Why Did The Tamaha Narrows Bridge Collapse
The report gives a clear and concise information to what happened on the 7th of November, 1940. The main reason to investigate the failure of the bridge is because “THE BRIDGE DIDN’T LAST A YEAR”. What was wrong with the bridge? But the incident completely changed the way in which bridges were built.
This report has been requested by the Board of Engineers and Washington State Authority, to provide a clear information to how the Tacoma Narrows Bridge had collapsed and how did this change bridge designing. The scope of the report is to give key information on how the bridge collapsed? What could have been done to prevent it from collapsing? How were future bridges designed?
2. Procedure
There were many websites and articles to read on why such a devastating failure had occurred. The references are authentic and …show more content…
Findings
1. The 1940 Narrows Bridge had very little resistance to torsional bending. Depth-to-width ratio of about 1 to 72 accounted for this problem. The Bridges long, narrow, and shallow girder made “Galloping Gertie” devastatingly flexible. R.F
2. On November 7, 1940 around 10 a.m., the cable band of the main-span on the north side of the bridge slipped. This separated the cable into two unequal segments. That contributed to the change from wave like movement to torsional movement of the bridge. R.F
3. As the resonance of the wind was equal to the resonance of the bridge, the bridge began to oscillate. Which was also one of the main reason for the collapse. (Billah & Scanlan , 1990)
4. Also contributing to the collapse of the bridge was torsional motion which induced "vortex shedding" in the bridge’s main span. Vortex shedding occurred in the Bridge as follows R.F:
4.1 Since there was nothing through which the wind could pass straight through. So the wind would get separated as it struck the side of the bridge’s deck i.e. the stiffening girders. So this would induce small amount of twisting in the bridge’s
This report has been requested by the Board of Engineers and Washington State Authority, to provide a clear information to how the Tacoma Narrows Bridge had collapsed and how did this change bridge designing. The scope of the report is to give key information on how the bridge collapsed? What could have been done to prevent it from collapsing? How were future bridges designed?
2. Procedure
There were many websites and articles to read on why such a devastating failure had occurred. The references are authentic and …show more content…
Findings
1. The 1940 Narrows Bridge had very little resistance to torsional bending. Depth-to-width ratio of about 1 to 72 accounted for this problem. The Bridges long, narrow, and shallow girder made “Galloping Gertie” devastatingly flexible. R.F
2. On November 7, 1940 around 10 a.m., the cable band of the main-span on the north side of the bridge slipped. This separated the cable into two unequal segments. That contributed to the change from wave like movement to torsional movement of the bridge. R.F
3. As the resonance of the wind was equal to the resonance of the bridge, the bridge began to oscillate. Which was also one of the main reason for the collapse. (Billah & Scanlan , 1990)
4. Also contributing to the collapse of the bridge was torsional motion which induced "vortex shedding" in the bridge’s main span. Vortex shedding occurred in the Bridge as follows R.F:
4.1 Since there was nothing through which the wind could pass straight through. So the wind would get separated as it struck the side of the bridge’s deck i.e. the stiffening girders. So this would induce small amount of twisting in the bridge’s