Girt Web check

[WARose]

I was reviewing this guy's calcs for girts.....and he didn't do a web check for the girt dead load transfer to the sag rod. (Putting bending stress in the web.) That's something I've always done (even though it typically is minimal for rolled shapes). He thinks it's overkill to check....do you normally check it for rolled shapes?

 

[KootK]

Rightly or wrongly, it's not something I've worried about in the past.

HELP! I'd like your help with a thread that I was forced to move to the business issues section where it will surely be seen by next to nobody that matters to me:

http://www.eng-tips.com/viewthread.cfm?qid=456235

 

[BAretired]

The notion of sag rods bracing girts or purlins is somewhat questionable. See thread507-236394 for some discussion on this topic.

BA

 

[WARose]

@ Kootk: thanks.

@BAretired: I agree. But I'm not talking about bracing.....just the (self-weight) transfer to the sag rod.

 

[hokie66]

Once upon a time, I did use sag rods. But never checked the web local stress.

 

[BAretired]

@WARose: Not too sure how you would check the self-weight transfer. The worst case would be the uppermost girt where the sag rod supports all of the girts in the curtain wall. That could be significant in very tall curtain walls. Bending in the web would depend on the spacing between sag rods above and below the girt being checked.

Do you perform a yield line analysis on the web of the girt? Have you ever found this to be critical?

BA

 

[hokie66]

The sag in girts should be resisted by a stiff member at the top, not just by another girt. Another way is to use struts instead of ties, so the sag is resisted at the bottom.

 

[Tomfh]

Never checked it.

Sag rod hang from something stiff up the top.

 

[MotorCity]

I have always checked the girt for weak axis bending between sag rods but not for any local effects on the web.

 

[WARose]

Do you perform a yield line analysis on the web of the girt?

Nope. Just a regular elastic calculation/model.

Have you ever found this to be critical?

Not for a AISC shape.