Aluminium Busbar joints & supports

At present we make bolted connections by drilling holes in busbars but some manufacturers (elsteel, rittal,cubic,modis etc) promote busbar joints without drilling holes in busbar.
What i can make from their catalogues is they follow 2 or more busbar/ phase, use u type clamps along with 8.8 grade bolts, bellivile washer & plain heavy washer. Similarly they are constructing busbar supports using them. Kindly refer to the below mentioned file for some application photos.

http://uploading.com/files/79d29839/BUSBAR%2BJOINT%2B%2526%2BSUPPORTS.doc/

In this case my apprehensions : the contact area is greatly reduced, steel bolt passing through busbar & use of sheet steel/stainless steel clamps (which is a different material as compared to conductor therefore different expansion coefficient, especially if we consider using this method for supporting busbar.).

Is this method feasible, what should be the clamp material, thickness, bolt material. Does the fact of lower area of contact is countered by higher joint pressure.

Kindly help to clarify.