Torsion of Structural Shapes

Charts and empirical formulas are provided for the accurate calculation of the torsion constant for the wide flange, I, channel, tee, zee, and angle structural shapes. The differential equation in solving the torsion stress function is replaced by a difference equation, and the stress function is evaluated at nodal points of a fine square mesh net by means of the digital computer. The formulas for the torsion constant make use of existing solutions for the rectangular section but provide accurate correction for the additional torsional rigidity resulting from the juncture of rectangular component parts including the effect of the fillets and the variation in flange thickness of the channel and I-sections. Shear stresses caused by uniform torsion are also evaluated. Calculations for both torsion constant and stress are aided by means of graphical charts.