Buckling-restrained brace and seismic force-resisting structure

A buckling-restrained brace, comprising:

• a core extending in an axial direction;
• and
• a restrainer encasing the core from an outer side thereof in a state where both end segments of the core in the axial direction protrude from the restrainer,
• wherein the core includes a first steel plate having a first yield point, a second steel plate having a second yield point different from the first yield point, and a third steel plate having a third yield point different from the first yield point, the first steel plate being sandwiched between the second steel plate and the third steel plate,
• the first steel plate includes a first yielding segment provided in a center segment of the first steel plate in the axial direction and having an axial strength smaller than an axial strength of both end segments of the first steel plate in the axial direction,
• the second steel plate includes a second yielding segment provided in a center segment of the second steel plate in the axial direction and having an axial strength smaller than an axial strength of both end segments of the second steel plate in the axial direction,
• the third steel plate includes a third yielding segment provided in a center segment of the third steel plate in the axial direction and having an axial strength smaller than an axial strength of both end segments of the third steel plate in the axial direction, and
• a length of the first yielding segment in the axial direction is different from a length of the second yielding segment in the axial direction, and is different from a length of the third yielding segment in the axial direction.