A Beam-Column Joint Model for Simulating the Earthquake Response of Reinforced Concrete Frames

Abstract

i Experimental investigation of the earthquake response of reinforced concrete sub-assemblages 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 sub-assemblages 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. ii