Currently I'm learning about concrete design. Concrete is an interesting material in that it is pretty good in compression for it's weight, but it can barely hold any tension by itself. This is where Rebar comes in. Rebar is short for Reinforcement Bars. What these do is they are placed in sections of concrete that would recieve tension forces. So this way most of the tension force is taken by the steel, and not the concrete.
One day my professor went off on a tangent. He was part of a crew to figure out what happened to the Murrah Federal Building (OK city bombing target).
In the process, he found out that the contractors were supposed to extend rebar through the columns, past the far end of the columns to just more then a foot past. But they didn't.
Had the contractors done this, the blast from the truck bomb would have destroyed the base column, but the building would not have collapsed.
The rebar and the concrete would have deflected a very large amount, but it would not have given out. Or at least it would have given sufficient time to evacuate the building.
This interesting fact is brought to you by PSU Architectural Engineering Department.
