Stress and Strain Relationships on Stress Ribbon Structures
A bridge is a type of transportation infrastructure that is built to join two separate points of land together. Bridges often undergo construction in order to provide passage over certain obstacles such as bodies of water or geographical depressions. They can be classified in several different ways including by their intended use or by the materials used to make them. A bridge built solely for people to cross over is classified as a pedestrian bridge. Likewise, a bridge made out of wood would be classified as a wooden bridge, while a bridge made out of concrete would be classified as a concrete bridge. However, the most efficient way to classify bridges is according to their structural form (“Bridges,” 2008).
The three most basic types of bridge structures are girder bridges, arch bridges, and suspension bridges (“Bridge Technology,” 2007). The girder structure consists of a chain of beams that are interconnected and supported vertically through the use of well allocated piers. The arch structure utilizes curved elements to disperse the applied forces downwards into end abutments. Finally, the suspension structure exploits the superior tensile strength of steel cables in order to help carry the massive loads applied to the bridge. While some bridges are built basic in structure, others are made through a combination of the structural forms mentioned above (“Bridges,” 2008).
Stress Ribbon Bridge
A stress ribbon bridge is a unique type of bridge structure that is characterized by its simple catenary shape and slender concrete deck. “The stress ribbon concept borrows the suspension bridge principle but develops it further by using high-strength materials and m...
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Steven Hermosillo Professor Wallace Fire Tech 105 15 November 2015 Silver Bridge Collapse According to Wikipedia, Forty-six people were killed in the silver-bridge collapse and another nine people were injured. “The Silver Bridge was an eye-bar-chain suspension bridge built in 1928 and named for the color of its aluminum paint. The bridge connected Point Pleasant, West Virginia, and Gallipolis, Ohio, over the Ohio River” (Wikipedia). This was a highly used bridge serving thousands of cars a day before the collapse.
Elastic strain region at small and big end of connecting rod is shown in figure no. 10. The maximum and minimum equivalent strain values are 0.00033975 and 2.1407e-10 respectively. Due to applied pressure there will be change in original dimensions of the connecting rod and hence strain developed can be
The area of where the bridge was to cross the Ohio River was said to be one of the hardest places to build but came with some advantages. The section of the river had a solid rock base for the supporting pier to be built on. Since the engineers knew they could build a pier that would not settle they decided on a continuous bridge design. This design type distributes the weight so the steel trusses could be smaller and riveted together. This alone saved an estimates twenty percent of steel that was originally thought to be need to make the bridge cutting down the cost. The two continuous trusses span a collective 1,550 feet across the water. With addition of the north and south approach viaducts, for trains to go under the bridge, the superstructure’s total length is 3,463 feet. The bridge was made to hold two sets of tracks making the width 38 feet and 9 inches. The design called for 27,000 cubic yards of concrete and 13,200 tons of steel with some members being four foot square beams that span a distance of seventy feet. The design was the first step in a long process that would take several years to
Following the collapse of the I-35 Bridge, other bridges in the country, with similar construction designs, were scrutinized. According to federal statistics, more than 70,000 of the 607,363 or roughly 12 percent of the bridges in the United States are classified as “structurally deficient.”
According to Suspension bridges: Concepts and various innovative techniques of structural evaluation, “During the past 200 years, suspension bridges have been at the forefront in all aspects of structural engineering” (“Suspension”). This statement shows that suspension bridges have been used for over 200 years, and that people are still using them today because they are structurally better bridges. This paper shows four arguments on the advantages of suspension bridges, and why you should use one when building a bridge. When deciding on building a suspension bridge, it has many advantages such as; its lightness, ability to span over a long distance, easy construction, cost effective, easy to maintain, less risk
Joseph B. Strauss, a famous designer of movable spans became interested in building a bridge at the Golden Gate so he submitted a proposal. His design was a hybrid structure that included a suspension span of 2,640 feet long along with a cantilevered truss span of 685 ft. on each end. However, his design was rejected by the public because they thought such a bridge would ruin the beauty of the area. Therefore, Strauss had to work with Othmar Ammann, Charles Derleth Jr., and Leon Moisseiff, consulting engineers, who together created a new design. They created a suspension bridge with a length of 4,000 ft. Their new design was approved by the U.S. War Department in 1930 and construction proceeded.
