Modeling the response of reinforced concrete bridge beam-column joints subjected to earthquake loading

Experimental investigation of the response of older and newly constructed reinforced concrete beam-column bridge joints indicates that inelastic joint action may contribute to global bridge response under earthquake loading. A model is proposed to simulate the response of these components under reversed-cyclic loading. This model provides a simple representation of the primary mechanisms that determine inelastic behavior: failure of the joint core under shear loading and anchorage failure of reinforcement embedded in the joint. The model is implemented as a 4-node, 12-degrees-of-freedom element that is appropriate for use with typical hysteretic beam-collumn elements in two-dimensional nonlinear analysis of reinforced concrete structures. A simple calibration procedure is proposed to define load-deformation response on the basis of material, geometric, and design parameters. The proposed joint model and calibration procedure are evaluated through comparison of simulated and observed response for a subassemblage tested in the laboratory. This comparison shows that this relatively simple model and calibration procedure can be used to simulate the fundamental characteristics of beam-column joint response under reversed-cyclic loading.