1. Bridges
Objectives:
Identify and describe the forces that act on very large bridges.
Explain how truss bridges counteract the forces acting on structures.
Describe the three major types of bridges.
Calculate the efficiency of a structure.
Create a structural model, test a design, and optimize a design.
Maintain a journal for an engineering-design project.
Contribute to a group endeavor by offering useful ideas, supporting the efforts of others, and focusing on the task.

2. The Big Idea
Construction is the systematic process of erecting structures to meet human needs and desires. It reflects cultural norms, environmental conditions, and the requirements of enterprises and institutions.

3. Purpose of Lesson
To familiarize students with bridge design and construction, including an understanding of the forces acting on structures.

4. It is the infrastructure.
Ever wonder how the electricity gets to everyone's house?
Ever wonder how large cities can supply everyone with water?
Ever wonder where all that waste material goes when you flush the toilet?
Ever wonder how your favorite store gets their products?
It is the infrastructure.
The underlying base or basic framework of our nation.

5. Bridges are a natural part of everyday life.
What about Bridges?
Everyone has seen a bridge, and it’s almost as likely that you’ve traveled over one today.
Maybe you laid a plank or log over a stream to keep from getting wet, you’ve even constructed a bridge.
Bridges are a natural part of everyday life.
A bridge provides passage over some sort of obstacle: a river, a valley, a road, railroad tracks, etc.
Think about the longest and highest bridge you have ever crossed.
Bridges are an important part of our nations infrastructure.

6. The Highest Bridge
The highest bridge in the world can be found in the Ladakh valley between the Dras and Suru rivers in the Himalayan mountains.
The valley lies at an altitude of about 5,602meters (m) (18,379 feet [ft]) above sea level on the India side of Kashmir.
Called a Bailey Bridge, it is only 30 m (98 ft) long, and was built by the Indian Army in August 1982.
Example of a Bailey Bridge being installed

7. Royal Gorge Bridge
The bridge that stands highest over water, is the Royal Gorge Bridge over the Arkansas River in Colorado.
Built in 1929 for $350,000, it spans 321 m and is 1,053 ft. above the water.

8. Trans Bay Bridge
The largest bridge in the world is the kilometers (km) (8.25 miles) long Trans Bay Bridge
Links San Francisco to Oakland. It was built in 1936 at a cost of $77 million.

9. Longest Bridge
The longest bridge in the world is the Pontchartrain Bridge in New Orleans, with a total length of 38.6 km (24 miles). It was completed in 1956.

10. The most expensive bridge is the Seto-Ohashi-Kojima bridge in Japan.
At km (8.21miles) long, it was built in 1988 at a cost of $8.3 billion.

11. Natural Bridge
The world’s largest natural bridge is the Rainbow Bridge, tucked away among the rugged, isolated canyons at the base of Navajo Mountain, Utah.
It is a natural wonder. From its base to the top of the arch, it reaches 88.4 m (290 ft.)—nearly the height of the Statue of Liberty—and spans 83.8 m (275 ft.) across the river. The top of the arch is 12.8 m (42 ft.) thick and 10 m (33 ft.) wide.

12. Types of Bridges

13. Types of Bridges Suspension Arch Beam Truss Cantilever Cable-Stayed
Movable/Draw

14. Types of Bridges
Beam Bridge – horizontal supports on which the roadway rests.

15. Types of Bridges
Arch Bridge - the load on the roadway is carried by an arch.

16. Types of Bridges
Cable-Stayed Bridge – this bridge supports the roadway by cables that run from the towers to the roadway.

17. Types of Bridges
Movable or Draw Bridge – has a section of the bridge that can be raised to allow large ships to pass.

18. Types of Bridges
Suspension Bridge – tall towers on both sides of the roadway support the main cables.

19. Types of Bridges
Truss Bridge – uses trusses to support the roadway.

20. Types of Bridges
Cantilever Bridge – beams extended from each end of the bridge connected in the middle by a suspended span.

21. Forces On Bridges

23. Compression is the action or state of being squished down or made smaller or more pressed together.

24. Tension is the force created by pulling something tight or a strain.

25. Torsion is the process or condition of twisting or turning one end while the other end is held firm or twisted in the opposite direction.

26. Shear is a force acting in a direction parallel to a surface with and opposite force acting in the other direction.

27. Forces on a Beam Bridge

28. Forces on a Beam Bridge

30. Weight that is added will cause the shape to buckle.
100 pounds

31. Vertical Bracing (columns) provide support
100 pounds

32. Weight that is added will cause the shape to shift.
100 pounds

33. Lateral Bracing prevents shifting.
100 pounds

34. Bridge Truss Types

35. Truss Types
Objective: SWBAT learn how to plan, design, calculate, and construct a model of a bridge. Find out how mathematical concepts of ratio, proportion, and scale are implemented in the bridge building process.

36. Multiple Kingpost (MKP) The kingpost that forms the basis for this truss is found in the center two panels. The multiple form is the simplest and by far, the most common type in Ohio

37. Queenpost (Q) A three panel truss used for short spans, the queenpost was devised as an extension of the basic kingpost by placing a horizontal member in the center panel.

38. Burr Arch (B) Patented in 1804 by Theodore Burr of New York, this design combined a large arch with a multiple kingpost truss. The addition of an arch was a traditional way of strengthening an existing truss. Many of Ohio’s bridges were stiffened in this way.

