Yield-Interaction Relationships for Curved I-Girders

Abstract

Yield-interaction relationships are developed for compact, compact-flange, and noncompact sections of curved girders under combined vertical and lateral (warping torsion) moments. These relationships define the bending strength of such compact, compact-flange, and noncompact sections if suitable web-slenderness, compression-flange slenderness, and compression-flange bracing limits are satisfied. The most convenient form of these relationships are equations defining reduced flange widths as a function of lateral moment. The correct vertical-bending strength can be calculated from a reduced steel section consisting of the actual web and reduced widths of flanges. Compact-flange sections have a compact compression flange and a noncompact web. For straight girders, there is no advantage in using a compact compression flange with a noncompact web. For curved girders, however, the compact flange permits a larger lateral moment to be carried in combination with a given vertical moment.