Nonlinear Responses of Low Strength RC Columns Retrofitted with External High-Strength Hoops

In the Standard for Seismic Evaluation of Existing RC Building of Japan (2001), the lower limit value of concrete compressive strength for the existing RC building is defined as 13.5 MPa, and the RC buildings are considered unsuitable for seismic retrofit if the compressive strength of concrete is lower than the limit. In this study, a novel seismic retrofit technique using external pre-tensioned high-strength hoops and steel plates is applied to the low strength RC column with smooth rebar and poor shear reinforcement under axial force ratio of 0.31 and 0.57. The experimental results show that both the ductility and the lateral capacity of the specimens can be improved significantly. Moreover, nonlinear analyses of the non-retrofitted and retrofitted specimens are carried out using VecTor2. The results from numerical models agree well with the experimental results.