WALL MINIMUM SHEAR REINFORCEMENT 1

[lutein]

I am designing a restrained retaining wall, the out of plane shear, Vu, due to soil lateral load, are more than 2x larger than Phi*Vc, in other words -
Vu > Phi*Vc/2

Per ACI 11.5.5.1, minmum shear reinforcement is not required in slabs, footings, or beams with total depth note greater than 10", 2.5xthickness of flanges, or 0.5xwidth of web, ...

How about wall? Since I am designing the retaining wall as flexural beam behavior, and if the wall thickness is less than 10", it should not be bound by ACI 11.5.5.1 - Minimum shear Reinforcement, is this correct?

I would really appreciate your valuable input on this. I hope you could shed somelights to this matter.

Thank you in advance.

 

[JAE]

Out-of-plane wall designs are similar to slabs. The [Φ]Vc / 2 requirement doesn't apply.

 

[WillisV]

Agree with JAE.

 

[scottiesei]

ACI318-02
Section 14.3 and 11.10

 

[scottiesei]

11.10.1 - "Design of shear forces perpendicular to face of wall shall be in accordance with provisions for SLABS in 11.12."

 

[lutein]

Thank you all for giving these valuable input. By studying all replies, here is my conclusion:

Per 11.10.1, shear perpendicular to wall is similar to slab design because out of plane shear is beam action, which refers to 11.12.
11.12 refers back to 11.1 thru 11.5
11.5.5.1 specifies minmum shear reinforcement is NOT required in slabs, footings, or beams with total depth note greater than 10", 2.5xthickness of flanges, or 0.5xwidth of web, ...
My understanding is out of plane shear is a beam action, so, if the wall thickness is less than 10", then it is not entitled to minimum reinf.

Please correct me if I am wrong
Thanks

 

[scottiesei]

I don't totally agree....see section 14.31, 14.3.2 and 14.3.3.

 

[lutein]

I am sorry for I did not clarify the question better, I am designing a retaining wall.

Scottiesei, I thought 14.3.1 to 14.3.3 is addressing in plan shear.

For out of plane shear, the shear reinforcement is cross ties. Please correct me if I am wrong.

 

[scottiesei]

I was just thinking of min. reinf. in general. I agree with your approach for out of plane shear. But the design is a wall. See 14.1.2, they discuss "cantilever retaining walls" and require min. horizontal stl. per 14.3.3. Your vertical steel would obviously be by design. Out of plane shear in slabs, footings and walls is typically handled by depth of the section, not by adding reinforcement. Even though your design is restrained, I would still think that you need the min. horizontal reinforcement.

 

[lutein]

I totally agree with you.
Thanks for your help.