1. IntroductionThis memo is a failure analysis report on the Tacoma Narrows Bridge. The bridge collapsed on November 7, 1940 just over four months after it opened to the public on July 1, 1940 (Green, 2006). The only victims (good word??) of the bridge collapse were journalist Leonard Coatsworth's car and dog. Bridge design and failure will be discussed, as well as new suspension bridge design methods.2. Failure Description Other similar bridges constructed such as the Golden Gate Bridge in San Francisco can have vertical sway with amplitudes of up to 2 feet and horizontal sway of up to 6 feet during severe wind storms (Levy, 1992). Due to sway visible in other similarly constructed bridges, sway was expected in the Tacoma Narrows Bridge. However, the extent of the oscillations experienced by the bridge and the time it took for the bridge to damp them were of concern to the engineers involved. The time it took for the Tacoma Narrows Bridge to dampen its oscillations was different from that of other similarly constructed suspension bridges, namely the Golden Gate Bridge, whose oscillations were quickly damped due to its larger width-to-span ratio. (connecting sentence needed) Shortly before the bridge's total failure, the oscillations changed from their normal vertical and horizontal motion to a violent twisting motion, this twisting motion, which reached nearly 45°, was what caused it to collapse the bridge. After a momentary pause in movement, the twisting began again and the bridge began to crack, starting with the smaller suspension cables connecting the bridge deck and the 2 large main support cables. Broken suspender cables meant that nothing was holding up that part of the bridge deck and it created...... middle of paper ......and stiffening trusses could have been used instead of solid stiffening beams to allow more air flow and reduced wind resistance (Levy, 1992). Furthermore the system would have to be damped to ensure that its resonant frequency cannot be duplicated in nature and create a positive feedback loop, and to ensure that any oscillations that occur are quickly slowed down. Works Cited Farquharson, F. B. (1940). The collapse of the Tacoma narrows the bridge. The Scientific Monthly, 51(6), 574-578.Goller, R.R. (1965). The legacy of the "galloping gertie". Civil Engineering, 35(10), 50.Green, D., & Unruh, W.G. (2006). The Tacoma Bridge Failure: A Physical Model.74(8), Retrieved February 23, 2010, from http://scitation.aip.org/journals/doc/AJPIAS-ft/vol_74/iss_8/706_1.html.Levy, M. (1992). Gertie galloping. WHY BUILDINGS WALL (pp. 109). New York: W. W. Norton.