Optimal design of steel frame with link beam considering soil-structure interaction

In this paper, the influence of the knee element on the behavior of the bending frame with considering soil-structure interaction has been investigated using the finite element method. The behavior of finite element models in a bending frame with a combined system of shear wall and knee element was studied. The investigated parameters are the number and states of link beams, shear wall thickness and span-to-height ratio. The parameters of shear stiffness, yield force, maximum force, yield displacement and energy are the basis of comparison of the samples. Results showed that maximum effect on the bending behavior of the frame occurs in the case of using four link beams that have a shearing behavior. Also, by changing the length of the link beam or knee element from bending to bending-shearing state and from bending-shearing to shearing state, stiffness parameters, flexural strength and energy have been increasing. In the case without link beam element, the stress concentration is concentrated in the corners and the beam-to-column connection. The results of the stress and plastic strain distribution of the bending frame without the link beam have a weaker performance compared to other samples. In the models with shear wall thickness of 2 mm, span to height ratio of 1, 1.25 and 1.5 and two link beams, highest increase in the parameters of shear stiffness, ultimate strength and dissipated energy have been achieved by 31, 16 and 15% respectively.