Amy's starting off the new year with a bang! Or maybe it's more like a boom.
Have you ever seen a building implosion? On December 8, 1996, two high-rise towers in Philadelphia, Pennsylvania, came tumbling and crumbling down. City officials called them the longest-standing vacant public housing high-rises in the country. Thanks to the well-planned placement of 350 pounds of dynamite, the Schuylkill Falls Apartments no longer stand.
Implosion has become the popular method for removing unwanted buildings from a city's skyline. Philadelphia, Detroit, Connecticut, and Las Vegas are just a few cities to have imploded buildings recently.
How do engineers learn about implosions? Practice. Each implosion offers new insight into the process. The secret to a good implosion is to use only the minimum amount of explosive and let gravity do the rest. An implosion relies upon dynamite, a well-known EX-plosive, but only in small amounts.
For example, the Schuylkill Falls Towers, two sixteen story buildings, needed only 350 pounds of dynamite, strategically placed, to crumble. First, the supporting columns of the structure were drilled with small holes. On the first and second stories, each column had five holes drilled. On the fourth and sixth floors, each column had three holes drilled. Then, about one-third of a pound of dynamite was pocketed into each hole. The dynamite was rigged with an electronic blasting cap. Then, the holes were plugged with clay or sand to keep the blasting device in place. The supportiong column was then surrounded with a wire meshing to keep the concrete pieces from blasting outward.
Each electronic blasting cap had its own built-in time delay. By positioning different blasting caps with different delays in different locations, you can "control" the explosion. All of the blasting caps were then wired to a "blasting machine," a control box for charging and blasting the system.
When ready, the engineer charged the system and then "blasted" the building. The first explosives helped to guide the building down. Subsequent charges destroyed the rest of the supporting columns. The series of "blasts" lasted for six seconds. Two seconds later, the building was completely imploded, mostly by its own weight.
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This isn't the first time that Amy has investigated an "implosive event." Take a look at the archives and see Amy's very first online investigation: Can Crusher.
Follow along with Amy's ongoing Lichen investigation.
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