Fatigue Shear Strength of Slender Web Plates

Abstract

Slender plates are used in a variety of structural engineering applications because of their high strength-to-weight ratio and their postbuckling reserve of stiffness and strength. However, relatively large out-of-plane displacements may be induced by in-plane loading close to or exceeding the buckling load, which in turn induces relatively high secondary bending stresses at welded plate boundaries. Under repeated loading the combined state of membrane and secondary bending stresses can result in fatigue cracking and premature failure. A series of fatigue tests on slender plate-girder webs subjected to repeated shear loading is described. Details of the test results presented include the load ranges and number of load cycles to fatigue failure, the location and extent of fatigue cracks, out-of-plane web deflections, and stress ranges at fatigue crack locations. The theoretical prediction of stress ranges at potential fatigue crack locations and fatigue-resistant design procedures are also discussed.