Although the Golden Gate Bridge design has shown to be sound, a subsequent Moisseiff design, the original Tacoma Narrows Bridge, fell shortly after completion due to an unforeseen aeroelastic flutter. The Bay Area experience shows that this type of failure can occur even with modern construction practices if you don't check them all out before they are completed.
The main cause of both bridges' failures was wind. In the case of the Golden Gate Bridge, strong winds caused large lateral forces on the structure, which led to severe fatigue over time. This problem could not be detected by traditional inspection methods since there were no existing standards for testing structures for wind load-carrying capacity at that time. As a result, the Golden Gate Bridge was declared "safe for traffic" even though it wasn't safe at all!
In the case of the Tacoma Narrows Bridge, high winds caused a large wave action in the ocean near the bridge that resulted in a vertical force on the structure. This force was great enough to pull some parts of the bridge away from its supports.
The Tacoma Narrows Bridge was mostly destroyed by aeroelastic flutter. Wind is permitted to travel through the structure in standard bridge construction by integrating trusses. In the case of the Tacoma Narrows Bridge, however, it was forced to migrate above and below the structure, resulting in flow separation. This caused the bridge to become statically unstable, leading to its collapse.
The collapse of this bridge has been cited as an example of why engineers should not only design structures but also analyze them dynamically. The structure was found to be dynamically stable under most conditions but became unstable when wind speeds increased beyond what was expected for the bridge.
Additionally, the failure mode involved the entire length of the bridge collapsing at once, which could have resulted in more deaths had it happened during weekday morning rush hour traffic.
Finally, the collapse led to the development of new standards for analyzing bridges for stability. These include requiring dynamic analysis of all structures where wind loads are significant, such as bridges and buildings. It also recommended that such analyses be performed periodically to ensure that changes to loading conditions do not make the structure no longer statically stable.
Bridge across the Tacoma Narrows The Tacoma Narrows Bridge is the historical name for the twin suspension bridges that crossed the Tacoma Narrows strait in 1940. Four months later, it crashed due to aeroelastic flutter. It was the first major U.S. highway bridge to be destroyed by its user.
The disaster led to improvements in the design of large suspension bridges. The destruction also prompted the United States Army Corps of Engineers to redesign the Bonneville Dunes National Recreation Area, which includes the world-famous Boneyard, where many vehicles are discarded.
The bridges were part of U.S. Route 99, which continues to cross the Tacoma Narrows today using the new Veterans Memorial Bridge. The old bridge has been replaced with a replica built to commemorate the 70th anniversary of the original bridges. This copy is now open to traffic, while the original remains under construction. It will be at least another decade before it is completed.
The collapse killed 43 people and injured several others. It is considered one of the worst transportation disasters in U.S. history.
After the crash, the towers were removed from the center of the main span and sold for scrap metal. The remainder of the bridge was repaired and reopened to traffic on November 12, 1945.
Construction employees risked perilous circumstances as the highway and towers took shape over open ocean, given the possibility for permanent employment during the Great Depression. The Golden Gate Bridge, first opened to the public in 1937, has stood the test of time as a picturesque landmark and technical wonder. Its importance was underscored when it was listed on the National Register of Historic Places in 1989.
The bridge's official designation is the "Golden Gate Bridge". It does not have any references to its length (663 feet) or its center span (427 feet). These numbers appear only on signage at each end. The term "golden gate" is used because the bridge is made up of three main sections: gold (north side), silver (middle), and white (south side).
The idea for a suspension bridge across the San Francisco Bay originated with John A. Roebling's design for a cable-stayed bridge that would be stronger than previous structures. His proposal won the contest held by the San Francisco Board of Trade in 1872. Construction began two years later with William Wallace Campbell as chief engineer. He was replaced by Joseph Baumiller after his death in an accident in 1876. In 1930, after decades of traffic under its management, the Golden Gate Bridge & Toll Authority decided to forgo maintenance efforts and submit a plan to replace the bridge section by section as funds became available. The last section was completed in 1997 at a cost of $57 million.
The Golden Gate Bridge. It crosses the San Francisco-Oakland Bay between San Francisco, California, and Marin County, California.
The bridge is 877 feet long and connects two cities with different climate conditions: San Francisco has a mild year-round temperature of 59 degrees F, while Oakland is located at 9 degrees F on average. The distance between the two cities is 29 miles along the ocean shoreline.
Golden Gate Bridge traffic is heavy, especially during rush hour when many people commute across it. Driving under the bridge is not allowed, but using other roads to access the waterfront is permitted.
There are three main approaches to the bridge from land: north, south, and east. All three converge at the center, where there is a large parking lot with room for hundreds of cars. The west side of the bridge is accessible via a footpath that leads up to the sidewalk on North Point Drive. Here you can walk across the bridge's upper level for views over the city.
You may have seen photos of the Golden Gate Bridge taken from underneath it.
Wind-generated vortices amplified the twisting motion of the bridge deck until it broke, causing the Tacoma Narrows Bridge to collapse. The wind was blowing toward shore from the open ocean, so this collapse had nothing to do with Hurricane Betty.
The bridge had been opened prematurely one day before it collapsed due to a mistake by a traffic engineer. This fact is clear from research done at the time of the accident. There were no signs that the bridge was about to collapse.
Photos of the wreckage show that the main span was twisted around its own axis, proving that it was the deck itself that failed. No part of the support structure showed any sign of distress before the collapse occurred.
The cause of the original defect in the deck has not been determined with certainty, but it may have been corrosion. Some observers thought they saw dust or debris on the road ahead of the storm's arrival; this may have been sediment thrown up by the retreating bridge. Whatever the case, it is clear that the damage was there long before the hurricane struck.
The Tacoma Narrows Bridge was one of the first large suspension bridges to be built using girders instead of trusses for its main supports.
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