Numerical Synthesis Method of Ground Motions for Seismic Design of Near-Fault Bridge Engineering

2017 ◽  
Author(s):  
Shuanglan Wu ◽  
Bhuddarak Charatpangoon ◽  
Junji Kiyono
Keyword(s):  
Seismic Design ◽  
Ground Motions ◽  
Synthesis Method ◽  
Bridge Engineering ◽  
Near Fault ◽  
Numerical Synthesis

scholarly journals Seismic Design of Bridges against Near-Fault Ground Motions Using Combined Seismic Isolation and Restraining Systems of LRBs and CDRs

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Xiaoli Li ◽  
Yan Shi
Keyword(s):  
Control System ◽  
Seismic Design ◽  
High Intensity ◽  
Seismic Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Near Fault ◽  
Combined Control ◽  
Quantitative Design

This paper focuses on the seismic isolation design of near-fault bridges under the seismic excitations of near-fault ground motions in high-intensity earthquake zones and proposes a combined control system using lead rubber bearings (LRBs) and cable displacement restrainers (CDRs) along with ductility seismic resistance for the reinforced concrete piers. As part of the performance-based seismic design framework, this study provides the quantitative design criteria for multilevel performance-based objectives of a combined control system under conditions of frequent earthquake (E1), design earthquake (medium earthquake), and rare earthquake (E2). Moreover, in this study, a preliminary performance-based seismic isolation design for a near-fault actual highway bridge in high-intensity earthquake zones (basic peak of ground acceleration 0.4 g) was developed. Using nonlinear time-history analysis of the actual bridge under near-fault ground motions, the feasibility of a performance-based design method was validated. Furthermore, to ensure the predicted performance of the isolated bridges during a strong earthquake, a relatively quantitative design in structural details derived from the stirrup ratio of piers, expansion joints gap, supported length of capping beams, and limited vertical displacement response was obtained.

STUDY ON THE SEISMIC VULNERABILITY OF A VIADUCT SUBJECTED TO NEAR-FAULT GROUND MOTIONS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Yong Li ◽  
Mengfei Xie ◽  
Lijun Meng
Keyword(s):  
Seismic Design ◽  
Seismic Vulnerability ◽  
Shear Failure ◽  
Ground Motions ◽  
Plastic Hinge ◽  
Design Guidelines ◽  
Severe Damage ◽  
Seismic Excitations ◽  
Near Fault ◽  
Bridge System

Piers, abutments and bearings of viaducts may suffer severe damage during earthquakes, so it's not insufficient to evaluate the seismic vulnerability of a bridge system only by plastic hinge curvature, which is adopted in seismic design guidelines. In this paper, the seismic vulnerability evaluation of a viaduct is conducted by incremental dynamic analysis under 30 near-fault ground motions, which are selected from PEER database. Then several damage measures are recommended to make an overall estimation for the seismic vulnerability of the viaduct, including plastic hinge curvature, shear failure and sliding displacement failure of bearings and pounding force between abutments and the girder. The analysis results show that the transversal seismic excitations may lead to more severe damage than the longitudinal ground motions. No matter in which direction the ground motions are inputted, the bearings' seismic vulnerability resulted by shear force or sliding displacement is higher than the plastic hinge of piers, which indicates that the seismic vulnerability of the bridge system is determined by the bearings to an extent. As a result, bearings should be designed according to both static and seismic analyses to guarantee the safety during earthquakes.

Maximum Spectral Demands in the Near-Fault Region

2008 ◽  
Vol 24 (1) ◽  
pp. 319-341 ◽  
Author(s):  
Yin-Nan Huang ◽  
Andrew S. Whittaker ◽  
Nicolas Luco
Keyword(s):  
Seismic Design ◽  
Ground Motions ◽  
Geometric Mean ◽  
Strong Motion ◽  
Next Generation ◽  
Seismic Performance Assessment ◽  
Near Fault ◽  
Crustal Earthquakes ◽  
Strong Motion Database ◽  
Fault Region

