Risk assessment for a long-span cable-stayed bridge subjected to multiple support excitations

Abstract

Current probabilistic seismic risk assessment framework does not fully address the impact of the spatial variability of ground motions on long bridges. However, recent studies have highlighted that long-span bridges are more vulnerable to damage due to spatial varying ground motions. To achieve this increased vulnerability, this research presents a reliable risk assessment tool for long-span bridges subjected to spatial varying ground motions. The proposed method includes the following tasks: (i) the simulation of spatially variable ground motions, (ii) creation of numerical bridge model, (iii) generation of probabilistic seismic demand models, (iv) development of component and system fragility curves, (v) estimation of annual exceedance of damage through site-compatible hazard curves, and (vi) computation of repair time. As an illustration, a cable-stayed bridge is selected to highlight the effect of spatial variability of ground motions on the seismic risk and repair time of individual bridge components and bridge system in comparison to uniform excitations. Additionally, a sensitivity analysis is performed to examine the effect of spatial variability parameters and hazard curve-related parameters on the seismic risk of the bridge.