Minimum Reinforcement in BONDED Post Tesioned Slab 1

[Yousef ZAA]

Dear Engineers,

ACI Code is a little bit biased for unbonded post tensioned slabs, back in the middle east we construct only bonded post tesnion, so regarding the minimum Top or Bottom mild reinforcement for the bonded PT is there any limitations I'm not aware of in ACI, I know that by providing a pre-compression stress larger than 130 psi, the shrinkage and temperature requirement is achieved by the PT, Am i missing something? please advice!

 

[rapt]

Not sure where the 130psi rule comes from.

Minimum reinforcement is normally based on the Cracking Moment for bonded PT and is in ACI if I remember correctly.

But that does not provide minimum shrinkage and temperature reinforcement in anything but a completely unrestrained member.

If there is significant restraint to shortening PT will not give good crack control.

It is essential that restraint be reduced to allow the PT to get into the member when stressing.

It is also necessary to provide sufficient extra reinforcement to provide crack control depending on thelevel of restraint experienced and the maximum crack width required.