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Tokyo, Japan - August 31, 2022 -The Lateral Buckling Stiffening Elimination Method Study Group, consisting of 10 general construction companies (Okumura Corporation (the leading company), Asunaro Aoki Construction, Asanuma Corporation, Kitano Construction Corporation, Konoike Construction, Penta-Ocean Corporation, Dai Nippon Construction, Tekken Corporation, Tokyu Construction and Haseko Corporation), jointly developed the "Steel Beam Lateral Buckling Stiffening Method Using the Constraining Effects of the Floor Slab " and obtained a structural performance evaluation (ERI-K21008) from Japan ERI Co., Ltd.

This method uses the constraining feature of the floor slab, which is continuously jointed into the steel girders with an H-shaped cross section using shear connectors, compensating the lateral buckling stiffening effect for steel beams. The method eliminates the need for the lateral stiffening members, which were necessary in the conventional method.

The ten companies intend to apply this method to construct steel-framed buildings, etc., mainly in design-build projects, in order to achieve more sophisticated building design and construction.

[Outline of the Technology]
In the construction of steel-framed buildings, H-shaped steel has been the first option for main girders. However, while they exhibit high strength in the strong axial direction, they are weak in the weak axial direction and are prone to lateral buckling. In order to fully demonstrate the bearing capacity of girders by preventing lateral buckling, it is common to design girders with lateral stiffeners (lateral stiffening to maintain bearing capacity), but these procedures were material-consuming and labor-intensive.

The effectiveness of the "Steel Beam Lateral Buckling Stiffening Method Using the Floor Slab" was already known from previous researches, etc. However, in addition to this insight, the Lateral Buckling Stiffening Elimination Method Study Group proved the effect of the said method through analysis and developed design guidelines, which led to the acquisition of the structural performance evaluation.

By applying the constraining effect of the floor slab connected to the steel girders by shear connectors, this technology can omit the use of the lateral stiffening material, which was conventionally required. In addition, the allowable bending stress does not need to be reduced according to the span of the girders and can be treated in the same way as the allowable tensile stress. Furthermore, the girders can be assumed as already laterally stiffened in terms of load-bearing capacity, and therefore, the ultimate bending strength of the girders equals the full plastic moment of steel girders. Also, the method is considered as a green technology for the fact that it omits the use of lateral buckling stiffening members, which were conventionally necessary.