Welded Aluminum Design

[lutein]

Greetings. I am designing a continuous aluminum beam, 2 spans, with square tube section, 6063-T5. the ends of beam and intermediate supports are to be welded to another aluminum beam.
The welded yield strength is much less than the non-welded, and the code specifies that the welded strength shall apply to 1" section from center of weld. So - Does it mean that I will have to use the welded yield strength at intermediate support to resist the huge negative moment? If the weldment is only at bottom of the tube section and is very minimal, it does not make sense to reduce the strength by using the welded yield strength.

What is your take on this?

 

[dhengr]

Lutein:
The welding heat takes the temper out of the aluminum in the immediate area of the weld, not necessarily 8" or 10" away from the weld, or on the other side of the member/tube. So, the question is, can you live with the lower allowable stress in the immediate area (1") of the weld? I can’t see your exact detail from here.

 

[lutein]

Sorry that I was not clear. Yes, the allowable stress was too low that nothing would work. I am just curious if a small tack weld at bottom of beam would cause the whole section to have to use the low weld strength.

 

[Ron]

The influence of the tack weld is 1-inch on all sides per the code, assuming only tension in the welded area. If there is shear in this location as well, the same restrictions apply.

So in response to your question....yes, even a tack weld influences the section to the degree noted in the code.