If you mean wide flange shapes (W sections), they're in part 2 of the AISC "Manual of Steel Construction." If you really mean "I-beams" which are now called S-shapes, there's not any load span tables in AISC. This is because I beams are typically used for monorails and it would be unusual and inefficient to use them as load carrying members.
But if you really need to determine what an "I" beam can do the material properties are in the first part of the code and you can calculate them based on the properties and the requirements in the commentary and specs. I used to have to check them frequently on an older building i worked on.
