RESPONSE OF STEEL BRIDGE BEARINGS TO REVERSED CYCLIC LOADING

This study investigates the seismic performance of low and high type steel bridge bearing specimens. Experimental apparatus was developed to allow large cyclic horizontal loads and displacements to be applied to bearing specimens while keeping gravity loads constant. Simple seismic retrofit strategies are proposed and investigated experimentally to increase seismic performance. To increase the resistance in the longitudinal direction of the high type rocker bearings, retrofitting consisted of welding steel wedges to the masonry plate. It is shown that retrofitting the existing high type steel bridge bearings provides sufficient strength and displacement capability to withstand substantial ground shaking. The weak link thus becomes the anchor bolts and/or the reinforced concrete pedestal. Results demonstrate the importance of considering the flexibility of the concrete pedestal-anchor bolt system.