I plan to build a shade structure over my deck, and wish to keep the deck open; i.e. I wish to use posts only at the edges.

The problem is that I have a rather large span to cross:

23 foot Joist Span.

8 foot Beam Span.

6x6 Posts (10 foot high).

To top it off, it might hold a little snow.

Assuming worst case, I attempted to use the deck tables; however, the Beam Size table doesn't support these large sizes.

How do I go about caclulating the required material?

How about alternatives? I would consider aluminum I-Beams, but I'm not sure where to start with this.

Any help would be appreciated.

-bf