Experimental testing of hybrid sliding-rocking bridge columns under torsional and biaxial lateral loading

摘要

Hybrid sliding-rocking (HSR) bridge columns are precast concrete segmental columns with unbonded posttensioning, end rocking joints, and intermediate sliding joints. Having been developed for construction in seismic regions, HSR columns offer self-centering, energy dissipation, and low damageability. Recent advances in the computational modeling of HSR columns have resulted in the proposal of a number of refinements to their original design, leading to the introduction of Second-Generation HSR columns. Compared to First-Generation HSR columns, Second-Generation HSR columns use a reduced number of sliding joints made of high-performance polytetrafluoroethylene (PTFE) materials to provide desirable levels of sliding and frictional energy dissipation. The seismic performance of Second-Generation HSR columns was recently investigated through an extensive experimental study. The present paper discusses the major results of the tests performed on two half-scale HSR column specimens under combined lateral-torsional loading and biaxial lateral loading to demonstrate their performance under such loading scenarios. A variety of loading protocols were used to test each column specimen, including both cyclic and arbitrary paths. Both columns sustained minimal damage under displacement demands representing 975- and 2475-year seismic hazards, meeting their design objectives. Because of the torsional sliding at sliding joints, the column subjected to lateral-torsional loading did not exhibit any distinct torsional damage. The biaxial lateral loading was, however, found more damaging to HSR columns than torsional and uniaxial lateral loading.