On first sight I must say that it looked really cool...
If I do this size of an installation again, I will consider stabilizing the bottom with poles, as I did to the top. I think that might help.
Though it doesn't have poles at the bottom now, I do think the double thickness of fabric at the bottom will hold the cable ties and that it should not rip through it this time.
This piece has been on exhibit since late September 2011. As much as I wish it hadn't of ripped in some areas, I am not upset about it. It's a good learning experience for me, and I expected some damage after having work outside over time. Some damage is much better than it being stolen, which happened to my work when it was on exhibit at another venue.
There is a history of art having wind problems on this site. It's an large open city block. A huge wooden piece also on exhibit blew over this past weekend, and last year, another artist's piece actually blew over the fence and down the block, and thankfully missed hitting people. What happened to mine is nothing in comparison and no one was at risk.