Seismic Analysis for Design of Retrofit of Gravity Bridge Abutments

摘要

A revised analytic method is described for determining the most criticalthreshold acceleration. The method considers the possibility of sliding, bearing capacity, or mixed modes of failure. Details of the load transfer between the bridge abutment and the bridge deck are also incorporated. To verify the accuracy of the newly developed analytic method, a series of shaking table tests was conducted on model bridge abutements. Models could fail by sliding, excessive tilting or a mixed mode depending on the geometry of the wall, connection details between the bridge abutment and the bridge deck, and properties of the backfill and foundation soils. The results from these tests verify the analytic procedure for predicting critical threshold acceleration based on simple theory. It is now possible, with this analytic tool, to evaluate the seismic vulnerability of existing abutments. The theory also relates directly to design recommendations to increase the seismic capacity of both existing bridge abutments and new designs.