A new effective hysteretic damping device for improving the seismic resistance characteristics of a X-braced frame structure, in which the seismic energy is absorbed into the plastic deformation of the perforated steel plate in the device, was proposed in the authors previous papers. In this paper, the low-cycle fatigue characteristics of the present damping device are investigated. The applicability of the fatigue relation and the linear accumulation damage rule to the device is confirmed through constant amplitude and high-to-low block loading tests. Also, the life prediction expression of the present device is shown and its availability is verified by non-stationary amplitude fatigue tests using the deformation time history of the hysteretic damper in the on-line computer-actuator control test. It is clarified that the accumulation damage value of the damping device is small in the responses of the building with proper dynamic structural characteristics under a severe earthquake ground motion (with about 60 kine in the maximum ground velocity), and thus the present device has enough energy absorption capacity.
