Bond Beam Req's

[engreg]

I am designing a small (20x30) 10 foot high square CMU building. Risk Cat 1, Seismic Design Cat C. I was planning on using running bond with ladder reinforcing @ 16" and a bond beam at the top of the 10 foot wall. To me that seemed plenty and meets code, then a colleague told me they use bond beams @ 4' o.c as a rule of thumb, and I found some similar opinions on the internet. I am pretty sure this negates the need for the horizontal reinforcing at 16", so with the ladder ties, the bond beam at the top should be fine, can anyone confirm or add their theory on bond beam design.

 

[phamENG]

4' on center was the standard for a long time, but as we've sharpened our collective pencils on masonry design, it's not really needed. It came from a couple things: the need for horizontal reinforcement, and the fact that you'd only do 4' lifts of grout anyway. So it made sense to stop every 4 feet, put in your bars, and grout.

Now, we have high lift grout procedures and the effectiveness of joint reinforcement is more widely accepted.

In short: you're good with joint reinforcement and a bond beam at the top as long as everything checks out.

Caveat: not sure of specific seismic requirements. I haven't done a masonry building above SDC B.