Long Term Deflection

[Lily_Linton]

Hi all experts,

Could you give me any sample calculation involving long term deflection using AS 3600-2018?
Its different from 2009 and that of 2009 is almost the same with ACI.

I know the code for Ief seems direct and easy for all of you but I would appreciate if there's any sample on it?


Thank you very much

 

[Settingsun]

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.

 

[Settingsun]

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.

 

[Lily_Linton]

This is a great help

Thank you very much!

 

[Trenno]

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