Feasibility Study on Re-Using Tennis Balls as Seismic Isolation Bearings

This paper presents an experimental study of a low-cost seismic isolator that can be used for the protection residential structures in low-income countries. The is based on mortar-filled, tennis spheres, rolling flat or spherical concrete surfaces. spheres serve as permanent, molds to cast mortar, and they are not removed after casting. thin rubber shell sphere offers increased damping reduces stress concentrations at contact areas. At same time, this procedure creates promising solution re-use spheres. Using closely-spaced grid such may allow avoiding diaphragm slab isolation level, reducing its thickness. Avoiding cost additional, heavily reinforced crucial making seismically isolated low-rise dwellings economically feasible regions globe. Initially, isolators were subjected monotonic uniaxial compression examine their behavior under vertical loading. Different mixes reinforcement approaches increase strength tested. Subsequently, cyclic tests performed obtain lateral force-displacement diagram system. effects geometry surface (i.e., concave) applied compressive load 2.08, 3.23, 4.74, 8 kN/sphere) investigated. It was found restoring force systems mainly originates from curvature surface. However, motion induced by compressed local casting imperfections negligible. When become significant, loops deviate bilinear curves rigid-body model suggests. properly cast, experience zero damage even kN force, have form. For tested configurations, friction (defined ratio displacement) range 4.7–7.2%, thus suitable applications. ball 0.05 $ per sphere.