If there's no specification within your code one needs of necessity assume one is left the the science of construction. Hence you may use any reference that can deal with your case properly, short that the code explicitly forbids to open the holes.
I made some Mathcad worksheets some years ago dealing with holes in steel or composite simply supported beams that I made available from the Mathcad 2000 Collaboratory site at Mathsoft, from where you may download them out of the Civil Engineering folder.
If your web is too thin or whatever other rare thing, then go for applicable akin codes, surely you will find some way to tackle your problem.