Experimental Investigation of Deficient RC Frames Retrofitted by RSFJ-Toggle Bracing Systems
This paper investigates the performance of the new retrofitting system, consisting of self-centreing damper resilient slip friction joint (RSFJ)-toggle bracing system. The RSFJ-toggle bracing system can be activated within small drift values of the frame and preserve the frame from excessive damage. Two scaled deficient RC frames representing typical pre-1970s RC moment resisting frames were constructed and tested to investigate the performance of such retrofitting system. Material testing of the concrete and steel rebars as well as the damper component testing were conducted and recommendations regarding the proper design of various aspects of this retrofitting system were provided. The experimental observations demonstrate the improved behaviour of the frame in terms of energy dissipation and enhanced stiffness and strength for the upgraded RC frame. As per the findings of this study, the proposed retrofit solution can strengthen the frames within a limited drift and improve the frame’s damping with a repeatable semi-flag shape hysteresis performance.