"How about using Hydrogen filled ballons with a graphite cable run up the center? You wouldn't have to worry about wind, birds, or airplanes, and you could get the hydrogen in situ."

This sort of idea could work better on Earth, where you could use Hydrogen to create bouyancy or partially buoyant structures. If you are thinking of using the pressure of hydrogen gas, you would essentially transferring a compressional load into a tensional load- there might be some value in that if you dealing with materials with high tensional strength- such as composite/carbon fiber. Other than that, it gets a bit too complicated for me to fiqure out- though in my wanderings, I did briefly wonder what the compressive strength of hydrogen metal was:). I was thinking of making the cones hollow- same vacuum as on the Moon. That idea gets a bit weird, so thought I would leave that to another post.