A numerical study on the seismic design of buildings seated over an RSM layer

Abstract

In recent years, there has been a significant effort to create innovative and affordable seismic protection systems that can be widely used in developing regions. Traditional isolators are often heavy and expensive, which restricts their application in residential buildings. To address this challenge, low-cost and low-tech approaches are being explored, such as the incorporation of rubber into the soil beneath a building’s foundation. This approach aims to dampen part of the seismic energy before it reaches the superstructure. This paper investigates the use of rubber-sand mixture (RSM) as a foundation layer to improve the seismic performance of structures. The effects of varying RSM dimensions on the footing acceleration response, structural weight, and base shear forces of a prototype five-story building are analyzed by numerical simulations. Results show that increasing the depth of the RSM layer and RSM content can significantly reduce the acceleration response, particularly for low-rise buildings with natural periods less than 0.3 s. Thicker RSM layers are found to be more effective in reducing input acceleration than wider layers, although such effect declines as the depth ratio exceeds 0.25. Furthermore, incorporating RSM as a base isolator can lead to a considerable reduction in both the maximum base shear force and structural weight, with up to 30% reduction achieved with RSM 35%. This study suggests that RSM has potential as a cost-effective and efficient solution for improving the seismic performance of low-to-mid-rise structures, and the effect of the depth of RSM layer and RSM content should be carefully considered for optimal design.