Standard Steel and Aluminium Profile Dimensions

buy yourself the handbook of steel construction

I am not sure of a website but there are a few good books that would help you out:

http://www.amazon.ca/s/ref=nb_ss_gw?url=search-alias%3Daps&field-keywords=aluminum+structural

Check out the Mech-Q plug-in for Auto Cad. Quite a bit of standard info on beams, C, angles, etc. Will also do some connection details and sizing for you. Also piping, ductwork, Perlins, bearings and the like. There is a free trial down-load. Check it out. http://www.asvic.com.au:80/products.asp?category=1&nav=

But in the end, get yourself a good set of ref. books starting with a used copy of AISC "Manual of Steel Construction" (I have 7th. edition 1973) No I am not dating myself, it was the cheapest available when I went to school.

I have a book named "Shapes and Plates", free from one of the steel producers. (I don't have it with me at the moment and don't recall which one). Check with your steel supplier or look for literature at the steel manufacturer's web sites.

The Aluminum Association has a lot of free literature, including cross section data on extruded structural sections.

The manufacturers sites are good places to look, companies like Baco have information on standard sections.

A word of caution, we don't know what you are designing but, just because you see a suitable section in a catalogue it does not necessarily mean that you can easily buy it. If for instance you pick on an extrusion which is not commonly used you might find that you have to buy a ton lot. Check with distributors to see what sections they keep, especially if you are not expecting to use a lot of it.