# Minimum Reinforcement Ratio



## MOOK (Aug 8, 2010)

Minimum reinforcement ratio in masonry walls with single layer of steel

ƍ = As/(b.d) or

ƍ = As/(b.t)

b = width of wall, t = thickness of wall, d = t/2

In concrete there is no big difference in the two equations but in masonry there is big difference, so which one is the correct one?


----------



## MA_PE (Aug 9, 2010)

MOOK said:


> Minimum reinforcement ratio in masonry walls with single layer of steelƍ = As/(b.d) or
> 
> ƍ = As/(b.t)
> 
> ...


Wait a minute. Which minimum reinforcing, temperature and shrinkage steel or minimum reinforcing for flexure?

In concrete temperature and shrinkage is based on the gross area of concrete (b*t), but minimum flexural steel would be required to resist 1.2*cracking moment and subsequently would be based on d.

Sorry, I don't have a copy of the masonry code handy to see what they are looking for.


----------



## McEngr (Aug 9, 2010)

Keep in mind for shearwalls it is the length of the gross wall.


----------



## 20-20 (Aug 10, 2010)

MOOK said:


> Minimum reinforcement ratio in masonry walls with single layer of steelƍ = As/(b.d) or
> 
> ƍ = As/(b.t)
> 
> ...



I don't believe there are any minimum reinforcing requirements for flexural design of masonry. ACI 530-05 2.3.4, ASD reinforced masonry, simply states "axial and flexural tension shall be resisted entirely by steel reinforcement"

There are minimum provisions for seismic requirements provided in ACI 530-05 1.14.  These provisions are for the gross section wall properties, As/(bt)


----------



## P/S Designer (Aug 11, 2010)

MOOK said:


> Minimum reinforcement ratio in masonry walls with single layer of steelƍ = As/(b.d) or
> 
> ƍ = As/(b.t)
> 
> ...


ACI 530-05 section 2.33, page C-29 should give you the appropriate guidelines for masonry members in axial compression and flexure.


----------

