You are supposed to think about your preconceptions, rather than just go back to the well for another link.
Could you show your expertise in structural engineering, since that is so frakking important to you? I am willing to bet that you have no science education or experience whatsover. You put great credence in the "experts" on the truther sites, but summarily dismiss the overwhelming amount of evidence contradicting those. Anyone can google up alternate explanations for WTC7 and for every single damn piece of "evidence" on the truthers' sites.
I would be surprised if you are a high school graduate (but schools are very poor at teaching how to analyze thought, so I wouldn't discount the possibility). Hell, we just found out that our federal science minister doesn't believe in science, so anything is possible.
If the theory makes sense, then you check to see if all available evidence supports it (and you look at all evidence, and not just that which supports the theory).
If the theory makes no sense whatsoever in the real world, one normally looks at other (and better) explanations for the evidence, and starts formulating a different theory.