Composite beam without required concrete cover

[VA-Struct-Engr]

Hi Everyone,
We have an existing composite steel beam supporting a slab over composite metal deck. We have been asked to cut 1 1/2" (deep) x 6" (wide) of the concrete slab above the steel beam to accommodate a nanawall storefront system. Currently, we have 1-1/2" cover over the headed studs. If the slab is cut as requested, we will have 0" concrete cover above the headed studs. Per AISC 360-16 specs, section I3.2c.1(b), "...and there shall be at least 1/2 in of specified concrete cover above the top of the steel headed stud anchor."
My question is, if I don't have this required cover, should I assume a non-composite section (a safe assumption) or can I somehow justify a reduction in my composite section properties? The non-composite beam will have a large deflection and will need to be reinforced (cover plate with WT section at bottom flange), which I am hoping to reduce as much as possible.

Thanks for your help in advance.

 

[JoshPlumSE]

If the cut is six inches wide along the entire length of the beam, then yes, it would probably have to be considered non-composite.

But, not in the following cases:
1) The cut is NOT along the entire length. Then you've got a reduction in composite behavior, but not an end to it. Just fewer studs that you can count on. If that is the case, I'd only ignore the studs that were exposed.

2) It's not unheard of for the actual cover at the top of the slab to be greater than you think. Especially if the beam deflected a bit under the concrete pour, which is extremely common.

3) I've hear about engineers who have strengthened composite beams by shoring, chipping out the slab in certain areas and welding in extra studs. You could do that in regions closer to the supports. I'm sure other people have additional ideas about strengthening or retro-fitting composite beams.

 

[KootK]

I would be willing to consider the beam to still be composite for the sake of serviceability checks. You know, because it obviously will be.

 

[VA-Struct-Engr]

Thank you for your responses. I found some additional information from AISC.
In their FAQ section, in response to question: "What is the minimum concrete cover required above the head of a shear stud connector?"
AISC's response is "At one time, such a requirement did exist in the AISC Specification. However, the strength of a shear stud connector depends upon the strength of the connector itself and the cone of concrete under the head, not the concrete over it. Accordingly, the cover requirement was eliminated. The reader is cautioned, however, to allow sufficient slab thickness to accommodate possible variations in composite beam shape, such as that due to camber, which could otherwise cause shear stud connectors to protrude through the top of the slab."

This does not make a lot of sense to me, since even the latest AISC specifications (AISC 360-22) has the 1/2" cover requirement. Not sure what I am missing. Link to their FAQ is below for your reference.

https://www.aisc.org/steel-solutions-center/engineering-faqs/4.5.-composite-design/#28819

@JoshPlumSE, the cut is along ~80% of the beam span. I will try to get the client to reduce the cut depth to 1" max, that will solve the issue, but not sure if they will go along with this idea so want to cover all my bases before presenting them the options.