The Next Generation Attenuation (NGA) relationships for shallow crustal earthquakes in the western United States predict a rotated geometric mean of horizontal spectral demand, termed GMRotI50, and not maximum spectral demand. Differences between strike-normal, strike-parallel, geometric-mean, and maximum spectral demands in the near-fault region are investigated using 147 pairs of records selected from the NGA strong motion database. The selected records are for earthquakes with moment magnitude greater than 6.5 and for closest site-to-fault distance less than 15 km. Ratios of maximum spectral demand to NGA-predicted GMRotI50 for each pair of ground motions are presented. The ratio shows a clear dependence on period and the Somerville directivity parameters. Maximum demands can substantially exceed NGA-predicted GMRotI50 demands in the near-fault region, which has significant implications for seismic design, seismic performance assessment, and the next-generation seismic design maps. Strike-normal spectral demands are a significantly unconservative surrogate for maximum spectral demands for closest distance greater than 3 to 5 km. Scale factors that transform NGA-predicted GMRotI50 to a maximum spectral demand in the near-fault region are proposed.

Effects of Fling Step and Forward Directivity on Seismic Response of Buildings

2006 ◽  
Vol 22 (2) ◽  
pp. 367-390 ◽  
Author(s):  
Erol Kalkan ◽  
Sashi K. Kunnath
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
High Amplitude ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Damage Potential ◽  
Near Fault ◽  
Forward Directivity ◽  
Fling Step ◽  
Far Fault

This paper investigates the consequences of well-known characteristics of near-fault ground motions on the seismic response of steel moment frames. Additionally, idealized pulses are utilized in a separate study to gain further insight into the effects of high-amplitude pulses on structural demands. Simple input pulses were also synthesized to simulate artificial fling-step effects in ground motions originally having forward directivity. Findings from the study reveal that median maximum demands and the dispersion in the peak values were higher for near-fault records than far-fault motions. The arrival of the velocity pulse in a near-fault record causes the structure to dissipate considerable input energy in relatively few plastic cycles, whereas cumulative effects from increased cyclic demands are more pronounced in far-fault records. For pulse-type input, the maximum demand is a function of the ratio of the pulse period to the fundamental period of the structure. Records with fling effects were found to excite systems primarily in their fundamental mode while waveforms with forward directivity in the absence of fling caused higher modes to be activated. It is concluded that the acceleration and velocity spectra, when examined collectively, can be utilized to reasonably assess the damage potential of near-fault records.

A simplified iterative approach for testing the pulse derailment of light rail vehicles across a viaduct to near-fault earthquake scenarios

2021 ◽  
pp. 095440972098741
Author(s):  
Ling-Kun Chen ◽  
Peng Liu ◽  
Li-Ming Zhu ◽  
Jing-Bo Ding ◽  
Yu-Lin Feng ◽  
...  
Keyword(s):  
Ground Motions ◽  
Simulation Software ◽  
Light Rail ◽  
Rail Transit ◽  
Light Rail Transit ◽  
Seismic Responses ◽  
Near Fault ◽  
Rail Vehicle ◽  
Pulse Type ◽  
The Impact

Near-fault (NF) earthquakes cause severe bridge damage, particularly urban bridges subjected to light rail transit (LRT), which could affect the safety of the light rail transit vehicle (“light rail vehicle” or “LRV” for short). Now when a variety of studies on the fault fracture effect on the working protection of LRVs are available for the study of cars subjected to far-reaching soil motion (FFGMs), further examination is appropriate. For the first time, this paper introduced the LRV derailment mechanism caused by pulse-type near-fault ground motions (NFGMs), suggesting the concept of pulse derailment. The effects of near-fault ground motions (NFGMs) are included in an available numerical process developed for the LRV analysis of the VBI system. A simplified iterative algorithm is proposed to assess the stability and nonlinear seismic response of an LRV-reinforced concrete (RC) viaduct (LRVBRCV) system to a long-period NFGMs using the dynamic substructure method (DSM). Furthermore, a computer simulation software was developed to compute the nonlinear seismic responses of the VBI system to pulse-type NFGMs, non-pulse-type NFGMs, and FFGMs named Dynamic Interaction Analysis for Light-Rail-Vehicle Bridge System (DIALRVBS). The nonlinear bridge seismic reaction determines the impact of pulses on lateral peak earth acceleration (Ap) and lateral peak land (Vp) ratios. The analysis results quantify the effects of pulse-type NFGMs seismic responses on the LRV operations' safety. In contrast with the pulse-type non-pulse NFGMs and FFGMs, this article's research shows that pulse-type NFGM derail trains primarily via the transverse velocity pulse effect. Hence, this study's results and the proposed method can improve the LRT bridges' seismic designs.

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