19 strand tendons 1

[Zambo]

We have a group of 12 tendons, each tendon consists of 19 strands (15.7mm diam 7 wire strands). For various specialist prestressing companies such as VSL Dywidag, Freyssinet what is their recommended minimum radius of curvature if the tendon is to be post tensioned within a corrugated steel duct.

For BS, PTI, DIN etc what are their recommended minimum radius of curvature.

Can anyone provide some assistance, perhaps a couple of Engineers can each provide some data so that I can draw up a comparison table.

Any more info needed? any help gratefully received

 

[rapt]

Zambo,

VSL - approx 6500mm
BBR - 6000mm

RAPT - 6650 (based on 70 * duct ID)

I cannot find Freyssinet's at present but it is in the order of 6500mm as well

 

[Zambo]

rapt,

thanks for the quick response. Duct internal diameter is 95mm. I have found Freyssinet and it is 100x i.e 9.5m. Does this info change the VSL or BBR?

What is RAPT?

for PTI I have 21feet curvature around an obstacal = 6.6m

thanks

 

[rapt]

Zambo,

No, the VSL and BBR figures are from their brochures. I did not think that the Freyssinet figures were usually that much higher.

RAPT is a computer program I develop and market around the world.

These radii are the absolute minimum values you would normally use over supports etc to ensure the compression on the inside of the curve will not crush the concrete or cause a butsting problem. If you are going to use them for horizontal curves, I would use much higher figures or look at the stresses induced in the concrete from the curves if you use the minimums.