SEISMIC RESPONSE OF A FLAG-SHAPED HYSTERETIC BEHAVIOR UNDER GROUND MOTIONS

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Daniel I. Silva ◽  
Cheng Chen
Keyword(s):  
Earthquake Engineering ◽  
Parametric Study ◽  
Ground Motions ◽  
Hysteretic Behavior ◽  
Far Field ◽  
Displacement Ductility ◽  
Engineering Research ◽  
Sdof System ◽  
Residual Drift ◽  
Near Fault

Self-centering systems have attracted significant interest in earthquake-engineering research, due to their excellent performance under simulated seismic loading through their self-centering capabilities. A comprehensive parametric study is presented to compare the ductility demands on single-degree-of-freedom (SDOF) systems, when subjected to ground motions with a probability of exceedance of 10% in 50 years in California. The influences of different parameters were analyzed under SDOF structural responses in terms of displacement ductility and absolute acceleration. The responses of the flag-shaped hysteretic SDOF systems were also compared against the responses of similar bilinear elasto-plastic hysteretic SDOF systems. Two ensembles of far-field and near-fault historical earthquake records, corresponding to ordinary earthquakes, were used for the parametric study to compare the ductility demands. Although a flag-shaped hysteretic SDOF system of equal or lesser strength can often match or better the response of an elasto-plastic hysteretic SDOF system with almost no residual drift, the analysis shows that seismic design of self-centering systems should account for the difference between far-field and near-fault ground motion.

EVALUATION OF SEISMIC DEMANDS IN A CONTINUOUS BRIDGE

2001 ◽  
Vol 01 (02) ◽  
pp. 235-246 ◽  
Author(s):  
CHIN-HSIUNG LOH ◽  
SHIUAN WAN ◽  
YI-WEN CHANG
Keyword(s):  
Earthquake Engineering ◽  
Ground Motions ◽  
Hysteretic Behavior ◽  
Earthquake Ground Motion ◽  
Far Field ◽  
Base Shear ◽  
Near Fault ◽  
Seismic Design Code ◽  
Cyclic Loading Tests ◽  
Earthquake Characteristics

This paper examines the dynamic behavior of a highway RC-bridge subjected to both near-fault and far-field ground motions. The bridge consists of a hinge supported continuous girder with six concrete piers and the bridge is designed according to the Taiwan seismic design code. To investigate the hysteretic behavior of the bridge piers, cyclic loading tests were carried out at the National Center for Research on Earthquake Engineering (NCREE). The Chi-Chi earthquake ground motion record was adopted as the near-fault earthquake characteristics whereas another earthquake record was selected for the far-field earthquake characteristics. The ductility demands and base shear demands due to the near-fault and the far-field earthquake ground motions are compared and conclusions drawn from the study. The stipulation of code limitations and the present calculated demands are discussed.

scholarly journals Quantitative Identification of Pulse-Like Ground Motions Based on Hilbert–Huang Transform

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Zhen Liu
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Ground Motions ◽  
Engineering Research ◽  
Hilbert Huang Transform ◽  
Near Fault ◽  
Identification Method ◽  
Recognition Quality ◽  
Complex Shapes ◽  
Selection Of

Aiming to address the problem of pulse-like ground motions being difficult to identify, this paper refines the Baker’s wavelet-based pulse-like ground motions identification method, followed by a new pulse-like ground motion identification method based on Hilbert–Huang Transform (HHT) being proposed. In this method, HHT is used to decompose ground motions instead of wavelet. HHT can overcome the dependence of wavelet analysis on the selection of mother wave, and thus more complex velocity pulses can be identified. In order to compare the effects of two pulse-like ground motion identification methods, HHT-based method and wavelet-based method, respectively, are used to identify ground motions in Pacific Earthquake Engineering Research Center (PEER). After identifying the 3066 groups of ground motions selected from PEER, it is found that the HHT-based method can identify 229 pulse-like ground motions, and the wavelet-based method can identify 150 pulse-like ground motions. More complex shapes of near-fault velocity pulses can be extracted by the HHT-based method. By analyzing the seismic response, fault distance, and cumulative squared velocity (CSV) of these pulse-like ground motions, it is found that the pulse-like ground motions identified by the HHT-based method have strong near-fault characteristics. If a high recognition quality can be guaranteed, the proposed HHT-based method can identify many kinds of near-fault velocity pulses and thus provide more pulse-like ground motions for seismic researches.

Behavior of CFST-RC Pier under Different Ground Motions

2018 ◽  
Vol 1145 ◽  
pp. 134-139
Author(s):  
Raghabendra Yadav ◽  
Bao Chun Chen ◽  
Hui Hui Yuan ◽  
Zhi Bin Lian
Keyword(s):  
Earthquake Engineering ◽  
Large Scale ◽  
Dynamic Testing ◽  
Ground Motions ◽  
Dynamic Test ◽  
Longitudinal Direction ◽  
Steel Tube ◽  
Engineering Research ◽  
Magnification Factors ◽  
Time Histories

The dynamic testing of large-scale structures continues to play a significant role in earthquake engineering research. The pseudo- dynamic test (PDT) is an experimental technique for simulating the earthquake response of structures and structural components in time domain. A CFST-RC pier is a modified form of CFST laced column in which CFST members are connected with RC web in longitudinal direction and with steel tube in transverse direction. For this study, a CFST -RC pier is tested under three different earthquake time histories having scaled PGA of 0.05g. From the experiment acceleration, velocity, displacement and load time histories are observed. The dynamic magnification factors for acceleration due to Chamoli, Gorkha and Wenchuan ground motions are observed as 12, 10 and 10 respectively. The frequency of the pier is found to be 1.42 Hz. The result shows that this type of pier has excellent static and earthquake resistant properties.

