Effectiveness of Elastomeric and Sliding Isolation Systems in Seismic Protection of Buildings

Abstract

This study evaluates the effectiveness of base isolation in improving the seismic performance of a six-story steel braced structure. A comparative analysis between fixed-base and base-isolated models is carried out using SAP2000 through modal, response spectrum, and time history analyses. The results indicate that base isolation significantly increases the natural time period and reduces base shear, acceleration, and inter-story drift. Although displacement at the base increases, it is controlled and protects the superstructure from damage. Overall, base isolation proves to be an efficient and reliable technique for enhancing structural safety and earthquake resistance. This study presents a comparative analysis of the seismic performance of fixed-base and base-isolated reinforced concrete (RC) buildings using SAP2000 software. A seven-storey building model is analyzed under seismic loading conditions as per IS 1893:2002. Two types of base isolation systems, namely rubber bearings and friction pendulum bearings, are implemented and compared. The results indicate that base isolation significantly reduces seismic forces, increases the fundamental time period, and improves overall structural performance. Friction pendulum systems show better re-centering capability, while rubber bearings provide effective flexibility and damping.

Introduction

This text explains the concept, research background, materials, and methodology of base isolation as a seismic protection technique for buildings.

Base isolation is an earthquake-resistant design method that reduces structural damage by placing flexible isolators (such as rubber bearings or sliding systems) between a building and its foundation. These isolators decouple the structure from ground motion, reducing seismic energy transfer and lowering key responses like base shear, acceleration, and inter-story drift. By increasing the building’s natural time period, base isolation helps avoid resonance and shifts seismic effects away from the structure, allowing most deformation to occur at the base while keeping the superstructure largely elastic and safe.

The literature review highlights previous studies showing that base isolation significantly improves seismic performance compared to fixed-base structures. Researchers have used different isolator types (such as lead rubber bearings, friction sliders, and elastomeric bearings) and analysis methods (nonlinear time history analysis, SAP2000 modeling, and E-TABS simulations). Most studies confirm reduced seismic demand, lower displacement, and improved energy dissipation, though effectiveness depends on isolator design and system configuration.

The study’s main objectives are to:

• Compare seismic performance of fixed-base and base-isolated steel structures
• Evaluate parameters like shear, drift, acceleration, and displacement
• Study changes in dynamic behavior and energy dissipation
• Optimize isolator stiffness and damping
• Assess practical feasibility, cost, and real-world applicability

Various materials used in base isolation systems include:

• Elastomeric rubbers (natural rubber, neoprene, high damping rubber) for flexibility and damping
• Metallic components (steel plates, lead cores, stainless steel, bolts) for strength and energy absorption
• Sliding materials (PTFE, chrome-coated surfaces) for low-friction movement
• Cables and restrainers to control excessive displacement
• Composite rubber-steel layers for combined strength and flexibility
• Protective rubber covers to prevent environmental damage

The methodology involves modeling a six-story steel structure in SAP2000, analyzing both fixed-base and isolated versions under identical seismic loading. Analyses include modal, response spectrum, and nonlinear time history analysis using the El Centro earthquake record. The results of both models are compared to evaluate how effectively base isolation improves seismic performance.

Conclusion

The study concludes that base isolation is a highly effective technique for enhancing the seismic performance of structures. By increasing flexibility and energy dissipation capacity, it significantly reduces base shear, acceleration, and structural damage. Although the displacement at the base increases, it is controlled and confined to the isolation layer, thereby protecting the superstructure. Different types of isolators offer varying benefits, with friction pendulum systems providing excellent reduction in forces and rubber bearings offering better control of acceleration. Overall, base isolation ensures improved safety, reduced damage, and better post-earthquake functionality, making it a reliable solution for earthquake-resistant design.

References

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Copyright

Copyright © 2026 Randeep Singh, Er. Rohit Kumar, Er. Lucky Thakur. 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.