The Change Between Suspension Bridges Before 1940 and Suspension Bridges Today

There are many reasons why we use bridges on a daily bases. Such as for roadway use, waterway, railway etc. Many people don’t think about the reasons behind a simple truss bridge because it takes no effort to drive over one, and because they are there for your use. If you don’t consider truss bridges you most likely don’t think of the physics, the timing, effort, and hard work to make the truss bridge. On my essay on Truss bridges I will over run the history of a truss bridge, the process, types of truss bridges, roadbed types, types of truss bridges, and famous truss bridges from around the world Created by

In the small town of Waco, Texas who would have thought it was once well known for the structure of a bridge, the Waco Suspension Bridge to be exact. Up until 1870, the Brazos River was just a simple river that had no special meaning to it. The land around it was empty, occasionally you would find cattlemen pushing their cattle across stream, but that was only because you could not find one bridge that spanned the eight hundred miles of river flowing through Central Texas. This caused a serious transportation issue for merchants and travelers. It became clear that a better means of crossing the river was necessary.

The report debates the Tacoma narrows bridge failure and the different theories of how it came about, using information about what type of bridge it is and the forces acting on it before and during the collapse. It also discusses ways in which the failure could have been avoided, from changes in the design to modifications to the bridge after its construction.

In Washington, the Interstate 5 bridge, which crossed the Skagit River, collapsed last month. The damage of this accident included two cars broke and three persons injured. According to officials, the bridge fell into the river after the large truck hit a beam. The bridge had a risky condition called facture critical. The U.S has a lot of bridges; however, nearly two thousand bridges were built between the middle of 1950s and the 1970s, so those ones are obsolete bridges. In addition, back then, the government cut corners in bridge buildings to cost reduction. Although gas and diesel taxes attempted to allocate to restored the bridge, the government cloud not collect money enough to repair the bridge because people began to use efficient vehicle.

The final primary component of a suspension bridge is the deck, or the roadway upon which cars drive and pedestrians walk. The deck is built from massive pieces of steel-reinforced concrete hoisted into the air and laid into place upon the bridge. Deck pieces are connected with bolts and rivets, then suspension cables connect each section of deck to the main

There are many differences between our bridge and other bridges. One being location. Another one being that thing that was sacrificed for it. Another one being cost. Also another difference would be weight and capacity, and the size or length.

Bridges are a vital part of people’s everyday life and without them people would not be able to do nearly as much as is possible today. The weather in the outer banks of North Carolina is very rough and can be very detrimental to the various structures on them. When hurricanes come near North Carolina the outer banks are hit the worst. Bridges on the outer banks keep being destroyed by weather and so the people there have to think about the cost, the effectiveness, and the need between a strong expensive bridge that will be able to handle rough weather or a cheap quick to build bridges that may fall with any extreme weather.

The Pratt truss bridge was originally founded by Caleb and Thomas Pratt in 1844. It is mainly used to carry trains. The biggest advantage of this bridge was its low costs for construction and the materials to construct a truss bridge are minimal. It also use materials that is cheaper and light in weight. We can easily identify a pratt truss by detecting its diagonal members, which (excluding for the very end ones) all slant down and in toward the center of the span. The pratt truss was designed by applying few laws that related to the mechanics of materials concept. The bridge is mainly built using steel girders to support the construction of the structure. The below part of bridge weight is high so, it need an enough support to prevent from

The Tacoma Narrows Bridge is perhaps the most notorious failure in the world of engineering. It collapsed on November 7, 1940 just months after its opening on July 1, 1940. It was designed by Leon Moisseiff and at its time it was the third largest suspension bridge in the world with a center span of over half a mile long. The bridge was very narrow and sleek giving it a look of grace, but this design made it very flexible in the wind. Nicknamed the "Galloping Gertie," because of its undulating behavior, the Tacoma Narrows Bridge drew the attention of motorists seeking a cheap thrill. Drivers felt that they were driving on a roller coaster, as they would disappear from sight in the trough of

As a replacement for the ferry system in place to venture across the Tacoma Narrows, the 2,800 feet long bridge was created. However, in an attempt to make the bridge more cost-effective, it was built with an unusual design for a suspension bridge- an extremely thin frame of only thirty-nine feet. This created sufficient space for only two lanes on the roadway. Originally, the bridge was supposed to be made more sturdy through the addition of trusses, yet there were inadequate funds. As a result, a cheaper alternative- 8-foot girders- were added on. They were included on the entire expanse of the bridge. However, there was not a sufficient stiffening effect created on the bridge by these girders. There was not enough research in existence on aerodynamic stability for suspension bridges, and wind tunneling/aerodynamic lift was thus not properly accounted

The Tacoma Narrows Bridge was designed for a wind speed of 100 miles per hour and a static wind pressure of 30 pounds-force per square foot but unfortunately the bridge failed at a wind speed of less than half and a static wind pressure of one-sixth (Delatte, 2009). This phenomenon raises a big question mark on how this is possible. At first, resonance was suspected to be the main cause of the bridge failure (The New York Times, 1940). After some proper research and thorough investigations by engineers, they came up with several theories on how did the bridge collapse. The primary cause of the collapse lies in the general proportions of the bridge and the type of stiffening girders and floor. The ratio of the width of the bridge to the length of the main span was so much smaller and the vertical stiffness was so much less than those of previously constructed bridges that

Suspension bridges need to be flexible enough to move with the wind, but not until conditions become severe and then breaks. Since movement needs to be applied to the bridge, the cable system will move in windy conditions, since movement needs to be applied to the bridge. It may require closure during strong earthquakes or in any extremely turbulent conditions.

(Vasani, 2011) Many components when assembled together form a bridge structure. Basic components of a bridge are superstructure or Decking, Bearings, Substructure which again consists of Piers and Abutments, Wing walls and Returns, and Foundation.

The superstructure elements will be defined as those inclusive to the portion of the bridge structure, which forms the horizontal span, all components above the bearings. The following will delineate the major superstructure elements, and investigate accelerated bridge construction techniques and technologies, which can be applied. The major structural components, which will be examined in the following section, will include girders, stay-in-place deck forms, deck panels and modular superstructure construction systems.

Another common environmental factor that engineers are concerned with when they consider the conditions of bridges is wind loads. These are especially a hazard to cable-supported bridges because the system relies on a delicate balance of pressure that holds up the bridge, which can be easily disturbed under high winds. One example of this is the Tacoma bridge failure in Washington state in 1940. While examining the evidence, engineers found that when the wind hits the body of the bridge, it creates forces that oscillated the bridge, which caused instability (Gianni and Gazzola). Additionally, when these bridges were built, the environment they were in was drastically different than it is today. Although engineers took population increase