Stress-strain relation of 7 wire strand to use for ULS design

[kww2008]

If I use a non-linear stress-strain relation of prestressing strands for ULS design to AS5100.5, I think it should be a characteristic relation rather than an average relation. What is your view on this?

 

[Agent666]

If you mean using the lower 5% characteristic values, then yes I'd agree with that. The average won't achieve the safety margins inherent in the design provisions (not specifically familiar with the bridge standards though).

 

[kww2008]

Thank you for the response Agent666. For the reading of texts and technical papers, the lower 5% characteristics is the one to use. I have not come across one for strands so the codes' (both AS 3600 and AS 5100.5) recommended elastic plastic relation would be the one to use.

 

[rapt]

AS3600 does not use an elastic plastic relationship! Clause 8.1.7 defines a stress/strain relationship for PT.