For anyone wanting to go metal arch here is a good choice for bending an arch
http://www.buildmyowngreenhouse.com/hightunnelbenders5999.aspx
http://www.buildmyowngreenhouse.com/hightunnelbenders5999.aspx
I am looking to make an arch over my driveway for this years display. I am wondering if anyone on here has done that and they they used to build it?
The driveway is slightly wider than a standard double wide and is about 30'-35' long.
I think once built I will use either LED string lights or LED net lights and multiple channels, probably 6-10 channels.
First, a question: is your 30-35 foot "span" the diameter, or the circumference? I think you mean diameter. I am at 33.5 foot circumference, and I am borderline 1 1/4" PVC. If your PVC thickness is too big for a given arch length, that stresses out the couplers and they snap (which is highly catastrophic). You've got to hammer in the PVC into the couplers real good. But if your PVC is too thin (e.g. 1/2"), as you know it's wobbly. If your 30-35 feet is strictly for the diameter, you would be at 1 1/4" minimum; possibly 1 1/2". And you'll need probably 2 or 3 guys to set it up.
I have tried any and all trusses to stabilize the base--mostly because I'm in the middle of a parking lot and I have 200 cars driving through. If you have access to grass on both ends, I would be okay simply relying on 4 guy wires, and affixing the PVC to 2-foot rebar on the ends. Actually, I would sleeve 3/4" PVC over the rebar, hammer in the 3/4" into the ground as well (which is not much...), then sleeving the 1 1/4" PVC over that.
OTOH, if your arch is THAT big, you will probably want to hang stuff on top of it. That zenith is way high, >20 feet in the air. If you want to hang stuff, then the guy wires alone aren't going to cut it in the wind. For that, I use a combination of cross couplers and right-angle couplers at the ends. You just need a system of PVC at the base to form a wider base, to resist the swaying motion in the wind. I'd have to draw it out.
No, the large size of the arch actually means you DON'T stress the PVC. At 40 feet, that means you only have to bend a 1 1/4" PVC 45 degrees over the span of 10 feet. It can handle that, no problem (more importantly, the PVC couplers can handle that). You can try it with a single 10' section.
My bigger concern is actually having to get up on a ladder. Also the guy lines have to go out quite a ways. If you have access to metalworking, you can lose the guy lines, but it sounds like neither of us have access to that.