Effect of Major Design Parameters on the Seismic Performance of Bridges with Hybrid Sliding–Rocking Columns

This paper explores the effects of major design variables on the seismic performance of the so-called hybrid sliding–rocking (HSR) bridge columns. The HSR bridge columns are precast concrete segmental columns with internal unbonded posttensioning, end rocking joints and intermediate sliding joints, which offer significant self-centering and energy dissipation capabilities. HSR columns introduce additional design variables, the effects of which on the seismic response of such columns have remained unclear. Using a recently developed robust computational modeling approach, this study identifies four major design variables, investigates their effects on the dynamic response of HSR columns, and proposes component-level design recommendations. The four design variables include the number of the sliding joints and their distribution over the column height, the incipient sliding base shear, the incipient bearing sliding amplitude, and the peak achievable sliding capacity. This study further investigates the effect of the vertical component of the earthquake excitation on the response of HSR columns and compares the seismic performance of an HSR column with that of a rocking-only column of the same strength. The findings indicate that HSR columns can be more damage resistant than rocking-only columns under earthquake excitations. The response of HSR columns was found to be insensitive to the vertical component of the earthquake excitation.