Minneapolis I35 Bridge Collapse

Originally posted by Palynka
My fair lady.

Was a hot day there...combine metal expansion with with the construction work on the bridge joints and....?

A survivor of the bridge said they felt is swaying/shaking just before it collapsed. It might have been that putting the cars into only one lane allowed pumping of the bridges natural frequency. I guess someone might still be to blame for not thinking of that, or maybe not.

For anyone who hasn't seen what can happen to a bridge when it's natural frequency is hit, you've got to go to youtube and type in "Tacoma Narrows" for the famous 1940 film of the wildly swaying Tacoma Narrows Bridge collapse. The original newsreel narrarator took some artistic license with "the motorist only had seconds to save himself!" and with all the added sounds of terrible wind. The wind was blowing at about 35-45 miles per hour, and the resonance had the bridge forming a transverse wave with an amplitude of 28 feet. yikes! The bridge was oscillating for a few hours like that, which is why a camera was able to get to the site to film this marvel, and why most of the bystanders are just walking around calmly.

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I'll be returning to the Minneapolis/St. Paul area in a month. My college is about seven or eight miles away from the bridge, so I'll definitely check it out.

Originally posted by Doctor Rat
A survivor of the bridge said they felt is swaying/shaking just before it collapsed. It might have been that putting the cars into only one lane allowed pumping of the bridges natural frequency. I guess someone might still be to blame for not thinking of that, or maybe not.

For anyone who hasn't seen what can happen to a bridge when it's natural frequ ...[text shortened]... o film this marvel, and why most of the bystanders are just walking around calmly.

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