Square U-bolts 1

[bones206]

Are square U-bolts permitted for structural applications? I haven't been able to find any definitive information in any codes or standards.

 

[phamENG]

I would imagine so, though it may depend on the method of bending. I imagine it's done in a similar fashion to L- and J- anchor bolts, and those depend on the capacity in the deformed area. If anything I'd say the bend is probably a little stronger due to the cold working (assuming they're bent cold), though the failure mode won't be ductile.

 

[bones206]

To clarify, I'm asking in the context of steel connections. I want to attach something to an existing HSS truss with square u-bolts, but I was struggling to define a capacity. In the past I've used round u-bolts from Anvil, which publishes load capacities, but I can't find anything similar for square u-bolts.

 

[bones206]

Here is an example with round HSS and round U-bolt from a DOT highway sign detail:

 

[phamENG]

May just be a matter of searching. McMaster Carr has some 5/8" square u-bolts with a rated capacity, but they don't indicate what the steel spec is.

 

[bones206]

Thanks pham, I had looked at those McMasters earlier and missed the load rating. But that alone doesn't give me enough confidence to use in a structural application where I need a well-defined factor of safety. I also need both a tension and shear capacity.

I did find a recent Iowa State study for rounded U-bolts, which tells me there is still work to be done to codify the use of structural u-bolts. I'll have to come up with another connection design for now. The problem is I can't weld or field drill...

 

[phamENG]

Have you tried contacting Portland Bolt? They have a responsive and knowledgable staff. Since they'll custom manufacture them, they should have some insight into strengths and safety factors.

This data has to be out there. Those things have been used in automotive applications for decades. I have a an old 1950's era trailer axle in my barn with these things on the leaf springs.

 

[bones206]

Portland Bolt wasn't aware of any codes or standards governing the use of u-bolts. I'll keep digging but it's looking like a lost cause.

 

[azcats]

If you can get your hands on the Telecom Code (ANSI/TIA-222-H) it has some design information for u-bolts.

 

[bones206]

That is tantalizing but TIA-222-H is $765...

 

[bones206]

I was able to find a past thread with a calc that alludes to the TIA-222 U-bolt equations. thread507-436955

Thanks

 

[stevenal]

If it helps any:
I note the vertical square u-bolts holding my boat trailer frame to the axles don't bear any weight. The horizontal u-bolts holding the bunks to the cross members bear the boat's weight in shear. Weight bearing does not depend on friction from tension.

 

[Rabbit12]

Would Lindapter have anything that works for your application?

http://www.lindapter.com/

 

[azcats]

bones - I'd help more.

 

[bones206]

For future reference if others are seeking this info -- ANSI/TIA-222-H does have a method to calculate capacities of round and square u-bolts.

Thanks again azcats!