ACI 318-19 - 25.4.3 "Development of standard hooks in tension" - Defintions of Terms

[Illbay]

The definitions of some terms in this section, provisions for "Development of standard hooks in tension," seem unusually complicated. Usually, ACI does a fair job of including accompanying illustrations or diagrams to help understand how physical parameters are defined, but in this case it seems to me a word-salad.

You have for example, the parameters A_sh, A_hs, A_th, and b_c, all of which contribute in various ways to determine the factor Ψ_r, which accounts for "confining reinforcement."

I realize that one could simply use the conservative value of 1.6 for Ψ_r, and let the rest go, but I'm trying to create a general design aid and it would be convenient to be able to accurately account for special circumstances for which Ψ_r may be set equal to 1.0. I'd like to understand how to interpret these.

Could anyone point me to a paper, treatise, or other resource that explains the definitions for these parameters more clearly than ACI 318-19 does?


"No one is completely useless. He can always serve as a bad example." --My Dad ca. 1975

 

[dauwerda]

Chapter 2 of ACI 318 provides definitions for all (most) of the notations used.

A_th = total cross-sectional area of ties or stirrups confining hooked bars, in²

A_sh = total cross-sectional area of transverse reinforcement, including crossties, within spacing s and perpendicular to dimension b_c, in²

A_hs = total cross-sectional area of hooked or headed bars being developed at a critical section, in²

b_c = cross-sectional dimension of member core measured to the outside edges of the transverse reinforcement composing area A_sh, in

 

[Illbay]

dauwerda, that was not my question. I am fully aware of the written definitions you have copied here - and if you noticed, I described them as "word salad."

Let me try again, perhaps I'll be more clear this time. I would like to see diagrammatic examples of these definitions, to help illustrate their meaning.

For example, b_c is stated to be "meassured to the outside edges of the tranverse reinforcement componsing are A_sh". What does that mean exactly? And what if you don't have crossties? What if you are looking at a floor slab, for example? How does this definition apply?

"No one is completely useless. He can always serve as a bad example." --My Dad ca. 1975

 

[dauwerda]

Maybe Figure R18.7.5.2 will help?:

 

[HTURKAK]

Copy and paste of definition of bc ( ACI 318-14)

bc =cross-sectional dimension of member core measured to the outside edges of the transverse reinforcement composing area Ash, in.

Acc. to Figure R18.7.5.2 ( Mr dauwerda posted )

- Transverse reinforcement formula is Ash/sbc

- For Transverse reinforcement parallel to long side (Ash2) use bc2 at expression Ash/sbc ( and there are 3 legs )

- For Transverse reinforcement parallel to short side (Ash1) use bc1 at expression Ash/sbc ( and there are 4 legs )








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