Full-scale seismic response test on a shallow foundation embedded in tire-derived aggregate for geotechnical seismic isolation

Abstract

This paper presents results from full-scale tests aimed at characterizing the seismic response of shallow foundations embedded in tire derived aggregate (TDA) with large particle size. The high shear strength, low shear modulus, and high damping ratio of TDA with large particle sizes make it ideally suited for low-cost Geotechnical Seismic Isolation (GSI) systems. Unidirectional shake table tests were performed on a single-degree-of-freedom superstructure connected to a 0.46 m-deep concrete strip footing embedded within a 1.89 m-thick TDA layer inside a laminar box. The TDA-footing system was subjected to a series of sine sweep motions with varying amplitudes and frequencies between 0.4 and 10 Hz. Substantial nonlinearity was observed in the moment-rocking response of the footing, where the specimen experienced rocking stiffness softening at moment demands slightly below its moment capacity. While the footing exhibited moderate transient settlement and uplift during dynamic oscillation, it demonstrated low residual settlement. The TDA layer offered the footing an effective recentering system with an average residual recentering ratio of 0.991. In addition to being low-cost, abundant, and recycled, the TDA layer had both favorable energy dissipation and recentering, with better seismic resilience than structural hinging and conventional foundation rocking systems in soil.