Prying in 2010 AISC SCM 1

[ToadJones]

I read a while back in Modern Steel that the new steel manual 2010 has "clarified what the 'p' dimension' is in the prying calc.

I haven't purchased the manual yet.

Anyone know what they clarified?

This variable has always driven me nuts....especially in connections with stiffeners.

 

[JoshPlumSE]

p = tributary length; maximum = 2b, but <= s, unless tests indicate larger lengths can be used. See Dowswell (2011) and Wheeler et all (1998)

There is a picture as well. I think the picture will probably hels as much as that description.


Hope that helps!

 

[ToadJones]

"s" being the bolt spacing perpendicular to the gage?

My biggest question regarding this in general is, say I place a stiffener between bolts the direction that "p" is measured, what is "p" now?
Do you just say "no need to check prying" in this case?

 

[JoshPlumSE]

Toad -

I think the diagram might clarify things for you. They show the p dimension spreading out from the bolt at a 45 degree angle towards the stem of the tee.

I really haven't put much thought into this, but off the top of my head:
If you had a perpendicular stiffener between the two bolts, then I would think the p distance would spread out at a 45 degree angle at a angle of your choice. Towards the stiffener, towards the tee, or at some angle between the two... sort of a bi-directional prying.

One day I really want to go through the Tom Murray's papers where he came up with the design procedures for bolted end plate connections. He uses yield line theory to come up with his plate capacity equations. I believe there is some bi-directional bending involved. And, I believe, he addresses prying for these bi-directional bending states.... But, that would require more free time than I normally have these days.

 

[ToadJones]

I got a hold of the diagram and it helps a bit.

I have always wondered:

If you place a stiffener in between the bolts.
In the diagram the stiffener would be where the dimension lines are or, in other words, where the two yield lines meet at the web.
Intuitively you know this must help prying but in fact if you took it to make the 'p' dimension smaller it makes prying worse.

But, you know the stiffener will stiffen the plate and help prying.

 

[nutte]

Toad, the prying action model in the manual works for plates without stiffeners. If you have a stiffener, the yield line mechanism is different, and you have a different model. It's not a simple case of changing the "p" dimension.

The Engineering Journal article "A Yield Line Component Method for Bolted Flange Connections" sheds some light on the prying of a flange near a stiffener.

http://www.aisc.org/store/p-2161-a-yield-line-component-method-for-bolted-flange-connections.aspx

 

[ToadJones]

thanks nutte-
Ive literally been looking for years for some literature on this.

I think most engineers just put the stiffeners in and assume no prying.
I have, in the past, applied some of the methods used in the moment end plate connection design guide where I could.