essay on bridge in 250 words
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Answer:
Bridges have been around sense the beginning of time. The Ancient Roman engineers used two significant innovations, the cofferdam and cement. The cofferdam is when the put wooden spikes in to the bottom of the river then used watertight clay over the spikes to make a bridge. Now today there are more efficient ways to make a bridge then just out of cement and clay. There are Suspension Bridges, Arch Bridges, Covered Bridges and many more. Suspension bridges have become a very common method of bridge construction in the last century. For example the Brooklyn Bridge, George Washington Bridge, Golden Gate Bridge and the Verrazano-Narrows Bridge. These bridges all use the conventional suspension bridge design were large cables…show more content…
Construction of cable-stayed bridges has proven to be less costly then suspension bridges. As a result, Cable-stayed bridges are more widely used. The Akashi-Kaikyo Bridge, connecting Kobe on the mainland with Awaji on Awaji Island, will be a huge three-span cable-stayed bridge some 3910 meters in total length with a center span of 1990 meters. When completed, it will be the longest bridge of its type in the world, surpassing the Number Bridge in the UK, which has a center span of 1410 meters. The bridge has a wind-proof and earthquake-resident construction, withstanding winds up to 80 meters per second and earthquakes reaching from 8.5 on the Richter scale. This bridge is due to be completed in spring of 1999. There is a suspension bridge which spans the Seine estuary in Normandy, France. The decks of the bridge are designed as special curves so that wind flows across them as easily as over a plane. The bridge has a central span of 2,800 feet. The span is so long that it has been built with a slight upward curve from end to end, to accommodate the effects of the curvature of the Earth. There are also huge cables that have to suspend the bridge in the air. If a bubble collides with another bubble, the result always ends up in a sharing unison. Regardless of there size, no matter what, they will meet the wall at an angle of 120 degrees.
Explanation:
Answer:
A bridge is a structure which provides passage over an obstacle without closing the way beneath. The passage may be required for a road, a railway, pedestrians, a canal or a pipeline. The obstacle which needs to be crossed may be a river, a road, railway or a valley.
A bridge is a structure to cross an open space or gap. Bridges r mostly made for crossing rivers, valleys, or roads. Nowadays most big bridges r made to carry vehicles but people have also walked across bridges for thousands of years. Bridges called highway overpasses carry a road over another road.
Military bridges r portable, so that they may be easily moved to where they r needed. This makes them much more complex than most civilian bridges.
The first man-made bridges were probably made from cut wood or stones. Some stone bridges have lasted thousands of years. In recent centuries large bridges are made mostly of steel. They don't last as long. Many bridges are in a state of disrepair.
There are five major structural types of bridges:
- Beam bridges
- Cantilever bridges,
- Arch bridges
- Suspension bridges
- Cable-stayed bridges