Erection Problem Requires Fix?
Erection Problem Requires Fix?
(OP)
I have a job that has concentric brace frames. During erection, the erector decided that it would be a good idea to cut the gusset plates in order to fit the bracing into the proper location (see attached picture). They cut these holes into all the gusset plates around the building.
I would like to have this fixed but am not sure about how to go about doing it. I believe new gusset plates should be installed but this would require a lot of field work. I'm also not sure if this is realistic or not.
The erector would like to CJP a new section of plate that he removed in order to set the brace. I'm not convinced that this can be done properly in the field.
Has anyone run into this problem before? If so, how did you go about fixing the problem?
I would like to have this fixed but am not sure about how to go about doing it. I believe new gusset plates should be installed but this would require a lot of field work. I'm also not sure if this is realistic or not.
The erector would like to CJP a new section of plate that he removed in order to set the brace. I'm not convinced that this can be done properly in the field.
Has anyone run into this problem before? If so, how did you go about fixing the problem?






RE: Erection Problem Requires Fix?
More clean solution might ask tu cut the braces etc with temporary substitute bracing, also cumbersome task. I more likely if permissible from codes and behaviour would go for the other.
RE: Erection Problem Requires Fix?
0) Submit an addservice to owner for repair & possibly include a fee for hiring a welding specialist & or FEM analyst.
1) Develop a detail with high fracture toughness (removal of backing bars, angle of cuts, edge prep).
2) Ask for a WPS submittal of proposed welds. I would also specify AWS D1.8 requirements for this weld. Review the submittal for heat input (evaluate HAZ), electrode toughness, etc.... You may even what to specify a mock-up (make that contractor work for his mistake). I would look into a double bevel to reduce heta input.
Worst case..sharpen that pencil or perform FEM to prove that notch is acceptable as is (with some grinding).
RE: Erection Problem Requires Fix?
Do you mean Ordinary Concentric Braced Frame (OCBF)?
How is that any different than waht Steel PE called it?
How can you look at a snapshot of one connection and tell what type of braced frame it is?
I am confused here?
RE: Erection Problem Requires Fix?
The building is actually relatively small. this problem happens at all brace locations... 4 in all.
RE: Erection Problem Requires Fix?
Did the contractor HAVE to cut the gusset like that?
RE: Erection Problem Requires Fix?
This is a bit of a debate. I contend that the erector didn't try hardest to try and fit the brace. It wasn't going to be easy. Making these connections never is. I believe (by looking at the shop drawings) that it could have fit without cutting the gusset plate.
Of course the erector says it's impossible to make the connection.
However, all of this finger pointing doesn't solve the problem.
RE: Erection Problem Requires Fix?
You can quickly tell a special from an ordinary brace frame because the offset requirements and assumed yield lines make SCBF gussets larger (whitmore requirements). With OCBF you can essentially place the brace right up against the beam/column. Google SCBF pics and look at AISC design guides.
looks like the contractor didn't sequence the construction properly.
RE: Erection Problem Requires Fix?
I understand the diffence between OCBF, SCBF, EBF etc, it just sounded like you were saying the same thing as SteelPE. There is an Ordinary Concentric Braced Frame.
SteelPE:
I would say this is the WHOLE debate. If the contractor couldn't erect the braces, the detailer is most likely at fault. When we detail, we make it very clear that the erector must clear any problem with us prior to say, cutting a huge notch in a brace gusset.
I have designed & detailed braces exactly like this before and I always make sure that they can be fit up in the field by making the slots long enough in the HSS and making sure there are no other interferences.
If these braces would have fit w/o cutting, i'd make the contractor replace all of the gussets.
RE: Erection Problem Requires Fix?
The cut-out also effectively reduces the length of weld along the brace, and the sharp corner is close to the toe of an adjacent weld, for which both are stress raisers. A patch plate over the cut-out (in my view) would cause problems with welds upon or close to other welds, and frankly would look messy. I'd just simply infill the cut-out so that the gusset has its original load bearing capacity.
corus
RE: Erection Problem Requires Fix?
RE: Erection Problem Requires Fix?
RE: Erection Problem Requires Fix?
RE: Erection Problem Requires Fix?
I guess my point is, the contractor should have contact the engr's and detailers prior to getting out the hot wrench.
RE: Erection Problem Requires Fix?
RE: Erection Problem Requires Fix?
The only way I can see the erector replacing the gusset is by removing the brace itself. By the time they are done they are probably going to need a new brace and gusset. Overhead welding of the new gusset to the existing beam isn't going to be easy.
If I go with the infill patch, I can have the erector grind the existing cuts smooth and square. I could then have the fabricator make a site visit to trace the infill pieces for fabrication. Have the fabricator prep the CJP weld, using a Double-Bevel-Groove weld. The erector can then install the new pieces and the have them UltraSonic test the new welds.
This seems more feasible.
RE: Erection Problem Requires Fix?
In addition to UT you may want to also specify dye penetrant or mag testing to locate surface flaws.
RE: Erection Problem Requires Fix?
RE: Erection Problem Requires Fix?
An out of position CJP weld in the field is a challenge. You'll then have to radiograph the completed weld.
Perhaps a stupid move on the erector's part, but "it is what it is"...
RE: Erection Problem Requires Fix?
Maybe this is an opportunity to build some capital which you might be able to spend elsewhere...
RE: Erection Problem Requires Fix?
But we engineers never make mistakes... Why would we need capital?
RE: Erection Problem Requires Fix?
RE: Erection Problem Requires Fix?
How long are the two flame cut notches - looks (by eye) to be about a 2x2x3-1/3 triangle, and is there additional flame-cut "notches" or "deep gouges" at the apex of the large notch?
That deep corner of the triangle is where your stress risers are going to be.