Closure Strip in a One-way PT Slab

[rahuldby]

Do we need to provide a closure strip for a typical one-way PT slab to eliminate restraint cracking? The length of the building is about 350 ft. The post tensioning manual suggests to consider two closure strips for slab length between 325 and 400 ft. Does anyone have experience of not having any closure strips under similar situations? Any thoughts and suggestings would be appreciated. Thanks.

 

[rapt]

Royces,

I think you need expansion joints, not just closure strips, over about 200'.

Have a look at the shortening effects (shrinkage + temperature change) over this sort of length you are suggesting and see if you can justify the columns in bending and shear for a start. Then look at the restraint effects in the slab.

A closure strip will do nothing to aleviate temperature movement and will only relieve a little of the shrinkage unless you leave it open for a long time (70% for 12 months if you are lucky).