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11-18-2009 My Curved-Roof Kayak Shed
Having built the grid shell/curved space frame roof structure I of course had to do something with it. One can't just leave these things sitting in the driveway. The neighbors start to get upset. So after much pondering I decided the easiest thing would be to create a little shed for the kayaks. With a lot of help from the family, and after a spectacular failure on the first erection attempt, it now sits happily protecting the kayaks.
9-7-2009 Adding Roofing to the Grid Shell / Curved Space Frame
With lots of help from my son Robin we finished cutting and attaching the triangles to the roof frame yesterday. The approach I'd figured out for cutting the triangles worked beautifully. It is a bit tedious but it creates triangles that fit perfectly on their triangular frames. OK, not perfectly, but well within the tolerances needed. Following are four images. One taken at the start, one with just one triangle left, one with all the triangles attached, and one shot of the underside.
If I were to make more of these I would want a better solution for the hubs. My current thinking is that short sections of steel pipe would be a good replacement for the PVC pipe sections. However, to use steel pipe some sort of joist hanger is needed to hang the beams from the pipe. The following two images illustrate what I have in mind. If you happen to know of any such product please send along the information.
Looking Down from Top
Looking Up from the Bottom
8-26-2009 Curved Space Frames Using SketchUp
I spent a fair amount of time this summer thinking about curved space frames, a topic near and dear to my heart. My goal is to have a framing system that will support building highly curved roofs. I had what I believe is a bit of breakthrough a few weeks ago. Up to now I've been thinking of the framing system as being basically a shell. The breakthrough was the realization that by giving the curved framing significant depth -either via a truss system or just through deep joists- that the roof framing becomes much stronger and a number of other issues related to the edges get resolved nicely.
Throughout my exploration of this subject I've used SketchUp to investigate ideas and to design models to test. The models in the image below have been the basis for most of my experimentation.
The two straw and pipe cleaner models in the next two images helped me develop the idea of a curved space frame.
These led me to realize that I could take a curved TIN dome-like surface and give it depth as shown in the next image.
Note the diagonals on many of the joists. It was while playing with this model that I realized I could just use deep joists instead of trusses.
The final piece I needed to fall into place to actually build this structure was a reasonably easy to create and use hub. It popped into my head that a section of 2" PVC pipe might do the trick. Some experimentation confirmed that the PVC pipe was strong enough for a prototype.
I next had to figure out how to incorporate the pipe hubs into the SketchUp model. Strong SketchUp skills proved very helpful for this task and I was able to solve this problem fairly quickly. The following images show my approach, and hint at the large number of measurements that need to be taken off the SketchUp model.
With the model, some PVC hubs, 1x6 pine joists, and a bunch of drywall screws I was able to create the structure shown in the images below.
The prototype frame is finished and came out quite well given all the things I had to figure out while constructing it.
While constructing the frame I kept thinking there has to be an easier way and I have an idea for a connector -basically a joist hanger that would hang down from the upper edge of the vertical pipe section- which I believe would make building these much easier.
The frame is very strong. I weigh 200 lbs and can stand on top of it and there is no perceivable deflection. There is definitely some potential here for creating highly-curved roofing structures.
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