Bolted Crane Bracket 3

[waytsh]

Does anyone know of any code references that would preclude the use of a bolted crane bracket connection as opposed to welded? I understand of course that all the requirements for fatigue would have to be checked on the bolts.

Thanks

 

[mrpid]

This does not preclude the use of bolts, but addresses the use of bolts for crane supports.

AISC 13th Edition Specifications(and 9th for that matter)J1.10 Limitations on Bolted and Welded Connections; Note (3).

Crane manufacturers may have additional information.

Hope that helps.

 

[waytsh]

Yes it does. Thank you!

 

[structuresguy]

You may also want to check out Gantrex's website, or order their catalog. If you are not familiar, they manufacturer several accessories for attaching crane rails to girders, and girders to supports. I have used their products before, and they are excellent quality.

I have also been involved with a failure of a crane girder bracket on a very large overhead bridge crane which was used by the Air Force to assemble the Titan rockets. They had two cranes that ran one over the other, a 300T and a 500T, which were supported 200+ feet above the ground on separate columns. But the girder of the lower crane was attached to the column of the upper crane for lateral support. The attachment was a very large WT shape, with the web welded to teh girder flange, and the flange bolted to the column. It did not provide any vertical movement capability without bending the web of the WT, which snapped off due to high strain low repetition fatigue. It was about 6" wide and 1"+ thick. The columns were shortening differentially, causing the bending. The solution was to replace the 1" A325 bolts with 5/8" Gr 8 bolts, which combined with teflon bearing pads, allowed the WT to slide up/down on the column, preventing any bending stress.

SOrry for the long story, but I just wanted to point out that bolts can be used, and at times it is critical to allow movement of the joints. Gantrex makes a bracket which is on ball joints for exactly the purpose I have described above. It is a shame it was not used, as the month long delay to investigate the problem and fix it cost the Air Force millions of dollars in downtime and penalties for delaying a launch.

 

[hokie66]

Thanks for that reminder, structuresguy. I saw the same thing happen years ago in a pot room in a reduction plant. It is a shame that lessons like that cannot be disseminated across the profession, but I suppose there will always be those who don't pay attention to things like elastic shortening.

I think waytsh was actually asking about a bolted bracket to support a crane runway vertically rather than a lateral brace. Bolted or welded brackets can be used for small cranes, but for large ones, stepped columns or separate crane columns are required.