Numerical analysis for low cyclic loading test of shear wall based on MFBFE shear wall element

Force-based fiber element, which ignores section shear deformation and assumes the section is plane, is the most commonly used element for the nonlinear analysis of reinforced concrete structures. However, for shear wall structures, the section is much wider than that of beam and column, thus plane-section hypothesis and section shear deformation ignorance will cause greater error. A Modified Force-based Fiber Element (MFBFE) considering the section shear deformation is proposed in this paper. In the modified force-based fiber element, the cross section is no longer plane section but curved surface. The MFBFE elements is first formulated and then implemented in the finite element program OpenSees. Numerical analysis for a group of nine shear wall specimens under low-cyclic loading is conducted using MFBFE element. Analysis results show that the entire hysteretic loops of shear walls, including the initial stiffness, yield strength, ultimate strength, unloading stiffness, residual displacement, ductility and energy dissipation, are well predicted. Trend analysis under variable axial compression ratio, variable aspect ratios and variable concrete strength, variable longitudinal reinforcement ratio, variable constraint zone length, variable stirrup ratio shows that the MFBFE element has broader applicability. The new element proposed in this paper can be used in shear wall structures design to resist earthquake actions.