The first Tacoma Narrows Bridge in Washington crossed over a strait in Puget Sound. At the time the suspension bridge was built, construction workers noticed that it moved up and down in the wind. Measures to stop the bridge’s movement were ineffective, but the bridge was opened to the public on July 1, 1940. The bridge collapsed on November 7, 1940. Luckily, no people were seriously injured.
Determine which technological design criteria the Tacoma Narrows Bridge did and did not meet. Explain your answer.
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Answers
Explanation:
The Tacoma Narrows Bridge is the historical name given to the twin suspension bridge—originally built in 1940—that spanned the Tacoma Narrows strait. It collapsed just four months later due to aeroelastic flutter. Since then, this topic has become popular, with several case studies discussing the failure phenomenon of suspension cable bridges.
In the state of Washington, the construction of the Tacoma Narrows Bridge was completed and opened to the traffic on July 1st, 1940. It was the very first bridge to incorporate a series of plate girders as roadbed support, and the first bridge of its type (cable suspension). It was also the third largest suspension bridge of its time, with a 2800-foot central span and two side spans of 1100 feet each.
A west-side approach had a continuous steel girder of 450ft, while the east side had a long reinforced concrete frame of 210ft. It had two cable anchorages of 26ft. along roadways, two 5ft. sidewalks and two 8ft. deep stiffening girders. Among several other structural details, the suspension cable anchorages to which the cables were connected were made of 20,000 cubic yards of concrete, 6 lakh pounds of structural steel, and 2.7 lakh pounds of reinforcing steel. Because of its extremely long length, it was considered a ‘narrow bridge’. The overall construction cost was estimated to be a whopping $6 Million in 1940. Considering inflation, this is equivalent to almost $1 Billion, and all of this for something that lasted just four months and seven days. Yet, this remains a great engineering feature for civil engineers to ponder over.
Answer:
the above answer is correct