You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
My Google Fu has failed me, or I don’t understand what I'm finding....possibly because I'm trying to oversimplify it.
Simple version - what is the usual thickness of a suspended concrete slab?
More complex version - commercial offices, 4 floors, suspended concrete slabs forming the floors, 12m span. Can someone point me to the correct page of regs or calculations to give me an idea how thick the concrete slabs are likely to be, assuming normal load for staff, furniture, M&E etc
Struggling to find an answer on a UK website, Americans seems to go with length/a number between 10-28.
Many thanks
Depends on a lot of factors, but probably 150-200mm. Likely poured on to profiled metal decking so depth won't be consistent across the slab.
Is it a metal deck or precast floor ?, I work for a steel fabricator ,12m span is quite large so will see if we have had anything near that previously. Ive put a link to cornish concretes hollow core tables which may help.
You'll struggle to find a rule of thumb or general guidance for that, other than plank spec's. as above.
Too many factors to consider - structural engineer job.
For a more accurate result you could but this: https://www.concretecentre.com/Resources/Publications/Economic-Concrete-Frame-Elements-to-Eurocode-2.aspx (or see if you can find a free copy).
Thickness will depend on various factors such as; precast or in situ, permanent metal formwork or not, prestressed or not. As has been said, 12m span is quite big.
Don't drill a hole if that's the plan, breaking a tensioned steel cable would be worrying!
12m span and just single thickness concrete, how wide is this 'slab' and how much is 'unsupported'?
Not done any for over a decade, but Hollowcore pre-cast concrete planks for a span like that. I think you would probably looking at 250mm planks + finishes ( usually 50-75 screed). Usually specced by a Structural Engineer , although i would imagine the supplier would know a thing or two. Have done these and metal deck floors in the past , though from memory, they have max spans in the 3-4 metre range.
Try https://www.milbank.co.uk/
Steel Frame?
Concrete Frame?
Half and half?
If you're talking in-situ concrete I don't think you would want a "slab" spanning 12m, the required depth would be too great. You will probably have beams maybe 4m apart (finger in the air figure there) probably around 600mm deep and slabs between of 150-200mm. As others have hinted could also be precast concrete or steel beams with in-situ or precast slabs between. But in any case it's a job for a structural engineer.
General rules of thumb, in situ concrete:
one way spanning flat slab - max span 6m, thickness L/32
two way spanning flat slab - max span 9m thickness L/36
ribbed slabs - max span 12m, thickness at ribs L/30
post tensioned - max span 10m, thickness L/40
All the above assume a repeating grid. A single 12m x 12m building with no internal columns will be 10-15% worse.
precast planks: max span 10m, thickness L/45
As Slowoldman says, generally not the arrangement you want - phenonmenal waste of concrete and subsequently weight on columns and foundations.
Try smaller slabs on deeper concrete beams, or metal deck permanent formwork on steel beams.
Appreciate all the comments and links, luckily not my building, trying to reality check what a contractor is saying they can do