Minimum Practical Concrete Slab Camber

[KootK]

What do we consider to be the minimum camber that can be specified without getting silly? Here's what I know:

1) I see default specs often with L/1000 specified as a minimum camber. This seems to lead to a lot of very small cambers (<8 mm).

2) The first clip below from structuremag suggests that cambers less than 6 mm (tolerance) should be ignored because contractors will just ignore them since 6 mm is less than tolerance. Of course that's not how tolerances should be used but that's another thread.

3) The second clip below from ACI 302.1 seems to suggest that 1/2" is the lower bound camber. This is consistent with what I've been doing in practice.

So, what do we like for a minimum camber?

For what it's worth, I'm not a fan of camber in general and try to avoid it whenever possible.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[SlideRuleEra]

Sorry, irrelevant content deleted.

 

[sandman21]

I think KootK is talking more about concrete slab/beams. I was taught that 1/2" is when you start to consider camber over additional reinforcing.

For steel beams current firm is a rebel and will spec cambers of 1/2".

 

[DETstru]

KootK, I'm in agreement on 1/2" being the lower bound. I don't have any references but this is what I hear from concrete subs.

As you said, I only use it when I absolutely need to.

 

[KootK]

Thanks for the feedback gentlemen. And I was indeed referring to cast in place concrete slabs as opposed to steel. Sorry I didn't clarify that from the get go.

I was taught that 1/2" is when you start to consider camber over additional reinforcing.

To clarify, do you mean:

1) When specified camber would be 1/2" or greater, you consider using it rather than adding reinforcing or;

2) When long term defelection exceeds 1/2", you start to consider using camber rather than adding reinforcing?

I'm fairly certain that you mean #1 but I want to be sure.



I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[sandman21]

Long term deflections