Racking Load

[EddyC]

Hello Folks,

Part of my current work responsibilites involve the design of roof mounted equipment dunnage. The applied loads on the dunnage are at right angles. I'm wondering however if there is a code prescribed requirement for "racking" loads (ie diagonal loads). Or is it left to the engineer's judgement to determine the "racking" load requirement?

Thanks.

 

[Grizzman]

Chapter C2.2b of the AISC Spec (13th ed) gives minimum out of plum lateral loads when designing by 1st order analysis.
Basically .007% of ASD loads when assuming no lean to the columns. Though there is more to the section than just that, it's a good starting point.

 

[msquared48]

This racking load is tanamount to torsion, which could be calculated by the center of mass relative to the center of rigidity.

Mike McCann
McCann Engineering