FACTORS INFLUENCING AXIAL FAILURE OF RC EXTERIOR BEAM-COLUMN JOINTS SUBJECTED TO HIGH VARYING AXIAL FORCES : ANALYTICAL STUDY ON EVALUATION OF CONCRETE EFFECTIVE STRENGTH

Referring to a previous experimental study of RC exterior beam-column joint structures subjected to high varying axial forces, a 3D nonlinear FEM analysis was conducted. The main parameters were the strength reduction ratio βj, the joint reinforcement ratio, and the varying axial force ratio. Based on the strain transverse to the direction of compressive strut, the damage level of the joint panel and the effective strength coefficient could be estimated. A change of the effective strength coefficient with respect to the experienced story deformation angle was quantitatively presented. The design factors that correlate with the effective strength coefficient were organized.