1. Public Infrastructure Bridges

2. What bridges do How do you design a bridge? Types of bridges

3. What Bridges Do Cross over a natural obstacle River/creek Canyon/valley Cross over a man-made facility Road Railroad Canal

4. How Do You Design Bridges? For most of history: Trial & error Beginning in 1800’s: Structural engineering Today: Use computers to model bridges & performance Bridge engineers need to understand physics, materials, construction methods, math

5. How Do You Design a Bridge? Safety Carry intended loads Economy Construction cost Maintenance cost Esthetics How it looks How it fits in to surrounding neighborhood

6. Bridge Forces How are forces resisted? Transfer Dissipation Tension Compression

7. 3 Basic Types of Bridges Beam bridge Up to 200 feet Arch bridge Up to 800 feet Suspension bridge Up to 7,000 feet

8. Beam Bridges The first bridges Logs across a stream Simple Cheap Need strong materials

9. Beam Bridge

10. Transfer of Force

11. Arch Bridges Ancient design Can last a long time Expensive & hard to build

12. Arch Bridge

13. Dissipate Force

14. Suspension Bridges Can bridge long distances Wide, high, clearances

15. Suspension Bridge

16. Transfer of Force

17. Cable-Stayed Bridges

18. Truss Bridges Use wood or steel to make triangles Early railroad bridges

19. Cantilever Bridges

20. Box Girder Bridges

21. Box Girder Sections Concrete Steel composite with concrete Polymer composites

22. Culverts Smallest Usually carry water under roads

23. Movable Bridges

24. Covered Bridges

25. Date of Construction of US Bridges

26. Chicago Skyway Opened 1958 7.8 miles Current $250 million renovation

27. Chicago Movable Bridges Types Vertical lift Swing Bascule Different types Many designs developed in Chicago 52 movable bridges in Chicago today Some immobilized