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Hanger-Type Connection

Hanger-Type Connection

Hanger-Type Connection

(OP)
Hello All,

I need to analyze 2L-4x4x1/4 (attached) that will be used to lift concrete pieces during a bridge demolition. I wanted to use table 15-2b of the 14th edition steel construction manual, but it only has 5/16" thick flanges and larger. I purchased "Procedure for Design and Analysis of Hanger-type Connections" from AISC and it has greatly simplified simplified pgs. 9-10 - 9-13 of the 14th edition steel construction manual. Per the reference, I have calculated the allowable tension per bolt based on three failure modes, plate failure, bolt failure with prying action, and bolt failure without prying action. As I suspected, with only 1/4" flanges, the plate failure mode governs. I am not very competent when it comes to the effects of prying action. How do I calculate my actual applied bolt tension? Are there any additional references I should be using? I also attached a beam model of the flange from the reference that I purchased.

Thanks!

EIT

RE: Hanger-Type Connection

Not a direct answer to your question - but don't forget to design to the BTH standard (see here)

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RE: Hanger-Type Connection

You may find this free resource helpful: Link. I believe it's the source document for the AISC stuff anyhow. You'll work out your bolt forces based on a model like the one shown below.

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: Hanger-Type Connection

Good, JAE pointed out BTH. Absolutely will have to adjust your calculations to conform to that, although it won't address your prying issues directly.

Also, if I'm understanding the application correctly (lifting sawcut panels of deck or similar), you'll want to account for that additional risk/complexity in your concrete anchor design. Anecdotally, colleagues of mine had trouble with a similar lifting arrangement where the concrete anchors (from a reputable manufacturer) pulled out of the deck panel well below their safe working load. Something about the installation process being trickier in an old bridge deck.

I'm not familiar with that hanger reference (or what KootK posted), but in the AISC 9-10 method, the actual tension on the bolt is T+q.

Also, what I presume to be the holes for your concrete anchor group are very closely spaced. I'd imagine you'll have big group action issues if you're counting on all of those.

RE: Hanger-Type Connection

(OP)
I am diving into the reference that KootK posted. JAE/Lomarandil, thanks for the heads-up about BTH. Lomarandil, yes, the concrete anchors are spaced very close together but I will only be using 4 of them. The spacing reduction factors reduce the capacity of the anchors by more than 50%.

EIT

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