Shear Transfer into Masonry Walls with Sloped Joist Seats

[Guastavino]

I have a load bearing masonry building where I planned to transfer diaphragm shears through the joist seats. Problem is that my loads are greater than the rollover capacity as recommended by vulcraft in their "Designing with Vulcraft" book. I'm curious if there are any references where providing masonry infill between joist seats has been used successfully (4-5" of infill based on 4-5" seat). Intuitively it makes sense that it would work, in that the joist seat would transfer load to the CMU infill. But, I'd like there to be some published study and/or research to reference.

Also, I'm totally fine with using misc. steel such as a channel or tube to weld to the deck edge angle and then connect it to the top of the masonry. My only issue with that is that since the joist seats are sloped, I'm concerned about fit-up in the field. IE, the joist seats differ from what I specify and my misc. steel doesn't fit.

Any thoughts?

Thank you!

PS - I saw a similar thread I would have responded to but it was closed

 

[mike20793]

I use channels or angles to match the depth of the joist seats on all my masonry load bearing wall buildings. I just dimension the joist bearing plates so that I can get at least 2 inches of weld on each end. Usually that is enough to take the diaphragm shear, but you could increase the length of the weld if needed.

 

[mike20793]

If your worried about fit up, you could use a bent plate? What slope do the joists have?

 

[Guastavino]

Thanks Mike!

It's about 3/8" per foot, so not a lot. My concern with the slope is more that the joist folks will provide seats that vary just enough to make fit up difficult. IE, if I spec 4" joist seats, they might provide 4.25" or 4.5" and then my 4" channel won't touch my edge angle (my deck supporting edge angle will be supported by joist seat). Does that make sense

 

[jayrod12]

They are rarely off on joist seat depth.

That's what shop drawing review is for. And their shop construction tolerances of OWSJ are pretty tight.

 

[Hokie93]

If you haven't already done so, you might want to inquire with joist manufacturer as to whether strengthening and/or stiffening the joist seat is a feasible option. Joist seat rollover capacity is typically limited by deflection so stiffening the seat would provide a greater capacity. It would also eliminate your fit-up concerns with the miscellaneous steel.