A new model to simulate joint shear behavior of poorly detailed beam–column connections in RC structures under seismic loads, Part I: Exterior joints

A new model that can simulate the shear behavior of reinforced concrete connections in structures subjected to seismic loads is proposed. The model uses limiting principal tensile stress in the joint as the failure criteria so that due consideration is given to the axial load on the column. The spring characteristics are based on the actual deformations taking place in the sub-assemblage due to joint shear distortion. The model can be easily implemented in any commercial nonlinear analysis package and does not need any special element or subroutine. The model is more rational than the rotational spring models and at the same time being easier to implement in analysis than the multiple spring models. The formulations to obtain the spring characteristics are given in the paper. Currently the model is used to perform nonlinear static analysis for the joints, however, the same can be utilized for the nonlinear dynamic analysis too with an associated hysteretic rule. Highly promising results are obtained using the proposed model for the cases against which the model is validated. This paper focuses on the modeling of exterior joints. An extension to interior joints will be presented later.