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Convention of bending moment signs

Posted: Sun Nov 24, 2019 8:39 am
by GianmarcoManzo
Hi,
I have modelled the same structure with STKO and with Seismostruct and I have seen that the sign of the bending moment is discordant. The global axes is the same and also the local axes of the elements. So, the question is: What is the Convention of bending moment signs in STKO? And why is It unlike the one obtained with seismostruct ?? Thanks.

Re: Convention of bending moment signs

Posted: Thu Nov 28, 2019 5:32 pm
by MassimoPetracca
Hi Gianmarco,

Can you post a picture comparing the two apparently discording results? It should be the same but let's check

Re: Convention of bending moment signs

Posted: Sun Dec 01, 2019 6:21 pm
by GianmarcoManzo
Place some photos showing both the orientation of the local axis of the element and the global axis (in both software). The diagram of the moment in STKO is visible with the colors while from seismo there is the diagram in 3D and I also reported the 2D one with the values. The values ​​are perfectly identical but with opposite signs everywhere (I report only the photo of a piece of the structure). What might it depend on? Different sign convention? What is that of STKO? thanks
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Re: Convention of bending moment signs

Posted: Mon Dec 02, 2019 9:57 am
by MassimoPetracca
Yes, Sign convention in OpenSEES appears to be the opposite of that of SeismoStruct or MidasGEN