Bridges_notes

Bridge:
A link or connection between two objects - usually places either side of an obstacle, such as a river, chasm, or estuary.

**Bridges work** dealing with two forces:


 * Compression is a force that acts to compress or shorten the thing it is acting on.
 * Tension is a force that acts to expand or lengthen the thing it is acting on.

It's the job of the bridge design to handle these forces without buckling (when the force of compression overcomes an object's ability to handle compression) or snapping( when the force of tension overcomes an object's ability to handle tension).

Basics **types of bridges**:

-The **beam bridge**: is basically a rigid horizontal structure that is resting on two piers, one at each end. The weight of the bridge and any traffic on it is directly supported by the piers. The weight is traveling directly downward.



-The **arch bridge**: An arch bridge is 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 **suspension bridge:** A suspension bridge is one where cables (or ropes or chains) are strung across the obstacle 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.     