Modeling of coupled nonlinear shear and flexural responses in medium-rise RC walls

A macroscopic finite element modeling approach was adopted in this study for simulating the in-plane hysteretic lateral load behavior of medium-rise reinforced concrete structural walls with moderate aspect ratios (1.5 and 2), with coupled nonlinear flexural and shear response components. The constitutive formulation of the model is based on a fixed-crack-angle modeling methodology. Improvements were made on the constitutive model formulation, for better representation of the shear-aggregate-interlock effects in concrete,and dowel action on reinforcing bars, constituting the shear stress transfer mechanisms across the cracks. The model formulation was implemented into Matlab and analyses were performed using a drift-controlled nonlinear analysis solution strategy. The model was extensively calibrated for five heavily-instrumented wall specimens with moderate aspect ratios (1.5 and 2), and model predictions were compared with experimentally-measured responses at both global and local response levels. Response comparisons revealed that the model provides reasonably accurate predictions of the lateral load capacity, stiffness degradation, hysteretic shape, ductility, and pinching characteristics of the wall specimens investigated. The model also provides reasonable estimates of the relative contribution of flexural and shear deformations to wall displacements, longitudinal strain profiles and rotations along the base of the wall, and crack orientations. Sensitivity studies were also conducted to evaluate the variation of the analytical results with model parameters. The modeling approach implemented in this study is believed to be a significant improvement towards reliable prediction of the coupled shear-flexural response of reinforced concrete walls under cyclic loading conditions.