Stochastic seismic responses and dynamic reliability analysis of long-span cable-stayed bridge with multi-dimensional isolation and energy dissipation devices

Abstract

To assess the seismic performance of long-span cable-stayed bridge with multi-dimensional isolation and energy dissipation (MIED) devices, a unified and adaptive framework for determining efficiently stochastic seismic responses and dynamic reliabilities via direct probability integral method (DPIM) is proposed. Moreover, to reduce the effects of near-fault ground motions, a superior MIED scheme is devised by comparative analysis in multiple conditions. Firstly, based on the probability density integral equation, the formulas for calculating time-variant statistical moments of responses and dynamic reliabilities in the component level and the system level are derived. Then, DPIM with fully adaptive strategy is suggested to calculate the stochastic seismic responses and dynamic reliability of cable-stayed bridge with MIED devices more accurately and efficiently than Quasi-Monte Carlo simulation. The comparative study indicates that the superior MIED scheme combines lateral elastoplastic cable pairs with longitudinal fluid viscous dampers (CP-FVD) in pylon-girder connection. CP-FVD system can reduce bending moments of pylons in lateral and longitudinal directions and displacement of the pylon-girder connection. The velocity pulses of near-fault ground motions lead to large seismic responses and failure probability of the bridge. Finally, the structural responses and reliabilities in the component level and the system level are remarkably affected by wave propagation speed.