1. Bridges

2. Important Words
Span: the distance between two bridge supports (column, tower, canyon walls…)
Abutment: a. The part of a structure that bears the weight or pressure of an arch. b. A structure that supports the end of a bridge. c. A structure that anchors the cables of a suspension bridge.
Girder: a beam, made of steel, wood, or reinforced concrete, used as a main horizontal support in a building or bridge – can be a box girder or truss girder

3. More Important Words
Compression: a force that acts to compress or shorten the thing it is acting on.
Tension: a force that acts to expand or lengthen the thing it is acting on.

4. Beam Bridge
A rigid horizontal structure that is resting on two piers, one on each side.
Load
Compression
Tension
Reaction Force

5. Beam Bridge Typical Span Lengths: 10m - 200m
World's Longest: Ponte Costa e Silva, Brazil
Total Length: 700m
Center Span: 300m

6. Truss Bridge
Supporting lattice work added to many types of bridges. Trusses are skeletal structures made up of many small beams (normally in the shape of triangles). As the size of a beam bridge increases, so must the size of the truss

7. Cantilever Bridge
Cantilever bridges are a modified form of beam bridge, with the support being placed not at the end, but somewhere in the middle of the span. A cantilever is a structure or beam that is unsupported at one end but supported at the other, like diving boards. 

8. Forces in a Truss Bridge

9. Truss Bridge Typical Span Lengths: 40m - 500m
World's Longest: Pont de Quebec
Total Length: 863m
Center Span: 549m

10. Arch Bridge
An arch bridge is a semicircular structure with abutments on each end. The arch naturally brings the weight (a force) of the load from the roadway to the abutments. Used by the ancient Romans. Can be made out of brick or stone.
Load
Compression
Reaction Force

11. Arch Bridge Typical Span Lengths: 40m - 150m
World's Longest: New River Gorge Bridge, U.S.A.
Total Length: 924m
Center Span: 518m

12. Suspension Bridge
The deck of the bridge is held up by cables that are strung across the water or canyon. In modern suspension bridges, there are two towers over which the main cables are strung. Numerous vertical or hanging cables (rods) support the road and are attached to the main cables. Thus, the towers are supporting the majority of the road deck’s weight. The main cables must be anchored on either end of the bridge.
Load
Tension
Compression
Reaction Force

13. Suspension Typical Span Lengths: 70m - 1,000m+
World's Longest: Akashi Kaikyo Bridge, Japan
Total Length: 3,911m
Center Span: 1,991m

14. Cable Stayed Bridge
A continuous beam with one or more towers built above piers. From these towers, cables stretch down diagonally (usually to both sides) and attach to the girder to support the bridge deck. The cables can all attach at the top of the tower (fan) or at various points along the tower (harp).
Tension
Load
Compression
Reaction Force

15. Cable Stayed Typical Span Lengths: 110m - 480m
World's Longest: Tatara Bridge, Japan
Total Length: 1,480m
Center Span: 890m