Seismic performance assessment of a sea-crossing cable-stayed bridge system considering soil spatial variability

Soil spatial variability at different supports is vital in the seismic performance assessment of large-span structural systems, including sea-crossing cable-stayed (SCCS) bridges. This study systematically investigates the influences of soil spatial variability on the seismic performance of SCCS bridges. In particular, the uncertain sites considering soil spatial variability are developed based on the random field theory and Latin Hypercube Sampling technique. The refined 3D finite element model of a representative SCCS bridge considering soil-structure interaction (SSI) is created in ABAQUS, and the spatially varying seafloor seismic motions (SVSSMs) with soil uncertainties are stochastically simulated. The tornado diagram sensitivity analysis method is leveraged to study the relative sensitivity of each soil property on the dynamic responses of the SCCS bridge. Finally, the component and system fragility curves are developed with and without considering soil spatial variability. The results show that soil spatial variability can significantly influence the SVSSMs and SSI, and lead to large variability of bridge seismic responses. The uncertainties of soil shear modulus and density have the most evident effects on the seismic responses of SCCS bridges. Furthermore, it is also found that neglecting the soil spatial variability would underestimate the component and system seismic fragility of SCCS bridges.