Strength reduction factor of self-centering structures under near-fault pulse-like ground motions

2020 ◽  
Vol 24 (1) ◽  
pp. 119-133
Author(s):  
Huihui Dong ◽  
Qiang Han ◽  
Xiuli Du ◽  
Canxing Qiu
Keyword(s):  
Ground Motions ◽  
Time History ◽  
Reduction Factor ◽  
Strength Reduction ◽  
The Self ◽  
Hysteretic Behavior ◽  
Hysteretic Model ◽  
Strength Reduction Factor ◽  
Vibration Period ◽  
Near Fault

Many studies on the strength reduction factor mainly focused on structures with the conventional hysteretic models. However, for the self-centering structure with the typical flag-shaped hysteretic behavior, the corresponding study is limited. The main purpose of this study is to investigate the strength reduction factor of the self-centering structure with flag-shaped hysteretic behavior subjected to near-fault pulse-like ground motions by the time history analysis. For this purpose, the smooth flag-shaped model based on Bouc-Wen model which can show flag-shaped hysteretic behavior is first described. The strength reduction factor spectra of the flag-shaped model are then calculated under 85 near-fault pulse-like ground motions. The influences of the ductility level, vibration period, site condition, hysteretic parameter, and hysteretic model are investigated statistically. For comparison, the strength reduction factors under ordinary ground motions are also analyzed. The results show that the strength reduction factor from near-fault pulse-like ground motions is smaller. Finally, a predictive model is proposed to estimate the strength reduction factor for the self-centering structure with the flag-shaped model under near-fault pulse-like ground motions.

Simulation and analysis of a vertically irregular building subjected to near-fault ground motions

2020 ◽  
Vol 36 (3) ◽  
pp. 1485-1516
Author(s):  
Jui-Liang Lin ◽  
Wen-Hui Chen ◽  
Fu-Pei Hsiao ◽  
Yuan-Tao Weng ◽  
Wen-Cheng Shen ◽  
...  
Keyword(s):  
Numerical Model ◽  
Seismic Response ◽  
Ground Motion ◽  
Ground Motions ◽  
Far Field ◽  
Near Fault ◽  
Study Results ◽  
Rc Building ◽  
Near Fault Ground Motion ◽  
Story Building

A shaking table test of a three-story reinforced concrete (RC) building was conducted. The tested building is vertically irregular because of the first story’s elevated height and the third story’s added RC walls. In addition to far-field ground motions, near-fault ground motions were exerted on this building. A numerical model of the three-story building was constructed. Comparing with the test results indicates that the numerical model is satisfactory for simulating the seismic response of the three-story building. This validated numerical model was then further applied to look into two issues: the effective section rigidities of RC members and the effects of near-fault ground motions. The study results show the magnitude of the possible discrepancy between the actual seismic response and the estimated seismic response, when the effective section rigidities of the RC members are treated as in common practice. An incremental dynamic analysis of the three-story RC building subjected to one far-field and one near-fault ground motion, denoted as CHY047 and TCU052, respectively, was conducted. In comparison with the far-field ground motion, the near-fault ground motion is more destructive to this building. In addition, the effect of the selected near-fault ground motion (i.e. TCU052) on the building’s collapse is clearly identified.

Inelastic Displacement Spectra and Its Utilization of DDB Design for Seismic Isolated Bridges Subjected to Near-Fault Pulse-Like Ground Motions

2019 ◽  
Vol 35 (3) ◽  
pp. 1109-1140 ◽  
Author(s):  
Yi-feng Wu ◽  
Hao Wang ◽  
Jian Li ◽  
Ben Sha ◽  
Ai-qun Li
Keyword(s):  
Design Method ◽  
Ground Motions ◽  
Single Degree Of Freedom ◽  
Sdof System ◽  
Inelastic Displacement ◽  
Displacement Spectra ◽  
Near Fault ◽  
The Mean ◽  
Displacement Based ◽  
Isolated Bridges

A variety of research has focused on the inelastic displacement demand of a single degree of freedom (SDOF) system when subjected to near-fault pulse-like ground motions, in which the concerned ductility, μ, is typically lower than ten for normal structures. However, for seismic isolated structures that are more prone to large displacement, the corresponding research is limited. The purpose of this paper is to investigate the inelastic displacement spectra of an SDOF system with μ ranging from 5 to 70 and further proposes a direct displacement-based (DDB) design method for seismic isolated bridges. More concretely, a pool of near-fault pulse-like records is assembled, the mean C μ as a function of T/ T p is developed, and the influences of the ductility, μ, and the post-to-pre-yield ratio, α, on C μ are carefully investigated. Then the corresponding inelastic displacement spectra, S d, are obtained, and a comprehensive piecewise expression is proposed to fit S d. After that, the utilization of the spectra for the DDB design of a three-span seismic isolated continuous bridge is performed, and the principal of simplifying the bridge to an SDOF system is carefully explained and verified.

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