CMU Shear Walls (non-stacking/perforated)

[TonyES]

I've looked in the MDG and other masonry books and can't find a solid answer, maybe someone can help. Can cmu shear walls be non-stacking from floor to floor? All the examples and books I've read show a multi story cmu building with openings that stack from floor to floor, what happens if the architect is set on staggering the windows? Can I use the bond beam as a strut similar to a top plate in a wood framed building? Can the bond beam resist the moments?

Also, can we design perforated shear walls with masonry?
Would there be different answers if it was a rigid or flexible diaphragm?
Thank you.

 

[mudflaps]

Sounds like you have a Palm Springs architect on your hands. Anyway, a lot depends on how deep the masonry sills/lintels are. If they are deep enough to take the development length of the pier jamb bars and can take the resulting shear (up and down) then you have a fighting chance. The calcs are going to get messy unless you have a program for a perforated masonry or concrete wall. Plan checkers usually don't want to wade through a three inch high stack of fan fold computer output. They usually just lift up the stack and say "Seems about right". Then there's the plan checker. Just hope you get an "old" guy with lots of experience. Of course the out-of-plane design will be real nasty if you have offset windows on the same story height. Good luck.

Old CA SE

 

[JLNJ]

I don't believe that there is a requirement for openings to line up floor to floor. If it's also a bearing wall and your floor-to-floor heights are not generous, I'd think the large gravity forces in the jambs may give you fits were the openings offset. I have on occasion had to go to CIP conrete lintels due to the large shear forces.

If your question is asking if there can be an offset in the entire wall then you get into a whole other set of issues with plan irregularity, variable story stiffness and big forces to drag from one row to the next.

 

[concretemasonry]

A CMU wall is just a structural member just as a reinforced wall or precast segment is.

Usually, a CMU wall is much closer to a reinforced concrete wall because of the load distribution and load transfer to the other structural elements.

Since the structural behavior of masonry as very predictable, the vertical and horizontal loads are spread out in a orderly manner and can be analyzed. If additional reinforcement and grout are required at lower levels they can be easily and economically added. Obviously, full grouting without reinforcing being required is quite foolish and not structurally desired.

Dick