Tendons in 2 way slabs - Flat bundles only?

[fredPE]

Just a quick question, is it absolutely required to have flat bundles in a PT 2 way slab? Or can you have stacked bundles to ease congestion over a column (such as two on top and two beneath). This would be in a 12" thick slab.

Thanks,

 

[hokie66]

Don't understand your terminology. What is a "flat bundle"? Usual practice is to use ducts which are about 70mm wide x 19 mm deep, and you can fit 4 or 5 strands in each duct. So why would you want to have two layers in the same direction?

 

[haynewp]

Do you mean laying out the tendons side-by-side to maximize the cgs? If the strands are all stacked together then it could be a cgs change from anticipated.

 

[271828]

It will be hard enough to get the tendons high enough at the column anyway. Stacking them on top of each other won't make that any easier.

 

[slickdeals]

I know the column is very congested, but placing tendons in layers reduced your eccentricity and hence, load balance. I think the fact that you are using cables lower than their usual high points at columns should be accounted for.

 

[shin25]

Also, during the ultimate time, the tendons near the top will contribute very less in the moment carrying capacity. More over, to maintain a minimum amount of precompression, you will have to increase the number of tendons. This will happen due to the reduced eccentricity of the tendons.