Nonlinear analysis of RC shear walls considering tension-stiffening effect

An analytical model which can simulate the nonlinear behavior of reinforced concrete (RC) structures (such as panels and shear walls) subjected to in-plane shear and normal stresses is introduced. Based on the concept of equivalent uniaxial strain, constitutive relations of concrete are presented in the axes of orthotropy which coincide with the principal axes of total strain and rotate according to the loading history. The proposed model includes the description of biaxial failure criteria which show compressive strength enhancement and tensile resistance reduction effects for the stress states of biaxial compression and tension–compression, respectively. After tensile cracking, concrete compressive strength degradation was implemented and the tensile capacity of concrete maintained by the reinforcing steel (tension-stiffening effect) is considered. Using the concept of average stresses and strains, a criterion is proposed to simulate the tension-stiffening effect based on the force equilibriums, compatibility conditions, and bond stress-slip relationship between reinforcement and the surrounding concrete. The finite element model predictions are validated by comparison with available experimental data. In addition, correlation studies between analytical results and experimental values from idealized shear panel tests were conducted. Load–displacement relations of shear panel beams and walls under various stress conditions are then evaluated to verify the soundness of the proposed model.