Foundation reinforcement extension

[structural87]

Hello

What is your common practise of extending reinforcement foundation rebars? Do you use the same bars extension defined in chapter 13 the aci and consider the foundation as an inverted slab?
In other words do you extend your bottom reinforcement 0.3/0.33 of the span and the top reinforcement 15cm inside the support or just extend as per the analysis requirement ?
Thank you

 

[atrizzy]

I assume you're referring to a large foundation with multiple column and/or wall loads bearing on it such that both positive and negative moments exist. In this case I would provide a full extent top mat and bottom mat to cover temperature reinforcing and basic strength requirements. Extra bars are then provided in locations where the temp reinf mats are insufficient.

 

[structural87]

Yes of course. I do always provide shrinkage and temperature reinforcement all over.. I was asking about the extra bars needed extension. Forgot to mention it in my initial post !

 

[atrizzy]

Seems to me that if there exist full mats, top and bottom, additional rebar can be simply placed as per analysis/development requirements and disregarding the detailing measures typically implemented for suspended slabs and beams (staggering, extending into support, column strip rebar, etc). Those detailing measures are important for slabs and beams since typically they define where the reinforcing "ends". With continuous T&B mats, the reinforcing doesn't really "end".

At least that's how I think about it.

 

[structural87]

Thank you atrizzy.
Any other opinions or thoughts to share ?