WELDING 18 GAUGE METAL

Sure. It takes an experienced welder and the right gear. However, I'd look about how to block out for the supports rather than fooling wi8th the door trim.

ajk1....yes. Welding 18ga material can be done easily by an experienced SHEET METAL welder, as OG notes. Make sure the welder is qualified for welding sheet steel under AWS or CWS. Typical structural welders might not possess the "finesse" to weld sheet material!

Also, consider that cutting out and welding back such a section might cost more than replacing with a pre-hung metal door.

To oldest guy and Ron: thanks for the responses. Much appreciated.

I did not want to remove the entire door trim because I believe it would be tied back to the block masonry at the sides (but probably not at the top), and on the left side of the door there is only an 8" width of block between the door frame and a concrete column. So if they remove the door frame they probably have to remove the entire block to the left and rebuild it. On the right side is a lot of sensitive communications wiring running along the wall, so the less that the wall gets disturbed, the less likely the wiring will be damaged. If the communications goes down in the building, it will be an unhappy event.

I am uncomfortable packing the channels out to clear the door frame, because I am fastening the channels to the wall with the 3/8" diameter Hilti HY70 adhesive and screens for hollow block, and if that is packed out it will be necessary to design these fasteners for a moment due to the standoff. I doubt that is a good idea or doable but I can check. If I abandon that and use thru bolts, I have no way of determining what shear capacity they have, and no way on ensuring that they fit tght to the block.

How much do you think it is to cut the pieces out if the door frame and weld back, and grind flush? Would it be more than 15 hours at say $100 / hour = $1500?

How much would it be to demolish the whole door frame, buy a new one, install and rebuild the block around it, dispose of the old door frame and old block which will be damaged when the frame is removed? Labour say 8 hours at $60, 2 labourers = $960, plus the cost of a new fire-rated door frame, masonry blocks, and disposal costs = ?

Maybe I should spec it with both options, and let the contractor submit cost for each, but it will leave me uncomfortable that they may damage the communications wiring fastened to the wall?

Through bolting with some HSS shimming sounds like the way to go even if the capacity determination is sketchy. I've often wondered if one could through bolt but still full the cavities with that same HY70 goo but I haven't gotten around to querying Hilti about that.

Here's another option. Moment splices either side of the door.





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.

What's wrong with bracing that channel up from the floor on the ends with minimal attachment to the block then needed?

To kootk -

1) your moment connection is very innovative! But the offset of the channel at the moment connection may be problematic. Will that cause moment about the weak axis, and horizontal deflection?

2) I am not following how the HSS would be used to shim the thru bolt.


To oldestguy - the floor is all being removed and rebuilt, so I do not think that anything can be supported from the floor.

I sketched up the moment splice in detail A below. There would be torsion but a) It would be quickly resolved as wall flexure via nearby bolted connections to the wall and) I'm guessing your design is deflection governed and stresses are pretty low across the board. I wouldn't even bother to investigate torsion.

The HSS shim idea is show in detail B.

Details C and D show a system hung from the slab above which, I believe, was a previous proposal of your own devising. It would eliminate the door frame issue handily as the channels could stop either side of the door.





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.

ajk1...I agree. Specify both option and let the contractor decide. They are equivalent and he/she can decide the lower cost option. I do that routinely for some aspects of remediation design.

ok, thanks.

Voodoo Hanger is a great name for a detail!. I always try to slip in a few odd names or words but that's a good one. I've managed to get into print drawings calling a big upside down "U" shape thing the "telephone". Also designed a big cart to remove a piece of eqpt walled a "wye" and called it the "Wye-Mobile".