AXIAL-FAILURE PREVENTION IN RC EXTERIOR BEAM-COLUMN JOINTS UNDER HIGH-AMPLITUDE VARIABLE AXIAL FORCES : ANALYTICAL EVALUATION OF CORE REINFORCEMENT

This study proposes a constructability-oriented design approach for preventing axial failure in RC exterior beam–column joints. A three-dimensional nonlinear finite-element model incorporating core reinforcement was conducted. Comparison of load–deformation responses and failure modes confirmed that axial failure can be suppressed, and joint lateral reinforcement can be reduced. Concrete damage was quantified by panel-deformation-based indices. Axial force sharing between steel and concrete was evaluated from the forces in the core-bar and column longitudinal-bar. Stress–strain responses and buckling assessments of the column longitudinal bars indicated that proper core-bar detailing limits the buckling of those bars, thereby contributing to preventing axial failure.