A great variety of earthquakes such as the long period and long duration are predicted in the future. A high-performance buckling-restrained brace that is effective for those earthquakes is necessary. The authors have studied the buckling-restrained brace that has high-energy absorption capacities even in the high strain amplitude domain. However, not only the energy absorption capacities but also the fatigue performance is important. Therefore the authors confirm whether the buckling-restrained brace that had high-energy absorption capacities would become high-performance in the fatigue life. As a result, this buckling-restrained brace shows the high fatigue performance at the high strain amplitude domain.

In the past study, authors have conducted the fatigue performance tests of the buckling-restrained braces using high-performance type and the basic-type specimens, and discussed the fatigue performance in the large plastic-strain amplitude. In this paper, the fatigue performance tests of the buckling-restrained braces are carried out in the small-plastic strain amplitude. The linear relations from the small plastic-strain amplitude to large plastic-strain amplitudes of the buckling-restrained braces have been shown on a logarithmic scale from the test results. The fatigue performance of the buckling-restrained braces is able to be evaluated on the basis of these relations.