Efficient three-dimensional shear-flexure interaction model for reinforced concrete walls

This paper describes the formulation of a computationally stable and efficient shear-flexure interaction model for reinforced concrete walls. The model is derived by combining two previously available models, a two-dimensional E-SFI model, and a three-dimensional SFI-MVLEM-3D model. The major enhancement in the model formulation compared to its parent SFI-MVLEM-3D comes from the implementation of a closed-form solution for the calculation of horizontal axial strains at fibers of the wall element. This significantly reduced the number of element degrees of freedom, which resulted in analysis run-time that is reduced to approximately 25% and convergence rate that is increased roughly two times. Validation of the developed analytical model is performed using test results obtained from a slender, flexure controlled, C-shaped RC wall specimen tested using multidirectional loading protocol, as well as two squat, shear-controlled, box-shaped wall specimens subjected to unidirectional cyclic loading. The comparison of analytical and experimental results revealed that the proposed model captures with good accuracy the stiffness and lateral load capacity of all examined wall specimens under cyclic loading. Model accuracy when predicting contributions of shear deformations was also good, while vertical strains are predicted with reduced accuracy mostly due to plane-sections assumption implemented in model formulation. The proposed analytical model is implemented in computational platform OpenSees.