Shear design requirement

[JanMac]

Hi to all of you. Can I ask your suggestion and insights.

I have precast panel with cantilver beam at its end. The end of the cantilver ia loaded with beam perpindicular to it. It has cut out to sit the perpendicular beam and then grouted. My question is that the small cut out at the end of the cantilever, should it be considered or not as corbel and be designed as per aci corbel design reqt? Because aci has different approach for shear requirements for the corbel and for a normal element loaded with flexure and shear.
Please see attached photo.
Thank you in advance.

 

[Lomarandil]

I'd wait for a more informed opinion from one of the other posters here... but my gut feel vote would be for designing as a corbel (or at least strut and tie) given the proportions shown.

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The name is a long story -- just call me Lo.

 

[JanMac]

Thank you Lomarandil.If it is considered as corbel then horizontal stirrup is required instead of vertical. But in my opinion since the end cut out is far from the face of support which is the panel then it is not conaidered as corbel..yes maybe someone can give clarification on this..well just wait.thank you.

 

[BridgeSmith]

Seems like a perfect application for the strut and tie method. You have at least 2 potentially critical failure zones - one below the beam seat, which could be critical in shear or flexure (including a potential for reinforcement development issues), and a flexural limit at the edge of the rectangular panel. There may be more locations within the panel, depending on where the support/restraint is located. Assuming the ACI corbel requirements are stricter than for general design, I would consider the piece below the beam seat to be a corbel. That's not the place to try to skimp on steel.

 

[Settingsun]

Strut and tie, or design using step joint equations (also called dapped joint or half joint). It's quite common and there are empirical equations but it's also given as an example in many S&T books/guides.

Corbels are usually supported from beneath ie they cause compression in a column. You don't have that so need to deal with the step area differently than a corbel.