I have a existing (precast) reinforced concrete beam that was connected to a girder by placing it on a ledge. (There is a formed shear key as well.) Apparently, after the placement, a floor was poured.....that essentially made it a t-beam. The slab is tied to the girder by top & bottom reinforcement.

By my model, some shear is attempting to transfer by shear stress in the slab (as you would expect) to the girder. But the "web"/precast part can take all the shear. So I am wondering: can I ignore the shear from the slab attempting to "help" in the transfer? My gut instinct is: "no". Go with the model. By any shear flow calculation, you'd get some shear.....no doubt. But I wonder if there is a loophole in code somewhere I am forgetting.

In case you are wondering about sizes: the precast beam is 4'x2', and the slab is 1' thick. Thanks.