Truss Bridge Corrosion

Bridges have been used for thousands of years, beginning with natural formations, such as huge rock arches (Appendix A). The first bridges made by humans were most likely simple spans of wooden tree trunks laid across streams, or planks, such as rafts tied together (Gascoigne, 2001). These simple designs evolved over time, as new materials became available, to form the hundreds of bridges we use today. Some basic bridge designs include truss, arch, beam and suspension bridges. The most basic of these is the beam bridge (Appendix B1), which consists of a deck, spanning a relatively short distance, that is held up by a pair of abutments (vertical supports at either end). When weight is placed on

Superstructure bears the load that is being passed over the bridge and it transmits the forces caused by the same to substructure. Load received from the decking is transferred on to the substructure by Bearings. They also distribute the load evenly over the substructure material as it may not have sufficient strength to bear the superstructure load directly. Piers and Abutments are the vertical substructures which transfer the load to the earth in the foundation. Wing walls and returns are constructed as the extension of

The first example of an external force is the static (dead) load, this refers to the gravitational forces acting on the bridge itself. Every structure has to be able to support the weight of its own materials in order for it not to collapse, this is before any live load is applied to it. Another example is dynamic (live) load which refers to traffic, from people or vehicles, which move across the bridge and apply additional weight to it increasing the magnitude of vertical forces acting on the bridge. But environmental factors such as changes in temperature, precipitation and winds can also create vertical and horizontal loads on the bridge. (Bagga

Initially, suspension bridges before 1940 were made of piers, towers, wires, anchorages, and roadways. Piers were the main foundation for the suspension bridges. There usually were two of them, which were made out of cement and were entrenched in ground underneath the body of water that the bridge was spanned across. Towers were built on top of the piers to provide a means of connection for the roadways and wires. Wires were connected to the towers, roadways, and anchorages to provide tension support for the weight of the bridge. The anchorages were large cement platforms that were planted into the ground on either side of the land so that the wires could be connected to it. Lastly, the roadways were the main point of the suspension bridge. They usually were wide enough to provide four lanes of traffic and stretched from one side of the bridge to the other. This was the basic design of the suspension bridges

Society relies heavily on metals in nearly every aspect of life; however the corrosion of such metals has become a costly and very prevalent issue worldwide. Large amounts of energy, time and money has been poured into

Structurally, the bridge is a composition of two key metals steel (2 x 1011 Nm-2) and aluminum. These metals are common in bridges due to their properties of high strength and

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

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 bridge was constructed of carbon steel, which tends to crack. Many cracks were found throughout the bridge among extensive corrosion. Upon investigation, it was found that the collapse was due to a defective eye-bar that experienced a cleavage fracture in the lower part of its head which was resulted from stress corrosion and corrosion fatigue. [26] Since the eye-bars were not designed to be redundant, failure in one eye-bar would disrupt the continuity of the suspension system. This disruption is what caused the bridge to collapse suddenly. The location of the flaw

• Expect corrosion in the sills, floorpans, wings and also the seams between the inner and outer wheelarches, unless the car has been restored. The welded-on wings have to be removed to properly repair the sills. Other corrosion hot spots include the bases of the A-posts and B-posts, the door

All are very effective and work well if built in the right conditions. The thing that separates these bridges from one another is that they all have different points of compression and tension. Tension is two forces of opposition that pull away from each other to keep it from being pulled together. If you imagine a rope in a game of tug-of-war, the rope has a lot of tension because it is being pulled apart, but the opposing force inside of the rope is trying to keep it together. The same can be applied to a bridge truss because the tension truss is opposing the compression truss by pulling the bridge apart. Tension also pulls the platform of the bridge by stretching it to keep the bridge from collapsing. Compression is two forces in opposition that push an object together to try to compress it. If you think of someone standing on a soda can, the soda can tries to resist being squished, but the weight of the person standing on the can still squashes it. This example can also pertain to the truss on a bridge. A compression truss opposes the tension truss by pulling the bridge together. Compression is also placed on the top of a truss and in its bases. The compression at the top of the bridge counteracts with the tension of the platform and balances out each force. The compression in its bases is from the weight of the platform and trusses. Bridge engineers calculate the tension and

Hecox (2011) says that the arch structure of the Tillman Bridge makes the canyon walls hold the weight of both vehicles and the bridge itself. In addition, the arch structure allows a better vision of the canyon for the drivers, which was a request of the population to the engineers of the project. In the other hand, according to Jones (2015), the truss structure of the new St. Anthony Bridge also was requested by the population because they wanted to keep a truss bridge in that place. The author also affirms that the St. Anthony Bridge is a truss, but the project team proposed adding a posttensioned concrete bottom chord to the steel truss in order to reinforce it. The project team made this choice because one bridge in Minnesota has collapsed in 2007, and the engineers wanted to lessen the fracture-critical issues to avoid a new catastrophe. In addition, this posttensioning approach wiil make the structure redundant for both resiliency and long-term durability. In conclusion, both bridge's structures were right chosen in order to provide safety and beauty in both

In 1989, an earthquake caused the top deck of the bridge to collapse. This has raised concern in recent years in the case of a large scale earthquake. During an inspection in September of 2009, a 1.5 inch crack was found in a structural truss called an eyebar. The system of the truss is meant to distribute report will describe the tensile load from the weight of the bridge over 4 eyebars. One of them being broken, this same load was now distributed between only 3 eyebars. Because these eyebars were not designed to carry extra load, it became crucially important to repair the eyebar as soon as possible. However, because the bridge is so old, its mechanisms were more complex than what would be designed now in the current day. The engineering company C.C. Myers was contracted to do the repair. C.C Myers decided to repair the eyebar by welding a crossbar to the saddles which had been placed on each end of the broken eyebar (Alfrey, 2010). Four tie rods were then bolted to distribute the tensile load (Reid, 2010). This repair was completed in only 70 hours (Carlsen,

For those with trucks, rust is a common problem. To determine how to fix this problem, you will need to