Collar joint between cmu and brick grouted solid

[WWTEng]

I am working on a small project where we are replacing an old concrete stair with a few one. The existing landing appears to sitting on a wall that is 8"cmu+4" brick with about 1" of solid grout joint (no air space). The landing is sitting only on brick. I am wondering if I could also use the brick. I always try to avoid attaching to brick veneer which an air space behind it. But since this existing wall has a grouted solid joint, could I consider the brick to be part of the load bearing system and not just a veneer?

 

[concretemasonry]

Based on your description, it seems the be a 2 wythe wall composed of a CMU and brick with a full collar joint to provide shear transfer of loads. It seems that the landing loads are on the 4" brick, but they can be distributed as you go down.

The vertical shear between the wythes should be distributed. Even though the books usually do not state it as fact, even joint reinforcement (tab system), if used, provides some comfort for a belt and suspenders analysis.

ACI 530 provides some good information on multi-wythe wall behavior, especially in the commentary section.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[hokie66]

Depending on the height of the supporting brickwork, I might want to ensure that the brick is tied to the block. If not, you could retrofit ties.

 

[WWTEng]

CM, thanks. "it seems the be a 2 wythe wall" is the prefect description.

Hokie, I'll have to address that too. Good suggestion.

 

[WWTEng]

BTW, I can't remember the last time I had to worry about concrete slab bearing because typically its always at least 8" with the items I had to deal with so far. Here it seems that I'll have 4" bearing. I am not sure if that's enough.

 

[hokie66]

As it is a stair landing, so thus only a short span, I think 4" should suffice. Think about the bearing lengths commonly used for precast stuff.