Given my wind speed (155mph ult.) and seismic zone (D2) I am probably looking at some serious holdowns at the first level (HDU 11). I would have to run the numbers but it would probably work. I would probably also sheath it with 5/8" plywood inside and out for some serious shearwall action, at least on the the first two floors. I would probably also frame the first two floor with DF No.2 2x8 studs or 2x6 studs at 12" o/c. I'm thinking spiral staircases between levels to save as much floor space as possible and to make it more interesting. Minimal windows on the first three levels and then the top level would have a lot of windows for the view. 11-7/8 TJI 210 for the floors with 3/4 sheathing T&G, 16" o/c.
The structure is 16'x16' with grade to top plate height of 38'8".
The roof is 6:12 pyramid hip with 2x8 rafters, I may go with a steeper pitch though.
On a structure like this overturning is a serious threat, I would need to check the dead weight of the structure and see if the seismic or wind forces could potentially lift the foundation right out of the ground. I think the solution would be to to increase the dead weight of the structure especially at the base, by upsizing the footing and stemwall. You will notice my stemwall is 10" thick, 36" deep and a 24"x12" footing, even this may not be enough. I'm also thinking about some larger spread footings at the corners where the shearwall studs drop down.
Anyone design something goofy like this before. I don't know if my county building dept. would give it an approval though even if its engineered (stamped).
A confused student is a good student.
Nathaniel P. Wilkerson, PE