Tacoma Narrows Bridge

Tacoma Narrows bridge % tangent 16 Taylor s series 32-34 tests of series convergence 35-36 thermodynamics applications 56-57, 81 first law 38-39 Jacobian notation 160-161 systems of constant composition 38 three-dimensional harmonic oscillator 125-128... 

When a fluid flows past a bluff body, the wake downstream will form rows of vortices that shed continuously from each side of the body as illustated in Figure 4.16. These repeating patterns of swirling vorticies are referred to as Karman vortex streets named after the fluid dynamicist Theodore von Karman. Vortex shedding is a common flow phenomenon that causes car antennas to vibrate at certain wind speeds and also lead to the collapse of the famous Tacoma Narrows Bridge in 1940. Each time a vortex is shed from the bluff body it creates a sideways force causing the body to vibrate. The frequency of vibration is linearly proportional to the velocity of the approching fluid stream and is independent of the fluid density. 

Amman, A. Y., tal, The failure of the Tacoma Narrows Bridge, Federal Works Agency, Washington D.C., March 1941. 

This is what happens when things shake themseives apart , most famousiy the Tacoma Narrows bridge. 

On November 7,1940, 42-mile-per-hour winds twisted the Tacoma Narrows Bridge and caused its collapse. The bridge, with a suspension span of 2,800 feet, had been completed just four months earlier. Steel girders meant to support the bridge were blocking the wind, causing it to sway and eventually collapse. 

The towing last July of the first 14,000-ton (12,700-tonne) Tacoma Narrows Bridge caisson to its moored position at the east end of Puget Sound was a historic sight witnessed by hundreds of people. What they didn t see, however, was the mooring system that restrained the caisson and its west-end counterpart until they took their underwater positions 60 to 70 feet (18 to 21 meters) below the Narrows mud tine. 

The fundamental feature of all engineering hypotheses is that they state, implicitly if not explicitly, that a designed structure will not fail if it is used as intended. Engineering failures may then be viewed as disproved hypotheses. Thus, the failure of the Hyatt Regency elevated walkways disproved the hypothesis that those skywalks could support the number of people on them at the time of the collapse the failure of the Tacoma Narrows Bridge dis-... 

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