Seismic Response Analysis Of Continuous Rigid Frame Bridges

As the development of transport, more and more continuous rigid-frame bridges are applied in practice, especially the continuous rigid-frame bridges with high piers, which are advantage in southwest and northwest in China, are applied economically and technically. While earthquake frequently occured in the areas, and the earthquake disaster data about this kind of bridges is not abundant. So, it is necessary to study the seismic response of the continuous rigid-frame bridge with high piers.In this paper, a continuous rigid-frame bridge with high piers, which locates in southwest in China, is studied, from the spectrum analysis in elastic stage to the time history analysis in elastic-plastic stage. According to the seismic design code about bridges and the actual condition, the design response spectrum and the design time history seismic wave are choiced. In elastic stage, we get to know that the fixed piers'bottom and top at bridge's longitudinal are the worst cross-sections through the response spectrum analysis. And the elastic-plastic stage is studied through the time history analysis, the most worst cross-sections are replaced by plastic elements which are modeled by fiber elements. In this stage, the seismic load, which increased gradually, was acted to the bridge, the plastic elements would yield and the bending curvature will exceeds yield curvature. During both of the stages analysis, we got to know the bridge's properties about mechanical and deformation and the different working state exerted in different seismic loads. We can know that this kind of bridges can act more well in good (II) site conditions, and the bridge bearings usually can't be destroyed due to the large-displacement because of the fixed piers during strong ground-motion. The outboard fixed piers'top may yield firstly, and then the 1/2 to2/3 of the fixed piers height may be both of the important cross-sections with the fixed piers'bottom. At the transverse, the bottom of pier between main span and approach span is the worse part of this kind of bridges.