半閉じ断面材の捩りについて

抄録

In general, thin-walled beams with open section have the defects that their torsional rigidity is very lower and their maximum shear stress for a given torsional moment is relatively larger than beams with closed section.
To avoid this, the method of making theopening edges of the beams locally connected by spot welding or rivetting have been taken. For this instance, Fig. 1(a) shows a beam in which the narrow opening edges are locally welded. In Fig. 1(b), the wide opening edges are connected by transverse braces.
In Fig. 1(c), the facing flange of the two beams with hat-type section are directly con-nected by spot welding.
These beams were named by the authors as semi-closed beam. In this paper, it was proposed to apply general theory of torsion based on the simple torsion theory (solution of Saint Venant) to these semi-closed beams, among which the effects of spot pitch on torsional rigidity or criterion of failure, etc. was cleared.
It was found that the the ory and experiments fairly coincided with each other comparatively with reasonable accuracy.