Pre-Class Monday 1-18-11

1. Pre-Class Monday 1-18-11 What do you think civil engineers do?

2. Civil Engineering “Mechanical engineers build weapons. Civil engineers build targets.”

3. American Society of Civil Engineers • The oldest branch of engineering • Design and supervise the construction of roads, buildings, airports, tunnels, bridges, and water and sewage systems • Main objective: functional, efficient, and durable systems • Very environmentally conscious, includes nature (plants), habitats (animals), and society (people) • Subsets include: architectural, construction, environmental, structural, transportation, urban planning, and water resource • Average salary in 2005: $43,774 • Starting salary in 2009: $48,509 (bachelor’s only)

4. EWB-USA helps create a more stable and prosperous world by addressing people's basic human needs by providing necessities such as clean water, power, sanitation and education. • What they do: http://www.youtube.com/watch?v=mW4L9SVk_nc • If you want more information, check out their website: www.ewb-usa.org.

5. Pre-Class Wednesday 1-19-11 How many squares do you see?

6. Types of Bridges • The downward forces acting on a beam bridge are gravity, the weight of the bridge itself, and the load that it carries. • The bridge is flat, so the downward forces are evenly spread across the length of the bridge. • They can span longer distances by adding middle piers to help carry the weight.

7. Other Beam Bridges • Clapper bridge • One of the earliest bridge constructions • Used stepping stones found at streams, spanned by stone slabs or logs. Cantilever bridge - Used by early Asian builders - Supported on two levers, weighted by piers - Downward force counteracted by weights Truss Bridge - The covered bridge are among the oldest in America - Designed to hide the trusses holding it up

8. Arch Bridges • The downward forces acting on an arch bridge are gravity, the weight of the bridge itself, and the load that it carries. • The downward forces are spread outward by the curve of the arch and concentrated on the end supports. • They can span longer distances by additional supports to redistribute the weight.

9. Other Arch Bridges • Developed by the Romans • Discovered it could support more weight than a beam bridge, and natural cement helped strengthen it • Modern arches reach above the deck of the bridge (typically made of steel)

10. Suspension Bridges • The downward forces acting on a suspension bridge are gravity, the weight of the bridge itself, and the load that it carries. • The curve of the suspension ropes or cables concentrate the downward forces inward where there is no support. • Typically droop, so not suited for heavy loads (foot traffic) • They can span longer distances and support enormous weights with steel cables, concrete anchorages, and steel towers/trusses.

11. Deliverables • Original brainstorming design and sketches (certified signature) • Bridge blueprint • Mass of bridge • Mass of load on bridge (necessary to break it) • Efficiency of bridge • Final drawing (if different from original sketch and blueprint)

12. Pre-Class Thursday 1-20-11 What type of bridge are you building for the project?

13. What’s a truss? • Combination of triangles to strengthen and distribute downward forces • Named after the people to first use them

14. Engineering Efficiency • Measure the mass of your bridge (scale). • Divide the weight of the load by the bridge mass. Watch your units! • This is your efficiency (record this value).

15. Deliverables • Original brainstorming design and sketches (certified signature) • Bridge blueprint • Mass of bridge • Mass of load on bridge (necessary to break it) • Efficiency of bridge • Final drawing (if different from original sketch and blueprint)

16. Pre-Class Friday 1-21-11 What is a truss? Be sure to turn-in your weekly pre-classes (4 total) to the Pre-Class tray.

17. Pre-Class Tuesday 1-25-11 What are the oldest bridges in America? Hint: two possible answers

18. Bridge Design • The building of a bridge is more than just spanning a gap, canyon, or river. • Make use of simulation tools before starting: • http://www.youtube.com/watch?v=4xcKlGh7Dm4 • If done right, the end result can be amazing: • http://www.parade.com/news/2010/10/17-the-birth-of-a-modern-marvel.html • Ask the question: what purpose does it serve?

19. Traffic Engineer • Objective • Observe the redesign of an intersection • Procedures • Divide into groups of 4 or 5. • Travel to the intersection of Hughes and Eastview. • Each group will complete the following: • Draw a top view of the intersection and label it. • Count the number of cars that pass through a green light for each lane. • Determine the cycle time for each road (red, yellow, green, and arrow). • Observe the turn lanes to see if they are long enough • Once you have completed step #3, answer the following questions: • Is there enough time to get every vehicle through in 1 cycle? • Are the turn lanes and road size sufficient for the capacity? • Do you think the time of day matters? Explain. • When would be the best time to check this intersection? • What improvements, if any, would you propose to the city of Madison?

20. Bartlett Efficiency Acceleration of bridge = weight of load mass of bridge • The acceleration acting on the bridge if no other force but the load acted on it. • Using Newton’s Second Law of motion: F=ma, where F is the force (Newtons, N), m the mass (kg), and a the acceleration (m/s2) • Weight equation based off Newton’s Second Law: W=mg, where W is the weight (force in N), m the mass, and g the acceleration of gravity (9.8 m/s2)

21. Pre-Class Tuesday 1-25-11 What was the biggest challenge in the Bridge Building Project (a.k.a. Civil Engineering Performance test)?

22. Pre-Class Monday 8-23-10 Write:Guest SpeakerGary Chynoweth City of Madison Engineer

23. Fall 2009