Free Essay On Tacoma Bridge Disaster
Tacoma Narrows Bridge was the third longest bridge in the world. It was situated in Washington State. The bridge was constructed between Tacoma and Kitsap Peninsula. Barely four months after it was opened to traffic in 1940 had the Tacoma Bridge collapsed. This pointed out to serious engineering flaws that characterized the construction of the bridge. The initial works at the bridge commenced in 1938. During windy conditions, the deck started moving vertically. Efforts to stop the movement did not succeed, leading to its eventual collapse on November 7, 1940. The initial Tacoma Bridge was built with girders of carbon steel. The steels were held firmly in big concrete blocks. The earlier designs consisted of open lattice beam trusses beneath the roadbed.
The initial designs allowed wind to pass freely below them via the truss. However, the new design was made in such a way that the wind would be diverted either above it or below the structure. Consequently, the bride buckled during windy days, causing severe vibrations. The vibrations led to uneven movement of the central plan and caused cars to rise and fall over the span. During this time, the mass of the bridge was considered sufficient to support the weight of the cars on it. The bridge’s failure finally occurred because of a strange twisting mode following the movement of the wind. The wind was moving at 64km/hr and caused a torsional vibration mode. This resulted in the unusual movement of the bridge in which the left side went down as the right side rose and vice versa. While these movements continued, the center of the road was not affected by the movements (aeroelastic fluttering).