Effect of notches in the flange

A finite element analysis was performed to determine the effects of notch cuts in the flange of steel plate girders which caused a bridge to collapse in Harrisburg, Pennsylvania. The original and deformed shapes before the cut in the flange were made, where displacements are symmetric with respect to the web plane is shown. Results revealed that initial instability due to lace of symmetry during removal procedures and not necessarily the size of the notch appears to be the more important cause of possible problems. Providing lateral supports at the location of the flange cuts should be considered in addition to bracing at other locations as needed.