Seismic Performance of Step-back and Set-back Building resting on Hill-Slope

The seismic behavior of SBS buildings resting on hill slopes is a crucial aspect of earthquake- resistant design due to complex interplay between structural configuration, topography and soil characteristics. Those buildings adapted to uneven terrain, often face significance challenges arising from irregular mass and stiffness distribution, increasing their susceptibility to seismic forces. This study investigates the dynamic behavior and structural response of such buildings under seismic loads, considering step-back configuration having slope angles of 15°, 30° and 45° respectively. This analysis insight SSI effects to capture the soil inflexibility on structural performance. This analysis is done in ESFM using ETABS V22 to evaluate key parameters such as base shear, time period and inter-stories drift. Results indicate that SSI significantly alters the structural response of building on slope as compared to fixed base assumption. In general, buildings on soft soil exhibit increased lateral displacement and reduced fundamental frequency, making them more susceptible to seismic design. SB buildings, characterized by an unsymmetrical mass and stiffness distribution, experience higher torsional effects and stress concentrations, particularly at the base of taller columns. This increases the risk of structural failure under strong ground motions. On the other hand, set back buildings, with their relatively balanced mass and stiffness distribution, exhibit lower displacement and base shear values. However, when SSI is included in the analysis, even setback buildings show increased flexibility and longer vibration periods, emphasizing the need for proper foundation design and soil improvement techniques. Overall, this research provides valuable insights into the seismic behavior of such buildings resting on hilly slope and highlights the critical role of SSI in influencing their dynamic response.