Deep Beam or Wall?

[WpgKarl]

I have a question regarding the design approach for cast in place concrete walls...

Lets say you have a 10 ft deep (high) continuous wall, which sits on piles spaced at 10 ft o/c (therefore it is a deep beam by defn). Wall receives vertical loads (applied to top of wall) from the load bearing masonry walls and hollowcore slabs on the upper levels.

Are vertical stirrups req'd for shear for this "wall", or are vertical bars (no stirrup hooks) in each face adequate? I almost never see consultants using vertical stirrups in walls, but the way I read the code they should be used??

 

[msquared48]

Based on the triangle theory of load application to a CMU lintel beam, the wall is not seeing much load that it has to transfer to the piling through beam shear. Chances are, considering the volume of concrete in the wall, that vertical hooked stirrups will not be required. Good thought to check though.

Mike McCann
McCann Engineering

 

[miecz]

If the shear exceeds V_c, then stirrups are required. Keep in mind that 11.1.3.1 allows sections located less than d from a support to be designed for the shear at distance d from the support. In your case, that would include all of the beam.

 

[civilperson]

This analysis is suitable for strut and tie analysis and design, (similar to deep beam). Use ACI 318 (10.2.2 and Appendix A)

 

[hokie66]

Agree with civilperson. Make sure your tie reinforcement is well anchored at the bottom corners.