge Engineering Dalian 116026 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664

Description:    The influence of local landforms on ground motion is an important problem. The antiplane response of a scalene triangular hill to incident SH waves is studied in this paper by using a complex function, moving coordinates and auxiliary functions. First, the model is divided into two domains: a scalene triangular hill with a semi-circular bottom; and a half space with a semi-circular canyon. Wave functions that satisfy the zero-stress condition at the triangular wedges and at the horizontal surface are constructed in both domains. Then, considering the displacement continuity and stress equilibrium, algebraic equations are established. Finally, numerical examples are provided to illustrate the influence of the geometry of the hill and the characteristics of the incident waves on the ground motions. Content Type Journal Article Pages 1-16 DOI 10.1007/s11803-009-8091-y Authors Shuzhi Lin, Xiamen Construction & Administration Bureau Xiamen 361004 China Faqiang Qiu, Central South University School of Civil Engineering & Architecture Changsha 410075 China Diankui Liu, Harbin Engineering University School of Civil Engineering Harbin 150001 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664

Description:    The current AASHTO load and resistance factor design (LRFD) guidelines are formulated based on bridge reliability, which interprets traditional design safety factors into more rigorously deduced factors based on the theory of probability. This is a major advancement in bridge design specifications. However, LRFD is only calibrated for dead and live loads. In cases when extreme loads are significant, they need to be individually assessed. Combining regular loads with extreme loads has been a major challenge, mainly because the extreme loads are time variables and cannot be directly combined with time invariant loads to formulate the probability of structural failure. To overcome these difficulties, this paper suggests a methodology of comprehensive reliability, by introducing the concept of partial failure probability to separate the loads so that each individual load combination under a certain condition can be approximated as time invariant. Based on these conditions, the extreme loads (also referred to as multiple hazard or MH loads) can be broken down into single effects. In Part II of this paper, a further breakdown of these conditional occurrence probabilities into pure conditions is discussed by using a live truck and earthquake loads on a bridge as an example. There are three major steps in establishing load factors from MH load distributions: (1) formulate the failure probabilities; (2) normalize various load distributions; and (3) establish design limit state equations. This paper describes the formulation of the failure probabilities of single and combined loads. Content Type Journal Article Pages 293-301 DOI 10.1007/s11803-012-0122-4 Authors Zach Liang, Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14261, USA George C. Lee, Department of Civil, Structural and Environmental Engineering, University at Buffalo, Buffalo, NY 14261, USA Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    The equivalent linearization method approximates the maximum displacement response of nonlinear structures through the corresponding equivalent linear system. By using the particle swarm optimization technique, a new statistical approach is developed to determine the key parameters of such an equivalent linear system over a 2D space of period and damping ratio. The new optimization criterion realizes the consideration of the structural safety margin in the equivalent linearization method when applied to the performance-based seismic design/evaluation of engineering structures. As an application, equations for equivalent system parameters of both bilinear hysteretic and stiffness degrading single-degree-offreedom systems are deduced with the assumption of a constant ductility ratio. Error analyses are also performed to validate the proposed approach. Content Type Journal Article Pages 415-425 DOI 10.1007/s11803-012-0131-3 Authors Liang Su, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058 China Nan Xiao, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058 China Yi Wang, China Aviation Planning and Construction Development Co., Ltd, Beijing, 100120 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    Tuned mass dampers (TMDs) have been widely used in recent years to mitigate structural vibration. However, the damping mechanisms employed in the TMDs are mostly based on viscous dampers, which have several well-known disadvantages, such as oil leakage and difficult adjustment of damping ratio for an operating TMD. Alternatively, eddy current damping (ECD) that does not require any contact with the main structure is a potential solution. This paper discusses the design, analysis, manufacture and testing of a large-scale horizontal TMD based on ECD. First, the theoretical model of ECD is formulated, then one large-scale horizontal TMD using ECD is constructed, and finally performance tests of the TMD are conducted. The test results show that the proposed TMD has a very low intrinsic damping ratio, while the