CMU Wall Vertical Reinforcement Termination into Bond Beam

[Deadblow]

Hello All,

I have a quick question. I am designing a concrete masonry unit wall to span vertically between the floor slab and the roof diaphragm. My design requires that the wall be reinforced vertically with #4 rebar at 3'-4" on center. I have a continuous horizontal bond beam at the roof diaphragm. Is it required that the vertical wall reinforcement shall be terminated into the bond beam with standard hooks? I guess if I want the bar to be fully developed, the answer is yes. I'm just curious if this is a typical means of construction in the U.S and if it is required. I couldn't find it to be necessarily required by the 2015 IBC.

Thanks

EIT

 

[KootK]

I see where you're coming from but I, personally, have not been hooking the bars. Looked at in detail, I think that you'd abandon the notion of full development past the underside of the bond beam and, instead, develop the bars for the expected tensile demand at that location like we can in concrete when you anchor positive reinforcement.. Given the low moment at the top of the wall, I'm sure that would work fine. So maybe just a 6" straight embedment.

In the interest of full disclosure: I've not been providing hooks OR checking this in any explicit way.

 

[EZBuilding]

Agreed with KootK.

For masonry walls which experience out of plane wind pressures only I have considered the required embedment as a function of the shear loads only and provisions of ACI for development of positive reinforcement. In a similar consideration, I have never seen exterior masonry walls consider continuity across supports for the purposes of deflection or strength calculations.

Masonry shear walls which experience in plane wind loads are a different story.

 

[Deadblow]

Ok, thank you both for your input! I appreciate it.

EIT

 

[msquared48]

I have always specified the hooks as the bars are shear reinforcing, whether from vertical loads or from in plane shear wall loads.

Just a habit by default...

Mike McCann, PE, SE (WA)

 

[WARose]

Is it required that the vertical wall reinforcement shall be terminated into the bond beam with standard hooks?

I typically do. (In fact I typically hook around the bond beam horizontal reinforcement with 180 degree hooks.) Since you are going to the roof.....it might help transfer the uplift forces (from wind).