Numerical Investigation of the Foundation Burial Depth on Earthquake Damage and Seismic Behavior of Steel Structures Considering Soil-Structure Interaction

Abstract: Typically, in the analysis of structures, it is assumed that the soil beneath the structure is rigid, and the interaction between the soil and the structure is ignored. However, the soil is not rigid in reality, and the presence of soil under the structure changes the dynamic properties of the structure and consequently its response. Buried and deep foundations are more important. Paying attention to the effect of soil on the performance of structures during earthquakes, particularly the depth of foundation burial, has been a subject of consideration for many researchers in recent decades. Studies on the effect of soil on the performance of structures have been mostly done in the field of site effect and soil interaction of the structure, and less attention has been paid to the phenomenon of buried depth of foundation. Therefore, this research aims to address the scientific gap: considering the interaction between soil and structure, as well as the depth of the foundation, how does the seismic behavior of the structure change? In other words, according to past research, the innovation in this research is that a complete structure has been analyzed by considering the interaction of soil and structure and the depth of the buried foundation under the earthquake. Therefore, the main purpose of this study in this study is to investigate the effect of different depths of foundation burial on seismic behavior and structural damages caused by earthquakes. To achieve this goal, using IACOS software, the three-dimensional model of 5, 10, and 15-storey steel structures under the El-Centro earthquake is analyzed. Deep is more similar to a buried foundation. Especially in cases where the slope length is smaller, due to less soil deformations within the slopes, the sloped foundation behavior tends to be more towards semi-deep foundations. In addition, according to the results of this study, in short buildings (5 floors), the effects of horizontal and cradle movement in the interaction of soil and structure are almost the same, but with increasing the height of the structure, the share of rocking motion prevails, so that in tall buildings (15 floors and above), more than 90% of the changes in the period of the structure are due to this movement. Keywords: Soil-Structure Interaction, Period, Seismic Behavior, Pier Cutting, Floor Drift, Earthquake Damage