## 1 Introduction
Reference [2] highlights that earthquake magnitude significantly influences the dynamic behavior of soil-pile foundation systems. Kinematic interaction analyses reveal that layered soil conditions, particularly when 75% of the pile length is in weak soil, create unfavorable scenarios during seismic events. Reference [3] indicates that during dynamic soil-pile-structure interaction in dry sand, inertial forces from the superstructure dominate, while kinematic forces from soil deformation are relatively insignificant. Reference [4] focuses on dynamic soil-pile behavior during liquefaction, highlighting the influence of excess pore pressure and soil nonlinearity on structural responses. It emphasizes the differences in interactive behavior between liquefied and dry sand under cyclic loading conditions. Reference [5] analyzed the influence of soil relative density on pile deformation and seismic response. The authors' findings indicate that higher relative densities reduce pile deformation, enhancing overall stability. Reference [6] studied the effect of superstructure mass on pile foundations under seismic loading. The authors observed that while an increase in mass generally amplifies inertial forces and bending moments in piles, beyond a certain threshold, seismic response diminishes due to reduced resonance. Reference [7] examined the interaction between kinematic and inertial forces, highlighting that denser soils and heavier superstructures intensify these interactions, significantly affecting pile seismic performance. Reference [8] investigated pile behavior in liquefied soils, demonstrating that lower relative densities increase the risk of buckling and lateral displacement, which can compromise structural integrity. Reference [9] examined how soil relative density affects the lateral response of piled raft foundations. Higher density increased stiffness, reducing lateral displacement and shifting more load resistance to the raft component. Previous studies have primarily focused on analyzing these effects separately, with limited research investigating the combined interaction of kinematic and inertial forces. Furthermore, a comparative analysis of the seismic behavior of single piles and pile groups remains necessary to provide practical seismic design guidelines. Several other studies have attempted to evaluate the dynamic interaction behavior of soil-pile-structure using various methods such as numerical analysis techniques [10; 11; 12; 13; 14; 15]. However, it is difficult to view them as studies focused on inertial and kinetic forces. This study aims to analyze the seismic behavior of group pile-supported structure using 3D numerical simulations with FLAC3D. The focus is on evaluating the effects of soil relative density and superstructure mass on the seismic response of pile foundations by examining the interplay between kinematic and inertial forces. Through quantitative comparisons, this study seeks to identify key factors influencing the seismic response of pile-supported structures and provide valuable insights for improving seismic design. Furthermore, this research addresses the existing gap in previous studies by comprehensively investigating the dynamic interaction of kinematic and inertial forces using a 3D approach. The findings are expected to contribute to the optimization of seismic design for pile foundations.