Shake Table Studies of a Geotechnical Seismic Isolation System Using Lightweight Expanded Clay Aggregates

This paper analyzes a novel geotechnical seismic isolation system designed to protect multi-story buildings from seismic loads. The system utilizes lightweight expanded clay aggregates, which improve damping performance while resisting physical, chemical, and environmental degradation. Experimental shake table tests were conducted with a 1:22 scale model of a multi-story building supported by a pile system and enclosed by isolating walls. A laminar box facilitated the transfer of dynamic motion from the shake table to the structure. The dynamic loads applied included actual earthquake records and harmonic loads to simulate various amplitudes and frequencies, all appropriately scaled. Test results, detailing time-history responses such as acceleration, velocity, displacement, and drift, demonstrated that the isolation system effectively mitigates seismic effects by shifting the period due to isolation and enhancing damping performance due to lightweight aggregate properties, thereby reducing structural drift during seismic events.