hunch floor drains pipe and sanitary pipe

[rsavani]

Hi,

Is there any thumb rule for Placing Plumbing Pipe in slab?
what are measures and methods take in to account for Hunching desing?

Thanks for you time

rakesh

 

[msquared48]

One thought - no aluminum piping.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[rsavani]

It is PVC pipe for floor drains.size varies 2" to 3".

thanks rakesh

 

[ishvaaag]

Normally all plumbing penetrations into slabs should run perpendicular to it to minimize the effect in the design. Then at least you will know the amount of structural slab eaten by the inset. Far from the supports, a 3" hole uses not to be of concern. Where more interfering is besides supports because they diminish the available load path; codes have drawings like two lines tangent to the pipe till some "shear" section concentrical with the column, that is what they think you can think as availabre to resist shear.

Codes also specifiy a maximum level of shear stress to be respected; when the failure is expected to happen for a given thickness by compressive strut failure, then adding more shear (or tension) steel is of no use, and then the slab needs to be thickened at supports. Traditional rules for thickened regions in a diametral length talk of around 1/8 of the span; I have seen them (almost invariably in waffle slab) in almost anything between 1/10 and 1/3, yet the smaller should be the more economical, waffle or not.

Finally, and whilst you are not in regions where the principal compressive stresses at the concrete are near those limiting strut crushing, a limited run of some inclined inclusion 2" in diameters should not be structural concern; but still perpendicular insets are to be preferred given the easier maintenance of both the service and the structure itself, you will know in all cases where the pipe is.

 

[cntw1953]

In some parts of Asia, it was a widespread practice to lay small diameter plumbing and electrical conduits in cast-in-place concrete slab. However, not so in the US. One obvious disadvantage is difficulty in maintenance and repair.

For pipe penetration through floor, try to get away from high stress area. If couldn't avoid, add'l bars shall be added to transfer the stress.

 

[rsavani]

Thanks