A325 bolts in bending
A325 bolts in bending
(OP)
Do any of you know whether there are any provisions or recommendations anywhere (from AISC, etc.) pertaining to high strength bolts in bending?
I know that the entire RCSC bolt spec never mentions flexure (tension and shear only) and also seem to recall that these bolts are typically never meant to be bent but only used in tight connection assemblies.
However, I was asked this question yesterday and didn't find anything in my references or online to specifically answer this question.
The detail in particular is a case where a high strength bolt is being used as a vertical pin, extending through an embedded seat plate, through an elastomeric pad, and into a slot on the bottom of a precast concrete member. Thus, if the precast member moves laterally, the elastomeric pad will flex just a bit and put some bending on the high strength bolt "pin".
I know that the entire RCSC bolt spec never mentions flexure (tension and shear only) and also seem to recall that these bolts are typically never meant to be bent but only used in tight connection assemblies.
However, I was asked this question yesterday and didn't find anything in my references or online to specifically answer this question.
The detail in particular is a case where a high strength bolt is being used as a vertical pin, extending through an embedded seat plate, through an elastomeric pad, and into a slot on the bottom of a precast concrete member. Thus, if the precast member moves laterally, the elastomeric pad will flex just a bit and put some bending on the high strength bolt "pin".
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RE: A325 bolts in bending
RE: A325 bolts in bending
RE: A325 bolts in bending
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: A325 bolts in bending
http://www.tboake.com/SSEF1/pin.shtml
RE: A325 bolts in bending
JAE...my thinking is along the lines of yours....the literature only considers that high strength bolts are placed in direct tension, shear or both, but not bending.
This consideration would require a separation of the restraint and shear planes by a sufficient length to create bending. I've had to deal with that in structural applications for aluminum where material isolation was necessary but the bolts were typically stainless steel of sizes such that upsizing to accommodate bending was not such a big deal.
RE: A325 bolts in bending
RE: A325 bolts in bending
RE: A325 bolts in bending
We could also assume that with bending you really end up with material compression and tension across the section, but there just wasn't anything explicit about flexure of A325/A490 in the literature.
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RE: A325 bolts in bending
RE: A325 bolts in bending
Honestly, I've just made sure the factor of safety is really big. Especially if there's a possibility of load reversal.
I'm pretty sure I've seen some information on bending in anchor bolts in european standards. I believe they take bending inside the grout pad into account. Other good places to look would be documents on the design of light pole bases and similar monopoles.
I'm not clear from your description whether you're intentionally putting the lateral load on this pin or not and where/how it's restrained. Is this simply supported at the top and bottom with the elastomeric pad applying a force in the middle? Is it cantilevered off the seat at the bottom somehow, maybe with a bolt on the top and bottom of the seat?
RE: A325 bolts in bending
See Chapter 3, Paragraph 3.7.4 Bending
at this link:
http://nees.org/data/download/NEES-2006-0202/Docum...
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RE: A325 bolts in bending
RE: A325 bolts in bending
NDS has stuff for bolts and lags spanning a gap. It is a place to start.
Generally, I would try to avoid it in a high load connection. All those threads would create points of stress concentration.
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RE: A325 bolts in bending
RE: A325 bolts in bending