CMU stacked bond

[FSS]

I am working through the analysis of a two-story building where the architect has specified stacked bond (in lieu of normal running bond) for the cmu walls. I know about the increased horizontal reinforcement requirements in the cmu, but am having trouble locating how out-of-plane flexural design is affected.

Can anyone provide additional insight?

 

[JAE]

With running bond CMU and out-of-plane bending, you can space out your rebar and utilize a width of the face shell as a flange...sort of like designing a T beam with the core and web shells serving as the main body of the "beam" and the face shell on the compression side serving as the flange.

ACI 530 and other specs dictate how wide that flange width can be.

With stack bond, you have vertical joints every 16" (+/- depending on the actual block you use - but most are 16"). This creates a slip plane that limits the flange width to the 16". This will affect your design for flexure. For shear you still rely on the web core fully grouted.

For shearwalls (in-plane shear) there are also reductions in strength.