Tension only bracing issue

[Anonymous]

Hello,

I am new to using Robot and am not sure if I am doing something wrong or if this is some issue in the program.  In the attached model I have tension only bracing in my structure.  The non-linear analysis I run reports no error's.  When I turn on the "exact deformation for bars" and look at nodes 20, 12, 2, 9, and 14, certain members do not appear to be connected to the rest of the structure.  Furthermore, if I look at the detailed analysis results for any of these odd members, all forces, moments, and deflections report zero values.  At first I thought I had drawn the structure incorrectly and the members did not snap to the correct nodes, however, after several attempts at redrawing the members I found this did not solve the problem.  The odd thing is that, if I switch the bracing members to beam elements and analyze the structure, the results appear to be correct with all the members properly connected.  Any help with this would be greatly appreciated.

[Rafal.Gaweda · Accepted solution]

Bars 35 38 42 71 do work work in this load case

Use ordinary Deformation diagram.

[Anonymous]

Ah yes, I see what I was doing wrong now.  I didn't fully understand the difference between "deformation" and "exact deformation" until now and that was what was throwing me.  I applied a few lateral loads to better analyse the structure and everything checks out.  Thanks for your help!

[Rafal.Gaweda]

http://docs.autodesk.com/RSAPRO/2014/ENU/filesROBOT/GUID-5FC08F87-E615-46AB-A35B-3D6B68DAD227.htm