Contraction joints in slab
Contraction joints in slab
(OP)
I have to design storage building with 4 floors, 100x100´ (lxw), 85´height with using of prefabricated concrete elements.
The posts and girders are in 20´x20´grid, ceilings could be from prestressed hollow panels (thickness 12´´) with
concrete slab (membrane) (th. 3,5´´) on the top of the panels. The slab is reinforced with mat. Loading - 500 psf.
My question is - is it neccesary to make contraction joints in the slab or is it possible to let it without? The slab would be used like horizontal stiffening.
Thank you very much for advise.
jb66
The posts and girders are in 20´x20´grid, ceilings could be from prestressed hollow panels (thickness 12´´) with
concrete slab (membrane) (th. 3,5´´) on the top of the panels. The slab is reinforced with mat. Loading - 500 psf.
My question is - is it neccesary to make contraction joints in the slab or is it possible to let it without? The slab would be used like horizontal stiffening.
Thank you very much for advise.
jb66






RE: Contraction joints in slab
RE: Contraction joints in slab
If you are talking about the slab-on-grade, space the control joints 36 times the slab thickness.
DaveAtkins
RE: Contraction joints in slab
RE: Contraction joints in slab
If the topping is not bonded, I would suggest spacing of joints in the topping similarin spacing to those recommended for a slab-on-grade of the same thickness.
If the topping will be bonded to the precast slabs beneath, then I would still recommend joints in the topping but much fewer in number and spaced much farther apart. The joints have to be located such as not to disrupt the composite action that you are trying to achieve. For instance, you would not want to allow them in the center of the span. I would suggest locating only directly over supports or parallel with the span.
I hope this helps!
RE: Contraction joints in slab
jb66