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Up Topic Welding Industry / General Welding Discussion / double beveled column splice question
- - By showme Date 05-03-2008 22:46
I'm welding on a new-build hospital n St. Louis, Missouri, (Barnes-Jewish), and I've come across something that looks like either the engineer or draftsman didn't know what they were doing when they designed\drew it. The interior column splices have a squared (non beveled) lower column top, which have flanges 2" thick. The upper columns are double-beveled on both flanges and web on their bottoms. There is no space left for an open root, and the upper column is actually heavy enough to leave the point of contact rounded, with almost a quarter inch contact at all places of contact. We're having to weld the insides of the flanges like a momen connection, then air arc the weld out from the front face, actually making the outer (now single bevel) opening much larger in the process. I've only seen single bevel connections, some flanges up to 4" thick with 6" caps on the finished horizontal welds, 24" across. This leaves the inside of the flange to be back-gouged and a pass or two to be welded on the inside of the flanges. From what I've found in a couple of my books, the single and double bevel connections like this should be welded as open root. Do you think these column splices should have been shimmed open for an open root? This seems like an awful lot of extra work for the hundreds of welds we're going to have like this. (One 12 story and one 14 story with splices every two floors) I think somebody screwed up somewhere. These connections have the standard bolt up 'ears' for setting the iron, which are cut off after welds are secured. Any comments on this type of thing? Thanks,  Butch
Parent - By 803056 (*****) Date 05-05-2008 04:18 Edited 05-05-2008 04:24
First of all, AWS D1.1 does not have provisions for a prequalified "open root" butt joint, so that is off the boards for now.

The butt joint you describe appears to have a substantial root face, thus it is highly unlikely you will burn through it if your welding parameters are typical of those used for either SMAW or FCAW(SS). Thus the root face serves the same purpose as a backing bar and the joint is CJP after you back gouge and weld the second side.

The double groove weld described reduces the volume of weld metal required to complete the joint. If you alternate between the inside and outside surfaces of the column flange, you will reduce the forces that would cause angular distortion. By welding on the inside and then the outside you balance the residual forces which has some beneficial effects.

The attached sketch is a standard joint detail I include in my WPSs for structural steel and it is similar to the joint you describe. The sketch shows a column splice detail and a couple of similar details that use a double bevel groove.

My personal preference is to weld the flanges first and then the web. Do not weld one flange to completion before starting the second flange. Weld both flanges together, alternating between them to reduce any tendency to pull the column out of plumb.

Best regards - Al
Up Topic Welding Industry / General Welding Discussion / double beveled column splice question

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