Effects of pier uplift and sliding isolation on seismic perfomance of highway bridges

The effects of pier uplift on sliding isolated highway bridges are studied for a symmetrical two-span continuous deck bridge. The seismic excitation uses the 1940 El Centro earthquake ground motion with a scaled peak ground acceleration 0.60g, which is comparable to the Caltrans bridge design spectra of 0.60g acceleration for rock. Pier uplift is found to enhance the effectiveness of sliding isolation for a highway bridge, especially for piers with inadequate lateral strength capacity. Elastic behavior of the pier is possible, while the seismic perfomance of a sliding isolated highway bridge is affected minimally by the pier uplift. These benefits are achieved with a relatively small amount pier uplifting.(AU)