Florida Residential CMU Design

[Raspo]

I am new to Florida and to reinforced CMU design for residential construction.

Most of the CMU design references that I have on had refer to 48"oc vertical reinforcement spacing as a maximum. However, I see that that majority of the designs here have spacings beyond 48"oc reaching as far as 84"oc.

On top of that, I also do not see horizontal reinforcement as would be expected.

Are these walls being designed as Detailed Plain Masonry Shear Walls?

 

[boo1]

Consider looking at the ICC Consensus Committee on Hurricane Resistant Construction (IS-HRC) SSTD-1099 ch 205.3 free Download at:

http://www.iccsafe.org/cs/standards/is-hrc/SSTD10/index.html

See FBC download free at:

http://www.floridabuilding.org/BCISOld/bc/default.asp

http://www.dca.state.fl.us/fbc/thecode/supp_051006icc_corrected0806_eff.pdf

 

[Lion06]

I recently saw an ASCE Webinar that said you COULD use the bed joint reinforcing as the horizontal steel, but recommended against it. The speaker actually recommended using a bond beam every 4'. We spec Ivany block which allows for the passage of horizontal bars at whatever spacing you decide.

 

[UcfSE]

Your observations are typical for residential masonry walls. Most of the time these walls do not exceed 10 feet or so in height. For custom homes that isn't necessarily true. Joint reinforcement is not common for residential in FL so if you spec it or try to use it, it will likely get left out. The 84-inch spacing you mention might be a bit unusual since 84 is not a multiple of 8 (perhaps a typo or mistake?). The 48-inch max spacing is a rule of thumb used for commercial and is not applied to residential in most cases.

 

[ron9876]

I design masonry walls (I am in Florida) as reinforced masonry based on ACI 530. Joint reinforcement is placed at16" c/c. This meets meets the FBC.

 

[UCFKnights]

I've heard of this issue before but never had to deal with it personally. From what I recall your answers may be in the Residental volume of the florida building code.

 

[XXIcentury]

I have seen vertical reinforcement #3 Fy=60 ksi @ 16" or 24" and horizontal reinforcement @ 24" or 32" for typical residences for 6" and 8" thick CMU walls used for shear due to sismic conditions, however in Florida you'll only have to worry about hurricanes...

 

[boo1]

In the Florida residential market, reinforcement type 40 is all that I ever see used in the field (even if 60 is speced).