ACI 318-11 Section 11.4.6

[tvar]

A question has come up in our design of a cut and cover subway station. Can walls be exempt from minimum shear reinforcement requirements of section 11.4.6 even though not specifically mentioned in the exemptions? Some say no because they are not specifically mentioned, however they are similar to slabs and footings mentioned in exemption (a) except vertical. They have the same two way action and loads can be shared between weak and strong areas.

 

[JAE]

See if this makes sense:

1. Section 11.9 applies to walls.
2. Section 11.9.1 states that walls with shear perpendicular to the face be designed per 11.11
3. Section 11.11 is the provision for slabs & footings.
4. Section 11.11 refers to applying 11.4 for shear.
5. Section 11.11.3.1 requires you to determine Vs (if needed per Eq. 11-2) from section 11.4

From the above it appears that the ACI logical flow would suggest that walls are to be designed similar to slabs and footings and thus 11.4.6 would apply.

However, having said all that, I always thought that the reason you were exempt was not because the slab or footing was able to distribute loads around but rather that these elements are most always situated on top of soil and thus pose a lower risk of catastrophic collapse that can occur via shear failure in more elevated structural elements.



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