Reply #148: Ever heard of resistance?

[Ezlivin]

Remember that you had tons of sound structural steel below the point of impact that was completely undamaged by the incident.

Why did this sound structure suddenly give way to the weight above, especially since it was designed for a load at least three (3) times as great? It offered no resistance to the falling mass. What one would expect to see is the falling mass being progressively slowed as it slammed into one intact floor after another. Instead we see that the existing structure offered apparently no resistance whatsoever.

Another thought experiment for you. Have you seen those collapsing highway safety devices? They are designed to absorb the impact of a moving vehicle and by progressively collapsing (in an accordion-like fashion) they arrest the forward velocity of a vehicle. Viewed in slow motion the first segment of the "accordion" appears to offer little resistance. However, each successive section slows the vehicle just a bit more so that by the end of all the segments the vehicle has completely stopped. Even though the "accordion" is nothing more than a series of plastic segments and the vehicle is a multi-ton mass of metal moving at speed it manages to halt the vehicle.

Even in spectacular fires, structural steel buildings have never exhibited a total top-to-bottom collapse.