Experimental tests on seismically damaged composite steel concrete walls retrofitted with CFRP composites

This paper presents the results of an experimental program on two composite shear walls with steel encased profiles (CSRCW), damaged under cyclic lateral loads and thereafter retrofitted and retested. The experimental program was conceived in order to analyze the possibilities of using CFRP materials for strengthening the CSRCW affected by seismic action. The Carbon Fiber Reinforced Polymer (CFRP) composites are becoming more frequently used in strengthening structural elements due to their superior characteristics and simple technology. From the damaged elements obtained in the first phase of the research program, two shear walls with steel encased profiles were selected to be retrofitted and retested. According to a thorough literature survey, the number of experimental campaigns on reinforced concrete walls (RC) retrofitted by FRP composite is rather low, compared to the large number of other structural members, and it does not exist for CSRCW. This paper presents an effective strengthening solution that can be applied to damaged elements to evaluate the availability of partial confinement, applied to parts with locally deteriorated strength. The retrofitting solution uses CFRP strips and plates, to restore the wall bending resistance and to provide a confinement effect at the ends. The experimental results indicate that the performance of the elements CSRCW_R, repaired and retrofitted, was similar to the reference elements in terms of load bearing capacity, but slightly smaller in terms of stiffness and energy dissipation capacities.