Tacoma Narrows Bridge

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INTRODUCTION:
The Tacoma Narrows Bridge was the third longest suspension span in the world at the time. It was suppose to have been revolutionary in it design, and it was known for it’s tendency to sway windstorm. Nevertheless, on November 7, 1940, a large storm caused it to collapse.
WHAT HAPPENED? WHY?
Even during the construction of the original Tacoma Narrow Bridge, the deck would go up and down by several feet with the slightest breeze. Construction workers on the span chewed on lemon wedges to stop their motion sickness but construction continued because the bridge have been designed specifically to withstand wind up to 120 miles per hour. The original Tacoma Narrow Bridge by Clark Eldridge was pretty conventional for a suspension bridge …show more content…

Having survived the collapse, but being damaged beyond repair as towers were twisted and the cables were damaged.
The current westbound bridge was designed and rebuilt with open trusses, stiffening struts and openings in the roadway to let wind through. Like other modern suspension bridges, the westbound bridge was built with steel plates that feature sharp entry edges rather than the flat plate sides used in the original Tacoma Narrows Bridge
The final designs of the Tacoma Narrows Bridge, once finalized, were a sharp and drastic contrast from the design by Leon Moisseiff. Instead of a thin plate girder, an open-air stiffening truss with a depth of 33 feet (10 m) would form the new road deck. Newer, larger towers that rose 58 feet (18 m) higher and 21 feet (6.4 m) wider than Gertie's towers, would support the bridge's main cables, now 20 1⁄4 inches (510 mm) in diameter versus Gertie's 17 1⁄2 inches (440 mm). Newer, larger anchor blocks would support a load that weighed 1.6 times as much as the original bridge. However, some elements of Galloping Gertie were incorporated into the 1950 span. The tower pedestals were enlarged and raised 17 feet (5.2 m). On the west end stood a 450-foot (140 m) long approach viaduct with the same 8-foot (2.4 m) deep girders Gertie's main deck had. This approach viaduct used three support towers, two with thin support beams and one with the structural complexity and design of one of Gertie's main towers - each spaced 150 feet (46 m) apart. The viaduct, after a structural examination, was kept and utilized as part of the 1950 bridge's design, with an additional box strut brace added to the tower closest the shoreline (officially known as Tower #3 in the design plans), and widening of the upper box strut for the new bridge's

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