The Analysis Of Seismic Response Of Curved Continuous Rigid Frame Bridges With High Piers And Long Span

Besides with parts of level cross country, western region of China is a mountainous zone, with high mountains and deep gorges, steep terrain. Building bridge in these mountains,especially in high-ranked highway, are required to meet the requirement of road line features, and the bridge axis is curved in planar to provide a smooth transportation alignment. Long span curved continuous rigid frame bridges have made a rapid advancement in recent years with the sharp development of the high level roads in mountain areas and urban viaduct.With the diversity of structure and the complication of force, the seismic design analysis and evaluation is more and more difficult, so, new seismic design code for this type bridges is urgently needed. Now some relevant departments are revising the seismic design code for bridges, so this article has theoretical and practical significance in the analysis of seismic response of curved continuous rigid frame bridges with high piers and long span, combining the mechanical properties of curved girder bridges and rigid frame bridges.Taking western approach bridge of Xiamen Haicang bridge (PC and curved continuous rigid frame of five spans, with 900m curvature radius)as project background, the paper carries out the seismic response analysis for curved continuous rigid frame bridge using the response spectrum method and the nonlinear time history analysis method respectively, the main work is listed as follows:1. This paper establishes bridge space finite element model, considering the soil-pile interaction, and compares the dynamic characteristics of bridge under the different geological conditions and boundary conditions; in order to analyze the influence of curvature radius for the curved continuous rigid frame bridges, the analysis for the curved rigid frame bridges with the same span and different curvature radiuses are carried out, and some change laws and useful conclusions are obtained.2. Seismic characteristic of structure studied by the response spectrum analysis is compared in one-dimensional earth action under the different geological conditions and boundary conditions.3. In the seismic analysis, the earthquake input principal direction for regular bridge having two clear principal directions is the bridge direction. But there is no clear principal direction for irregular bridges. So the problem of the earthquake input principal directions for irregular bridges is concerned by the designers. This article carries out the response spectrum analysis for bridges under different earthquake inputs and curvature radiuses. the results obtained from that are compared to reach some beneficial conclusions.4. The seismic response of the curved continuous rigid frame bridges is studied by the nonlinear time history analysis method, and the results are compared with that of the response spectrum analysis method.Based on the analysis of seismic response to western approach bridge of Xiamen Haicang bridge, some conclusions are gave out, expecting to provide the theory basis for establishment of the new seismic code and the seismic design for the curved continuous rigid frame bridges with high piers and long span.