The Study of the Pounding of Adjacent Buildings with Different Structural Material Considering Torsion and Soil-Structure Interaction and Determination of the Safe Distance

Iran's location in a seismic zone and the existence of numerous structures built based on outdated seismic design codes necessitate a closer examination of the building design process. Among the issues arising during earthquakes, especially in large cities, is the occurrence of structural pounding. Most studies conducted on structural pounding have been two-dimensional, with rigid supports and for homogeneous structures. However, two-dimensional modeling eliminates torsion and neglects soil-structure interaction effects, which alters the structural behavior compared to reality. Moreover, there is a significant difference between the behavior of structures made of different materials, such as steel and reinforced concrete. Therefore, it is necessary to investigate the pounding phenomenon for heterogeneous structures, considering torsion and soil-structure interaction, and to determine a safe separation distance. In this research, by three-dimensional modeling of steel and concrete structures subjected to seven scaled selected earthquake records, adjacent to each other, at heights of 5, 11, and 17 stories, situated on a flexible soil foundation at various distances, the structural pounding phenomenon and the determination of a safe separation distance were studied. The results indicate that torsion leads to an 11% increase in the maximum pounding force, and soil-structure interaction causes a 2.6% increase in this quantity. In determining the safe separation distance, the spectral difference method, considering the behavioral characteristics of the structures with the help of their period, resulted in a 38% average reduction in this distance compared to the permissible separation distance predicted in the 2800 standard.