damping ratio due to ECD is the dominant damping source, which can be as large as 15% in a proper configuration. In addition, the damping ratios estimated with the theoretical model are roughly consistent with those identified from the test results, and the source of this error is investigated. Moreover, it is demonstrated that the damping ratio in the proposed TMD can be easily adjusted by varying the air gap between permanent magnets and conductive plates. In view of practical applications, possible improvements and feasibility considerations for the proposed TMD are then discussed. It is confirmed that the proposed TMD with ECD is reliable and feasible for use in structural vibration control. Content Type Journal Article Pages 391-401 DOI 10.1007/s11803-012-0129-x Authors Zhihao Wang, Wind Engineering Research Center, Hunan University, Changsha, 410082 China Zhengqing Chen, Wind Engineering Research Center, Hunan University, Changsha, 410082 China Jianhui Wang, Wind Engineering Research Center, Hunan University, Changsha, 410082 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    This paper evaluates different characteristics for earthquake early warning. The scaling relationships between magnitude, epicenter distance and calculated parameters are derived from earthquake event data from USGS. The standard STA/LTA method is modified by adding two new parameters to eliminate the effects of the spike-type noise and small pulsetype noise ahead of the onset of the P-wave. After the detection of the P-wave, the algorithm extracts 12 kinds of parameters from the first 3 seconds of the P-wave. Then stepwise regression analysis of these parameters is performed to estimate the epicentral distance and magnitude. Six different parameters are selected to estimate the epicentral distance, and the median error for all 419 estimates is 16.5 km. Four parameters are optimally combined to estimate the magnitude, and the mean error for all events is 0.0 magnitude units, with a standard deviation of 0.5. Finally, based on the estimation results, additional work is proposed to improve the accuracy of the results. Content Type Journal Article Pages 435-443 DOI 10.1007/s11803-012-0133-1 Authors Qingkai Kong, Building Engineering Department, Tongji University, Shanghai, 200092 China Ming Zhao, Building Engineering Department, Tongji University, Shanghai, 200092 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    In this study, through novel drift-based equations of motion in the frequency domain, optimum placement and characteristics of linear velocity-dependent dampers are investigated. In this study, the sum of the square of the absolute values of transfer matrix elements for interstory drifts is considered as the optimization index. Optimum placement and characteristics of dampers are simultaneously obtained by minimizing the optimization index through an incremental procedure. In each step of the procedure, a predefined value is considered as the damper characteristic. The optimum story for this increment is selected such that it leads to a minimum value for the optimization index. The procedure is repeated for the next increments until the optimization index meets its target value, which is obtained according to the desired damping ratio for the overall structure. In other words, the desired overall damping ratio is the input to the proposed procedure, and the optimal placement and characteristics of the dampers are its output. It is observed that the optimal placement of a velocitydependent damper depends on the damping coefficient of the added damper, frequency of the excitation, and distribution of the mass, stiffness, and inherent damping of the main structure. Content Type Journal Article Pages 403-414 DOI 10.1007/s11803-012-0130-4 Authors Seyed Amin Mousavi, R&D Department, Sabok Sazan Sarie Engineering Company, Tehran, Iran Amir K. Ghorbani-Tanha, School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    In this paper, an experimental and analytical study of two half-scale steel X-braced frames with equal nominal shear strength under cyclic loading is described. In these tests, all members except the braces are similar. The braces are made of various steel grades to monitor the effects of seismic excitation. Internal stiffeners are employed to limit the local buckling and increase the fracture life of the steel bracing. A heavy central core is introduced at the intersection of the braces to decrease their effective length. Recent seismic specifications are considered in the design of the X-braced frame members to verify their efficiency. The failure modes of the X-braced frames are also illustrated. It is observed that the energy dissipation capacity, ultimate load capacity and ductility of the system increase considerably by using lower grade steel and proposed detailing. Analytical modeling of the specimens using nonlinear finite element software supports the experimental findings. Content Type Journal Article Pages 313-329 DOI 10.1007/s11803-012-0124-2 Authors Parviz Ebadi, Structural Engineering, Khaje Nasir Toosi University of Technology, Tehran, Iran Saeid Sabouri-Ghomi, Structural Engineering, Khaje Nasir Toosi University of Technology, Tehran, Iran Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3