Applies To
	Product(s):	STAAD.Pro
	Version(s):	All
	Environment:	N/A
	Area:	Postprocessing workflow
	Subarea:	N/A
	Original Author:	Bentley Technical Support Group

Why shear stresses are not included in the Von Mises stresses for solid elements?

Have a look at the attached figure which is from the following link: http://en.wikipedia.org/wiki/Von_Mises_yield_criterion

There are 2 equations for calculating Von Mises stresses.

The first equation uses the STAAD.Pro terms SXX, SYY, SZZ, SXY, SYZ and SZX.

The second equation uses the terms S1, S2 and S3. These are the principal stresses. There are no shear terms in this equation. This is the one implemented in STAAD.Pro.

The Von Mises stress should be the same from both equations.