Yield Modes for a threaded weld stud used for nailer attachment

[Ron247]

When welding threaded studs to a Channel web or plate to fasten a nailer to, which of the Yield Modes would be investigated? This is my first time welding studs to a plate. In the past, everything has been bolted through. I am assuming the plate thickness is somewhat irrelevant other than possible distortion from twist of the stud. I am having the bottom of the nailer set on the channel flange but I am not relying on that in my calcs.

Any thoughts would be appreciated.

 

[bones206]

I would think the only additional check would be shear capacity of the stud weld. All the other checks would be the same as for a through bolt.

 

[dhengr]

Ron247:
You say…, “I am having the bottom of the nailer set on the channel flange but I am not relying on that in my calcs.” I would do and think just the opposite of your thinking. The bearing on the flg. is a much more positive load transfer path than wood bearing on a few stud holes. While the studs may take some load in shear, depending upon the accuracy of the hole drilling for them, the edge bearing of the 2x nailer is a certainty, as long as it is fit pretty well. I would have them make two rips on the edge of the 2x nailer: one to comform with the slope of the top of the bot. flg., they should measure that in the field; then a second 45° chamfer to clear the radius btwn. the flg. and web in the “k” area. It is a little fiddly, but it is the right way to do it. Now, you say you have 375lbs. per stud, say 24” o/c, times 2 studs, that’s 375lbs./ft., or 375/(12” x .75 or 1” nailer width), that’s 31psi bearing on the nailer edge. Then, the studs are there to hold the nailer in place, if they do a good job of drilling the holes. Set the nailer on the studs, and hit each stud location with a hammer (for hole layout), paying some attention to the vert. position of the nailer w.r.t. its final postion on the flg. The studs may see a little shear, as they bear on an ill placed hole or two or a little tension as they stabilize the C12, but otherwise the gravity load is taken to the bot. flg.

As for bolt yield modes, if that was part of your question, I’d say the stud is basically fixed at the C12 web (~ .28” thk.), and its bearing on the wood hole (side piece, nailer) would be akin to Modes III_m or III_s. But, I don’t think that’s much of an issue here, since you shouldn’t get the movement/slippage needed to bring side bearing in the holes into play.

 

[Ron247]

dhengr:
I agree the bearing on the channel is more reliable but in the case of this builder, I am going to assume a reliable and accurate cut is not going to happen. As I stated in another post related to this project, I have little faith in what occurs in the field. I am going to require it bears on the flange, but not rely on it to happen to a high degree of accuracy.

This is the kind of project I hate being involved in, one where the contractor thinks he is a structural engineer and by osmosis, the Owner who hired him is also now a structural engineer. My original design that matched what the Architect wanted the porch to look like was completely changed by the Builder and Owner without any conversation with me. I knew what the Architect wanted would cost more and advised it would before I ever hit the calculator. Once the Owner got the estimate they drastically change everything but sent me steel submittals that reflected their design but felt I should blindly OK the submittal without checking anything. In their eyes, they had changed nothing structurally. I even got a "nastygram" from the Owner that he was tired of my childish BS and actually fired me. Or so he thought. Then he found out he needs someone to sign off on the new design. I actually like the contractor but am tired of having to defend my design.

My childish BS consists of the following:
[ul]
[li]Refusing to agree with the Contractor that if you place a wall tight under the center of a 27' beam that is capable of spanning 27' unsupported, it is not a load bearing wall and therefore does not require a foundation. After 4 separate discussions of this concept, I told them I was no longer going to try to convince them and was not going to discuss it anymore.[/li]
[li]Telling the Contractor that the fact the IBC code does not state you MUST HAVE a rebar dowel that connects the strip footing to the masonry wall above it does not mean you do not need one and the inclusion of it is just being conservative. This site has poor soil conditions. There was more than one instance of him wanting me to show him where the code stated you had to have something specific present in concrete or masonry. "Where does the IBC say you must have stirrups?"[/li]
[li]Steel bolts and by extension steel threaded studs have similar loading capacities whether you put them in wood or steel. In other words, a 5/8" bolt through wood can hold 3,000 lbs in shear.[/li]
[li]They reversed the channel so I had to check more torque since the center of nailer was no longer close to shear center. When I was explaining that I had to check torsion again, I could actually hear his eyes rolling around over the phone.[/li]
[/ul]