Nutte:
I don’t doubt what you are saying, I see that same thing in my older Eds. of AWS. I don’t know about the last few Eds. of AWS and AISC well enough to comment on the rationale for all of their changes in design stresses, tabulations and prequalified welds, etc., since I was last doing weld design every day. Most weld processes would limit you to a throat of ‘S’ or less, the groove depth or less. That was std. when I was practicing on a regular basis also. But, it was also common to some industries and codes to allow the use of the actual throat for design, once you proved you consistently achieved that grater throat. So, in practice we could to take advantage of the improved penetration of some weld processes, on some types of joints, and your ref. to Mike’s page 6 would have been one of those, as I remember it. Of course, this was contingent upon good quality welding, good fit-up, attention to detail, etc. I would not allow tension across that weld, at the root.
Finding this was like pulling teeth. I found some discussion on this actual throat vs. effective throat (or theoretical throat) issue, in several older AWS Welding Handbooks, and some Lincoln literature and Handbooks, but was not finding it in AISC or AWS manuals or codes. And then, finally a lead from some Lincoln lit.... in the AISC manuals:
7th Ed., sec. 1.14.7, Effective Areas of Weld Metal, can add .11" to throat size for SAW
8th Ed., sec. 1.14.6.2, do.abv.
9th Ed., ASD, sec. J2.2.a, do.abv.
1st Ed., LRFD, sec. J2.2.a, do.abv.
Don’t know after these Eds. what happened in AISC, and can’t find it in AWS
And, I think AISC was being safe/conservative with the +.11" added throat. I allowed this same design criteria on a groove weld (PJP) as long as I wasn’t dealing with tension across the weld, in which case I would not use the PJP weld. Someone above mentioned a convex top on the weld to increase the throat, but that is not allowed to be considered, at least I never did. I figured my throat to the theoretical surface of the weld and still always wanted the convex finish. Many times, to pick up throat size, I would detail a 1/8 or 3/16" bevel on the web pl. on a built-up girder, and the like. We could nibble or grind these bevels almost as fast as one of the guys could walk down the edge of the pl., that is, fairly min. extra prep. work to pick up that extra 1/8 or 3/16" (plus my .11 to 3/16") for root area penetration. I doubt that most Structural Engineers on bldgs. would go to this trouble, but for the most part we were always doing the design, piece detailing and the fab’ing., and I would actually ask for specific welders for some details, because I knew what they could or would do.
If I were designing today, either bldgs. or bridges, with the job to be let out to anyone who owned a welding machine, and offered a low bid, I’d probably use S - 1/8" too. I suspect the current codes account for a very competitive fab. market, not knowing who’s going to be welding it, fast and min. cost fab’ing., the fact that some grooves are tough to access with some processes, thus inferior root, etc., and this might be left to the fab’er. to determine. However they’ve screwed around with design stresses and the phi, phy, and pho-phum factors, the way welds work and the general engineering concepts involved in weld design really haven’t changed, just because they’ve changed the codes. A new name for an old concept is always a good way to add confusion to the whole process.
48V.... if you are going to use “velds” you have to use ‘machrovetching’ also.
