Bending and torsion of stiffeners with L sections under the plate normal pressure

The stiffened panel cross-sections, shown in Figure 1a, due to asymmetry of the cross-sections, under uniform normal plate pressure, deform as shown in Figure 1b, where bf is the stiffener flange breadth, bp is the stiffener spacing, h is the stiffener height, tf is the flange thickness, tp is plate thickness and tw is the web thickness.