Experimentation and numerical modelling of recycled rubber pads under ageing for base seismic isolation of a historical masonry church

Base seismic isolation is one of the efficient technical solutions to reduce the vulnerability of new and existing structures. The designs of the base isolation device have been developed in the past decades by many researchers. In this work, a recycled rubber material derived from industrial waste is used for rubber pad fabrication to reduce significantly the cost. A series of uniaxial tensile test and relaxation test is conducted to characterize the hyperelasticity and viscosity of the recycled rubber, both in fresh and aged condition to evaluate its durability. The recycled rubber specimens are then used to fabricate an unbonded fiber reinforced elastomeric isolator (UFREI), which does not need any thick steel plate for the installation. It may reduce significantly the cost and weight of the isolation system. The proposed UFREI is investigated through a shear test simulation, both in fresh and aged condition, to investigate the behavior after long-term use. The proposed UFREI is then implemented to isolate a historical masonry church in the center of Italy. A time-history analysis is performed in Abaqus FE software, by applying a concrete damage plasticity (CDP) model for the masonry material. The results of the dynamic analysis show that the application of such low-cost isolation system can mitigate the damage of the masonry church under 0.25 g of PGA, from extensive damage to slight damage. The proposed UFREI shows also a negligible reduction of the isolation performance under ageing effect. The results reveal a promising advantage of the UFREI system using recycled rubbers.