Seismic Response Analysis Of Large-Span Rigid Frame Bridge Under Complex Site Conditions

With the implementation of the western development policy, transport services have also been developed rapidly, as a result, more and more bridges have been constructed in the complex western mountains area. western mountainous area possess complex terrain, uneven geological structure, high seismic fortification intensity, which caused the bridge with the characteristics of big span, high pier and poor seismic. Bridges are an important transport corridors of the western mountains, and are an important lifeline for relief works. In recent decades a large number of bridges destroyed in the earthquake, indicating that there is a certain kind of structural problems remain in the seismic design requirements must adopt a new approach to analysis and design.The research of seismic bridge are concentrated the seismic analysis of the upper part of bridge structure, and the scattering of seismic waves in complex superposition of the venue and soil-structure dynamic interaction are ignored currently. In the problem of seismic bridge, SSI effect, terrain effects and soil character are important pole in bridge dynamic analysis method and all those facts should be considered.The main conclusions in this paper as follows:1、The damage characteristics of the bridge and the current seismic response research situation of large-span bridges at home and abroad are summarized. The existing problems and the importance of seismic research of bridge in western mountain are also introduced.2、the dynamic time-history analysis method considering multi-span bridge excitation of long-span bridge is introduced firstly, and the applied loads of sv/p inclined wave on the artificial boundaries in two-dimension model are proposed based on the viscous-spring artificial boundary theory, as a result, an seismic analysis method of overall bridge accounting for soil-structure dynamic interaction and topographic effect is built.3、A finite element two-dimension model accounting for foundation soil found--ation soli under P\SV incident wave is built by using the Ansys, seismic analysis of a four-span continuous bridge considering the those factors, for example, SSI, terrain effects and soil character,was carried out by method.The calculating results will provides a theoretical basis of big-span bridge in complex site conditions the western mountain in this paper.