Truss Bridge Corrosion

I will be explaining four of the most popular types of truss bridges in this paragraph. One type of truss is the Allan truss bridge. The Allan truss bridge been in the world of truss bridges for a long time. A fact of the Allan truss is it was first ever build in the 1800s, and the first time the Allan truss was designed was on the date of August 13, 1894. Aldo Alan truss aren’t as common as today there still a very good truss bridge, and quite efficient. Next truss bridge is the Warren truss bridge. A Warren truss bridge is one of the most commonly built truss bridge. That because a Warren truss bridge is simple and is not a big task to build. It uses equilateral triangles to spread out all of the loads from the bridge. It works very well due to all of the triangles minimizing the forces of tension and compression. It’s said to be really light but very efficient, and strong. Another type of truss bridge is a much known truss bridge which is the Baltimore truss bridge. A Baltimore truss bridge is very common to a Pratt truss, the only differences are its additional branchy which is much lower compare to the Pratt truss. The reasons of that are it prevents bucking in the members. The Baltimore truss was first built in the year 1871 for railroads it was first build in the areas such as Baltimore, Pennsylvania, and Ohio. Today it’s one of the most famous type truss bridges in the world. The last bridge on the list is a Pratt truss bridge. It was first develop in the 1800s, and was designed by Caleb Pratt and Thomas in the year 1844. It has a unique and good usage of iron and was first used as a railway which was very popular. It’s very solid and good at taking on compression and tension. Its form is vertical and diagonal that go towards the center of the bridge. Today it’s known as a simple and strong truss bridges that work very efficient and give it one of the tops spots as one of the truss bridges

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

The I-35W Mississippi river bridge also known as Bridge 9340 officially was an eight-lane, steel truss arch bridge which carried the Interstate 35W across the Mississippi river connected the downtown east and Marcy-Holmes. Its construction began in the year 1964, was finally opened in 1967. It connected the northeast of Metrodome on its south end and the University of Minnesota on the North end. The bridge was the boundary of “Mississippi Mile” downtown riverfront parkland. The north foundation of the bridge was near the hydroelectric plant built in 1988. The south abutment was in an area polluted by the coal gas processing plant. There weren’t any mentions of this in the failure investigations. The bridge was a continuous truss bridge that had a total span of 1,907 ft. It was an 8-lane bridge having a width of 113.3ft. and was 115 ft. high. It was designed by Sverdrup & Parcel to 1961 AASHO (American Association Of State Highway Officials) standard specifications. The construction contract worth more than US $5.2 million at the time, went to Hurcon Inc. and Industrial Construction Company, which built the steel trusses and deck. The piers were not built in the navigation channel instead the center span of the bridge consisted of a single 456- foot steel truss over a 390-foot channel being the longest span of the bridge.

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

Bridges are structures that become very susceptible as time passes. In Oregon there have been many bridges being identified to be seismic vulnerable. In an article by Ed Jahn, he sates, “nearly sixty percent of state-identified lifeline bridges likely to collapse or be potentially taken out of use after a quake” (Jahn). Bridges are a whole different story because they aren’t easy to be re-evaluated when they are used constantly by people to get around. The problem with many of these structures, though is that more than half of these bridges were built before 1970 (Jahn). Because of this they aren’t reinforced with new building codes making them highly vulnerable to any disaster to the point of collapsing. It isn’t an easy thing to fix the problems with a bridge because many seem stable but are still at great risk. It is known that “Today, they're still building fracture critical bridges with the belief that they're not going to break,” (Rosenker). Even when a bridge is being identified to see if it’s stable a lot of the time they are thought to be ok, but are really in a bad condition. Because they aren’t fully evaluated, and if a disaster were to hit in a certain location it could cause the bridge to

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,

The most common types are the beam bridges, arch bridges, suspension bridges, cantilever bridges, cable-style, and the kind I am going to research is truss bridge.

When the bridge was tested, at 26 pounds of pressure, it began to buckle. The top support near the middle of the bridge on one side caved in, and as the weight increased, more of the top supports collapsed. At 47.3 pounds of pressure, the bridge snapped in half. By the end of the testing, the bridge had lost all of it’s top supports, two sections of diagonal supports on either side, and a small portion of the roadway.

N.p. "Lead: Corrosion, Scaling and Metal Mobility Research." EPA. Enviromental Protection Agency. 10 Sept. 2014. Web. 9 Aug. 2015.

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

Improperly designed welds on the cross bracing led to the failure of 3 of the bridge’s beams. Extremely cold weather and constant morning rush-hour traffic also added to the list of causes. This caused the bridge to buckle inwards.

Referring to the Table 1 for comparison between the two design for bridge which are Cable Bridge and Truss Bridge, Truss Bridge is the better solution. We can see that the cost for building a truss bridge is less than cable bridge. The score for other economic in both bridge designs are equal. In environmental aspect, Truss Bridge have a better score compared to cable bridge. In social aspect, Cable bridge comes out to be better than Truss Bridge. By referring to the table, we can see that Truss Bridge have an average score on all other economic, environmental and social aspect. In my opinion, this is a better option than having one excellent and one worst score.

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