I would like to build a monkey-bar/playground structure in my backyard. It's not your standard monkeybars, but I made a 3D visualization at staktrace.com/pub/structure.html if that helps. I'm planning to buy steel tubing (1.25" or 1.5" diameter) and getting a welder to assemble it. However I'm trying to figure out the best way to actually attach it to the ground.
My plan was to dig a 2.5' hole for each post, fill in 6" of gravel, put the post in on top, and pour concrete to fill the hole. After reading some of the info on this website I'm wondering if burying 2' of a 9' or 10' post is going to be enough. In terms of "load" on the structure it's going to need to hold maybe two people swinging around (let's say 500lbs). Also given that the posts are all going to be welded together using crossbars at the top I feel like it should be pretty stable already so I shouldn't have to go that deep.
Also I've never done stuff with concrete before so I have some general questions about that.
So my questions:
- Given the nature and intended use of this structure, how much of the post should be buried if I want the "ceiling" bars to be 7' off the ground?
- What diameter should the hole be?
- Would it be better to weld the structure first and then attach it into the ground? Or install the posts first and then weld the rest of it to the posts?
Any other advice or recommendations are also welcome.
[Edited to add: in terms of weather, this is southern ontario so it has to deal with +30 to -30 degrees C and everything in between]