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Copy of Cantilever Bridge

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by

Komila Abdusalom

on 7 April 2013

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Transcript of Copy of Cantilever Bridge

Cantilever Bridge FEATS AND FAILURES PROS AND CONS The positive and negative impacts of cantilever bridges in our environment The pros and cons of cantilever bridges What was the first
cantilever bridge ever built? What is the most successful cantilever bridge ever built? What is it? How does it work? What is it used for? What is a cantilever bridge? A cantilever bridge is a structure formed by cantilevers that are joined in the center of a suspended span. Cantilever bridges are used for any things. They are used for crossing large spans over water, especially ones with heavy loads. The bridge can carry many things such as pedestrians, automobiles, trucks, light rail and heavy rail. As it said in the video, the blue members act on compression and push the cantilever down while the orange members act on tension and pull the cantilever up. With the bottom members in compression, and top members in tension, the cantilevers connect the roadway. -crosses St. Lawrence River to Quebec City, and Levis Quebec, Canada
-is the world's longest cantilever bridge
-549 meters (1,800 feet) of clear span between its main pillars
-was accomplished with great difficulty and only after decades of expectation and two unsuccessful attempts that caused the death of 89 workers.
-the Quebec Bridge was, at last successfully completed on September 20, 1917
-today, it is considered as a world-class masterpiece
-has been called as an International Historic Civil Engineering Landmark and National Historic Site of Canada. Which cantilever bridges
did not succeed? The first modern cantilever bridge was built by engineer Heinrich Gerber and his workers in 1867.
-the name of the cantilever bridge is Hassfurt Bridge.
-he designed and constructed the Hassfurt Bridge over the Main River in Germany
-it has a main span of 130 meters (425 feet). Negative: If a cantilever bridge is built over water and it collapses...
many habitats of underwater animals can be destroyed
even some animals can die because of the fallen bridge pieces. What is a cantilever? A cantilever is a beam that is supported at only one end and carries a load at the other end. For example, a diving board is anchored at one end and hangs out over the pool on the other end which carries the load (the person). It would be considered a cantilever. cantilever diving board supporting end end that carries the load What are the parts of a cantilever bridge? anchor arms
beams
the load simple truss
members in tension
members in compression load anchor arms simple truss beams members in compression members in tension Pont de Quebec Firth of Forth
-up until 1917, the Firth of Forth Bridge was the longest bridge ever built.
-it is located at Edinburgh, Scotland
-521 meters (1,710 feet) of a clear span between its main pillars
-the construction began in 1882
-took 8 years to complete
-cost the lives of 63 workers
-used nearly 3.5 million pounds of metal.
-spans a total length of 2,528.7 meters
-connects Scotland's capital city, Edinburgh, with Fife
-had collapsed a few years earlier when it was called the Tay Bridge http://www.teachersdomain.org/asset/phy03_vid_bbcantilever/ Here is a video to show how it works: Here is another example: red= tension
green= compression BY: KOMILA Although both the Pont de Quebec and the Firth of Forth cantilever bridges are successful now, they did have difficulties during construction. The Pont de Quebec had collapsed twice while being under construction. Also, The Firth of Forth experienced a horrible disaster that caused it to fall apart.
The first time, the weight of the bridge was way over its carrying capacity and it collapsed beacause the dead load was too heavy. - August 29, 1907
The second time, when the central span was being raised into position, it fell into the river making it the world's worst bridge construction disaster. - September 11, 1916
In earlier times, the Firth of Forth bridge was called the Tay Bridge. The Tay Bridge disaster occurred during a violent storm when it collapesed while a train was passing over it. - December 28, 1879 Pont de Quebec
failures Forth of
Forth failure are designed and constructed to be very strong and durable
many heavy cars, trucks and trains can cross over the bridge all at once and the bridge would keep it strength
they now have a proven life span extending to well over 100 years. is very long and therefore it is useful and favourable to many people. Negative: causes pollution in the air
the machines use too many fuels that cause pollution
if various amounts of machines are used to construct the structure, it can cause noise pollution
the loud noises will disturb the balance of animal wildlife and people. since cantilever bridges are one of the strongest bridges in the world, they are trustworthy to cross over. Negative: Grass land/farm land is destroyed as the structure is built on top of it. Pont de Quebec Firth of Forth Bridge Although it wasn't that long, after a few years, other people started building cantilever bridges thanks to his creation. Now, many cantilever bridges are more than 500 m! The cantilever bridge is known to be one of the strongest bridges in history! PROS: are beneficial when crossing large spans. CONS: Cantilever bridges require a lot more material to make than other bridges. They use tons of iron, structural steel and prestressed and reinforced concrete. Because of this... are very heavy, since depended on many strong materials, the weight of them is very massive. -Ex. the Firth of Forth bridge used 3.5 million pounds of metal! materials needed to build a cantilever bridge would cost a lot of money building a cantilever bridge can cost up to 100 million dollars and that is just the minimum amount. Building this structure is very expensive. chemicals from the materials affect the water. due to its size, this bridge is not the
most econamical option available Positive: Since cantilever bridges are used for crossing large spans without too much distance, less pollution is created. When there aren't any bridges, more cars, trucks and boats are used to get somewhere taking a longer amount of time and using more fuel and gas. MY OPINION I personally believe that cantilever bridges are amazing structures, although I don't necessasarily think more of them should be built. Considering that cantilever bridges have more cons about them and more negative impacts on the environment, there aren't as many pros and positive impacts on the environment. I agree that it is an easy way to get across one area to another, but they are not the most eco-friendly way. Since cantilever bridges use lots of strong materials, are heavy and cost lots of money to built, I believe its best to make less of them. I do think they are very strong and sturdy structures however they are a bit short compared to other bridges such as suspension bridges. Overall, i think cantilever bridges aren't the best types of bridges. Negative: Since birds use rivers as flyways, when there is cloud cover or fog, birds can collide with the cantilever bridge THANKS FOR WATCHING!
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