Here is a cable reinforced system for protecting a floor from collapse, via boing boing.

To test the cable system, Astaneh and his students built a full-scale typical building floor with five support columns in Berkeley's civil engineering test bay. The steel cables passed through one-inch holes in the columns and were affixed to the concrete model floor. In one test, a support column was knocked out and a massive hydraulic jack — the largest in the country — applied 240,000 pounds of downward force to simulate the weight of a floor above. The test floor dropped three feet, but stayed connected to the remaining columns that carried the extra weight.

Reserve Cal Day, April 12, for a talk by the leading researcher, A. Astaneh.