External strengthening of RC structures with buckling-restrained braced frames

Abstract

Abstract Four ½ scaled, 3-dimensional, 2-storey, deficient reinforced concrete (RC) specimens were examined by applying reverse static cyclic excursions. One of these specimens was the reference frame, and the others were externally strengthened using buckling-restrained braced steel frames (BRBFs). The BRBFs were connected to the RC specimens using anchorage rods. Therefore, these rods transferred the horizontal loads from the RC structure to the BRBFs. The BRBFs, as a novel lateral load-carrying mechanism, were able to withstand the lateral demands placed on the deficient RC structure. For the BRBFs, a new foundation was constructed adjacent to the existing foundations of the RC specimens, and they were connected to each other using anchorage rods. Hence, both foundations carried the forces induced by the steel and RC members with the help of anchorage rods. The test results showed that strengthening existing deficient RC buildings with BRBFs increased their rigidity, energy absorption, and load-carrying capacities when the structural RC elements remained in the elastic region or underwent limited plasticization. Thus, the strengthened RC specimens were effective at resisting the lateral demands as well as the self-weight and dead loads on them. Numerical analyses were also carried out, and the performance criteria for strengthened RC specimens were discussed in addition to the experimental studies. Thus, design proposals were presented for the exterior upgrading of RC buildings with BRBFs and their foundations.