Examining the seismic response of the ground surface and its impact on structures due to topographic effects and soil-structure interaction (TSSI) is highly significant. If the site has sloping topography, the importance of this study is further amplified, and the slope effect on soil-structure interaction must be considered. This research uses Loma Prieta (1989) earthquake records to analyze the seismic response of a 5-story concrete building located 5 meters from the crest of the slope for four angles: 15, 30, 45, and zero degrees (SSI), using 3D numerical analysis. Modeling was conducted with MIDAS GTS NX software for both TSSI and SSI systems. An elastic model and an HSS model were used for the building and soil, respectively. The seismic response of the building was evaluated by comparing maximum lateral displacements, base shear forces, inter-story drifts, and horizontal accelerations in TSSI and SSI analyses. As the slope angle increased from zero degrees (SSI) to 15, 30, and 45 degrees (TSSI), the average lateral displacement of the floors increased by 44%, and the average maximum horizontal acceleration increased by 21%. Additionally, with the slope angle increasing from zero degrees (SSI) to 15, 30, and 45 degrees (TSSI), the average ratios of inter-story drift and maximum base shear force increased by 14% and 21%, respectively.
