Reinforced Masonry Design

[SteelPE]

I have a general question about masonry design (which is really dumb).

I am referencing ACI 530-08 equation 2-23 (fv=V/bd). I am wondering what is the appropriate value to use for the bd in the equation. Say I have a 20’ long 8” wall that is grouted at 40” o.c. do I use bd = 7.625*20*12 or do I figure an 8” wall grouted 40” o.c. has an equivalent area of 58.3 square inches per foot so bd = 58.3*20?

The equation, while intuitive, isn’t written that well in my opinion.

 

[msquared48]

For the appropriate shear area and effective weight use the "equivalent solid thickness" of the CMU based on the filled cells.

That value can be found in Table B-3a, page 278 of the Reinforced Masonry Handbook by Amrhein.

Mike McCann, PE, SE (WA)

 

[UcfSE]

I use the net cross-sectional area from NCMA TEK 14-01B

 

[SteelPE]

That is what I thought, but it is just not written well in the equation and then the definition lists b as "width of section".

 

[mike20793]

Agree with UcfSE, use the NCMA TEK paper to get the effective section properties.