On the morning of november 7, 1940 shortly after 10 a.m., a critical event occurred. The cable band at mid-span on the north cable slipped. This allowed the cable to separate into two unequal segments. That contributed to the change from vertical (up-and-down) to torsional (twisting) movement of the bridge deck.
What Happen to the Tacoma Narrows Bridge? Explain Why It Happen.
The Tacoma Narrows Bridge, also known as Galloping Gertie, was a suspension bridge in Pierce County, Washington. Built by the Washington State Department of Transportation in the late 1930s, the bridge was the third-longest suspension bridge in the world at the time of its opening. But due to an unfortunate design flaw, the bridge was destroyed after less than five months.
On July 1, 1940, a mild and sunny day, the bridge quickly achieved notoriety. As the bridge carried cars and trucks across the Tacoma Narrows strait, a phenomenon known as “aeroelastic flutter” occurred. The sustained wind of just over 40 mph made the roadway undulate from side to side. It soon reached a maximum amplitude of almost ten feet and began to break apart as the resonance frequency increased. After about 45 minutes, the northwest half of the bridge had to be closed by the police. Eventually, the leading cable supporting the bridge snapped and finally collapsed into the strait on the morning of November 7, 1940.
The cause of the collapse was attributed primarily to the shape of the bridge. The Tacoma Narrows Bridge was designed with an aerodynamic shape that was extremely thin and “tapering