With the increasing population and the growing need for construction in urban areas near fault lines, along with land value and insufficient oversight on building regulations, most structures are built in close proximity to each other, often separated only by an expansion joint. As a result, the importance of evaluating the effects of earthquakes and fault ruptures on structures and infrastructure has significantly increased. Previous studies have primarily focused on the impact of seismic waves on buildings, while less attention has been given to fault rupture effects, permanent ground deformations, and the collision of both foundations and upper building sections due to seismic-induced displacements. Moreover, strike-slip faults, due to their complexity, have been less studied in both research and building codes. In this study, two adjacent rigid mat foundations near a strike-slip fault were analyzed using the FEM and 3D modeling by ABAQUS. The modeling employs a hardening-softening constitutive model to accurately simulate soil behavior, examine strain distributions, and track the propagation of failure. The results indicate that the collision of foundations depends on the fault slip angle. When the fault angle exceeds 90 degrees, the foundations collide, whereas at angles below this, they tend to move apart. Additionally, the location of the fault rupture directly influences the movement mechanism of the foundations. If the fault rupture occurs near the center of the foundation, it induces rotational motion, while faulting farther from the center primarily leads to translational movement of the foundation.

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