Elastic-Plastic Seismic Response Analysis of the Long Span Combined Highway and Railway Continuous Rigid Frame Bridge

In order to study elastic-plastic seismic response characteristics of the long span combined highway and railway continuous rigid frame bridge, in this paper, one combined highway and railway continuous rigid frame bridge with the span of 92+2×168+92m is taken as an example. The space finite element model is established by MIDAS to analyze the elastic-plastic seismic response of this bridge. The model is simulated pile-soil interaction by the equivalent soil spring stiffness method, and arranged plastic hinge by Clough model. The computed result shows that, under the worst load condition of frequent earthquake, there is a large surplus of material strength in the key section of the piers, and the eccentric distance and stability coefficient are far less than the regulatory limit. In a rare earthquake, the top and bottom of the piers are the first trick to yield and the first to damage. The non-linear displacement ductility ratios are all much smaller than the limit, of which the maximum is 3.32. This type of bridge has a good seismic performance, and it is suggested to keep the top and bottom of the piers as key sections in the design.