9/11 Reality

[skono4]

"The trend over the past half-century is to create lightweight high buildings. To do this you use thin steel bent bar truss construction instead of solid steel beams. To do this you use hollow tube steel bearing walls, and curved sheet steel (corrugated) under floors. To do this you eliminate as much concrete from the structure as you can and replace it with steel . Lightweight construction means economy. It means building more with less. If you reduce the structure’s mass you can build cheaper and builder higher. Unfortunately unprotected steel warps, melts, sags and collapses when heated to normal fire temperatures about 1100 to 1200 degrees F. "
http://vincentdunn.com/wtc.html