Dead loads, a 20 psf roof live load, and wind loads (uplift and lateral) are always applicable. Depending on the location and nature of the project, seismic and snow loads might also control in the design. [tt][/tt]Might also want to consider some sort of impact loading from a vehicle running into it as well.
Unless you have a senior civil/structural engineer who regularly engages in the design of carports who can directly oversee your design of such a structure, including MLFRS, C&C w/r to trib's, ASCE 7-10(or 16) open structure criteria, all wind load cases, yes Up! and down, including unbalanced loading, proprietary detailing for cantilever construction, sure of your redundancy factors, ability (possibly structural design software) to analyze many different load combinations, in well 4 different directions, minimum welding sizes with respect to materials/grades/electrodes, ACI 318 App D anchorage, the list goes on, I would highly recommend to defer this design to another engineering firm. IMHO
With regards to vehicle impact,...put it in the drilled pier. Which you have,....yes?
But seriously, don't let this be your first carport without direct, within area of practice (say carports) senior mentor-ship. Again IMHO,...others will disagree. Higher a guy who's done it,....give him your fee (plus some more because you didn't charge enough, we never do), pay careful attention to his calcs, hopefully they are stellar, and then do the next one yourself. Again IMHO. Have a super day!