Seismic Response Analysis of Long-span Cable-stayed Bridges Subjected to Multi-support Excitation

摘要

A long-span cable-stayed bridge often has multiple supports separated by certain distances. If a long-span bridge is located r in a complex terrain with different local soil conditions ,the spatial variability may result in quantitative and qualitative r differences in seismic response as com -pared with those produced by synchronous motion at all supports. Therefore, how to r simulate the ground motion propagating in the field soil becomes imperative and crucial. The conditional simulation method r proposed by Vanmarcke et al (1993) is adopted in this study for simulating properly-correlated earthquake ground motions at r an arbitrary set of closely -spaced points. The absolute ground displacements at the different supports are then used as the r essential seismic loading in the dynamic equilibrium equation which is solved by the Newmark direct integration method. The r Stonecutters cable-stayed bridge located in Hong Kong is finally taken as an example to illustrate the con -ditional r simulation of seismic ground motion and seismic effects on the bridge. The results show that the conditional simulation of r seismic ground motion , considering wave-passage effect, incoherence effect and site-response effect, is important to reflect r the spatial variability of ground motion. The computed seismic responses , including bending moment, stress, and r displacement responses , also show that the spatial variability of ground motion shall be taken into consideration for the r seismic re -sponse analysis of long-span cable-stayed bridges with multiple supports.