Bending Pilaster to Footing Detail 1

[Yao1989]

Hello fellow structural engineers, I have some concrete detailing questions.

I read from a post previously (

http://www.eng-tips.com/viewthread.cfm?qid=284040)

that when designing retaining walls connecting the back footing, the dowels should be turned towards the inside (still feels counter-intuitive).
By that logic, does it mean that when I design a column on footing that is expected to resist large moment, the dowels would have to turn to face each other as well?

Also second question, what rebar should be considered effective in the footing? see picture below.

 

[KootK]

Let's speak of two different cases:

1) What is the theoretically correct thing to be done?

You've pretty much nailed it. The hooks should face inwards. And, surely, the bars nearest the pier would tend to be more effective in flexure. An interesting, analogous condition is that of a roof slab in a concrete building. It's basically the same joint turned upside down. Many designers will consider this joint pinned for some or all aspects of design due to the inability of conventional detailing to transfer moment. If you can access a copy, there's some excellent information here: ACI 352.1R-11: Guide for Design of Slab-Column Connections in Monolithic Concrete Structures

2) What do most of our peers do?

Most folks will turn the hooks outwards and not worry about how much of the footing is effective in flexure. They will do the following and assume the joint to be properly designed:

a) Ensure that the vertical bars are tension developed into the footing.

b) Check the footing for eccentric punching shear.

Based on the proportions, perhaps you could get away without the footing and just use the pier as a laterally loaded pile (Brohm's method design etc).



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.