Experimental investigation of the earthquake response of reinforced concrete subassemblages indicates that stiffness and strength loss resulting from beam-column joint damage may be substantial. To simulate inelastic joint action, a joint element is developed that is appropriate for use with traditional beam-column elements in two-dimensional nonlinear frame analysis. The proposed element formulation includes four external nodes with a total of 12 external degrees of freedom; however, the element is a super-element and includes four additional internal degrees of freedom. The super-element comprises 13 one-dimensional components that explicitly represent the three types of inelastic mechanisms that may determine the earthquake response of beam-column joints: anchorage failure of beam and column longitudinal reinforcement embedded in the joint, shear failure of the joint core, and shear-transfer failure at the beam-joint and column-joint interfaces. Calibration models are proposed for each of the three types of components. These calibration models enable a user to predict response as a function of concrete compressive strength, transverse steel ratio, frame-member longitudinal steel properties, and joint geometry. Comparison of simulated and observed response for subassemblages tested in the laboratory indicates that the proposed model is appropriate for use in simulating the earthquake response of building joints with moderate earthquake load demands.
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