Dynamic response of RC frames retrofitted with friction-damped brace system through shaking table tests

This study presents the shaking table test results of two-dimensional reinforced concrete (RC) frames retrofitted with a simplified friction damped brace. An easy-to-manufacture and install friction damper with economical design, was proposed and tested under reversed cyclic loading and used to retrofit RC frames. The splice of a conventional steel brace was converted into a friction damper, which not only dissipated seismic energy but also helped avoid the buckling of the steel brace. The test scheme consisted of four RC frames, and the behaviors of the three retrofitted frames were compared with that of a non-retrofitted (bare) frame. The shaking table tests were conducted using an artificial seismic wave that reflected the short-period response characteristics of the Korean earthquake. The test results of the bare and retrofitted frames were analyzed by considering several important performance indicators, such as the cracking and fracture mechanism in the RC frames, base share, and story drift ratios. The results of the shaking table tests demonstrated that the proposed damped brace effectively reduced earthquake-induced drift demands and successfully shifted the fracture and damage concentration from the columns to the beams.