Imperfect Tapered Plate Girder Web Under Shear

Abstract

Steel plate girders substitute conventional hot rolled I-shaped beams in case of high applied loads where it becomes uneconomic to use hot rolled beams. It is more economic to employ tapered sections following shape of bending moment distribution throughout the plate girder. Most of the bridges are designed as simple spans as it is cost-effective which results in pure shear stresses in the tapered end web panels. However, specific design guidelines for tapered plate girders under shear are not available. Initial geometrical imperfections (IGIs) are usually random and depend mainly on the fabrication, shipping and construction processes. As the amplitude of initial imperfection increases, through-thickness bending stresses are enlarged, resulting in a reduction in the ultimate shear strength of the plate girder. As such, this study aims at the investigation of the ultimate shear strength of tapered imperfect end web panels in steel plate girders. The effect of initial geometric imperfections (IGIs) on the ultimate and post-buckling shear strengths of these plate girders is studied using a validated numerical model. Around two hundred finite element models representing plate girders are constructed and analyzed to cover a wide range of geometric parameters including: aspect ratio of end web panel, depth–to-thickness ratio of end web plate, inertia of intermediate stiffeners, and angle of tapering. Moreover, effect of imperfection is considered. Results are used to conclude design guidelines for evaluating the ultimate shear strength of tapered imperfect end web panels.