Experimental Investigation on Seismic Retrofitting Scheme of Using Self-Centering Damping Braces for Deficient RC Frames

Abstract

Many deficient reinforced concrete (RC) frames have been damaged in recent earthquakes, suggesting that their collapse prevention capacity should be improved. Conventional braces can efficiently improve structural strength and damping capacity, but they may not necessarily address after-event functional recovery. In contrast, self-centering damping braces (SCDBs) are emerging as a more versatile solution. However, experimental investigations on this solution are rarely found, although the feasibility has been discussed by some numerical studies. In this experimental study, pseudo-static cyclic loading tests were conducted to verify the retrofitting scheme of using SCDBs for deficient RC frames. Considering that the connection between braces and frame is critical to retrofitting efficacy, this study explored the feasibility of using a group of postinstalled chemical anchors to fix the brackets. The test results showed that the suggested connection activated the SCDBs at small drifts and the chemical anchors remained intact until 5% drift. Compared with the original frame, the retrofitted frame had increased lateral strength, higher energy-dissipating capacity, and reduced residual deformations. In addition, due to the restraining effects provided by the anchor brackets, the occurrence and propagations of concrete cracks at the column bases were well delayed in the retrofitted frame.