Long Term Deflection

• Jun 12, 2019

• #2

Settingsun

Structural

Aug 25, 2013

1,513

AU

I can't post the calculation here but there's a similar calculation in the book 'Time-Dependent Behaviour of Concrete Structures' (Gilbert & Ranzi, 2011) - section 3.6.6. The formula for Ief is the same as AS3600 but the calculation of Mcr is slightly different. Gilbert & Ranzi use a Beta factor from Eurocodes rather than the Sigma,cs from AS3600.

Gilbert & Ranzi also don't use the long-term multiplier; they calculate the creep and shrinkage deflections separately and take account of the actual creep and shrinkage parameters of the particular concrete mix.

 

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• Jun 12, 2019

• #3

Settingsun

Structural

Aug 25, 2013

1,513

AU

Here you go:

https://www.sciencedirect.com/science/article/pii/S1877705811011258

(Download Full Text button at top of page)

This uses the Beta factor instead of Sigma,cs as I mentioned in the previous post, but it should be easy enough for you to substitute Sigma,cs if you want to. Beta is a simpler calculation though.

This also calculates the shrinkage and creep deflections using a rational method whereas AS3600's 'kcs' factor is really rough (but far simpler). If you want to use kcs, just multiply the instantaneous deflection by kcs. kcs is only for reinforced concrete though; you need a rational method for prestressed members.

 

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• Jun 12, 2019

• Thread starter
• #4

Lily_Linton

Civil/Environmental

Nov 23, 2017

21

HK

This is a great help

Thank you very much!

 

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• Jun 13, 2019

• #5

Trenno

Structural

Feb 5, 2014

831

AU

I'd suggest you do a search of this forum for further discussion on the use of the crude "kcs" factor.

 

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