Read these posts Joker you may learn something.
Your windshield bolt got me thinking about the sheer strength of a bolt. Tensile strength is the force need to stretch a material lengthwise until it breaks, sheer strength it the force required perpendicular, to the length to sheer it sideways. Imagine the bolting system in the WTC. Even Jokers picutres show 3 beam segment bolted togather at the top and bottom, and laterally braced by the floor segments. These bolts were designed for vertical holding of the loads and swaying in the wind, so they probably had very high tensile strength bolts, like heattreated high carbon, or other added elements to make them strong and hard.
This also increases the sheer strength, which sheer normally is considered the sheer strength of static loads simply hanging. Not shock loads. If you have ever watched a punch press they sheer the metal in a very fast impact, and the material is well backed up, so it can not move or shift, consequently the entire impact load, is dedicated to sheering the material. In the WTC, the weight of the building downward provided complete backing and bracing of the material(the beams), and they could not move any appreciable amount, or fast enough, plus they are preloaded. If 2 football players on a line were pushing each other, the stonger will prevail, if one of the has a second player behind him holding and bracing him, what would that do? When the airplane hit, the beams preloaded and braced, with noplace to move, all the force was on the sheering of the bolts, just like a punch press.
Imagine bolting plates of 60.000 PSI steel togather, with 1" bolts on the corners of 100,000 psi tensile strength. Now imagine that you placed the holes leaving only 1/2" from the edge of the steel place. The vertical static load would be sufficient to all hold it togather. Impact that with a load perpenticular to vertical, and the weaked link will probably be the narrow span of material to the edge of the plate. The edge of teh plates would probably be first to sheer. Its not hard to see that when the plane hit, the airplane did not bounce off, it penitrated the building, and the pictures show the beams all were what sheered. You can clearly see 3 beam segments sheered off level in the picture at the blot line, meaning the first implace sheered the bolts and/or plates.
2 solid objects of that weight plus volocity crashing togather, the weakest link was the bolting system, had nothing to do with Aluminum vs steel, everyone watched it live Joker.