Weld Access Holes - lite built up sections

[NBEEBE]

The company I work for is currently on its way down the road of fabricating a "manufactured metal building" which will be constructed of built up tapered beams. My question pertains to the use of access holes in areas that involve CJP welds. Each "main frame" is made up of 4 rafters that bolt together to create a peaked span of roughly 110' which bolt to built up columns. The connection plates are welded to the flanges of the built up sections with CJP weld ans the flange is joined to the connection plate with a fillet weld. The web thickness is typically 1/4" and flanges between 3/8" and 1/2". the material is a572 grade 50. I have never seen a metal building manufacturer (NCI, Nucor, etc) use access holes in the mentioned areas.

Is this permissable in some section of code? or should there technically be acces holes to reduce the possibly of web shrinkage leading to cracking?

Any guidance on this would be great. I have looked at FigC-J1.2 in AISC MANUAL, and this is where my confusion comes in as it seems that this is a must. (AISC 360 seems to only address built up sections using material > 2" as far as access holes go)

 

[connectegr]

Weld access holes should be provided. In addition to providing access for a continuous backing bar, weld access holes increase ductility and aid in reducing stress concentrations. If beam web connections are field welded as well, the web welds should be completed after the flange CJP welds are completed and cooled. If the web welds are completed first they can resist the weld shrinkage in the flanges and cause cracks. Also note that continuous backing is required for prequalified CJP procedures. A gap in the backing will also result in a defect in the weld.

The only moment connection I am aware of that suggests the elimination of the weld access holes are end plate moment connections. The design guide for these connections recognizes the issues I have mentioned and identifies the welds in the region of the beam web as partial joint penetration welds.

http://www.FerrellEngineering.com

 

[connectegr]

Sorry I should have looked at your picture first. You do have a typical end plate moment connection. Refer to Dr Murray's AiSC Design Guide 4.

Dr Murray's research found that end plate moment connections performed better without the weld access holes. He clear identifies that the backing will not be continuous and the welds in the region of the beam web will be PJP welds. Incomplete fusion in the region is expected.

http://www.FerrellEngineering.com

 

[connectegr]

Page 18 of Design Guide 4, provides a specific welding procedure for your condition.

http://www.FerrellEngineering.com

 

[RFreund]

Connectegr -

Where/How do I gain this knowledge about welding/connections. Or where is a good start. Every time you post something I learn something new.
Not to say I haven't learned a few things from others on here as well.

EIT

 

[connectegr]

RFreund
I am amazed when I read the posts on this site how diverse even "structural" engineering can be. I learn far more than I can contribute most of the time. I enjoy reading posts that may never impact my practice. But, I file many ideas and discussions away. Although the engineering principals are the same, each construction arena has their specific issues. I have been fortunate to work on some very complex and unique construction projects, both industrial and commercial. I am one of those "one trick ponies" that I read about in some posts. I have been fortunate to work with some excellent mentors, and I am happy to have a specific engineering talent. Mostly I really enjoy this stuff. With only two hobbies, work and golf, I spend a lot of time trying to get better at both.

http://www.FerrellEngineering.com

 

[RFreund]

Very well said.

EIT

 

[NBEEBE]

Just wanted to say thanks for all of the replies. Its very much appreciated. I have also been directed to take a look at AISC 358 per Robert Shaw os SSTC, which he mentioned states that access holes are not neccesasary for these connections. I will read design guide 4 as well. Thanks again

 

[connectegr]

AISC 358 does provide the same end-plate moment connection weld information as Design Guide 4. However, 358 is primarily a reference for prequalified seismic moment connections. Seismic considerations may not be the reasoning behind your detail, but the arguments for removal of the access holes are the same.

Bob is always a helpful resource.

http://www.FerrellEngineering.com