Shaking table study on rubber-sand mixture cored composite block as low-cost isolation bearing for rural houses

Historical and recent earthquakes have caused severe damage to rural houses worldwide, which are often characterized by low story heights, high stiffness, and limited budgets. In this regard, low-cost seismic isolation strategies hold great potential for protecting low- and medium-rise buildings. This paper proposes a novel rubber sand mixture cored composite block (RSMCB) as a low-cost alternative to conventional expensive isolation bearings. The construction of the RSMCB involves filling the hollow of a plain concrete block with a lightweight material made of granulated rubber and natural sand and then covering the surface with a square brick slightly smaller than the hollow's size. To evaluate the effectiveness of the RSMCB, a series of shaking table tests were conducted, covering factors of rubber content, cover plate size, upper block mass, and paving mode. The results indicate that the utilization of the RSMCB layer effectively mitigates large displacement in the superstructure during the cyclic loading, thereby functioning as an energy dissipation and seismic reduction measure. Moreover, the isolation effect of the RSMCB layer increases with the seismic intensity attributed to the nonlinear variation of dynamic parameters of the mixed granular material with shear strain. These findings suggest that the proposed isolation strategy improves the strength and vertical stiffness of the original sand-rubber layer, making it a desirable and sustainable solution for seismic design applications in rural housing.