Bridges

Bridges

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Presentation Transcript

1. Bridges

2. 5. Construction Technologies Construction technology involves building structures in order to contain, shelter, manufacture, transport, communicate, and provide recreation.5.2 Identify and describe three major types of bridges (e.g., arch, beam, and suspension) and their appropriate uses (e.g., site, span, resources, and load). 5.3Explain how the forces of tension, compression, torsion, bending, and shear affect the performance of bridges.5.4 Describe and explain the effects of loads and structural shapes on bridges. Learning Standards

3. At the conclusion of the lesson students will be able to: Learning Objectives • Define Bridge • 2) Identify & describe 5 major parts of a bridge • 3) Identify & describe 5 forces that affect bridges • 4) Identify & describe 7 types of bridges

4. Bridge A structure built to span a physical obstacle

5. Parts of a Bridge Thick wire that supports the deck of the bridge Cables Heavy column above the bridge that supports cables Surface on which traffic moves Tower Deck Heavy column that holds up a bridge Abutments Pier Span Distance between 2 supports or towers Heavy supports at the end of a bridge

6. Parts of a Bridge Truss Triangular framework used to support the bridge

7. Early Bridges The first bridges were: Stepping Stones Log Over a Stream

8. Early Bridges Later people used large flat rocks connect the stepping stones allowing them to cross over the bridge with small carts

9. Forces Upon Bridges Forces must be considered when building bridges A force that pushes Compression A force that pulls Tension A force that twists Torsion What happens when something heavy crosses a structure Bending A force acting across any structure Shear Click here to learn more about the forces that affect bridges

10. Beam Bridge Most common & oldest type of bridge Example: Highway overpasses

11. Beam Bridge Unsupported beams can span distances only up to 250 feet Longer Beam Bridges need piers for support along the span

12. Beam Bridge Top of Beam Bridges & piers are under COMPRESSION Bottom of Beam Bridges are under TENSION

13. Drawbridge A Beam Bridge that has surfaces that can be raised or lowered to allow the passage of boats

14. Arch Bridge First designed & created by the Romans First Arch Bridges were made of wedge shaped stones locked in a curve

15. Arch Bridge Arch bridges rely on the force of compression to work effectively

16. Suspension Bridge Bridge is suspended (hangs) from large vertical cables Used to cross very wide spans (2000 - 7000 ft)

17. Suspension Bridge Cables & abutments (anchorages) are under the force of tension Towers are under the force of compression

18. Cable Stayed Bridge Cheaper & easier to construct than traditional Suspension Bridge Cables connected to towers stretch down diagonallyto support beam

19. Cable Stayed Bridge Cables are under the force of tension Towers are under the force of compression

20. Truss Bridge Made of steel beams constructed into rigid triangle shapes called trusses The trusses can be above or below the bridge Why triangles??? Triangles are considered one of the strongest shapes

21. Truss Bridge Forces affecting Truss Bridges Blue Arrows represent TENSION COMPRESSION Red Arrows represent

22. Cantilever Bridge (using trusses) Cantilever: Self supporting beam that is fastened to the ground at one end 2 cantilevers meet in the middle & are connected by trusses The strong design of these bridges resist high winds

23. Types of Bridges Beam Bridge CantileverBridge Types of Bridges Drawbridge Arch Bridge Cable StayedBridge Truss Bridge SuspensionBridge

24. Notable Bridges

25. Braga Bridge 5780 ft long Opened in 1965 Cantilever Bridge (using trusses)

26. Glen Canyon Bridge & Dam Lake Powell, Az Crosses Colorado River Opened in 1966 1560 ft long Steel Arch Bridge

27. Brooklyn Bridge Crosses East River in New York City Connects Manhattan & Brooklyn Opened May 24, 1883 – it took 13 years to build Longest Suspension Bridge in the world when it was built 5989 Feet

28. Golden Gate Bridge Crosses SF Bay Connects SF & Marin County Opened May 27, 1937 Longest Suspension Bridge in the world when it was built 8981 Feet

29. Akashi Kaikyo Bridge OpenedApril 5, 1998 Connects Kobe & Awaji Island Also known as the Pearl Bridge Built to withstand 178 MPH winds, earthquakes measuring 8.5 on the Richter Scale & harsh sea currents Currently the world’s longest Suspension Bridge 12,831 Feet Center Span 6,532 Feet

30. Mt. Hope Bridge Opened October 24, 1929 Crosses Mt. Hope Bay Connects Bristol & Portsmouth Rhode Island 6,130 Feet Center Span 1,200 Feet Suspension Bridge

31. Crosses the Narragansett Bay – Connects Newport & Jamestown Claiborne Pell Newport Bridge Suspension Bridge

32. Leonard P. Zakim Bunker Hill Memorial Bridge Crosses the Charles River Opened in 2003 Widest Cable Stayed Bridge in the world: 183 feet wide 1432 feet long

34. Millau Viaduct Located in France Tallest bridge in the world – one of the masts has a summit of 1,125 ft Just about as tall as the Empire State Building Opened December 14, 2004 – Took only 3 years to build Total length: 8,071 ft

36. Veterans Memorial Bridge Somerset, Mass.

37. London Tower Bridge Drawbridge with Suspension

39. Bourne Bridge Arch Bridge (w/ suspended deck)Crosses Cape Cod Canal in Bourne, MaOpened in 1935 Sagamore Bridge Crosses Cape Cod Canal in Sagamore, MaOpened in 1935

40. IWayBridge – Providence, RI IWay Video Part 1 IWay Video Part 2

41. Cape Cod Railroad Bridge Lift BridgeCrosses Cape Cod Canal in Bourne, MaOpened in 1935

42. MCAS Question Which of the following bridges is an example of a Suspension Bridge? D. A. B. C. C. 73%

43. MCAS Question A Beam Bridge supporting a toy truck is shown in the diagram below. When an object pushes down on this bridge, the bottom edge experiences a force that tends to pull it apart as shown. What is the type of force labeled X? A. Compression B. ShearC. Tension D. Torsion C. Tension 52%

44. MCAS Question Support cables in a Suspension Bridge are most stressed by which of the following forces?A. ShearB. TorsionC. TensionD. Compression C. Tension 74%

45. MCAS Question An engineer designing a Suspension Bridge discovers it will need to carry twice the load that was originally estimated. One change the engineer must make to the original design to maintain safety is to increase the A. length of the wires in tensionB. diameter of the wires in tensionC. height of the support towersD. length of the bridge B. diameter of the wires in tension 57%

46. MCAS Question The diagram below shows the supports of a proposed bridge. Which of the following wooden bridge designs, if built from one support to the other would withstand the heaviest load? D. B. C. A. D. 87%

47. MCAS Question Several students are entering a bridge building contest that requires ice cream sticks & glue to construct the strongest bridge possible. The bridges must be 5 in. wide & span a length of 18 in. Which of the following tests is the most accurate way to determine the strongest span design of these bridges?A. Roll toy cars across each bridge until it collapsesB. Place concrete construction blocks on top of each bridge until it collapsesC. Stack coins on both ends of each bridge until it collapsesD. Place D Cell batteries at the center of each bridge until it collapses D. 47%

48. MCAS Question The figure below shows examples of bridge numbered 1 through 6. a. Identify 1 example from the figure that represents a type of Arch Bridgeb. Explain how an Arch Bridge is different from a Beam Bridgec. Identify 1 example from the figure that represents a type of Beam Bridged. Explain how a Beam Bridge is different from a Suspension Bridge