Securing a Carport
I'd recommend checking with your building department to determine what your footing/foundation requirements are. You may have a minimum frost depth (depth below ground so that cold weather does not affect foundation). They may also be able to tell or describe to you how these are typically constructed in your area. Building department is always an excellent source of information and guidance (at least in my area). They may be able to let you know if you have any setback issues (required distance from property lines to structures).
I do not know what building code you are under, what your frost depth is if any, what your ground snow load requirement is, or basic wind speed so I can only speak in generalities.
I agree with oh'mike, I'd be using concrete piers set into the ground with a stand-off post base anchored into the pier. I don't know what a pin driven 2-feet into the ground would do to resist wind loads. Around here we'd typically use a 10" or 12" sonotube (round tube that's filled with concrete) set to our frost depth (48" depth in Massachusetts). Size of footing is based upon actual loads and soil bearing capacity.
Stop and think about the construction. Your columns act as a lever. If you want to lift something heavy you can stick a lever over your fulcrum under it and use the mechanical advantage to move the object. A force applied at the top is increased at the bottom. You have to have something to resist these forces. In your case wind blows against the roof (like a sail on a boat). these forces are transferred from the roof through the columns to the ground. If not designed and built properly you'll have issues, and no one wants that for you.
You may want to consider hiring an engineer. If you need a building permit typically you need drawings. The engineer would prepare the construction drawings that would not only get you your permit but explain the proper construction. Doing it correctly the first time what you want so it would be money well spent.
Hope this helps! Good luck!
"You get what you pay for, and sometimes free costs more!"
Last edited by GBrackins; 02-11-2013 at 07:14 PM.