I think you are mistaken on a number of points...
1. The analysis is only for relatively small loads. The numbers show that - they are in newtons - so a load of 100kg. No slamming into the ground here.
2. The tensions at 4 and 8o'clock are small beer - not "snapping" tensions at all. They may be for you gross distortion scenario, I don't know, but not for the analysis in the OP. The numbers are merely 3-4kg of weight hanging from a spoke - almost infinitely far from "snapping" tension.
3. Spokes do not snap from excessive tension. For that they are too ductile. No, they snap from metal fatigue due to thousands of times of small bendings to and fro at the spoke elbow as the tension relaxes a bit when the spokes go through BDC. This develops metal fatigue - micro cracks which propagate and eventually the spoke hangs by a thread, so to speak, then only a small amount of excess elbow flexing will make it go, such as when you hit a bump. For a spoke to snap from tension like you are thinking of, it will rip the nipple thread right out before it pulls a neck and finally gives. You can safely put that scenario completely away from you.
Last edited by jur; 02-16-09 at 06:05 AM.