Inelastic Beams under Moment Gradient

The paper examines the behavior of wide flange beams loaded into the inelastic range under moment gradient conditions. It is shown that loads in excess of the plastic moment can be expected and that lateral buckling is not as critical as previous studies had indicated. Frequently, local buckling is a controlling factor and this allows the rotation capacity to be determined. A theory based on local buckling has been used to show that the hinge angle that can be delivered is a constant, and a lower bound estimate of the hinge angle has been presented. Test results confirm the lower bound nature of the hinge angle theory, but there is a need for further tests to define the limits within which the theory is applicable. It is shown that a primary consequence of high shear forces is to reduce the rotation capacity of the beam.