Forming concrete slab by hanging soffit formwork from steel beams
Forming concrete slab by hanging soffit formwork from steel beams
(OP)
Is it possible to hang slab soffit formwork from steel beams? It seems to me that 40 years ago this was routinely done with inverted U hangers over the top of the steel beams, but today contractors don't seem to want to do it. We don't want to use steel deck as a form because we are putting a urethane waterproofing membrane on the top side of the new concrete slab, and the soffit therefore must be left free to breathe (as per CSA Standard S413). The new slab is 5 storeys up, so forming it from the ground level below would not seem economical.






RE: Forming concrete slab by hanging soffit formwork from steel beams
Dayton Superior and National Concrete Accessories (NCA) supply the hangers you are thinking of. Just make sure that the beams can handle the slab load non-composite, if they are designed to be composite with the slab. That to me would be the difference between a building and bridge here. Bridges are designed for the deck as a non-composite load. If you are not the one designing the beams, the designer may not have considered this case.
RE: Forming concrete slab by hanging soffit formwork from steel beams
RE: Forming concrete slab by hanging soffit formwork from steel beams
RE: Forming concrete slab by hanging soffit formwork from steel beams
RE: Forming concrete slab by hanging soffit formwork from steel beams
RE: Forming concrete slab by hanging soffit formwork from steel beams
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.
RE: Forming concrete slab by hanging soffit formwork from steel beams
RE: Forming concrete slab by hanging soffit formwork from steel beams
Thanks for all the comments. Much appreciated.
To EZBuilding (Structural): yes we did, but our engineer tells me that the CANAM acoustic deck available in the Toronto area has perforations only in the bottom of the flute and they are only 0.5% of the area of the bottom of the flute. Perhaps there are acoustic decks with larger percent area of perforations. Some waterproofers are skeptical that even acoustic deck with greater perforation area will be ok.
To Steele6707 - yes, ok thanks.
To Kootk- The idea of precast is interesting but I don't like hollow core in garages, so it would be I suppose solid plank as you note.
To Sawbux - interesting
I had not thought about the fact the forms have to be stripped, so this might be difficult to do at 5 storeys up without building scaffolding below. Thanks for this reminder.
RE: Forming concrete slab by hanging soffit formwork from steel beams
Some manufacturers, in some markets, do produce a vented deck product which is actually distinct from the acoustical deck product (obviously both have holes). Whether or not not that product would suit your purposes is still debatable I suppose.
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.
RE: Forming concrete slab by hanging soffit formwork from steel beams