Seismic Analysis and Design of Bridge Abutments Considering Sliding and Rotation

摘要

Current displacement based seismic design of gravity retaining walls utilizes asliding block idealization, and considers only a translation mode of deformation. Authors update and extend the coupled equations of motion that appear in the literature. A newly developed fundamental theory on seismic bearing capacity of soils is used to compute the seismic resistance of bridge abutments and the resisting moment offered by the foundation soil. Also, equations presented are extended to consider the case of bridge abutments and load transfer from the bridge decks. Algorithms for predicting permanent deformations were applied to a number of test cases that were modeled in the laboratory. Model bridge abutments were constructed within a seismic testing chamber, and seismic loading was applied to the models via a shaking table. Failure was possible by sliding, tilting or a combination of both. The mode of failure could be accurately predicted and depended on model parameters and properties of the backfill and foundation soil. Comparisons between observed and computed model responses serve to verify the ability of the proposed algorithms to predict sliding, tilting, or mixed modes of deformation.