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Properties of RC Beam with cuts

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Message 1 of 2
pnacht
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Properties of RC Beam with cuts

I have created the following section:

6-11-2014 10-58-01 PM.jpg

 

As you can see, the section is, with the exception of the cut on the right side, symmetric. According to Robot, the section has the following properties:

IZ = 86576.269

VY = 20.01

VPY = 19.99

 

Now, if I change the cuts to the left, the properties change to:

IZ = 86586.269

VY = 19.99

VPY = 20.01

 

That VY and VPY invert is obvious, but I don't understand why IZ changes. Changing the cuts from right to left is essencially a mirror transformation of the section around its centroidal axis (due to the cuts, not along the axis of the web). Moment of inertia is supposed to be an invariant of the section, constant independent of transformations to the section, no? 

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Artur.Kosakowski
in reply to: pnacht

Thank you for notifying us about this situation. We will investigate it.



Artur Kosakowski

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