Experimental Investigations on the Lateral Cyclic Response of Post-Tensioned Rocking Steel Bridge Piers

Abstract

This paper presents the results of a series of unidirectional quasi-static cyclic tests on 1/3-scale post-tensioned rocking steel bridge column specimens designed to rock at the interface with the foundation. The objective was to examine the effects of column diameter-to-thickness ratio, base plate, and energy dissipaters and their locations on the lateral cyclic behavior of the system. Site-specific cyclic displacement loading protocols were developed by performing time-history analyses of the pier. Emphasis was placed upon the sources of lateral response degradation including elastic restoring force reduction, local buckling, and energy dissipater failure. Strain distribution at the rocking plane and along the height, local bulging of the column, and uplift profile are discussed. The influence of multiple loading on the lateral response was also investigated. A component testing program was conducted to characterize the cyclic loss of post-tension force due to wedge seating in a typical industry monostrand anchorage system. The column test results demonstrate that a stable and robust self-centering response can be achieved with minimal damage to the column and most of the hysteretic energy is confined within the replaceable elements.