This report presents the results of experiments performed on 24 wide-flange steel beams subjected to loads causing a moment gradient. The primary objective of the investigation was to relate the flange slenderness ratio to the rotation capacity; however, an attempt was also made to explore the effects of changes in moment gradient, web slenderness and bracing spacing.

The specimens were of G40.12 steel, which has a specified minimum yield stress of 44 ksi. Each specimen was deformed well into the unloading range. For members having small values of L/ry (high moment gradient), unloading was triggered by local deformations, and the flange slenderness ratio, b/t, had a definite effect upon the delivered rotation capacity. For tests on specimens having low moment gradients, unloading was due primarily to large lateral deformations and for these specimens the b/t ratio had very little effect.