Can anyone help explain the sign of the member responses?

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kakue
Posts: 5
Joined: Sun Jul 12, 2009 8:07 am
Location: Tokyo Institute of Technology

Can anyone help explain the sign of the member responses?

Post by kakue »

I have a question about sign of the response.
Here is the link to the picture

http://img694.imageshack.us/img694/5324/signge.png

You can see, I set the global axis like that then I connect the elastic beam column element from node 1 to node 2 always.
Then I analyze 4 cases as shown.

In the table, the left column shows the local axis for each case. S1 M1 S2 M2 mean local shear and moment responses from node 1 and node 2 respectively.
The question is the sign coming out. How to figure it out. I've been trying to do it, but I couldn't figure it out.

I know this should be simple to most of you. Anyone, please enlighten me on this.

Thank you very much
Best Regards
vesna
Posts: 3033
Joined: Tue May 23, 2006 11:23 am
Location: UC Berkeley

Re: Can anyone help explain the sign of the member responses

Post by vesna »

Draw the forces at the element ends (not force diagrams) and compare them with the local axis orientations.
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