STRUCTURE

To suppress fracture at an origin position of the strength change in a beam member reinforced in a longitudinal direction end portion.SOLUTION: A structure comprises: an expanded portion 14 projecting from a side end of a flange portion 11 located at a beam end portion 10a of a section steel beam 10 joined to a column member 20; a pair of inclined ribs 15 projecting from a side surface of a web portion 12 at positions adjacent to the extent where the expanded portion 14 is provided; and an auxiliary reinforcing rib 16 provided at positions close to rear ends of the respective inclined ribs 15. An end face of each of the pair of inclined ribs 15 on the side facing the flange portion forms an inclined face which is inclined so as to approach a center in the height direction of the web portion 12 as it goes away from the joining portion with the column member 20. The auxiliary reinforcing ribs 16 are present over a range up to the position where the inclined surfaces intersect each other when the inclined surfaces of the inclined ribs 15 are virtually extended from the rear end position of the inclined ribs 15.SELECTED DRAWING: Figure 1 【課題】長手方向端部が補強された梁部材において強度変化の起点位置での破断を抑制する。【解決手段】柱部材２０に接合された形鋼梁１０の梁端部１０ａに位置するフランジ部１１の側端から張り出した拡張部１４と、拡張部１４が設けられた範囲と隣り合う位置でウェブ部１２の側面から突出した一対の傾斜リブ１５と、各傾斜リブ１５の後端に近い位置に設けられた補助補強リブ１６と、を備える。一対の傾斜リブ１５の各々の、フランジ部と対向する側の端面は、柱部材２０との接合箇所から離れるにつれてウェブ部１２の高さ方向中央に近付くように傾斜した傾斜面をなしている。補助補強リブ１６は、傾斜リブ１５の後端位置から各傾斜リブ１５の傾斜面を仮想的に延長させた際に傾斜面同士が交差する位置までの範囲に亘って存在している。【選択図】図１