AutoCAD Mechanical 2005 -structural shape calculation

[gwasilevich]

Has anyone noticed that AutoCAD does not give the correct moment of inertia, Ix-x, to the structural shape - 8" x 6" x 1" ANSI L (angle)? AutoCAD gives it 97.87in4 while all structural shape reference materials give it 80.8in4. Even in a W21x50, the Ix-x is larger. Are they using detail dimensions in their shapes when they should be using theoretical? This could pose problems especially when we need to calculate the Sx-x for a composite shape based upon AutoCAD's Ix-x result.

[Ron Oldenbeuving]

I'm just wondering if you have setup the part orientation about the axes and origin is correct, as this will give variant answers if its not.