1. Types of bridges 1
or Truss bridge 2 3

2. Beam Bridge

3. Beam Bridge
A beam bridge is a rigid horizontal structure which is resting on two piers, one at each end.

4. Truss Bridge

5. Trusses

6. Truss Bridges
Trusses are added to beam bridges to provide extra support and strength.

7. Arch Bridge

8. 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.

9. Suspension Bridge

10. Suspension Bridge
A suspension bridge is one where cables (or ropes or chains) are strung across the river (or whatever the obstacle happens to be) and the deck is attached or 'suspended' from these cables.

11. 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.
Two types
Classic Suspension
Cable Stayed Bridges

12. Classic Suspension Bridge

13. Cable Stayed Bridge

14. Forces Applied to Bridges
Compression Stress
Tensile Stress
Shear Stress

15. Forces
Shear - Twisting

16. Compression and Tension
Compression is a force which acts to compress or shorten the thing it is acting on.
Tension is a force which acts to expand or lengthen the thing it is acting on.

17. Compression
The force of compression on the top side of the beam on the bridge's deck (or roadway). This causes the upper portion of the deck to shorten.

18. Tension
The result of the compression on the upper portion of the deck causes tension in the lower portion of the deck. This tension causes the lower portion of the beam to lengthen.

19. Example
If you take a two by four and place it on top of two empty milk crates, you would have a crude beam bridge.

20. Now place a 50 pound weight in the middle of it
Now place a 50 pound weight in the middle of it. Notice how the two by four bends.
The topside is under compression and the bottom side is under tension.

21. If you kept adding weight, eventually the two by four will break
If you kept adding weight, eventually the two by four will break. Actually the top side will buckle and the bottom side will snap.

22. Compression & Tension

23. Compression

25. Tension

26. Shear Stress

31. You Guess the Type of Bridges that follow

56. How Bridges Work

57. A rigid structure supported at one end.
Cantilever
A rigid structure supported at one end.

59. Draw Bridge

60. Cranes

65. Other forms of Cantilever’s