Stack Bond Masonry Design

[pioneer09]

Due to previous construction, I am stuck with stack bond. I have been looking at past threads and trying to research the design of stack bond masonry for both in-plane and out-plane loading. When looking at stress design, the compression width in a nut shell is based on if there are horizontal bond beams at 48" oc or less. If taking the strength design approach, I do not see any talk of having horizontal bond beams. I assume this horizontal bond beam requirement is so the wall acts together like running bond construction.

So if no horizontal bond beams are used, is it correct to assume:

1. Out of plane design is based only on a single block length; b=15.625".


For in-plane design I am at a loss, seems as if horizontal bed reinforcing would not be enough to transfer load. Any thoughts?

 

[mike20793]

Yes, if you don't have bond beams, your effective width is limited to the head joint, so one block length. In plane design does assume that your horizontal joint reinforcement is sufficient to transfer the load. It's important to note that the ladder reinforcement can be used as long as you meet the minimum reinforcement prescriptive requirement, but the commentary in the masonry code notes that bond beams are the only effective way to transfer load across the head joints. I always include the bond beams when I have a shear wall. If it's just a bearing wall, I just design it based on one block effective width and forego the bond beams.