Farshad Homaei
Abstract
Accurate seismic response estimation of structures requires adequate consideration of soil nonlinear behavior and its interaction with the superstructure. This paper presents a comprehensive study on the effect of Soil-Structure Interaction (SSI) on performance-based seismic response of typical mid-rise steel setback buildings and the demand distribution over the structure height. Therefore, foundation flexibility effects are investigated on the maximum displacement, inter-story drift ratio, shear and moment distribution over the structure height, and the maximum plastic hinge rotation of beam and column elements at different story levels. Results show that foundation flexibility alters the demand distribution pattern over the structure height. The level of nonlinear behavior of setback buildings plays a critical role in the structural seismic response. The shear and moment forces reduce due to the SSI effect. Meanwhile, the drift and displacement demand of flexible base setback buildings increases in comparison with the fixed base models. A large portion of demand is concentrated near the base and around the setback area, in a way that the plastic hinges of beam and column elements are affected. Moreover, SSI increases the plastic hinge rotation in beam and column elements. In conclusion, the design of setback building, especially on soft soils requires particular attention.
Keywords
Performance-based seismic response; Setback buildings; Steel structures; Soil-structure interaction; Seismic demand; Vulnerability