end forces = -ve value

[mhafiz377]

Hye all, my model seems to have -ve value for end forces for bar 22 and 26. What is wrong with my model (accept the instability problem).

https://www.dropbox.com/s/sgbqbp9smlsl0mq/20130527%20-%203%20-%2069B%20Lrg%20Melayu.rtd?v=0rc-

[Artur.Kosakowski]

I'm not sure what you mean by end forces = -ve value yet the problem I can see is that you should not accept (ignore) the reported instability of types 1 and 2. If you look at the displacements you will see this

Try to redefine the definition of releases used in the model replacing full releases for RX rotations with the partial ones similar to the solution proposed for http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Steel-design/m-p/3573540

[mhafiz377]

actually I want to check the forces at bar 22 for example, I want to check how much load that bar carrying to the beam downside, so I figured I've to check the Fz value of node 9 which is at the bottom of bar 22.Then the value I got is negative value and I think it should be bigger than that ( I don't know either this way correct or not). Btw, I'll try to do redefine the release as you suggested first.

[Artur.Kosakowski]

What about checking the FX force in the bar 22 itself?

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[mhafiz377]

Is it because the 'Local System' on that bar is towards 'X' axis?

[Artur.Kosakowski]

Correct.

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[mhafiz377]

Thanks Artur, I shouldn't ignored the instability type 1 and type 2. but another question, is there any minimum size for rc beam?

[Artur.Kosakowski]

I'm not sure what you mean. For static analysis this may be the the stiffness of such element compared to other in the model so that this difference is not excessive.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.