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.

Not many codes deal with holes very well, some exclude it because it is too hard, others take a conservative route. The Australian codes are fairly vague and really leave the solution up in the air.

The best way is to return to the basic theory, work out the stresses and then work out how much stiffening the web will need to overcome the stresses. Generally this may end up as longitudinal stiffening and conjunction with web stiffeners.

I'm not familiar with Roarks, but I would be surprised if there isn't some form of solution in it.

Good luck
sc

The second volume of AISC's Design Guide series covers Beams with Web Openings.  It is available on their website, www.aisc.org.

the are several papers that deal with this topic in the ASCE Journals, I think the first ones started being published around the late 1960's