External shrinkage restraint

[AH22]

Hi,
I have a PT slab with perimeter pour strip of 1m to disconnect the peripheral capping beam during construction. Even with the pour in place is it recommended to design the slab for 'severe' external shrinkage restraints?

Please guide.

 

[hokie66]

Yes, because the slab will continue to shrink for several years.

 

[AH22]

Agreed. But does it have to be designed for a severe shrinkage condition rather than a moderate?

Wont considering severe be too conservative?

 

[Tomfh]

In some cases severe isn’t enough. Some of these restrained PT slabs crack like hell, especially if all the PT compression is lost into the walls. It’s a tricky one. If you go too conservative people will say you’re crazy and “no one does that”, and if you don’t go conservative enough you can get 1mm shrinkage cracks and everyone pointing their finger back to you as the engineer.