Abstract
Studies on the seismic response of skewed integral abutment bridges have mainly focused on response under far-field non-pulse-type ground motions, yet the large amplitude and long-period velocity pulses in near-fault ground motions might have significant impacts on bridge seismic response. In this study, the nonlinear dynamic response of an skewed integral abutment bridge (SIAB) under near-fault pulse and far-fault non-pulse type ground motions are analyzed considering the soil–structure interaction, along with parametric studies on bridge skew angle and compactness of abutment backfill. For the analyses, three sets of near-fault pulse ground motion records are selected based on the bridge site conditions, and three corresponding far-field non-pulse artificial records are fitted by their acceleration response spectra. The results show that the near-fault pulse type ground motions are generally more destructive than the non-pulse motions on the nonlinear dynamic response of SIABs, but the presence of abutment backfill will mitigate the pulse effects to some extent. Coupling of the longitudinal and transverse displacements as well as rotation of the bridge deck would increase with the skew angle, and so do the internal forces of steel H piles. The influence of the skew angle would be most obvious when the abutment backfill is densely compacted.
Highlights
Seismic safety of bridge structures has always been a major concern
Model analyses were performed on 16 skewed integral abutment bridge (SIAB) models, in which the skew angle varied from 0◦, 15◦, 30◦ to 45◦, and the abutment backfill varied from no-backfill to loosely, medium-densely and densely compacted sand
From the time-history analyses on all SIAB models, it was found that the maximum longitudinal and transverse displacements of the abutment were always located at the abutment top
Summary
Seismic safety of bridge structures has always been a major concern. In the last few decades, several major earthquakes had occurred and caused serious damage to infrastructure including bridges across the world, such as the Northridge (USA) earthquake in 1994, the Kobe (Japan) earthquake in 1995, the Kocaeli (Turkey) and the Chi-Chi (Taiwan) earthquake in 1999, the Bam (Iran) earthquake in 2003, the Wenchuan (China) earthquake in 2008 and the Haiti earthquake (Haiti) in 2010, etc. Xin et al [19] investigated the seismic behavior of a long-span concrete-filled steel tubular arch bridge subjected to near-fault ground motions, and found that the forward-directivity and fling-step effects might induce significantly higher seismic demands and damage to the bridge structure. Seismic design and analyses of integral abutment bridges only involve the far-field non-pulse type ground motions [21,22,30,31], while the large amplitude and long-period velocity pulses of the near-fault pulse type ground motions might have quite different influences on bridge seismic response, especially considering the complex soil–structure interaction. This paper presents a study on the nonlinear seismic response of skewed integral abutment bridges (SIABs) under near-fault pulse and far-field non-pulse type ground motions, with parametric studies on bridge skew angles and the compactness of abutment backfill. This study could provide a reference for future studies on the seismic behavior and design of SIABs in near-fault regions
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