Behavior of Circular Fiber-Reinforced Polymer–Steel-Confined Concrete Columns Subjected to Reversed Cyclic Loads: Experimental Studies and Finite-Element Analysis

This paper studied experimentally the behavior of circular fiber-reinforced polymer (FRP)–steel-confined concrete columns subjected to reversed cyclic loads. The influence of main structural factors on the cyclic behavior of the columns is discussed. Test results showed the outstanding seismic performance of FRP–steel-confined RC and steel-reinforced concrete (SRC) columns. The lateral confinement effectiveness of glass fiber–reinforced polymer (GFRP) tubes and GFRP–steel tubes was verified and a simplified OpenSees-based finite-element method (FEM) model was developed to simulate the experimental results of the test columns. Based on the proposed FEM model, a parametric analysis was conducted to investigate the effects of main factors on the reversed cyclic behavior of GFRP–steel-confined RC columns. Based on the test and numerical analyses, the study discussed the influence of variables such as the lateral confinement on the plastic hinge region (PHR) height and peak drift ratio of the columns under reversed cyclic loads. Results indicate that lateral confinement significantly affects the PHR height of circular confined RC columns. Based on the analyses of the data from this study and literature, a simple model was suggested to predict the peak drift ratio of confined RC columns.