Effect of Initial Web Out-of-Flatness Imperfections on the Shear Strength of Low-Frequency Sinusoidal Plate Girders

Slender steel plate girders with deep webs provide flexural and shear strength to resist large loads. However, under shearing forces, web plates are susceptible to shear buckling. During the forming and fabrication of plate girders, initial out-of-flatness imperfections on the web plate are introduced and have demonstrated to reduce the shear buckling strength. Existing measures to enhance the shear buckling strength and improve the behaviorof flat steel plate girders include welded stiffeners or corrugated web plate profiling. These methods introduce practical and fabrication challenges as well as increased labor and material for fabrication. Therefore, to overcome these challenges and improve the performance of steel plate girders, the authors propose an alternative to enhance the shear buckling strength of thin steel plates by imposing a low-frequency sinusoid (LFS) shape along the web's longitudinal axis. This paper evaluates the effect of initial web out-of-flatness imperfections on the shear strength and behavior of plate girders fabricated with LFS webs. Additionally, comparisons with numerically developed LFS plate girder specimens are provided. Overall, this work demonstrates that LFS webs can enhance the shear strength, design, efficiency, and economy of plate girders.