Prestress losses 1

[Isntbard]

Does anyone know of a good reference that discusses the calculation of axial shortening losses for prestressed beams? I am particularly interested in comparing the calculation of these losses for non-transformed sections to transformed sections.

Thanks

 

[Qshake]

isntbard,

For me the staple of Prestressed Design is by Edward Nawy. You will find a good balance of theory and practicle applications in that text. Including complete treatment of losses.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[Isntbard]

Thanks Qshake,

I also found an article in the November/December 2002 PCI Journal.

Conspan does not calculate elastic shortening losses to prestressed beams when using transformed section properties. Leap bases this on the PCI Journal article. I’m not sure if this correct or not. Any comments?

 

[yakpol]

Isntbard,
It's an interesting subject: why no shortening losses calculated when transformed section properties are used. Not only LEAP but some other software companies are following same trend. I have not read the article, but it sure conflict with the common logic.

 

[Isntbard]

Thanks Yakpol. I agree that it is an interesting topic. I was hoping to find some justification for not including shortening losses when the transformed section is used but so far I have not found what I was looking for. For now I will continue putting in the losses.

The lack of responses also interests me. Is it because this is well known and obvious to most, or is it because people are just counting on the software to calculate losses?

 

[yakpol]

Isntbard,
Answering your first question. PCI Bridge Design Manual gives simple but precise method to determine elastic shortening losses in pretensioned beams. If you are interested to see let me know and I will scan the relevant pages.

yakov@yakpol.net