Efficient Longitudinal Seismic Fragility Assessment of a Multi-Span Continuous Steel Bridge on Liquefiable Soils (original) (raw)
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Earthquake Spectra, 2013
This paper explores the effects of vertical ground motions (VGMs) on the component fragility of a coupled bridged-soil-foundation (CBSF) system with liquefaction potential, and highlights the unique considerations on the demand and capacity model required for fragility analysis under VGMs. Optimal intensity measures (IMs) that account for VGMs are identified. Moreover, fragility curves that consider capacity change with fluctuating axial force are derived. Results show that the presence of VGMs has a minor effect on the failure probabilities of piles and expansion bearings, while it has a great influence on fixed bearings. Whether VGMs have an impact on column fragilities depends on the design axial load ratio. Finally, more accurate fragility surfaces are derived, which are compared with results of conventional fragility curves. This study highlights the important role that VGMs play in the selection of optimal IMs, and the capacity and fragility representation of certain component...
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Seismic Vulnerability Assessment of a Skew Highway Bridge Using Fragility Curves
Recent earthquakes have shown the vulnerabilities that many existing highway bridges possess. An emerging decision tool, which is becoming popular in the assessment of seismic risk and for setting retrofit and repair priorities, is seismic fragility curves. Fragility curves are conditional probability statements which give the probability of a bridge reaching or exceeding a particular damage level for an earthquake as a function of ground motion indices, e.g. PGA, PGV, and Sa, for a given intensity level. The purpose of this paper is to use an analytical method to generate rational fragility curves for a highway bridge in Tehran. The methodology adopted uses 3-D finite element models, nonlinear static and nonlinear time-history analyses. Nonlinear models of the bridge are developed in Opensees. First a simple 3-D finite element model of the bridge was created. Then by taking the existing inventory of the bridge into consideration and assessing typical characteristics and details, a ...
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