topic Re: Instability in Robot Structural Analysis Forum

Instability

Anonymous — Sat, 19 Oct 2013 09:00:06 GMT

Im working on a 34 m rectangular truss.After running calculations..the results showed "instability" in some members.

Some had yellow color, others had red and yellow.

What do the colors means?

What is the efficiency ratio?

How can I solve this?

Anonymous — Sat, 19 Oct 2013 12:02:52 GMT

most likely (this yellow symbol) is to do with member slenderness.

Anonymous — Sun, 20 Oct 2013 03:56:07 GMT

please find attached an image that shows the error..waiting for your feedback

Anonymous — Sun, 20 Oct 2013 10:15:10 GMT

red symbol is because the member is either over capacity (efficiency ratio > 1.0) or deflection is above the limit you specified.

yellow symbol is what i mentioned before, the element slenderness is above what you have the maximum set to.

Anonymous — Sun, 20 Oct 2013 10:47:08 GMT

Thank you

Anonymous — Sun, 20 Oct 2013 11:53:57 GMT

Is there any plug in for AASHTO automatic load combinations ?

Anonymous — Sun, 20 Oct 2013 12:30:58 GMT

not sure but the truck database is already in there.

Anonymous — Sun, 20 Oct 2013 12:36:46 GMT

What about reinforced concrete combinations? i.e automatic load combinations conforming to AASHTO LRFD

Anonymous — Sun, 20 Oct 2013 12:45:42 GMT

not sure, but doubt it

Rafal.Gaweda — Mon, 21 Oct 2013 09:15:28 GMT

No AASHTO LRFD in Robot.