Question about Pile Cap Footing Design

The Area is reduced linearly. For example, at the end of development length(ld), rebar is fully developed and so 100% Ast-provided is available. At a location X' from the end of rebar, which is < development lengh, Aeff will be ( X * Rebar area / ld).

The Development length is designed based on AASHTO article 5.11.2 and the AsT/b eff is calculated as follows.

Example: At any location, if development length is 4' and location is 1'

The Ast/b eff = Ast_provided* (1’ or 2’) /4.

Ast_eff = Ast min (L/ld , 1)

Hi, Dear Vanay,

Thank you for your quick answer. I have one further question, please help. :D

My pile cap footing size is 19' by 29'. In the table, the flexure check locations are +/- 3.74', so they are sections in the middle of the footing (around the column). The reinforcement in the middle of the footing is far away from the footing edge and they should be fully developed, right?

Thanks,
Dong

Yes you are right the should be fully developed and I don't see any red flags in the screen shot you had attached along with your question.

Hi, Dear Vinay,

You are right there is no flag, but the effective reinforcement area is not equal to provided reinforcement area in the middle of the footing. My understanding is in the middle of the footing, the effective reinforcement area should be qual to provided reinforcement area since there is no development length issue.

Let me show you another example here. This is a 19'X19' footing. The flexure check location is +/- 3.29'. I think the "Asb_eff" should equal to "Asb_prv". I think I may miss something here, but I could not find it.

 

Thanks,

Dong

 

Its very difficult for me to figure out where the problem is just by seeing the screenshot. There is a possibility of Minimum reinforcement criteria or rebar spacing criteria not being met as per AASHTO requirement.
Please email me the File to this email ID Vinay.Mysore@Bentley.com