Improving Seismic Behavior of Existing Multicolumn RC Bridge Bents Using Low-Damage Retrofit Strategy

Abstract

Implementing a low-damage design (LDD) approach to improve the seismic behavior of existing RC bridge bents as a retrofit strategy is the main focus of the present study. Experimental and numerical studies were carried out on two 1/4-scale multicolumn RC bridge bents, which had been built based on conventional practice. The LDD approach was implemented by cutting the longitudinal rebars of the columns at both ends to allow rocking, adding unbonded post-tensioned tendons to supply self-centering, and adding two different external devices [buckling-restrained bars and reduced angle sections (RASs)] to provide energy dissipation. Cyclic reversal loading tests were conducted, and the results were compared with a reference nonretrofitted specimen, which was representative of the conventional semiductile design. Nonlinear time-history analyses were performed on calibrated numerical models to study the displacement demands of specimens at design basis earthquake (DBE) and maximum considered earthquake (MCE) events, both far- and near-field. The results showed that the low-damage retrofitted specimens have a better postearthquake condition compared to the reference specimen, particularly in terms of residual drift and damage. The LDD specimens successfully passed the DBE and MCE demands without experiencing failure of cables or dissipation devices.