Experimental Investigations of Precast Segmental Bridge Columns Seismically Isolated with Lead-Rubber Bearings

This paper presents a United States-Taiwan cooperative research project on seismic performance of segmental bridge columns for accelerated bridge construction, jointly supported by the Federal Highway Administration (FHWA) and the National Center for Research on Earthquake Engineering (NCREE) in Taiwan. Precast segmental bridge column construction is an effective approach in accelerating on-site bridge construction. However, in the current design practice of segmental bridge columns, mild steel longitudinal reinforcement is normally discontinued at the segment joints for ease of on-site erection. This leads to columns with significantly lower lateral strength and hysteretic energy dissipation capacity than conventional monolithic column for a given column size. To address this issue, the authors examine the use of seismic isolation bearings in segmental bridge columns to decrease the seismic demand. Among typical seismic isolation bearings, the use of lead-rubber bearings is first investigated. Large-scale specimens of segmental bridge columns seismically isolated with lead-rubber bearings will be tested to investigate their seismic performance. The tests will include quasi-static cyclic loading and bidirectional pseudo-dynamic loading with a spectrum-compatible earthquake. The experimental program is in progress and expected to be completed by the end of 2008.