Thursday, February 26, 2009

The first Tacoma Narrows Bridge was revolutionary in its design and historic in its collapse. The failure on November 7, 1940 marked the end of a trend in bridge engineering towards a maximum of lightness, grace and flexibility. Since the turn of the century, suspension bridge construction valued structural grace and slenderness to achieve an artistic appearance. With its shallow stiffening trusses and slender towers, the bridge across the Narrows was the epitome of artistry in bridge construction.

The Tacoma Narrows Bridge was known for its tendency to sway in windstorms. The shape of the bridge was much like that of an aircraft wing and under windy conditions it would generate sufficient lift and become unstable. On November 7, 1940 a large windstorm caused severe and catastrophic failure if the bridge deck.

The significance of the first Tacoma Narrows Bridge, to a large extent, is derived from its startling collapse on November 7, 1940. The collapse brought engineers world-wide to the realization that aerodynamic phenomena in suspension bridges were not adequately understood in the profession nor had they been addressed in this design. New research was necessary to understand and predict these forces. The official investigation into the collapse recommended the use of wind-tunnel tests to aid in the design of the second Tacoma Narrows Bridge and resulted in the testing of all existing and future bridges across the country. New mathematical theories of vibration, aerodynamics, wave phenomena, and harmonics as they apply to bridge design arose from these studies.

The collapse of the Tacoma Narrows Bridge was a hallmark in the history of bridge design and civil engineering. The remains, located on the bottom of the Sound, are a permanent record of man's capacity to build structures without fully understanding the implications of the design and the forces of nature.

Jasley was here @
5:05 PM