The figure shows two thin-walled box sections with overall dimensions given in terms of a. The thickness of the vertical flanges is t, while the thickness of the top and bottom flanges is 2t, and a = 12t. Both sections are loaded by a torsion moment Mx.
a) Determine the torsion stiffness parameter K of the closed cross-section in Fig. a).
b) Determine the maximum shear stress τmax in each of the flanges of the closed cross-section.
c) Repeat a)-b) for the open cross-section in Fig. b) and compare the results.
