Slab on grade directly over grade beams
Slab on grade directly over grade beams
(OP)
I'm designing foundations for an office building. System is steel moment frames in short direction and braces in long direction.
Steel columns are rigidly connected to foundation beams with cast in place anchor rods.
Plan is to first pour the main foundation system, then compact gravel between the beams and then pour slab on grade directly over foundation beams. Slab will be reinforced top and bottom.
My question is, do I need control joints in lines of tie beams? I would rather not do that because contractors hate them and slab will not be visible (covered with screed). I would rather provide additional reinforcement to control cracks but the slab is quite long.
Would you leave the slab and foundation system disconnected? Should I put another layer between the slab and foundation to separate them completely?
On the other hand connecting them with rebar seems complicated and unnecessary. What do you think?
Please see my sketch. Any help or insight is highly appreciated.
Steel columns are rigidly connected to foundation beams with cast in place anchor rods.
Plan is to first pour the main foundation system, then compact gravel between the beams and then pour slab on grade directly over foundation beams. Slab will be reinforced top and bottom.
My question is, do I need control joints in lines of tie beams? I would rather not do that because contractors hate them and slab will not be visible (covered with screed). I would rather provide additional reinforcement to control cracks but the slab is quite long.
Would you leave the slab and foundation system disconnected? Should I put another layer between the slab and foundation to separate them completely?
On the other hand connecting them with rebar seems complicated and unnecessary. What do you think?
Please see my sketch. Any help or insight is highly appreciated.






RE: Slab on grade directly over grade beams
RE: Slab on grade directly over grade beams
Dik
RE: Slab on grade directly over grade beams
Please note that I have my foundation beams also on the perimeter in the long direction. There the slab will be poured over and will be additionally restrained when shrinkage occurs.
How deep is the sawcut? Do I cut/terminate my top reinforcement? Is there any other easier method for control joints?
Where would you predict construction/cold joints? Probably there is no problem to pour everything in one phase.
RE: Slab on grade directly over grade beams
Dik