Experimental Evaluation of Cyclic Deformation Capacity of U-Shaped Steel Dampers for Base-Isolated Structures

U-shaped steel dampers are used widely for energy dissipation in base-isolated structures. However, dynamic loading tests of full-scale U-shaped steel dampers had not been conducted yet. Therefore, effects of dynamic loadings on cyclic behavior and cyclic deformation capacity of the dampers had not been made clear. In this paper, dynamic loading tests of full-scale U-shaped steel dampers were carried out to verify these effects. The major findings obtained from the tests are: (1) cyclic deformation capacity of various-sized U-shaped steel dampers can be evaluated based on horizontal shear deformation γ calculated from the lateral displacement δ divided by the height of the dampers; (2) in-plane (0-degree) loading is the critical direction for U-shaped steel dampers in the range of horizontal shear deformation γ from 20 to 200% ; (3) the effect of dynamic loading on cyclic behavior and fatigue characteristics is minimal.