Experimental evaluation of RC frames retrofitted by steel jacket, X-brace and X-brace having ductile ring as a structural fuse

Abstract

Due to several reasons as the low resistance of constructed concrete and also change in codes or application of structures, some concrete frames need to be retrofitted. By adding the steel brace to the reinforced concrete, many seismic parameters such as resistance, ductility, stiffness and the resistance reduction coefficient change. This study experimentally investigates the impact of adding the prop, the convergent steel brace and also the convergent steel brace with a ductile ring on resistance, stiffness, ductility and energy dissipation of RC frames. Four samples of RC frames with one span and one story with the same characteristics were constructed and retrofitted by different methods. All frames were subjected to the cyclic loading, and the hysteresis and pushover-displacement graphs of them were plotted. The novelty of the work was using such braces in RC frames. The results obtained from the tests showed that although the frame retrofitted by the X-brace showed a better performance in terms of resistance and stiffness, but the retrofitted frame with a ring also showed a better behavior in terms of resistance and stiffness compared to the RC frame and the sample with the jacket as well as compared to the sample with the X-brace showed more ductility and energy dissipation (with a slight reduction in resistance).