1. What Kind of Bridge?

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. Girders

4. More Important Words
Compression: a force that compresses or shortens the thing it is acting on. Pushing together force.
Tension: a force that expands or lengthens the thing it is acting on. Pulling apart force.

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

6. Beam Bridge Typical Span Lengths: 10m - 200m (can be up to 300m +)
World's Longest: Shipanpo Bridge, China (restressed Concrete Girder)
Center Span: 330m
Ponte Costa e Silva (Rio-Niteroi Bridge), Brazil (Steel Box/Plate Girder)
Center Span: 300m

7. Continuous Span Beam Bridge
Several Beam Bridges linked together
World’s Longest (over water): Lake Ponchartrain Bridge in Louisiana – 38.4 km (nearly 24 miles) long

8. More Continuous Span
World’s Longest (over water & land): Jiaozhou Bay Bridge in China – 42.5 km (about 26 miles) long (longest span 260 m)
World’s Longest (high speed railroad): Danyang – Kunshan Grand Bridge between Beijing and Shanghai – km (about 120 miles) long (longest span 80 meters)

9. 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. 
Queensboro (59th St) Bridge over the East River

10. Cantilever Bridge

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

12. Firth of Forth Bridge Under Construction (1890)

13. Firth of Forth Bridge - Scotland

14. Basic Spans

15. Truss
Supporting structure - 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

16. Forces in a Bridge with Trusses
load
Compression
tension
Reaction force

17. 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

18. Arch Bridge Typical Span Lengths: 40m – 150m (can be 500m +)
World's Longest: Chaotianmen Bridge, Chongqing, China
Total Length: 1741 m
Center Span: 552 m

19. Arch Bridge USA’s Longest: New River Gorge Bridge, U.S.A.
Total Length: 924m
Center Span: 518m

20. Suspension Bridge The deck of the bridge is held up by cables.
main cables strung over two towers and anchored on either end
vertical (or hanging) cables connect to the main cables and connect to the road (called suspenders)
towers support most of the road deck’s weight.
Compression
Load
Anchorage
Tension
Reaction Force

21. Suspension
Typical Span Lengths: 70m - 1,000m+ (can be close to 2000 m)
World's Longest: Akashi Kaikyo Bridge, Japan
Total Length:
3,911m
Center Span:
1,991m

22. Longest U.S. Suspension Bridges
Rank
Name
Location
Feet
Completed 1.
Verrazano-Narrows
Lower New York Bay
4,260
1964 2.
Golden Gate
San Francisco Bay
4,200
1937 3.
Mackinac
Mackinac Straits, Mich.
3,800
1957 4.
George Washington
Hudson River at New York City
3,500
1931 5.
Tacoma Narrows II
Puget Sound at Tacoma, Wash.
2,800
1950 6.
San Francisco–Oakland Bay
2,310
1936 7.
Bronx–Whitestone
East River, New York City
2,300
1939 8.
Delaware Memorial
Delaware River near Wilmington, Del.
2,150
1951, 1968 9.
Seaway Skyway
St. Lawrence River at Ogdensburg, N.Y.
1960
10.
Walt Whitman
Delaware River at Philadelphia
2,000

23. 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.
Tension
Load
Compression
Reaction Force

24. Cable Stayed Typical Span Lengths: 110m - 480m (can be 1000m +)
World's Longest: Russky Bridge, Russia
Total Length:
3,100 m
Center Span:
1,104 m

25. Every 100 ft = about 30.5 m m m m
152 – 914+ m

26. Summary of Forces on Bridges

27. Summary of Forces on Bridges