Trapezoidally corrugated steel webs are composed of a series of flat and inclined subpanels and have been used as the webs of prestressed concrete box girder bridges to reduce superstructure weight and increase the effectiveness of prestressing. Because of accordion effects, the corrugated web resists only the shear stress, and the flanges resist most of the bending stress. The shear stress in the web can cause three different modes of shear buckling: local, global, and interactive (zonal) buckling. Several studies have been performed to determine buckling formulas for each mode. However, there are differences regarding the buckling strength, and some of the formulas are found to overestimate it. The results of a study are presented; a series of experiments was done with large corrugated plates. The specimens were designed to fail by the local, global, or interactive buckling mode in elastic and inelastic states. The effect of geometric parameters on the shear buckling strength was also studied. Nonlinear buckling analysis, which considered both geometric and material nonlinearity, was also performed to verify the test results. The results from this and previous studies are used to propose a shear buckling formula, which can be applied to all three buckling modes.