Openings in flat plate PT

[Lion06]

Does anyone know where I can find guidelines on openings in flat plate PT construction? I can find information for mild reinforced flat plate all over the place, but can't find any guidance on PT flat plate.

 

[larsacious]

I would follow ACI 318-05, section 13.4.2.1 & 13.4.2.2. If you read 13.4.1 it allows you to locate the openings of any size as long as you meet strength and serviceability requirements. I would avoid placing the opening in the column strip regions.

Detailing of additional mild steel reinforcing and how the interrupted tendons are displaced around the opening will be critical for crack control.

 

[slickdeals]

Unless you have seen this document already

http://www.concrete.org/members/ci2807mota.pdf

 

[Lion06]

Larsacious-

That's specific to mild reinforced two-way slabs. I'm trying to find something that addresses PT. Even if I could find something that says the mild reinforced guidelines are applicable to PT....... that would be helpful.

Slick-

I did come across that one, but it looked like it was for mild reinforced slabs.

 

[slickdeals]

I remember seeing some details for post-tensioning cables around openings in the PTI Post-Tensioning Manual. I am not sure if it has design recommendations though.

 

[larsacious]

I believe that 13.4 would also be appropriate (conservative) guidelines for PT slabs as long as you design your equivalent strips so they account for the section loss due to the missing concrete area.

I also remember that the PTI manual has some details for slab openings. Perhaps you can find this manual and let us know what you find.

 

[rapt]

PAStructuralPE,

The concept is exactly the same as for an RC flat plate. The only problem is that ACI says RC and PT slabs/beams are different. But that is only because they are about 50 years behind and they try to make special rules for every possible different situation!

Use your engineering judgement to apply the RC flat plate rules to PT flat plates.