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Hooked Beam Bars in CMU Lintels

Hooked Beam Bars in CMU Lintels

Hooked Beam Bars in CMU Lintels

(OP)
I recently stumbled upon a great set of CMU details produced by an authority on masonry. One of the details surprised me however. See below. I was shocked to see the bottom rebar detailed with the hook facing downwards. I was taught that the inside bend of the hook should always be oriented such that it containw whatever compression strut occurs naturally in the member. In this case, that would lead one to turn the hook upward. Certainly, that's what I'd expect to see in a concrete beam. Is it the end of the world to have the hook pointed the wrong way? Probably not. But still, why not do it right given the choice?

The only explanation that I can think of is constructability. Is it exceedingly difficult to place a bar with end hooks facing upwards in a fresh course of masonry? Would they just flop over to one side or the other?

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

RE: Hooked Beam Bars in CMU Lintels

I guess if you had a cold joint in the wall right above the lintel then this would make more sense so the bars don't cross the cold joint.

Maine EIT, Civil/Structural.

RE: Hooked Beam Bars in CMU Lintels

It would be more constructable as shown due to gravity as you described. When all the cores are filled, I don't think the bar orientation makes much difference strengthwise.

RE: Hooked Beam Bars in CMU Lintels

I doubt that it makes a significant difference. I have never been terribly concerned about the orientation of the hook. Perhaps you should upload these nice details to your fellow engineers....pretty please

RE: Hooked Beam Bars in CMU Lintels

(OP)
You got it: Link. I was pleasantly surprised. 43 respectable details.

In this scenario, turning the hook down will result in a compressive strut that emanates from the inside corner of the hook and heads down and to the right towards the door jamb free edge. It becomes an anchorage issue of sorts as the compressive strut wants to pop out the side of the jamb masonry. That never actually seems to happen but that's the theory.

My main intent with this thread is really the constructability question. When I show hooked bars in my masonry details, should I always show them facing down no matter what the situation is? If I really, really want them pointed up, can I expect that to actually materialize?

Thank you for your responses so far.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

RE: Hooked Beam Bars in CMU Lintels

I think in general if your compressive strut isn't an issue then the detail should show it hooked down. That's the way the mason wants to install it, and he's bitching that you are showing it facing up.

Then if the odd detail in your drawing set shows them facing up it's easy to argue that there is a reason. Instead of just showing all of them up.

RE: Hooked Beam Bars in CMU Lintels

I would think you never see failures because the bottom bar is developed for general building integrity, and not actual demand of the bar at that location. The direction of hook depends largely on how the mason grouts the wall.

RE: Hooked Beam Bars in CMU Lintels

KootK,

On rereading, I want to amend my comment. The hook orientation does matter as you pointed out. I was looking at the picture with 24" embedment AND a hook. With just a hook in, say the first core, the hook should turn up.

RE: Hooked Beam Bars in CMU Lintels

I don't think there is much wrong with that detail. I have rarely seen more than 2 cores grout-filled to make the jamb. This detail has it bar anchored into the third core past the opening.

Thanks for the details.

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