Steel plates in combined shear and moment: Flat versus LFS profiles

Slender steel plates are susceptible to shear buckling in nearly all of their myriad applications, including plate girders. Traditional strategies to enhance web shear buckling strength include welded stiffeners and corrugated webs, but these are subject to higher fatigue sensitivity and specialized fabrication requirements, respectively. The authors propose a novel strategy, introducing low-frequency sinusoids (LFS) in the web along its length. The LFS have been shown to increase web shear buckling strength substantially with minimal increase in material and greater fabricability. However, their combined shear and moment capacity have yet to be studied. This paper studies various combinations of pure shear, high shear – low moment, pure moment, and high shear – high moment. Experimentally validated finite element analyses are used to determine elastic shear buckling loads and ultimate loads as well as web stress distributions. Results show that LFS have slightly greater moment strength than corrugated webs but less than flat webs; they are thus suitable for high-shear low-moment situations, though additional flange reinforcement may be needed for high-shear high-moment situations.