Friday, June 6, 2008

November 16th 2006

Bellevue A Liebherr 420 (US designation) tower crane collapsed in Bellevue Washington outside of Seattle. The falling crane struck three other buildings including the apartment of Mathew Ammon killing Mr. Ammon.

The crane was on a designed base structure that can be found here.

The base did not maintain the crane in a plumb condition of 1:500 or a tolerance of 1 inch out of plumb for every 40 feet of vertical elevation. There were multiple points of failure that eggheads will debate for quite some time, but the beam ripped due to metal fatigue, a weld failed, and the crane was outside of tolerances for plumb. Everything else is academic and about making money.

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