Post-tensioned Slabs - Long term effects 1

[NAFTALI-HAKOHEN]

Hi all,

I have studied PT design in the past but am new to the actual live design practice of designing PT slabs,

What are the long term issues with PT slabs that i should be aware/familiar with, and what types of failures are most common?

Thanks

Naftali

 

[KootK]

What are the long term issues with PT slabs that i should be aware/familiar with, and what types of failures are most common?

It's mostly pretty great stuff in my opinion:

1) PT slabs tend to be thin and not have drop panels. So punching shear can be more challenging that with mildly reinforced slabs.

2) Moisture getting into unbonded PT systems has caused lot of corrosion problems in the past. In my opinion, these problems are mostly solved given modern practices of:

a) Using extruded sheathing on the tendons and;

b) Using encapsulated anchorages at balconies etc.

c) Using modern building envelope systems at plaza areas and the like.

You might enjoy this article: Link

 

[cliff234]

Post tensioned construction is great - provided it is properly designed and detailed. When used in parking garages it is very durable. Crack-free as long as there are no restraint-to-shortening issues. We designed a PT garage about 30 years ago and it is still in pristine condition. With all the talk of “green design” these days, PT is just about the “greenest”. Span/depth ratios of up to 54. Thinner slabs = less concrete, lower carbon emissions. Half the reinforcing steel(versus conventional concrete construction). And depending on the market PT construction is very economical.