What exactly do you mean by withstand? Do you know what the failure strength of the rest of the components of the door (hinges, locks, etc.) are? Those are more likely to fail before the door itself yields.

You can get a reasonable estimate of the drag force on the door using simple fluid mechanics. The drag coefficient of a flat plate (which approximates a door) is about 1.98.

The equation for drag force is F=(C_d*p*V^2*A)/2
Where C_d is the drag coefficient
p is the density of air
V is the velocity of the air
A is the projected area of the door (in this case, the height*width, thickness isn't a factor for this approximation)

If you solve for V you can have an equation that takes into account all the factors you have, but you need some value for the failure strength of the aluminum door before you can get a maximum velocity.

Hope that helps.

Wow...I have a hard time believeing that an insurance company expects such information from a client...sort of strange! Nice of you to actually be helpful, excaza. You don't see much of that around here of late.