Shear stress due to torsion

The St. Venant and warping torsion is considered during the analysis. For St. Venant torsion, the shear stress τ_t is calculated for torsional moment T_t. Following expression is used for open cross-sections:

Where is:	*T_t*	The torsional moment
	*I_t*	The rigidity moment in St.Venant torsion
	t	The thickness of the plate in the considered point

The stress τ_t for closed cross-sections is given by the expression

Where is:	*T_t*	The torsional moment
	*Ω_t*	The area bounded by the centre lines of plates increased by a factor of two
	t	The thickness of the plate in the considered point

For warping torsion, the shear stress τ_ω is calculated for torsional moment T_ω using following formula:

Where is:	*T_ω*	The torsional moment
	*S_ω*	The warping constant in the considered point
	*I_ω*	The sectional moment of inertia
	t	The thickness of the plate in the considered point

The shear stress is verified according to the following expression:

Where is:	*f_y*	The yield strength
	*γ_M0*	The partial safety factor

The values of shear resistance V_Rd,y and V_Rd,z are reduced due to torsion for combination of shear forces and torsional moments. The reduction is based on following expression

for I- and U-profiles and

for other cross-sections.

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