Hooks for single mat footing , cantilever beam 4

[Penpendrum]

is it required for a single mat footing to be hook at the ends of the Rebar?

I have seen some engineers practice those kind of procedure. . but is it really required?

and also is it required to hook all top bars of the cantilever beam at the tip of it?

 

[canwesteng]

Longitudinal bar should be developped beyond where it is required for moment when it is needed to resist shear... Depends on your loading but generally the bars should be hooked. In CSA A23, two ways of checking if the longitudinal bar is required to resist shear is to model the area via strut and tie methods, or check the tension demand on the bar via cl. 11.3.9.2 if you are using the sectional method. ACI should be the same but I don't know the clauses.

 

[KootK]

is it required for a single mat footing to be hook at the ends of the Rebar?

I would say that there is not a theoretical need for the hooks unless there is concentrated load of some sort at the edge of the footing that creates a condition whereby flexural demand for than rebar grows faster than the rebar is developed without the hook. Maybe a column or wall at the footing edge. This tends to be somewhat of a regional thing. In some parts of the world, footing reinforcement gets hooked all the time as a matter of perceived good practice.

and also is it required to hook all top bars of the cantilever beam at the tip of it?

Almost the same answer. In theory, you could omit the hooks if the cantilever load is purely uniform (no concentrated load at the tip). In this instance, however, it's been my experience that everyone, in all parts of the world, chooses to hook the top bars as a matter of good practice.

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.

 

[hokie66]

It is good practice to hook cantilever beam and slab bars. Bars in spread footings are cantilevered slab bars, so the same logic applies. The hooks may not always be working hard, but standard practice should prevail.

 

[JAE]

We don't usually hook footing bars.

On mat foundations we don't either unless the load is directly at the edge of the mat. Most times for buried vaults with mat base slabs our mat extends out from the exterior face of the wall enough that the bars don't need hooks along the edge.

For cantilevered structural beams and columns we do typically hook at the edge.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[Penpendrum]

Thankyou for your help everyone..