Welded Beam: the Welding aspect

[XFEM]

Hello, i am an new bridge design engineer. usually we design the welded wide flange in bridge truss and girder member as 100% capacity, and let the fabricator gave the member weld. Lately another fabricator asked about how it should be welded?
And i was said that should be CJP [Complete Joint Penetration] and the fabricator bargain about the fillet, and PJP, and PJP with extra fillet.

All welded beams are Wide Flange with fy 355 MPa.

Question mark 1: can my welded beam welded like that?
note: several beam use 8-10 thick web at stringers.
several beam use 12-14 thick web at crossgirders
many beams use 8-30 thick web at truss members
the tender code, i put was AWS D1.5
the fabricator usually use AWS D1.1

Question mark 2: I saw D1.5 today. It said the force tension pararel to weld efective can be PJP. It is for truss beam right? not for girder/stringer/

My opinion: I would like to bargain to fabricator:
The girder and stringer should be CJP.
The truss beam <= 19 mm thick web can be PJP with double beveled, others thicker should be CJP.
Right?

Note the process is SAW.

 

[Ron]

Several points come to mind.....

1. If you have an experienced mentor, let him deal with the fabricator the first few times while you attend and watch (assuming he is capable of doing so).

2. If the fabricator bid the project knowing it required CJP welds, he's just trying to get you to let him make more profit by doing PJP and fillet. Those take less time and effort.

3. PJP welds are more difficult to inspect and test. Further, you can create stress risers with PJP and fillets that do not exist with CJP welds. This can be significant in fracture critical structures such as bridges.

4. If you allow the contractor to control the design, you will be putting yourself in a liability position you do not want. You're the designer..you decide what is acceptable and what is not acceptable. Yes, fabricators can design weldments through the shop drawing process, but you have to approve or disapprove them as the engineer of record.

Good luck.

 

[bridgebuster]

In the northeastern US fillet welds are commonly used for built up girders, or as you wrote "wide flanges". Truss projects that I was involved with that used closed box members were either CJP or fillets, depending on the load in the member.

I agree with Ron, particularly item #2. He bid it; he bought it.

 

[XFEM]

Thanks for the answers. We are in SouthEast Asia.

Likely not at my firm understands AWS and welding details, because we rare use built up members [primarily business in buildings].

The fabricator wants to use less CJP because it need to be checked using UT not as PJP [according to D1.1, he said].
All the bridge fabricators use D1.1 in here. And they don't know the AWS D1.5M, even their experts from abroad.

Well, i think im go to use CJP, but the project is late, because of the new year. Can anyone gave me the minimum bargain proposal welding?

I think the Girder can be go to PJP, or fillet since it not the FCM. And the Truss should be assumed as FCM, and should be welded as CJP. Right?

The contract didnt say about CJP,PJP,etc. I just mention 100% capacity and must be according to D1.5

 

[HgTX]

This just hit something that drives me nuts about D1.5. Because the inspection requirements for PJP, no matter how big the PJP, are no more than that for a fillet weld, people try to go for PJP just to escape the volumetric inspection. The other side of it is that designers may specify CJP where only PJP is needed because they want more inspection.

We need a better way to inspect the PJPs so as to separate the design & inspection questions. Okay, y'all, get working on that and report back to me next week!

Hg

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[bridgebuster]

the tension members of the truss would be FCM.