Seismic Fragility Analysis of V-Shaped Continuous Girder Bridges

Abstract

This paper presents an improved approach for evaluating seismic performance of V-shaped continuous girder bridges with different V-angles. A 3-D finite element model is established using the OpenSees for tracing the response of a typical three-span V-shaped continuous girder bridge. The analysis is performed in three steps: component fragility analysis, validated system fragility analysis and V-angle analysis. A series of nonlinear time history analysis (NLTHA), considering the uncertainty in bridge structural parameters and ground motions characteristics, is carried out to investigate the potential fragile position of a V-shaped continuous girder bridge. Subsequently, a new improved product of conditional marginal (PCM) method is validated successfully and utilized to form the system fragility curves. The application of the validated method is used to analyse the influence of V-angle on the bridge structural system fragility. The analysis result shows that variation of V-angle has significant influence on seismic fragility of V-shaped continuous girder bridges. The V-shaped continuous girder bridges with 80° V-angle has good seismic performance when PGA ≤ 0.8 g. Smaller V-angle can result in higher seismic fragility of V-shaped continuous girder bridges.