Seismic risk and loss assessment models for highway continuous girder bridges in large-scale zones

This paper innovatively proposes a seismic risk model for continuous girder bridges considering updated seismic vulnerability levels using probability statistics and risk assessment theory. The proposed model was validated and optimized using the loss data of 115 continuous girder bridges affected by the 2008 Wenchuan earthquake. An empirical algorithm-based seismic failure probability matrix for actual highway continuous girder bridges was developed. A total of 1594,257 acceleration records monitored by nine typical seismic stations were collected and processed. Nonlinear dynamic and spectral algorithms were used to generate dynamic time history and response spectrum curves which considering the directional effects of ground motion. The seismic vulnerability comparison curves and undetermined parameter matrices of continuous girder bridges in different intensity zones are established using nonlinear fitting algorithms. A vulnerability loss index considering actual bridge losses is proposed, and the vulnerability surface of the vulnerability loss index for continuous girder bridges in different intensity zones is generated. An updated vulnerability membership index function considering single and coupled vulnerability levels was proposed using a fuzzy decision algorithm and probability vulnerability theory. The seismic vulnerability membership curves (single and coupled parameters) were generated considering the actual failure dataset of regional highway continuous girder bridges.