Experimental Study on the Lateral Response of Large‐Scale Unbonded Steel‐Mesh‐Reinforced Rubber Bearings

Conventional unbonded elastomeric bearings (ULNRs) are cost‐effective but prone to sliding during earthquakes due to their limited shear deformability. Unbonded Steel‐Mesh‐Reinforced Rubber Bearings (USRBs) offer a solution with increased deformation capacity. Utilizing high‐strength flexible steel wire woven mesh as reinforcement, USRBs undergo rollover deformation similar to fiber reinforced elastomeric isolators (FREIs), delaying sliding at large displacements. This paper investigated the lateral performance of full‐scale USRBs for the first time, particularly regarding their deforming pattern, mechanical properties, influencing factors, and failure modes. Cyclic loading tests were conducted on nine specimens with varying geometric characteristics and different loading conditions. Results show stable rollover deformation in full‐scale USRBs without delamination or compressive failure, demonstrating the effectiveness of steel mesh reinforcement. However, USRBs with large width‐to‐height ratios exhibited distinct edge‐curling instead of rollover and experienced sliding before full rollover. Both geometric characteristics and loading conditions significantly impacted the lateral stiffness and damping ratio of USRBs. Notably, one‐third of the tested USRBs slid before full rollover, but sliding initiated at an average displacement of approximately twice the bearing height. This finding shifts the lateral deformation capacity of such bearings from being governed by the displacement at full rollover to the displacement at initial sliding, suggesting that initial sliding displacement may be more suitable for defining damage states in future guidelines.