Nonlinear FEM analysis for RC multi-story shear walls with vertically-aligned door openings

Reinforced concrete (RC) shear walls have been widely used in building constructions for providing high lateral stiffness and strength to resist lateral loads due to wind or earthquake. However, it is inevitable that openings are planned in shear walls for functional requirements, such as ventilating and lightening. And some architectural requirements lead to repeated openings from floor to floor, namely, continuously-aligned openings along height, resulting in isolated walls connected by beams. These openings may significantly affect the structural performance of shear walls, such as changing their stress transferring mechanism, lowering their stiffness and strength. A series of experiments were carried out on RC shear walls with continuous vertically-aligned door openings, and the fundamental structural performances, such as strength and failure mode were investigated. As a result, the shear walls with openings failed with concrete crushing at the bottom of walls beside the openings, and premature shear failure of the beams above openings; thus, the maximum strengths were influenced by the existence and the row number of door openings. However, it was difficult to quantitatively evaluate the shear contributions of wall components from the experimentally observed data. In this paper, in order to clarify the stress transferring mechanism and contributions of the wall components to the overall lateral strengths, the experimental results were simulated by two-dimensional FEM analysis. The verification of the analytical models was performed through comparisons between the experimental and analytical results in terms of shear force versus drift angle relationships and crack patterns. Major findings from the analysis were as follows: 1) the highest shear contribution among the wall components was observed in the partial wall divided by openings with boundary column on the tensile side for its high amount of tensile reinforcement; 2) thus, the significant strength deterioration was mainly caused by the compression failure of the wall bottom; 3) moreover, the total shear contributions of the beams above openings were not negligible because of high compressive axial forces passively applied to the beams.