Comparison of Seismic Resistance between LRB and FPB on Energy Dissipation per Cycle and Equivalent Damping

In order to compare the seismic resistances of isolators, the compressive shear test and the compressive friction test were conducted in accordance with guidelines and equations. Two seismic isolators, LRB and FPB, which have different mechanical properties were used in experimental specimens. LRB specimens (Ø500mm ⅹ 300mm) consist of steel reinforcing plates, rubber layers and lead core. FPB specimens (Ø725mm ⅹ 169mm) have the main and sub-friction plate. The shear stiffness, EDC and equivalent damping were calculated and used to evaluate seismic resistance. As a result, shear stiffness, EDC and equivalent damping were shown more than the design value of seismic resistance. However, FPB specimens show higher value of EDC than LRB specimens. The differences of EDC values affected the variables of the compressive friction test. The equivalent damping ratio of the LRB and FRB specimens did not show significant differences. From the test results, it is confirmed that the LRB and FPB can be used to dissipate a seismic load as seismic isolators.