Bridge_project

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===A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle. ===

===The bridges have many benefits, one of the most important is the ease of getting to places in the shortest time possible. Bridges have joined cities, islands, and many places that had always been separated by many hours of travel, with the bridges many ways life has become easier. ===

=== **Beam bridges ** are the most simple of structural forms being supported by an abutment at each end of the deck. The moments are transferred through the support hence their structural type is known as simply supported. ===

=== **Cantilever bridges ** are built using cantilevers—horizontal beams that are supported on only one end. Most cantilever bridges use a pair of continuous spans extending from opposite sides of the supporting piers, meeting at the center of the obstacle to be crossed. Cantilever bridges are constructed using much the same materials & techniques as beam bridges. ===

=== **Arch bridges **** have abutments at each end. The weight of the bridge is thrust into the abutments at either side. ** ===

=== Suspension bridges are suspended from cables. The earliest suspension bridges were made of ropes or vines covered with pieces of bamboo. In modern bridges, the cables hang from towers that are attached to caissons or cofferdams. The caissons or cofferdams are implanted deep into the floor of a lake or river. === === **Cable-stayed bridges, ****like suspension bridges, are held up by cables. However, in a cable-stayed bridge, less cable is required and the towers holding the cables are proportionately shorter. ** === === Movable bridges are designed to move out of the way of boats or other kinds of traffic, which would otherwise be too tall to fit. These are generally electrically powered. === ===A bridge is designed for trains, pedestrian or road traffic, a pipeline or waterway for water transport or barge traffic. ===

===<span style="font-family: 'Arial','sans-serif'; font-size: 11pt; line-height: 115%;">To create a beautiful image, some bridges are built much taller than necessary. Other garden bridges may cross only a dry bed of stream washed pebbles, intended only to convey an impression of a stream. Often in palaces a bridge will be built over an artificial waterway as symbolic of a passage to an important place or state of mind ===

<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">Brooklyn Bridge
===<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">Brooklyn Bridge is located in New York City. It was built between 1870 and 1883, is a suspension bridge with a main span of 1,595.5 feet (486.3 m), it was the longest suspension bridge in the world from its opening until 1903, and the first steel-wire suspension bridge. ===

===<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">The main function of this bridge is attached by land on the island of Manhattan to the Brooklyn area, because the people there needed the bridge to go to their jobs in Manhattan. Without this bridge, the route was to be made by ferry, exposing people to great danger by the speed of the river and the changing climate of the city. Besides the trip was always a little long and tedious, so the City of New York, decided to implement the construction of this work. ===

===<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">Brooklyn Bridge was originally designed by an engineering firm owned by John Augustus Roebling, of Trenton (New Jersey). They had previously designed and constructed suspension bridges shorter. ===

===<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">While conducting surveys for the bridge project, Roebling sustained a crush injury to his foot when a ferry pinned it against a piling. After amputation of his crushed toes he developed a tetanus infection which left him incapacitated and soon resulted in his death, not long after he had placed his 32 year-old, son Washington Roebling in charge of the project. ===

===<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">Washington Roebling also suffered a paralyzing injury as a result of decompression sickness shortly after the beginning of construction on January 3, 1870. After Roebling's debilitating condition left him unable to physically supervise the construction firsthand, his wife Emily Warren Roebling, became his aide, learning engineering and communicating the instructions of her husband to the field assistants. When the bridge opened to the public, she was the first person to cross. ===

===<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">The bridge is built with limestone, granite and cement. Its architectural style is Gothic, with its characteristic pointed arches in the two lateral towers. ===

===<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">Roebling had calculated that with wire rope supports the bridge was six times stronger than strictly necessary, explaining that still hold up when much of the suspension bridges built at the same time had to be replaced. ===

===<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">The direction of the bridge is NW - SE (northwest - southeast), and aims to make a perpendicular to its base with respect to the river to prevent further erosion possible because of the tractive force from the River. Its location also takes into account find the right angle to generate the shortest distance between two shores. ===

===<span style="font-family: 'Arial','sans-serif'; margin: 0cm 0cm 10pt;">In building The main problem occurred in the early stages of the project, the foundation. Not only had to get to the bottom of the river situated over 20 meters deep but once you reach the bottom of the river was necessary to excavate some almost 30 meters to find a soil with sufficient strength to withstand the weight of the structure. ===

===<span style="font-family: 'Arial','sans-serif'; font-size: 11pt;">Were Placed moored on the river to ensure its correct position two huge boxes that were kept afloat by the air contained inside. Taking the surface those two base drawers and began building the two towers on them. While the towers were built the drawers were sinking due to the weight of granite. Once the crates arrived at the bottom of the river a team of workers located inside the drawer to 25 feet deep began digging on the muddy river bottom, allowing each drawer continued progress towards solid ground, while construction of the two towers remained on the surface. ===

===<span style="font-family: 'Arial','sans-serif'; font-size: 11pt;">600 immigrant workers were used and they had to work in miserable conditions and dangerous. For the excavation of the ground below the river, where constructed bunkers tires, dynamite was used for rocks that were found. The continuous accidents and the disease caused by pressure changes in the water killed 20 workers. ===

===<span style="font-family: 'Arial','sans-serif'; font-size: 11pt;">Upon completion of this bridge the advantages were many, especially for people in both places, because they get to Manhattan is now faster and more comfortably. Furthermore, the increased marketing bringing great benefits to both places. With the construction of this bridge will benefit all citizens because this bridge is both for people with a car as people without cars. ===

===<span style="font-family: 'Arial','sans-serif'; font-size: 11pt; line-height: 115%;">The main disadvantage of this bridge was the year of construction, because for the time was unaware of many diseases and technologies, for this situation, the construction was more tedious and also caused the deaths of many people, including the chief engineer of the work, and the inability for the son, leaving to a woman who had to learn physics, mathematics, technology and engineering during construction ===