Jul

13

Tacoma narrows bridgeAs an engineer, it is indeed fascinating that even after all of this time, and with enormously sophisticated computer tools, there is still contention as to what caused the Tacoma Bridge to fail.

I don’t think this is a shortcoming of modern engineering; rather it underscores just how darned complicated these systems can be, how many ways in which they can interact with themselves, other structures, and the environment, and how difficult it can be to plan for every possible occurrence, while still keeping cost, schedule, and original design intent within reason.

Perhaps one of most interesting observations of all, however, about the Tacoma disaster, is one that never was: there has not subsequently been a bridge failure that spectacular since. Thus, even without computers, Wiki, massively online resources, or even a pocket calculator, the engineers of the day managed to figure out what not to do in subsequent bridge designs to avoid such failure in the future. That, to me, is incredibly impressive.

It would have been nice to corner one or two of those folks and get their thoughts on what they think happened.

-Jon

Jon Longtin, Ph.D.

Associate Professor and Undergraduate Program Director

Department of Mechanical Engineering

SUNY Stony Brook

Stefan Jovanovich adds:

One of the rent-a-faculty members who was allowed to teach structures for a semester at the school of Architecture at Harvard in the early/mid-60s had been an ironworker in his youth. He showed us the footage of Galloping Gertie's spectacular collapse and then told us a story. He said that he had known two men who worked on the Tacoma Narrows, and they had both told him that the thing was going to be a lemon because the bridge deck "had too little steel in it". The point of the lecture, from our teacher's point of view, was that we future architects might want to solicit the opinions of the people who will actually build our perfectly imagined castles in air.

The Bronx-Whitestone Bridge in NY was cast from the same mold as the Tacoma Narrows. Its web site has a picture of the original bridge deck and the retrofit made at the Tacoma Narrows collapse when Warren Trusses were added. The Wikipedia web site for Othmar Ammann says that the trusses have been removed and replaced with fairings to solve "the wind problem". (Can the New Yorkers confirm whether or not this is true?)


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