There is a great article in "Handy" magazine this month about how to build a curved deck. But I believe you need to be a member of the Handyman Club of America. I can tell you that they trimmed the outside fascia of the deck with a strip of 5/16" exterior plywood. They said to soak the plywood in water for about an hour to help with the bending. To frame the deck, it looks like they leave the joists long, and then apply bracing between the joists to create the curve. Then they trim the joists to length at the curve line.