Shear strengthening of concrete columns by textile reinforced UHPC jacketing

Abstract

This thesis demonstrates the application of textile reinforcement, which recently has been drawing attentions due to its excellent ductility and applicability, with ultra high performance concrete (UHPC) as a retrofitting techniques of RC columns. This study investigated the enhanced seismic performance of RC columns retrofitted with textile reinforced UHPC attributed to enhanced ductility as well as strength. Seven RC columns for main test variables including different retrofitting material and the degree of axial force were prepared for experimental program. In addition, the finite element analysis of retrofitted RC column was carried out using a Vector 2 program to evaluate the relevance of the test results from the experimental program. Furthermore, this study theoretically applies the limit analysis to predict the shear strength of retrofitted RC column. Both lower bound limit analysis of truss-arch mechanism and upper bound limit analysis using virtual work method of failure mode were performed in the framework of the theory of concrete plasticity. The enhancement of shear strength and ductility were observed in the RC column retrofitted with textile reinforced UHPC. The experimental test showed that the use of textile reinforced UHPC as one of retrofitting materials is a viable option in construction site. According to the results by the program analysis and numeriacal analysis, a modified shear strength model for RC column retrofitted with textile reinforced UHPC was proposed. The modified shear strength model presented in this study guides engineers to design in the field of predicting maximum strength of RC column retrofitted with textile reinforced UHPC. In order to increase the applicability and to propose rational design guidelines for RC column retrofitted with textile reinforced UHPC, the experimental and theoretical studies of direct tensile strength and interfacial strength between RC column and textile reinforced UHPC is additionally required.