A parametric study on sustainable scrap tyre pad isolators and development of design aid for application in masonry structures

Scrap tyres, a significant source of environmental pollution, have been identified as excellent materials for vibration isolation. The steel cords in the tyres provide vertical stiffness, while the rubber offers lateral flexibility, making them suitable for base isolation. However, variations in tyre sizes, pad thickness, steel strand arrangements, and properties under different loading directions and pressures present practical challenges. This paper investigates the basic strength properties of scrap tyre pads to assess their suitability for base isolation. Key factors influencing the structural properties of scrap tyre pad isolators are identified. Tyres of size 175/65/R14 are chosen for the study. Structural properties are estimated through experimental and finite element modelling. A detailed parametric study examines the effects of secondary shape factor, loading direction, vertical pressure, and tyre layer thickness and arrangement. The study reveals that secondary shape factor and vertical pressure predominantly control the structural properties of unbonded scrap tyre pad isolators. A Design Aid is developed, showing the structural parameters of isolators with different configurations under varying pressures. The design aid's application is demonstrated in designing base isolators for a two-story masonry building.