Inelastic response analysis of bridges subjected to non-stationary seismic excitations by efficient MCS based on explicit time-domain method

This paper is devoted to stochastic response analysis of large-scale bridges with local plastic deformations under non-stationary random seismic excitations. A force-based fiber beam–column element is employed to simulate the inelastic behavior of bridges. By use of the explicit time-domain expressions of seismic responses, an effective dimension-reduced method is developed for fast inelastic time-history analysis of a structure with local nonlinearities. Only the nodal displacements that are associated with the inelastic elements need to be solved through iteration process, which leads to a significant reduction in computational cost for inelastic time-history analysis. With the merit of high efficiency, the dimension-reduced method is further used as a computational tool for repetitive inelastic time-history analyses in Monte Carlo simulation, and the statistical moments and mean peak values of critical responses can be readily achieved under random seismic excitations. To demonstrate the feasibility of the present approach, the nonlinear random vibration analysis of a long-span suspension bridge with a main span of 1200 m is carried out under rare earthquakes, in which the inelastic behaviors of the main towers are investigated with the use of inelastic fiber elements.