Experimental Study on Cyclic Response of Concrete Bridge Columns Reinforced by Steel and Basalt FRP Reinforcements

Abstract

This paper presents the seismic performance of concrete bridge columns reinforced with both steel and fiber-reinforced polymer (FRP). A bond-based parametric experimental study was conducted on five FRP steel–reinforced concrete (FSRC) bridge columns—using basalt FRP (BFRP) bars and BFRP sheets—and two steel-reinforced concrete (SRC) bridge columns served as references to investigate the fundamental characteristics of the proposed reinforcement. The investigated bond parameters included the texture of the FRP bars (smooth and ribbed), diameter of the FRP bars, location of the FRP bars with respect to the steel bars, and application of external FRP confinement. All columns were tested under the combined effect of constant axial load and reversed cyclic loading. The experimental results showed that the FSRC bridge column could realize the existence of a stable postyield stiffness (hardening behavior) as well as a reasonable displacement ductility of up to 10 before encountering strength degradation. Moreover, the FRP bars added for column longitudinal reinforcement did not have a substantial impact on the column elastic stiffness. The bond condition of the FRP bars to the surrounding concrete had pronounced effects on the column failure mode, postyield stiffness, residual displacement, and ductility; thus, it could be adopted as a design parameter.