Greenhouses, Sheds and Sun Rooms - Curved ramp for shed

I am about 1/2 finished with a relatively large "shed"...it's 16' x 20' with a wood joist floor and concrete pier foundation (12 of them). I was required to get a permit to build it, and the inspectors made me adhere to the 12" distance from grade to the bottom of any girders. On this site, that means the floor of the shed in the front is about 48" off the ground. ANYWAY, I'm building among some fairly large trees that we want to keep, and to avoid some trees and to make an interesting effect, I'd like to make the access ramp to the shed curved. I'm thinking of making it about 18' long, and the curve would end up between 30 and 45 degrees from straight (I hope that makes sense). Of course, if the ramp were straight I would build a frame underneath the ramp of, say, 2x6's on edge and put some boards across the frame and...voila! I'd like to do the same or similar for a curved ramp. Anybody have any ideas about how to curve the frame members OTHER THAN bent lamination, steam bending, or kerf bending? If no other idea, which of the above 3 do you think would be better? Kerf bending seems easiest, but I fear that it would weaken the frame member significantly. If the choice were between bent lamination or steam bending, I'll use bent lamination on cedar or redwood (if I can find any). Any ideas would be much appreciated.

I would build the frame for your ramp as a series of short straight sections that approximate the curve you want. Then put down the deck boards letting them overhang the frame, then cut your gentle curve in them.