Biaxial Constitutive Models for Simulation of Low-Aspect-Ratio Reinforced Concrete Shear Walls.

A novel biaxial finite-element (FE) model is proposed and validated by a total of 32 reinforced concrete (RC) shear walls with aspect ratio below 1.5. First, a biaxial concrete model package, which was previously developed in ABAQUS software for RC panel tests, is adopted to evaluate its accuracy of simulating RC shear walls. The FE modeling scheme, the biaxial FE model of concrete before and after initial cracking, and the uniaxial FE model of concrete are illustrated. The developed model considers the following five significant features including the concrete compressive softening, tension softening, concrete shear softening, pinching effect, and strength reduction because of lateral cracking. Second, the traditional rebar model without buckling and the longitudinal rebar model considering buckling are also illustrated. Third, the discrete Fréchet distance is adopted to quantify the relative error between FE simulation results and test results. Subsequently, the constitutive model in ABAQUS simulates a total of 32 RC shear walls under axial and lateral forces. The simulated RC shear walls cover a wide range of parameters, including aspect ratio, rebar orientation, reinforcement, and section shape. The FE simulation results are compared with test results including the force versus lateral deformation curves, load-shear displacement curves, and failure modes. According to the comparison, the developed constitutive model shows high accuracy for RC shear walls with aspect ratio below 1.5, including the replication of pinching effect and residual capacity. The developed model overestimated the initial stiffness of some test specimens, which may be attributed to the omission of concrete cracking induced by shrinkage. In general, the overall accuracy of the developed constitutive model is validated. [ABSTRACT FROM AUTHOR]