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question about embedding WF in concrete

question about embedding WF in concrete

question about embedding WF in concrete

(OP)
I need to participate in the design of a welding training centre.
As the welding engineer, I have to foresee the actual training facilities. Concrete guys and contractors will also intervene in this process.
This is all on private ground, if it should matter.

Problem: This is a training centre for large pieces, which will need to be fixated somehow. So I need a level slab, with plates with sleeved holes in order for the piecess to be clamped on.
As we're talking about pieces upto 2 tonnes, this means two things: the fixation needs to be somewhat sturdy, and it alse needs to be forklift-proof, as the pieces will be placed with a large forklift (side-loading type).

I don't have any experience in this side of the game, so bear with me:
See attachment:
A) is the most simple, commonly used, but has as a major disadvantage that the top side of the plates is not free (nut and piece of all-thread sticking out).
Also, if you grout them up, you cannot reach the bottom side. So clamping is only possible if they're not grouted, and I don't know whether that's a good idea.

I would like to see if option B is viable.
We're talking about WF beams of about 4 feet long each (and about 48 in total, in a concrete slab of about 40 x 100 feet, evenly spread over this surface.
How do you place rebar? Will the concrete not crack along the sides of the bottom flange? Do they need to be HDG'd ? any other remarks?

If not, what are viable alternatives? I'd like to have an idea of what is doable and what not, before discussing with contractors, just to be "armed" against all kinds of prejudices.

Thanks in advance.

RE: question about embedding WF in concrete

I think others may not understand why you are embedding the WF? To act as rails for other pieces of steel to sit on that can be clamped down to?

RE: question about embedding WF in concrete

(OP)
Basically, yes, they serve only one purpose: to clamp (bolt) the large pieces to, (hence the sleeved holes). Pieces that are irregular of shape deform easily while welding, which is unfavourable during repair welding.
They need to be as low as I showed on the drawing (2-3 inches off the ground) because of the size of the pieces.

Also, there's no need for it to be WF, any other viable alternative solution is more than welcome.

RE: question about embedding WF in concrete

Kingnero:
It seems to me that with your hold down rails 2" above the slab all over the shop floor, you are going to be constantly tripping over them. And driving over them with forklifts and the like won’t be easy either, and the rails may get bent in the process. I believe that there are slotted rails available, much like the clamping slots in the bed of a milling machine, which can be cast flush to the top of the conc. slab (or only slightly above and in a level plane). You can clamp down via the tee slots and you can also weld lugs down to the top of the rails, and gouge the lugs off when you are done. As you suggested, the embedded WF beams cause problems in placement of slab rebars, unless you punch holes in the beam webs and thread the rebar through these holes. Also, with your two arrangements, they aren’t as stiff as you think because plate and flange bending will come into play as you apply hold down forces. You want to apply your hold down force over (or near) the web if you can. You might be better off buying 1" or 1.5" bars, 8 or 10" wide, and applying welded and headed studs to the underside, which are then cast into the conc. floor. You can weld clamping devices anyplace you want to these floor plates. We used to take heavy/large “C” clamps and cut the solid foot off of them, then weld their vert. leg of the clamp to the rail. Another device is just a “L” shaped steel block with one leg welded to the rail; the other leg extends over and above the bot. flange on you work piece, and a wedge is driven btwn. them to lock your work piece down. A plate with a large hole can be welded down as a hook point for a chain and come-along, to clamp the whole piece down.

We also had a bunch of ‘strong-back’ tables of various sizes, which could be moved around. For each application the ‘strong-back’ has to be stiffer than your workpiece to be effective. These consisted of any number of parallel WF beams, with some cross members to form a flat topped work surface above the conc. floor. Some of these were as large as 10 or 12' wide and 80' long, build with the largest/deepest WF beams we could get.

Contractors may be good at pouring concrete or setting steel, but they tend to suggest what is easiest for them to do, not always what best the final design in any given situation. It might be good to get a local Structural Engineer involved in this design. He can design the slab, its reinforcing and the size and spacing of the welded studs, so you get a good sturdy job.

