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LET’S LEARN ABOUT BRIDGES. BEAM BRIDGE  Simplest bridge form  A log across a street was the earliest form of a beam bridge  Consists of a horizontal.

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Presentation on theme: "LET’S LEARN ABOUT BRIDGES. BEAM BRIDGE  Simplest bridge form  A log across a street was the earliest form of a beam bridge  Consists of a horizontal."— Presentation transcript:

1 LET’S LEARN ABOUT BRIDGES

2 BEAM BRIDGE  Simplest bridge form  A log across a street was the earliest form of a beam bridge  Consists of a horizontal beam supported at each end by a pier  The weight of the beam pushes down on the piers  The farther apart the piers, the weaker the beams  Beams can be placed at points other than the beginning and end  Usually these bridges are not longer than 250 feet. Pier Horizontal Beam

3 BEAM BRIDGE EXAMPLES

4 BEAM BRIDGES  Why are these bridges a good idea….  Usually pretty easy to build  Inexpensive when compared to other bridge types  Can be used in rural or urban areas  Why are these bridges not such a good idea….  Ships cannot go under them  Construction not attractive  Costly if many piers are needed  Concrete used is cheaper but not as strong as steel

5 TRUSS BRIDGE  Made of a series of triangles  One of the oldest types of bridges  A flat bridge is laid and then supports are built on both sides in triangle shapes both above and below the flat bridge  Can be any length  Many are railroad bridges

6 TRUSS BRIDGE

7  Why are these bridges a good idea….  Very strong  Can support heavy loads  Made or steel  Economical to build  Easy to build and design  Why are these bridges a bad idea…  Difficult to construct  Take a lot of time and money to repair  Difficult to widen the bridges  Not very attractive

8 ARCH BRIDGE  Difficult to build  Built a long time ago by the Romans  One of the most popular types of bridges  Different styles of arches can be used  Some of these bridges were built using stone and have stood the test of time

9 ARCH BRIDGE

10  Why are these bridges a good idea…  Can be made from a wide range of materials including wood, stone, concrete, and steel  Considered attractive  strong  Why are these bridges not such a good idea….  Expensive to build  Limited to where can be placed because ground needs to be strong enough to support it

11 SUSPENSION BRIDGE  These bridges can span 2,000 to 7,000 feet -- much farther than any other type of bridge!  Cables are hooked on vertical suspenders that support the road.  Found in harbors with lots of boat traffic.  Usually longer than other types of bridge.

12 SUSPENSION BRIDGE

13  Why are these bridges a good idea…  Very strong  Can span long distances  Attractive  Allow boats and ship traffic to pass under them  May withstand earthquakes better than other kinds of bridges  Why are these bridges not such a good idea….  Expensive  Long time to build  Require large amounts of material


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