The Reliability Analysis Of Bridge Structures For Near-fault Ground Motion

In recent years, with the development of economy and traffic construction, a great deal of long-span bridge have been build and expanded, especially, the scale of bridge bigger and bigger, the number of high tower and long-span cable-stayed bridge increasing gradually, as the lifeline project, the earthquake resistant design and seismic reliability analysis of bridge structures is become significant.In recent twenty years, the seismologist and seismic engineering expert have payed more attention to the characteristic of near-fault velosity pulse. Now with the increasement of records containing velosity pulse are collected, especially in 1999 Chi-chi earthquake in Chinese Taiwan, many researchers begin to apply themselves to observe and research velocity pulse.First of all, this paper introduces the basic theory and calculating methods in common use of aseismatic reliability of bridge structures. Based on the theory of random vibration, the calcualting method of aseismatic reliability applied to long-span bridge is analysed by using non-uniform multi-supported seismic excitation theory.After that, the records containing velocity pulse of Chi-Chi earthquake in Taiwan are collected and sorted by the styles of site. Basee on comparion between recording response spectrum and coded response spectrum and realtion between fault distance and recording acceleration(velocity) peak values, simply analyse the characteristic of near-fault seismic ground motion containing velocity pulse.At last, the cable-stayed bridge model is buid by using large FEM software. It analyses the dynamic characteristic of structure, compares the results of response spectrum analysis which uses coded response spectrum and near-fault response spectrum in different directions, studies the structural reliability using the method of response spectrum method under non-uniform multi-support seismic excitations.