Shear Strength Degradation Model for Performance-Based Design of Interior Beam-Column Joints

Under cyclic loading, the shear strength of reinforced concrete (RC) beam-column joints is decreased by diagonal cracking and beam bar-slip, as the inelastic deformation increases. In the present study, a joint shear strength model was developed for the performance-based design of interior beam-column joints. As the primary design parameter, the bar bond parameters were used to define the joint shear deformation and shear strength. All possible failure mechanisms of beams and joints were considered: flexural yielding of the beam end (bar fracture or concrete crushing), diagonal cracking and concrete crushing in the joint panel, bar bondslip, and bar elongation. For verification, the proposed model was applied to 50 existing beam-column joint specimens. The prediction results of joint shear capacity and deformation capacity were compared with the existing test results. The results showed that the predictions generally agreed with the test results.