Bridge_Project


 * On a blink of the eye… **

INTRODUCTION:

 A bridge is a structure built to span a physical obstacle for the purpose of providing passage through that obstacle. The many different designs of bridges diverge depending on the function of the bridge and the nature of the land where the bridge is constructed.   There are three major types of bridges: __ The beam bridge __: Beam bridges are horizontal beams supported at each end by piers. The weight of the bridge and any traffic on it is directly supported by the piers. The weight is traveling straight downward. The force of compression manifests itself on the top side of the beam bridge's deck. This causes the upper portion of the deck to shorten. And the result of the compression on the upper portion of the deck causes tension in the lower portion of the deck and this tension causes the lower portion of the beam to extend. __ The arch bridge: __ it’s a semicircular structure with abutments on each end. The design of the arch, the semicircle, naturally diverts the weight from the bridge deck to the abutments. Arch bridges are always under compression. The force of compression is pushed outward along the curve of the arch toward the abutments. The tension in an arch is insignificant. The shape of the arch itself is all that is needed to effectively dissipate the weight from the center of the deck to the abutments. As with the beam bridge, the limits of size will eventually overtake the natural strength of the arch. __ The suspension bridge: __ A suspension bridge is one where cables (or ropes or chains) are strung across the river (or whatever the obstacle happens to be) and the deck is suspended from these cables. Modern suspension bridges have two tall towers through which the cables are strung. Thus, the towers are supporting the majority of the roadway's weight, the force of compression pushes down on the suspension bridge's deck, but because it is a suspended roadway, the cables transfer the compression to the towers, which dissipate the compression directly into the earth where they are firmly entrenched. The supporting cables, running between the two anchorages, are the lucky recipients of the tension forces. The cables are literally stretched from the weight of the bridge and its traffic as they run from anchorage to anchorage. The anchorages are also under tension, but since they, like the towers, are held firmly to the earth, the tension they experience is dissipated.

The basic use of a bridge is solving the problem of crossing an obstacle in such a way as to cut down the effort and time needed to do so. This means that the supplies of food and other goods can get across the obstacle in a shorter time and this means that, in economic terms, the cost of travel and trade goes down. Other longer-term payoffs from easier travel, which is crucially dependent on good bridges, come as a result of increased opportunities to share ideas – intellectual, political and religious.

THE BRIDGE

Name of bridge:  Gateshead Millennium Bridge <span style="font-family: 'Tahoma','sans-serif'; font-size: 10pt;"> Location: <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin;"> Between Newcastle upon Tyne, Tyne and Wear , North East England , England , United Kingdom and Gateshead , Tyne and Wear , North East England , England , United Kingdom. <span style="font-family: 'Tahoma','sans-serif'; font-size: 10pt;">

Purpose of the bridge: <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin;"> is a pedestrian and cyclist bridge <span style="font-family: 'Tahoma','sans-serif'; font-size: 10pt;"> Type of bridge <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin;">: it’s a mixture of an Arch bridge and a Bascule bridge. Statically can be conceived as an arch bridge because of the semicircular form that held’s the deck with cables, but functionally it’s a bascule bridge. A bascule bridge is a moveable bridge with a counterweight that continuously balances the span, all the way through the entire upward swing in providing clearance for boat traffic. Bascule is a French term for seesaw and balance, and bascule bridges operate along the same principle. They are the most common type of movable bridge in existence because they open quickly and require relatively little energy to operate.

<span style="font-family: 'Tahoma','sans-serif'; font-size: 10pt;">Designers: <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin;"> conceived and designed by architects Wilkinson Eyre and structural engineers Gifford <span style="font-family: 'Tahoma','sans-serif'; font-size: 10pt;">.

Materials: <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin;">The cables are made of stainless steel and the arch it’s also made of steel. <span style="font-family: 'Tahoma','sans-serif'; font-size: 10pt;"> Dimensions: Main span: 105 m Width: 8m Total length: 126m Height: 50m Weight: 850 tones. Cost: GBP £22 million <span style="font-family: 'Tahoma','sans-serif'; font-size: 10pt;"> Design: <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin;">The bridge not only looks stunning but also uses precision engineering to tilt – like the opening of an eye. The bridge's design breaks down into several elements: The supporting deck that forms an arch over the river, the deck that contains the pedestrian walkway and cycle path, the dividing hedge, and the caissons, which contain the hydraulic system. The pedestrian and cycle deck is an almost-horizontal curve, suspended above the river from a series of suspension cables. These suspension cables go from the arch to the deck, helping to give stability for those crossing the bridge. The pedestrian deck is about a foot higher than the cycleway to provide clear views of the river and to allow a higher safety guard to be used for cyclists. There are two glass canopies at each end of the bridge, which are used to operate the hydraulic system. Finally, in order to alert pedestrians and cyclists to the bridge's opening and closing, recessed in-ground units were custom-designed; green LEDs feed into a fiber-optic shape of a “go” arrow symbol. Red LEDs feed into a no-entry symbol. The bridge tilts as a single, rigid structure. As the arch lowers, the pathway rises, each counterbalancing the other. This ensures a minimum amount of electricity is used during each tilt.

<span style="font-family: 'Tahoma','sans-serif'; font-size: 10pt;">Technology involved in its construction: <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin;"> Everyone is familiar with the concept of the bascule bridge, a structure that splits open in the middle, with both halves raised in order to allow ships to pass through. It's a standard engineering concept that has not changed much in decades. But the Gateshead is the world's first “tipping” bridge. This elegantly arched structure literally tips on its side to make way for maritime traffic. The tipping movement of the two curves that make up the bridge's structure has been compared to the opening of an eyelid. The action is powered by six 45 cm diameter Hydraulic rams (three on each side, each powered by a 55 kW electric motor) rotate the bridge back on large bearings to allow small ships and boats (up to 25 m tall) to pass underneath. The bridge takes as little as 4.5 minutes to rotate through the full 40° from closed to open, depending on wind speed.

<span style="font-family: 'Tahoma','sans-serif'; font-size: 10pt;">Advantages / disadvantages of the bridge for the specific community: <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt;">Some of the advantages of this bridge are: <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">- <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt;">The possibility to rotate every time a ship has to go through. <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">- <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt;">The bridge takes as little as 4.5 minutes to rotate. <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">- <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt;">The effect is notably silent. <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt; mso-fareast-font-family: Arial; msofareastfontfamily: Arial; msolist: Ignore;">- <span style="color: #666666; font-family: 'Arial','sans-serif'; font-size: 9.5pt;">It’s so energy efficient that it costs just £3.60 each time it opens.

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