Experimental Investigation on the Mechanical Properties of Silicone Elastomers Filled with Fumed Silica for Seismic Isolation Bearings

Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance. However, despite their resistance to temperature fluctuations and environmental aggressors, silicone elastomers exhibit relatively low stiffness, limiting their direct applicability in seismic isolation. This study investigates the effect of fumed silica as a reinforcing filler to enhance the mechanical properties of laminated silicone elastomeric bearings. Elastomeric samples were fabricated with varying fumed silica proportions and subjected to Shore A hardness, uniaxial tensile, and lap shear tests to assess the influence of filler content. Additionally, quasi-static tests were conducted on reduced-scale bearing prototypes under combined vertical compression and cyclic horizontal shear to evaluate their seismic isolation performance. The results demonstrate that fumed silica reinforcement significantly increases stiffness, as evidenced by higher Shore A hardness values. However, a trade-off was observed in tensile properties, with reductions in tensile strength and elongation at break. Despite this, the equivalent elastic modulus did not show substantial variation up to large deformations, indicating that stiffness is preserved under most working conditions. Lap shear tests showed that fumed silica improves shear resistance, while quasi-static tests revealed inelastic behavior with small increases in equivalent shear coefficients but no substantial loss in damping ratios. These findings suggest that fumed silica reinforcement enhances silicone elastomers’ stiffness and shear resistance while maintaining moderate damping properties, making it a promising approach for improving the mechanical performance of elastomeric bearings in seismic isolation applications.