All-welded moment connection 2

[suzpari]

I designed a cantilever beam with a moment connection to a column web using a web plate for shear and bolted flange plates for the moment. However, the contractor just welded around the beam end to the column - no web plate, no flange plates, no bolts! I now need to check this to ensure that the connection is adequate. Can anyone direct me to an all-welded moment connection design or example? I know that I came across an example a few years ago but I cannot remember the reference. Any help or guidance would be appreciated. Thanks!

 

[TehMightyEngineer]

It's not too crazy to have an all-welded moment connection using fillet welds and/or groove welds, usually works fine from what I've found. The reason it's not done is it's very hard to ensure beam is level and correctly positioned and the correct length. In addition, the overhead welds that are typically involved are difficult.

However, they changed your connection detail and now you have to perform additional work to prove and verify their connection works. Charge them a change order to review it or have them rip it out.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[KootK]

I dislike the connection for two reasons:

1) You'll have to do some fancy yield line analysis on the web to assess the strength.
2) Assessing web flexibility, and there for cantilever deflection, will be tough.

This won't really answer your question but might provide some useful ideas: Link

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[TehMightyEngineer]

KootK is correct, I might have made this sound simpler than it is. Depending on how this was welded, the thickness of the webs, what part of the column it's welded to, and how the beams are loaded; you may have additional issues.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[andriver]

If it is a full-pen weld that was properly beveled, you do not even need to check it, as it exceeds the strength of the member.

However your statement that they welded all around sounds like a fillet weld, in which you would need to do some analysis. If they didn't RFI and get this change in writing, I am in agreement with TehMightEngineer. Need to back-charge them for the extra work.

 

[hokie66]

andriver,
That might be true for the weld, but as others have indicated, the weak link is likely the column web.

 

[andriver]

I missed that bit

 

[BUGGAR]

If you spec'd AISC and AWS, look up AWS welding requirements, including required WPS etc. Did they submit all of this or have it on record?

 

[suzpari]

Thanks everyone for the responses and advice. It sounds like I really do have a lot of work to do. I was sure it was just a matter of a quick calculation to design/check the welded connection for the moment. I think AISC has an example of that but I cannot remember where.

Buggar, nothing was submitted. I visited the site and noticed that they installed the beam differently from what was on the drawings.

 

[KootK]

If it were me, I'd have a flange plate installed top and bottom that connects the flanges of the beam to the flanges of the column. Unless there are fifty of these or some other special circumstance, the four billable hours that you'll spend trying to evaluate this will be worth more than the fix.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[suzpari]

Andriver, you are right. It is a fillet weld all around the beam onto the column web.

KootK, that's what I eventually did....had them install the plates.

Thanks All!