A Rentangular Tanks Design - Rebar for direct tension in wall

[KOJUNGMO]

Hello

Another simple question that I wonder is

PCA Example No.1 they mentioned about "Steel required for direct tension in long wall"

Steel required : [A][/s]=[N][/u]/(0.9 X [f][/y])

Where does this formula come from?

I've found "ACI 350-06 Clause 11.7.4 Shear-friction design method"
Those two are similiar but not same.

Would you give me a reference for the PCA design?

 

[JedClampett]

ACI has very little guidance on direct tension. So I'm not sure if or where that formula is. But since using .9*fy is pretty standard for the tension in bending members and for shear friction, it's commonly assumed that it can be used in tension members.
Just make sure Nu has all the proper factors on it and your laps are conservative.

 

[joengineering]

Hello,

Anyone have the PCA on pdf?

JO

 

[KOJUNGMO]

To JedClampett
I agreed with your reply. However, I found a similar formula that could be used in this case.
If you have ACI 350 then look into Clause 11.7.4(Shear-friction design method).
ACI 318 - 11.6.4(Shear-friction design method).

But there is "mu - coefficient of friction".

So I'd like to re-ask you whether this section(clause) could be applied to my case.

 

[hokie66]

Direct tension is an entirely different thing than direct shear, so you should not confuse the two.

 

[KootK]

Second Hokie's comment. I've been using 0.75 as my phi factor for direct tension. In my jurisdiction, that's the number used for ties in strut and tie models. I see parallels there and like the extra conservatism given the usual lack of redundancy in such members. A while back, we had a lengthy discussion here on splice requirements for direct tension members. I'll see if I can dig that up.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

 

[KootK]

This thread: Link

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

 

[KOJUNGMO]

To Hookie66
Thanks and I agree with you.
But would you tell me some reference for direct tension
Of course that formula can be derivated from simple engineering thought
"Tension will be resisted by reinforcement."
But there's a phi factor and I can't find reference.
And do you ageee with that direct tension should be considered in this
Tank wall design?
To sum up
1. Reference for the PCA FORMULA for the Direct tension?
2. Should Direct tension be applied to tank wall design?

 

[KOJUNGMO]

To kootK
Thanks! I'll look through it.

 

[KootK]

I'm no tank design expert but I wonder if your design ought not be governed by crack control.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.