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 the wave. On the last day of the bridge's existence it gave fair warning that its destruction was eminent. Not only did it oscillate up and down, but twisted side to side in a cork screw motion. After hours of this violent motion with wind speeds reaching forty and fifty miles per hour, the bridge collapsed. With such a catastrophic failure, many people ask why such an apparently well thought out plan could have failed so badly?(This rhetorical question clearly sets up a position of inquiry-which iniates all research.) The reason for the collapse of the Tacoma Narrows Bridge is still controversial, but three theories reveal the basis of an engineering explanation. (Jason then directly asserts what he found to be a possible answer to his question.)
The theoretical basis for the structural design of bridge is well established. In contrast, the mechanics of flow and erosion in mobile-boundary channels has not been well defined and it is
Figs 21-22 in Case 3 and 25-26 in Case 4 show the normal bending behavior for the box girder under 100% of the total applied load. The load-displacement graphs in both cases clearly indicate the elastic behavior of the bridge, because the girder was able to carry all of the applied load with no failure, Fig 23 and 27. Since the truck loads in Case 4 are acting on one side of the bridge only, the stress concentration is high at that part as observed in Fig 25-26. The bending displacement in Case 3 is 0.024 inches, which is less than that in Case 4 (0.026 inches) because the bridge in Case 3 under the dead load only as mentioned
The reason I picked the design I did was because it seemed like a solid and traditional style of bridge. The bridge mirrored a Warren Truss bridge which is general, but efficient at distributing the weight across the bridge. I am relatively inexperienced at building, so the Warren Truss seemed like the best idea since it is both simple and effective.
Bridge efficiency is important as it helps reduce cost of building while maximizing the strength of the bridge. Many things can influence the bridge’s strength and weight, but the two main things that can cause a bridge to be a failure or success is the design of the bridge and construction of its joints. In order to build a potent balsa truss bridge, it is crucial to know how the layout of members and style of gluing can help increase or decrease strength.
The 1.78 mile western span of the bridge between San Francisco and Yerba Buena Island presented the first obstacle. The bay was up to 100 feet deep in some places and required a new foundation-laying technique. Engineers developed a type of foundation called a pneumatic caisson to support the western section. A series of concrete cylinders were grouped together and then capped-off, having the air pressure of each cylinder identical to balance the beginning of the structure. From there, the workers added sets of new cylinders until the caisson reached the bottom of the bay. Then, in order to reach the bedrock, they inserted long drills down the cylinders, digging until they reached bedrock. After the caisson was balanced at the bottom of the bay, workers filled it with 1 million cubic yards of concrete, more concrete than was used for the construction of the Empire State Building! This caisson connected the two suspension bridges that make up the western part of the bridge.
Bridges were invented in order to get from place to place even over physical obstacles such as water; the idea of a bridge was in fact inspired by nature. A fallen log, piles of stone and dirt, any of these were the perfect form of a natural bridge and were used before a technical “bridge” was invented. The first bridges made by humans were made of cut wooden logs or planks and eventually stones, using simple support systems and cross-beam arrangements. The greatest bridge builders were the ancient Romans. The Romans built arch bridges and aqueducts that could stand in conditions that would damage or destroy earlier designs.
Specifically, it shows a visual representation all the possible pathways someone could walk on the actual bridges. Specifically, the graph theory states since each node has an odd number of edges then the bridges cannot be crossed with a continuous line. The graph theory representation of this real-world phenomena is an everyday explanation of the bridges has to do with the specific layout and the number of bridges. In addition, this theory is able to be applied to many different scenarios of bridges to explain whether or not different combinations of bridges could hypothetically be crossed. The goal of science is to be able to explain phenomena with generalized observations.