Strut-and-tie model for shear strength prediction of RC exterior beam-column joints under seismic loading

Based on the Kupfer failure envelope of concrete, an analytical model called the "interactive strut-and-tie model" (ISTM) for predicting the joint shear capacity of exterior beam-column joints (EBCJs) was formulated and is presented in this study. The ISTM consists of the interaction of the strengths of concrete struts and tension ties, and the strength contributions from shear reinforcements consisting of column ties, intermediate column vertical bars and crossed inclined bars are taken into account. The proposed approach was calibrated and validated using a large dataset of 328 EBCJ test results, covering a broad range of important parameters such as the aspect ratio, axial load ratio, beam reinforcement ratio and horizontal joint reinforcement ratio. Finally, the joint shear strengths computed by the ISTM were also compared against those obtained from state-of-the-art models and were found to have resulted in much more precision and uniformity.