Seismic Retrofit of Square RC Short Columns with Shear-Flexural Failure Mode via CFRP Composites Using Different Confinement Techniques

Abstract

Short columns undergo larger drift ratios during earthquakes compared to ordinary ones, making them vulnerable structural elements if they are unable to withstand the demanded drift ratio and shear force without significant deterioration. In order to ensure proper structural performance, deficient reinforced concrete (RC) short columns should be effectively retrofitted. Carbon-fiber-reinforced polymer (CFRP) composites can be utilized effectively to provide adequate shear capacity and confinement for RC short columns to have a desirable performance during an earthquake event. In this study, six RC short columns were subjected to constant axial and reversed cyclic lateral loads to compare the three different confinement techniques of full-wrapping (FW), corner strip-batten (CSB), and corner strip-wrap (CSW) in terms of their efficiency. Moreover, the effect of a novel configuration of fiber anchors was investigated in improving the behavior of such short columns. Results indicated that the performance of a typical RC short column improved significantly with the use of the CSB technique, because its ductility and dissipated energy increased by 125% and 800%, respectively. Furthermore, the application of fiber anchors was observed to further improve the overall performance of short columns confined through either the CSB or the FW techniques.