Effects of Pounding and Abutment Behavior on Seismic Response of Multi-Span Bridge Considering Abutment-Soil-Foundation-Structure Interactions

This study aims to analyze the longitudinal seismic performance of a typical multi-span continuous girder bridge with seat-type abutments under earthquake excitation, especially accounting for different abutment behaviors. Three-dimensional finite element models of typical multi-span bridges are built considering the nonlinearity of the bridge columns, bearings, abutment-backfill interactions, pile-soil interactions, and the pounding at expansion joints. One of the models adopts a simplified bilinear model to express the force-displacement relationship of the abutment backwall. The other adopts a more practical multi-linear model, and the abutment backwall is used as a sacrificial component to control the damage to the abutment’s foundation by changing the strength of the abutment backwall. Comparisons of the results of the analysis of two bridge models with and without a sacrificial backwall indicate that it is more favorable for bridges with a sacrificial backwall to protect the foundation, but it is likely to arouse a larger displacement response of the main beam and even cause the unseating of girders. The recommendation for a sacrificial abutment in seismic design is that the right yield strength of the backwall should be selected to reach the balance point of force and displacement, and a collapse-proof system could be employed to prevent the beam from unseating.

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