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THE STONE SLAB BRIDGE AND MODERN BEAM BRIDGE | |
V. Ryan © 2001 - 2024 | |
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At the same time as wood beam bridges and wood frame bridges, stone slab bridges were also used widely. They are still used today as they are very strong especially if used to cross small gaps. | |
This is a stone beam bridge. A slab of stone is laid across a stream. | |
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The stone slabs are selected for their shape/form. They must be flat and also wide enough for one or two people to pass over the gap. Sometimes the stone needs to be shaped a little, by the use of a stone chisel. Even the best stone slabs may need some shaping. In early times the chisel would be made from wrought iron. Today stone chisels are made from steel which is specially hardened. |
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The introduction of stone bridges allowed people to cross wider streams and small rivers. This is achieved by building small pillars of stone and laying the stone slabs across them. In this way wide gaps can be crossed. in the animation below a stone pillar holds up two stone slabs. |
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A TYPICAL STONE SLAB BRIDGE | |
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QUESTIONS: 1. In your opinion which is the strongest, a stone slab bridge of a wood frame bridge? Explain your answer. 2. Draw a diagram that represents three stone slabs laid across a gap (for example a stream). Remember to include two stone pillars. |
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THE MODERN BEAM BRIDGE | |
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A modern beam bridge is a rudimentary structure, with a roadway and beams supported by piers. They are generally constructed from steel and reinforced concrete, which gives the bridge a long working life, durability and strength. A typical beam bridge can be seen above. However, there are various types including, girder bridges (above), box girder and those made from steel plate. The components for this type of bridge are manufactured in a factory and transported to the site’s location, where they are assembled, forming the bridge. The weight of the bridge and transport travelling across it, is transferred by compressive forces, through the piers and into the ground. The span ( distance between supports) of a typical beam bridge, should not exceed 76 metres. This type of bridge is popular for crossing motorways and highways (including pedestrian bridges). They are also common as railway bridges. |
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WELL KNOWN BEAM BRIDGES | |
Donghai Bridge - 2005 - China Chesapeake Bay Bridge-Tunnel - 1964 - United States Tianjin Grand Bridge - 2010 - China Confederation Bridge - 1997 - Canada |
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