Seismic strengthening of existing RC beam-column joints by wing walls

Numerous non-ductile reinforced concrete (RC) buildings with little or no shear reinforcement in beam-column joints can be found in regions of moderate seismicity. To strengthen such substandard beam-column joints, this study proposes a method in which RC wing walls are installed beside existing columns, which overcomes the lack of realistic strengthening methods for congested connections in RC buildings. The proposed strengthening mechanism improves the joint moment capacity by utilizing tension and compression acting on the beam-wing wall boundaries; thus, brittle joint hinging failure is prevented. Three 3/4-scale RC exterior beam-column joint specimens without shear reinforcement, two of which were strengthened by installing wing walls with different strengthening elements, were fabricated and tested. The test results verified the effectiveness of the proposed strengthening method and the applicability of this method to seismically substandard beam-column joints. (c) 2017 The Authors. Earthquake Engineering & Structural Dynamics Published by John Wiley & Sons Ltd.