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RE: Moment Connection Question[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: RE: Moment Connection Question
- From: "Robert E Shaw Jr" <rshaw(--nospam--at)steelstructures.com>
- Date: Wed, 7 Feb 2007 09:33:30 -0500
AWS D1.1 addresses this situation adequately. See the following from AWS D1.1:2006.
126.96.36.199 Correction. Root openings greater than those allowed in 188.8.131.52, but not greater than twice the thickness of the thinner part or 3/4 in. [20 mm], whichever
is less, may be corrected by welding to acceptable dimensions prior to joining the parts by welding.
184.108.40.206 Engineer’s Approval. Root openings greater than allowed by 220.127.116.11 may be corrected by welding only with the approval of the Engineer.
Figure 5.3 allows the root opening to exceed that specified by 1/4” for one with backing, not backgouged. Assuming the typical 3/8” root, this allows 5/8” without correction. Using 18.104.22.168, the contractor may face the groove with weld metal until brought within these tolerances, then make their groove weld. The difficulty in facing the groove is that the access to the weld face makes consistent fusion more difficult, and grinding of the weld face is often needed to get a good, smooth groove face to weld to.
I suggest allowing the weld to proceed without groove facing, but require bead placement to be from the column face toward the flange, reducing the risk of lamellar tearing on the column face. The only major problem here is shrinkage of the joint, cause by the additional weld passes. Because of joint width, you may get an extra 1/16” to 1/8” of shrinkage, depending upon joint width. I doubt that, with the magnitude of the members, that this would cause any problems in appearance or performance.
I’m also assuming that these joints will be ultrasonically tested upon completion, to find if cracks or lamellar tears were created.
The SEOR has required full pen moment connections for a truss bottom chord connection to the supporting columns. The bottom chords are W14x311's while the columns are W14x257's. All steel is A992 Grade 50. The W14x311's top and bottom flanges are full pen welded to the W14x257's flanges using TC-U4a preqaulified weld joints.
After erection of these members, the inspector observed the root opening widths to range from 1/2" to 1 1/16" which of course exceeds the TC-U4a parameters. This issue occurs at eight locations.
As a repair, flange plates added/welded to the W14x311's top/bottom flanges with a full pen weld where the plate edge abuts the column flange were proposed. The SEOR has rejected this fix due to appearance (the steel wiill remain exposed; it's part of a bridge that connects two buildings).
Has anyone encountered this sitaution previously? If so, any suggested repairs (without adding flange plates)? Is the only option to cut a section of the flange and butt weld a new flange piece with a width that provides the correct root opening?
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