Hook of columns or piles

[geo321]

Hi.
Regarding the hook of end column reinforcement(roof floor) or other member (pile reinforcement developed in a pile cap), does it matter if it is inwards or outwards the column or pile (as long as the minimum development length is respected) ?
thank u

 

[Ron]

Conventionally...to the inside. Fundamentally, it makes no difference.

 

[KootK]

I'll disagree with Ron on this one.

In the regions in which I've practiced, the usual practice is to turn the hooks outwards. It promotes constuctability. It makes footing dowel cages more stable and it makes it so that the hooks don't interfere with the pouring of concrete into vertical elements.

I feel that the direction of the hook has a huge impact on the fundamental behaviour. Bars hooked outwards are developed but usually not anchored.. Vertical bars in tension are usually in tension due to applied moments. In such cases, the goal of the vertical reinforcing in the joint is to anchor the compression strut emanating from the other side of the member (flexural compression block). As a result hooks in make the most mechanical sense.

In general, good practice is for hooks to always face the compression struts that they are meant to constrain.

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.

 

[ooox]

My experience for columns is the builder will always prefer to have the hook end or cog bent to the inside - that way they can drop the formwork tube over the top.