Investigating the effect of stiffeners on the seismic behavior of concrete frames equipped with semi-connected shear walls

Semi-continuous steel shear walls are one of the lateral-resistant systems that do not apply any force to the column until the final moment. Since these shear walls are connected to the structure only at the bottom and top, they are prone to buckling, and the presence of stiffeners improves their behavior. In this research, parametric studies were conducted to investigate the seismic behavior of these shear walls equipped with stiffeners. For this purpose, the numerical model was first verified using two experimental samples. Then, the influence of the stiffener placement geometry on the seismic parameters of the frame, including elastic stiffness, ultimate strength, ductility, and energy dissipation, was investigated. The stiffener geometry was considered in three different shapes, while the shear wall width was considered in ten modes. Also, the effect of stiffener geometry on the dynamic behavior of the frame was evaluated. The research findings indicate that when a stiffener is added, it reduces the out-of-plane buckling and causes the maximum stresses to concentrate at the bottom of the shear wall. Moreover, increasing the width of the shear wall directly impacts the effect of stiffeners. Additionally, using X-shaped stiffeners results in the highest energy dissipation, elastic stiffness, and strength.