Steel beam for deck
I want to build a 40 x 16 dec off the front of my house and have as much room underneath to enter the garage. I would like to get away with using only 2 posts if I can and this is what I am hoping will work. The deck is 10 feet high and I am planning on using a 6 inch piece of steel well casing as the posts with a 40 foot steel I beam resting on top for the joists. The deck is 16 feet deep and am going to put the beam at the 12 foot mark and cantilever 4 feet using 2 x 10 joists 16 inch on center. Is this possible and if so, how thick an I beam should I use? Being that it is steel and thick joists should I still worry about bracing between the posts and the beam?