The Torsion Properties report is created when you select Torsion Properties from the Compute menu (only available for sections with one part). This report contains key properties at several locations in the section which may be used to calculate torsional stresses. These properties include:

R_{o} | Perpendicular distance from shear center to centerline of element |

W_{n} | Normalized unit warping, used for warping longitudinal stress |

S_{w} | Warping statical moment, used for warping shear stress |

The locations reported include both ends of each flat element of the section, edges of holes, and
the location of the peak value of Sw in each flat element, where W_{n} is equal to 0. The shear
center location (x_{o}, y_{o}), warping constant (C_{w}) and St. Venant torsion
constant (J) are also included for convenience.

Warping longitudinal stresses can be calculated for any location in the section as
EW_{n}ϕ'', where E is the modulus of elasticity and ϕ''
is second derivative of the twisting displacement function with respect to the distance along the member.

Warping shear stress can be calculated for any location in the section as
ES_{w}ϕ'''/t, where t is the material thickness and ϕ'''
is the third derivative of the twisting displacement function with respect to the distance along the member.

Pure torsional shear stress can be calculated as Gtϕ', where G is the shear modulus and ϕ' is the first derivative of the twisting displacement function with respect to the distance along the member.