Effects of Soil on the Seismic Design of Long Span Steel Frames Using Contemporary Building Codes

Abstract

Seismic excitations and other lateral dynamic distress cause the structure’s foundation to interact with the superstructure’s response. Consequently, the surplus stress distribution takes place. This disturbance in the lateral stiffness of the system can cause un-satisfaction with the adopted code provisions. In the above scenario, soil structure interaction of the Moment Resisting Frames (MRFs) becomes very crucial. This article deals with soil stiffness on the long-span MRFs designed with two modern building codes, namely Saudi Building Code (based on American Standards) and Eurocodes. High and medium ductility with parameter and spatial frame configurations are considered in this study. Each frame is analysed considering the foundation stiffness, calculated based on FEMA recommendations. Hence, a total of 18 cases are examined, conducting a modal response spectrum analysis. The period, top displacements, reactions, and damageability criterion for the analyzed frames are compared. It is shown that the consideration of SSI (Soil Structure Interaction) is paramount for frames with such spans, especially when subjected to high seismic forces.