Bridges_project

=[]= =media type="youtube" key="BBNCd2qrrtE?version=3" height="315" width="560"= = = =__ **THE LONGEST BRIDGE IN THE WORLD.** __=


 * __ INTRODUCTION __**

The bridges are constructions that are made in order to facilitate pedestrian or vehicular traffic in areas that present landforms. They allow cross rivers, mountains, streets, straits, and railways. Bridges can be of various types according to: their use or function, materials or technology used. According to their use or function, the most famous bridges are viaducts and overpasses. According to the materials used for construction may be of stone, wood, steel, concrete or mixed. And by technology can be cable-stayed, suspension, or suspension, arch braced, lifting, or bridge beam. In this paper makes reference to the Akashi Kaikyo Bridge, which is considered the longest suspension bridge in the world.



__**THE AKASHI KAIKYO BRIDGE. (1988-1998)**__



__**LOCATION:**__ This bridge crosses the Akashi Strait, between the City of Kobe and Awaji Island. Japan.

**__TECHNICAL INFORMATION:__** Date of construction: 1988-1998 Total length 3,910 m Main span length of 1,991 m  Length of the access openings 960 m  Height of the towers 297 m  Total length of wire cables 300,000 km  Total cost $ 4,300,000,000 Used steel 200,000 tons Concrete used 1,250,000 t

__**PURPOSE:**__ To facilitate the mobility and safety of the inhabitants of the area, because when there are storms, many person have died crossing the Akashi Strait by ferry sinking. This bridge has a six-lane highway connecting the city of Kobe with the island of Awai, allowing the inhabitants of fishing villages that place move quickly to schools and hospitals.



__**BRIDGE TYPE: (suspension bridge)**__ The suspension bridge design is easy, on the water extends two main cables supported by two towers. The road hangs of these cables are anchored at both sides thereof. This bridge is 280 meters high, is the highest suspension bridge in the world and each of its two towers measuring as much as a 80-story building. With a more central arch of 1, 6 km.



__**ADVANTAGE OF THIS TYPE OF BRIDGE:**__ - Take advantage of great tensile strength steel and represents a radical change in the concept of arch bridges, based on the compressive strength of traditional structural materials such as masonry. - Is designed to support its own weight, and strength to spare will be used to support the traffic load. So this bridge supports 91% of its own weight and only 9% of its load corresponds to vehicular traffic.

__**DISADVANTAGES FOR CONSTRUCTION:**__ Climate. Typhoons and earthquakes are common in the area, and the average rainfall of 23 cm per year.

__**MATERIALS:**__ Steel, Concrete silica fume.

__**TECHNOLOGY USED IN CONSTRUCTION:**__ To counteract the winds of the typhoon placed a vertical stabilizer in the form of a "fin coil" steel below the gangway bridge, along the whole line of the central section. The work began in May 1988 with the reclamation project near the anchors at each end of the bridge. In 1989, they sank and were filled with huge concrete bins for the two central towers. In 1992, begins the erection of the towers, the components are manufactured on land, transported by barge to the point of location, were erected and welded. In the construction of this bridge were taken the necessary precautions not to prevent the daily traffic of more than 1,400 vessels through the Straits, so a helicopter was used to extend the suspension wires pilots aramid fiber. To maintain traction of 60 t, necessary for these wires were manufactured lifting winches large capacity. Once extended these cables could put a walkway and after you install this began to lay the main cable. The gateway is supported by a truss. For the construction of this bridge using new technologies for concrete and steel. Thus, for the vast foundations of the tower, was used a new concrete silica fume, to prevent segregation manufactured under water. Another progress was a new additive that prevented the need for vibrating the concrete used for anchors. The cables are improved with a wire of high tensile steel, allowing to use only two wires of the four originally planned by the designers. The prefabricated cables that were made in a factory were made with strands of 127 wires that were transported to work instead of braiding in situ.



The construction of this bridge is a monumental work, which involved more than two million workers. Were used 200,000 t of steel. 1,250,000 t of concrete. Its foundations are the size of a 20 floored building, the towers are almost as high as the Eiffel Tower in Paris and cables could circle the world seven times.



The completion of the bridge with the mounting of the road takes longer than 15 months placed on the narrow piece at the beam sections 280.

__**DESIGNERS:**__ It was designed and built by the Department of Bridges Honshushikoku, in collaboration with teams of advisers and Japanese construction consortia

__**BENEFITS TO THE COMMUNITY:**__ It allows a faster mobility between areas covered by this bridge.