Performance of low-cost unreinforced elastomeric isolator for masonry building: Experimental investigations and numerical analysis

Rubber-based seismic isolation devices have been widely implemented globally to safeguard structures such as buildings and bridges against the impact of seismic events. Recent studies have concentrated on various cost-effective rubber-based isolation mechanisms to mitigate seismic hazards in rural areas of developing nations. Although certain techniques have shown encouraging outcomes, the implementation of these techniques continues to pose significant challenges. The current investigation introduces a cost-effective base isolation method that is practical and achievable for masonry structures. The primary objective of this research is to investigate the effectiveness of using unreinforced rubber as a seismic isolator. To ascertain the efficacy of the concept, an experimental evaluation was carried out to study the dynamic characteristics of the unreinforced elastomeric isolator. The impact of various conditions was also examined by testing the proposed isolator with varying the vertical load, shear strain, and excitation frequency. The isolation period of tested isolator was less than the design isolation period due to increase in horizontal stiffness of the loaded isolator. Hence, slightly higher isolation time period should be considered in the initial design stage. A numerical model was formulated and subsequently validated against the experimental data. The model was utilized in the numerical simulation of a masonry building, followed by the execution of a time-history analysis. The analysis reveals a significant decrease in seismic response, specifically in terms of roof acceleration. Hence, the proposed isolator has the potential to serve as a valuable option for the implementation of a cost-effective seismic isolation system in low-rise structures within developing nations.