2021 年 28 巻 110 号 p. 110_73-110_82
This paper investigates cycling properties of the concrete-filled square steel tube (CFT) beam-columns to assess their number of cycles for limit state in the plastic region. Limit state for cyclic loading is defined by the state in which the shear force is reduced to 90% of maximum load. This investigation is based on a database including parameters such as rotation angle, axial compression ratio, width-thickness ratio of steel tube and ratio of buckling length to depth of cross section from previous test results for constant amplitude cyclic loading. Predictions from regression formulas, which involve the rotation angle, axial compression ratio as a main factor, almost agree with test results for number of cycle for limit state in the plastic region.