39. Pratt (PR)

40. Long (L) In 1830 Col. Stephen H. Long of the U. S
Long (L) In 1830 Col. Stephen H. Long of the U.S. Topographical Engineers became the first American to use mathematical calculations to develop a truss. It became known as an "X" truss.

41. Town (T) Connecticut architect Thiele -Town received a patent for a truss of crisscrossed diagonals, or lattice, in 1820.

42. Howe (H) In 1840 Massachusetts builder William Howe introduced iron into wooden truss design by substituting adjustable iron rods for the vertical members of Long’s truss.

43. Smith (S) Tipp City, Ohio, native Robert W
Smith (S) Tipp City, Ohio, native Robert W. Smith received truss patents in 1867 and Three different variations of his basic design still exist in Ohio’s bridges.

44. Partridge (P) Reuben L. Partridge of Marysville, Ohio, received a patent for a design that was remarkably close to Smith’s truss. He was especially active in Union County.

45. Childs (C) Developed in 1846 by Horace Childs, the Childs truss was used exclusively after 1883 by Ohio bridge builder Everett Sherman. The truss simply added diagonal iron rods to a multiple kingpost design.

46. Warren (W) Patented in 1848 by two Englishmen, one of whom was named James Warren, it utilizes isosceles triangles.

47. Warren + Arch (W + Arch)

48. Wernwag (WW)

49. King Post Truss

51. Toothpick Stick Bridge Pictures

52. Toothpick Bridge

53. Toothpick Bridge

54. Toothpick Bridge

55. Toothpick Bridge

56. Toothpick Bridge

57. Toothpick Bridge

58. Toothpick Bridge

59. Resources

60. Research - Building a Toothpick Bridge

61. Research - Building a Toothpick Bridge

62. Activities and Assignments

63. Activities and Assignments
Groups are expected to complete all assignments in their Engineering notebooks.
Work should be completed together…not copied.
Due dates for each assignment will be announced (and written on the board).

64. Forces - Activity #1 Tension Compression Torsion Shear
Based on your definitions of the forces acting on bridges, discuss with your partner four examples of each force:
Tension
Compression
Torsion
Shear
Example: Tension – pulling up pants, tying your shoestrings, etc.

65. Definitions (Copy)
Live Load – Weight that moves or changes; A variable weight on a structure, such as moving traffic on a bridge.
Dead Load – Weight that does not move; The invariable weight of a structure, such as a bridge. It may also include any permanent loads attached to the structure.

66. Loads – Activity #2 Using the definitions, identify which loads on a bridge are “live” and which are “dead”.
Trucks parked
Concrete road
Wind
People walking
Grocery in the trunk
Bridge signs
Snow
Paint lines on the road
Street lamps
Rain water

67. Vocabulary Terms – Activity #3 Using internet sources, define the following terms AND use them in a sentence that relates to bridges:
Arch Bridge
Cable-stayed bridge
Cantilever bridge
Girder
Pier
Span
Suspension
Truss
Anchorages
Compression
Tension
Buckling
Snapping
Dissipate
Transfer
Torsion

68. Bridge Forces Diagram – Activity #4
Draw a side view of your bridge (full scale);
Identify which popsicle/toothpick sticks are in compression and tension;
In 1-2 paragraphs, explain how your bridge supports loads both of these loads.

69. Sales Pitch – Activity #5
Includes:
Your choice truss type
Why you choose that particular truss;
How you plan to support loads (compression, tension, torsion and shear) on your bridge;
Why your bridge should be selected as dependable, safe, and strong.

70. Grades and Grading

71. Bridge Requirements Bridge teams of up to two members
The structure must have the minimum dimensions of 10 inches long
The structure must weigh no more than 1 pound.
The structure may be of toothpicks only.
Any type of standard white glue may be used, or wood glue.
The bridge must be pre-built before the weigh-in and stick count.

72. Bridge Requirements
Before the test of the Bridge, each team must promote their bridges - give a sales pitch to the public (2 minutes time limit strictly enforced).
The weights loading and testing apparatus will be provided.
The weights may be added in any order.
The structure must support the weight for five seconds.

73. Weight Rubric A = 60+ B = 59 – 50 C = 49 – 40 D = 39 – 30 Pounds
Bridges must support a minimum of 30 pounds
A = 60+
B = 59 – 50
C = 49 – 40
D = 39 – 30 Pounds
E = 29 pounds or less

74. Assignment Grading Rubric
ASSIGNMENTS
POINTS
Activity # 1 - Forces
Activity # 2 – Live/Dead Loads
Activity # 3 – Definitions and Sentences
Activity # 4 – Bridge Forces Diagram
Activity # 5 – Sales Pitch
Warm Up Assignments (3)
12 Step Engineering Design Process
TOTAL

75. Breaking Bridges Video Series (50 additional points)
Extension
Breaking Bridges Video Series (50 additional points)
Directions: Choose one video to watch (YouTube) and answer the following questions:
How does the Popsicle stick bridge hold up to the weight that is placed upon it?
What forces cause the bridge to fail?
How do the forces cause the bridge to fail?
Describe how your bridge will withstand the weight placed upon it?
Breaking Bridges Video #1
Breaking Bridges Video #2
Breaking Bridges Video #3
Breaking Bridges Video #4