The plastic deformation capacity of the structural system for thin‐web steel beam reinforced with stiffener plates

Japanese buildings are generally designed as moment‐resistant frames, and beam ends are required to have high bending strength and high plastic deformation capacity. With H‐shaped beams, the contribution of the web to the bending strength is small, so H‐shaped beams with thick flanges and thin webs are used to reduce the amount of steel required for construction. However, H‐shaped beams with thin webs are prone to local buckling at the ends of the beam, resulting in poor plastic deformation performance. The authors have developed a structural system of steel structures in which the ends of beams are reinforced by stiffener plates with the aim of improving the plastic deformation capacity. Especially when these structural systems are applied to a high‐rise building with large‐sized beams, the effect of reducing the amount of steel is high by reducing the thickness of the web. Reducing the amount of steel can be expected to reduce the loads on the environment and the construction cost. In this paper, the simple stiffening method is proposed with stiffeners that can improve factory manufacturability. Secondly, to confirm the plastic deformation capacity of a stiffened steel beam, a series of cyclic loading tests is carried out using 1/2 scale specimens.