Effect of SSI Model on the Response of Building

Abstract

The interaction between a structure and its supporting soil, known as Soil-Structure Interaction (SSI), plays a crucial role in accurately predicting the seismic response of buildings. Traditional structural analysis often assumes a fixed-base condition, neglecting the flexibility and energy dissipation characteristics of the underlying soil. However, recent studies and advancements in numerical modelling have demonstrated that SSI can significantly alter the dynamic response of buildings, especially under seismic loading. This paper investigates the effect of SSI models on the seismic performance of buildings by comparing fixed-base and flexible-base conditions using various analytical and numerical approaches. The results highlight that incorporating SSI leads to modifications in natural frequencies, mode shapes, base shear forces, and understory drifts. In particular, softer soils tend to increase system flexibility and period elongation, potentially reducing seismic demand but increasing displacement. The findings emphasize the necessity of including SSI effects in structural design, especially for critical infrastructure and buildings situated on soft or variable soil profiles. Understanding and accurately modelling SSI is essential for improving seismic resilience and ensuring the safety and performance of structures during earthquakes.

Introduction

Soil–Structure Interaction (SSI) describes the mutual and interdependent behavior between a structure and the supporting soil, where neither soil deformation nor structural response can be considered independently. Unlike traditional fixed-base design approaches, SSI accounts for the nonlinear, deformable nature of soil and its influence on settlement, stability, vibration, and load transfer, particularly under dynamic loads such as earthquakes. SSI effects are especially significant for soft soils, deep foundations, and complex loading conditions, making integrated geotechnical–structural analysis essential for safe and efficient design.

Recent research highlights the importance of modeling nonlinear soil–structure behavior using interface shear stress–displacement relationships and realistic load–settlement functions for foundations such as piles. The literature consistently shows that neglecting SSI can lead to inaccurate seismic demand predictions, unsafe designs, and misestimation of displacements, natural periods, and damping.

Studies reviewed demonstrate that SSI significantly affects the seismic response of adjacent buildings, irregular RC and steel structures, stilted and mid-story isolated buildings, historical masonry structures, and large-span spatial structures. SSI also alters the effectiveness of vibration control systems such as tuned mass dampers (TMDs), prompting the development of semi-active tuned mass dampers that adapt to changing soil and structural conditions in real time.

Conclusion

From the above literature review paper, it is observed that the Abaqus software has lot of advantages as compare to the other software available at present. From the literature review paper, it can be depicted that there is lot of saving in material and overall cost of the project. Thus, in our project we are taking as case sample of the existing SSI and designing the same with software with comparison of the cost will be carried out. The study demonstrates that SSI has a substantial impact on the seismic performance of mountain structures. To ensure accurate and safe design, SSI effects especially with variable soil conditions should be incorporated into seismic analysis and design of buildings in mountainous regions.

References

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Copyright © 2025 Neha Katre, Dr. Ashwini Tenpe. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.