Seismic Performance of Steel Plate Girder Bridges with Integral Abutments

This report presents the results of a pilot study on the seismic behavior and response of steel bridges with integral abutments. Analytical investigations were conducted on computational models of steel bridges with integral abutments to determine their seismic behavior as a system and to develop seismic design guidelines. The effect of the superstructure flexibility due to inadequate embedment length was investigated using 3D finite element models. This flexibility, modeled as translational and rotational springs, proved to have significant effect on the overall bridge dynamic characteristics in terms of periods and critical mode shapes. Lateral and longitudinal load paths and the seismic response were investigated using modal pushover and nonlinear time history analyses. A limited investigation on the effect of skew was conducted on a single-span integral abutment bridge. A procedure for incorporating the system level damping due to the yielding and inelastic responses of various components was proposed for use in the seismic analysis. Based on the analytical investigations and available experimental research, guidelines for the seismic analysis and design of integral abutment bridges were developed.