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.

scholarly journals Inelastic displacement ratios for non-structural components in steel framed structures under forward-directivity near-fault strong-ground motion

2021 ◽  
Author(s):  
M. A. Bravo-Haro ◽  
J. R. Virreira ◽  
A. Y. Elghazouli
Keyword(s):  
Strong Ground Motion ◽  
Ground Motions ◽  
Structural Elements ◽  
Structural Components ◽  
Framed Structures ◽  
Inelastic Displacement ◽  
Near Fault ◽  
Forward Directivity ◽  
The Mean ◽  
Strong Ground

AbstractThis paper describes a detailed numerical investigation into the inelastic displacement ratios of non-structural components mounted within multi-storey steel framed buildings and subjected to ground motions with forward-directivity features which are typical of near-fault events. The study is carried out using detailed multi-degree-of-freedom models of 54 primary steel buildings with different structural characteristics. In conjunction with this, 80 secondary non-structural elements are modelled as single-degree-of-freedom systems and placed at every floor within the primary framed structures, then subsequently analysed through extensive dynamic analysis. The influence of ground motions with forward-directivity effects on the mean response of the inelastic displacement ratios of non-structural components are compared to the results obtained from a reference set of strong-ground motion records representing far-field events. It is shown that the mean demand under near-fault records can be over twice as large as that due to far-fault counterparts, particularly for non-structural components with periods of vibration lower than the fundamental period of the primary building. Based on the results, a prediction model for estimating the inelastic displacement ratios of non-structural components is calibrated for far-field records and near-fault records with directivity features. The model is valid for a wide range of secondary non-structural periods and primary building fundamental periods, as well as for various levels of inelasticity induced within the secondary non-structural elements.

Constant damage inelastic displacement ratios for the near-fault pulse-like ground motions

2014 ◽  
Vol 59 ◽  
pp. 599-607 ◽  
Author(s):  
Wei-Ping Wen ◽  
Chang-Hai Zhai ◽  
Shuang Li ◽  
Zhiwang Chang ◽  
Li-Li Xie
Keyword(s):  
Ground Motions ◽  
Inelastic Displacement ◽  
Near Fault

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.

scholarly journals Seismic Behavior of a Bridge with New Composite Tall Piers under Near-Fault Ground Motion Conditions

2020 ◽  
Vol 10 (20) ◽  
pp. 7377
Author(s):  
Zhehan Cai ◽  
Zhijian Wang ◽  
Kaiqi Lin ◽  
Ying Sun ◽  
Weidong Zhuo
Keyword(s):  
Design Method ◽  
Ground Motions ◽  
Time History ◽  
Steel Plates ◽  
Nonlinear Time History Analysis ◽  
Steel Beams ◽  
Box Section ◽  
Near Fault ◽  
Rigid Frame ◽  
Cfst Columns

Currently, the seismic designs of reinforced concrete (RC) bridges with tall piers are often accomplished following the ductility-based seismic design method. Though the collapses of the RC bridges with tall piers can be avoided, they are likely to experience major damage and loss of functionality when subjected to strong near-fault ground motions. The objectives of this study are to put forward an innovative design concept of a tall-pier system and its application in tall-pier bridges. The concept of the innovative tall-pier system is derived from the principle of earthquake-resilient structures, and is to improve the seismic performances of the tall-pier bridges under strong near-fault ground motions. The proposed tall-pier system has a box section and is composed of four concrete-filled steel tubular (CFST) columns and energy dissipating mild steel plates (EDMSPs). Trial design of a bridge with the new composite tall-pier system is performed based on a typical continuous rigid frame highway bridge with conventional RC box section tall piers. Both static analysis and nonlinear time history analysis of both the bridges with the new composite tall piers and conventional RC tall piers under the near-fault velocity pulse-type ground motions were conducted in Midas Civil2019 and ABAQUS. The results show that: under the design-based earthquake (DBE), the CFST columns and connecting steel beams remain elastic in the bridge with the new composite tall piers, while the damage is found in the replaceable EDMSPs which help dissipate the seismic input energy. The displacement responses of the new bridge are significantly smaller than those of the conventional bridge under DBE. It is concluded that the bridge with the new composite tall piers is seismic resilient under near-fault ground motions.

Displacement-Based Probabilistic Seismic Demand Analyses of Earth Slopes in the Near-Fault Region

2016 ◽  
Vol 32 (2) ◽  
pp. 1141-1163 ◽  
Author(s):  
Adrian Rodriguez-Marek ◽  
Jian Song
Keyword(s):  
Ground Motions ◽  
Seismic Demands ◽  
Adequate Treatment ◽  
Ground Shaking ◽  
Nonlinear Seismic Response ◽  
Near Fault ◽  
Probabilistic Seismic Demand ◽  
Earth Slopes ◽  
Displacement Based ◽  
Fault Region

Near-fault pulses can result in high seismic demands on slopes in the proximity of a fault. A probabilistic methodology to capture the effects of near-fault pulses on seismically-induced slope displacements is proposed. This methodology allows for a separate and more adequate treatment of the sliding displacement of slopes when these are subject to pulse-like near-fault forward directivity motions. Simplified pulse parameters are used to predict displacements for cases where the near-fault pulses may induce resonances in the slope. The method explicitly includes the effects of near-fault pulses both on the ground shaking and nonlinear seismic response of slopes. An example application illustrates the use of the proposed procedure. Results show that the proposed approach increases the predicted earthquake-induced displacements of earth slopes located near the fault. Finally, the proposed procedure generates hazard deaggregation plots that are a useful tool for selecting ground motions for the design of slopes near faults.

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