Does angle of hook extension matter? 2

[ScratchyFilm]

Typically we hook extensions parallel to the force that is affecting them. Once the hook development length is reached, does it matter in which direction the extension is relative to the direction of loading? In my mind, tension is tension and shouldn't matter directionally.

Assume red arrow is the direction of loading in this example.

 

[phamENG]

If it's resisting moment, then you want the hook extending into the compression zone to improve confinement around the hook - tests have shown that not doing so reduces the strength of the joint to less than calculated values. If it's pure tension...then no, it shouldn't matter as long as you have proper cover, etc. everywhere.

 

[ScratchyFilm]

That's an interesting point. I just pulled up an image for sake of discussion - would you say the hook should be flipped around in this example to keep in the compression part of the footing?

 

[phamENG]

There is compression coming down from the face of the retaining wall. That compression will confine the hook if it faces into the toe as originally detailed. Not talking about the compression face of the footing.

 

[ScratchyFilm]

I see what you mean. Thanks for clarifying.

 

[KootK]

The principles that inform the detailing of the moment/retaining wall condition are discussed in detail here.

For moment resisting joints, it's important to recognize that what you've been calling a "hook" isn't really a hook in the code sense. A hook, in the codes sense, is a device used to speed the development of the reinforcement requiring that development. For moment resisting connections, what we're really dealing with is a bar bend designed to transfer rebar tension around a corner. Viewed in this light, it becomes apparent that the rebar ought to be detailed such that it restrains and incoming compression strut as shown below.