Investigation on Seismic Performance of RC Beam–Column Joints Retrofitted with Steel Jackets in Presence of Transverse Beams

Steel jackets are widely used for the seismic retrofitting of reinforced concrete (RC) beam–column joints. However, the details and efficiencies of steel jackets are directly impacted by the presence of transverse beams. An in-depth understanding of this issue has been lacking so far. In this study, using realistic configurations of transverse beams, the seismic performance of exterior RC beam–column joints retrofitted according to the modified steel jacketing method were investigated numerically and theoretically. The refined nonlinear three-dimensional finite element approach was adopted and verified against experimental observations. A series of parameters were considered, including the number of transverse beams; the thickness, width and spacing of the steel strips at joint panels; and the axial compression ratio of columns. The results obtained from twenty specimens in terms of load response, cracking pattern, stress distribution, stiffness degradation and energy dissipation confirmed the effectiveness of the modified steel jacketing method. Significant differences among the roles of the parameters were revealed, and the reasons behind the differences were analyzed. Moreover, by means of significance analysis, the width and thickness of the steel strips were identified as the most influential parameters on the shear capacities of the joint panels with single- and double-sided transverse beams, respectively. Furthermore, based on the softened strut-and-tie model, a design approach for predicting the shear contribution of steel jackets in the presence of transverse beams was proposed for engineering applications.