RE: question about embedding WF in concrete

(OP)
Slotted rails might be a good alternative - but google didn't work for me on this one. any particular brands or references to look for?
But, won't they corrode fast as they're cast into the concrete, and when water and/or dirt gets collected in them?

As for the other suggestions, the pieces are too irregular of shape to use short pieces of bar or welded C-clamps or reversed L-pieces or a similar set-up.
Slotted rails or WF with milled longitudinal slots are the best choice for this application.

RE: question about embedding WF in concrete

Kingnero:
Irregular shapes, flange thicknesses and piece sizes are exactly the reason you want to be able to weld down a clamping device or a tie-down plate almost anyplace, not just at your slots, thus our strong-back tables. I do not have a manuf’ers. name for the slotted rails, but I have seen them used. And, they certainly could be shop made to any length. I would check with a welding supply house, particularly those who make welding positioners and the like, or those who sell steel fabricating or machine shop supplies. Some of them may have been machined steel castings which were then embedded in the floor. There were also large cast, flat plates, which had regular spaced holes and slots which were used in machine shops and blacksmith shops, etc. for holding and bending large work pieces. We never galvanized any of this stuff, we were welding to them and the galvanizing is not good in that situation. We didn’t paint the strong-back tables either, just raw steel. We didn’t have any particular corrosion problems, they just rusted a little, but not enough to cause a measurable thickness change. Obviously, they would rust if you left them buried in wet mud; you do have to keep your shop floor semi-clean. And, slots and the like had to be cleaned out from time to time, a disadvantage. Casting steel in conc. will not cause any particular corrosion problems, its done all the time. Again, I would not be in favor of casting this stuff 2" above the conc. fl. for a number of reasons. You seem kinda fixated on WF beams embedded in the conc. fl., but they really complicate reinforcing the fl. slab. And, in fact, the floor slab is the real stiffening element in the system, once your floor rails are properly embedded. I would think in terms of 20' long bars, spaced at 2 or 3' o/c for 10 or 12' of working width; then a service isle. This space might provide several work stations depending upon the work piece size.

You seem to have missed my point about the “C” clamps and other hold down bars and fixtures. They are placed where your work piece dictates, welded down to the floor rails and then clamped down, wedged down, jacked down or chained down. They are gouged off the rail when you are done. This gives you max. flexibility for your floor rail spacing and hold down cap’y.

RE: question about embedding WF in concrete

(OP)
This is an outdoors slab, as we do not have the facility of a hangar large enough for these pieces.
This might be a concern for the slotted rails, I'll talk to a welding manipulator/mechanical aids fabricator.

Flatness is a major concern, hence I would prefer a bolted-down construction of the workpiece.
As this is a training (and examination) place, there will be activity on a daily basis, which also means each day we will have to replace the pieces. That would also mean a large amount of (re-)welding the C-clamps or L-pieces. When you weld fixtures on hold-down bars, they will inevitably warp over time, which is not a situation we encourage.

I am not fixated on embedded WF's, but I want to best possible solution. Once we start this, there is almost no way back. So a well thought out design is a must.

The 2-3" above concrete level is for allowing space for bolt heads and/or nuts underneath the flange. There will be places reserved for a side-loading fork-lift to manouvre inbetween.
Going much higher than that is negative for the weldors. We currently have 18" high WF beams of each 2.5m in length lying on a concrete floor. The parts are too high, and the WF's lift due to the warping of the pieces. That means their own weight isn't enough. Hence my idea of embedding them, but as I said, I am open for all other suggestions. After all, this will probably continue for long after I'll ever be retired, so I'd prefer a good design before all other things.

When I talk to our concrete guys, they cannot really help me with the design of this (strong-back), but they are willing, once I make a suggestion, to do all the necessary work.
Whether it'll be embedded WF's, hold-down bars, or any other alternative.

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