Introduction to Bridges

Transcription

1 Introduction to Bridges Clinton Pandaraoan Civil Engineer Japan Engineer District February 5, 2010 US Army Corps of Engineers

2 Scope Definition of a bridge Examples of the different types of bridges Principles of a Truss bridge

3 What is a bridge? A bridge is defined as a structure that allows people or vehicles to cross an obstacle such as a river, canal or railway, etc.

4 Types of bridges

5 What are the different types of bridges? Beam Arch Suspension Cable-Stayed Truss Suspension bridge Cable-stayed bridge

6 What are the different types of bridges? A Beam bridge is the simplest kind of bridge. They are derived from a log bridge. Today, you can find them made of I beams, box girders, or reinforced concrete.

7 Common Beam bridges Walkway bridge Log bridge

8 What are the different types of bridges? An Arch bridge can be best recognized by its arching span. Loads in this type of bridge are carried outward along the curve of the arch to the supports at each end or abutments.

9 Example of an Arch bridge Kintai bridge, Iwakuni, Japan

10 What are the different types of bridges? A Suspension bridge can be best recognized by the load bearing portion, or deck, suspended by vertical cables. Suspension bridge

11 Example of a Suspension bridge Golden Gate bridge, San Francisco, California, USA

12 What are the different types of bridges? Cable-stayed bridge A Cable-Stayed bridge is a bridge that consists of one or more towers or pylons with cables supporting the bridge deck.

13 Example of a Cable-Stayed bridge Millau Vaiduct, France

14 What are the different types of bridges? A Truss bridge consists of trusses connected together to form a rigid framework. Most trusses are made up of interconnected triangles.

15 Example of a Truss bridge Skygate bridge, Kansai, Osaka, Japan

16 Basic Principles of a Truss bridge

17 Basic Principles of a Truss bridge You will be designing Truss bridges for this competition Truss bridges are composed of trusses made up of triangles These triangles are formed by interconnecting structural members

18 A basic Truss bridge

19 Basic Principles of a Truss bridge As load is applied, internal forces act in tension or compression on each member of the triangles Compression Tension

20 Triangle diagram

21 Basic Principles of a Truss bridge Failure of a structural member can result in: Buckling (under compression) or Yielding (under tension)

22 Example of structural member failure Buckling under compression load Yielding under tensile load

23 Basic Principles of a Truss bridge In this competition, structural members will be limited to Hollow tubes or Solid bars

24 Basic Principles of a Truss bridge Hollow tubes Tend to resist buckling forces more efficiently than a solid bar of the same mass Tend to be more expensive than solid bars, in cost per kilogram Solid bars (Usually most economical to use hollow tubes for members primarily under compression) Tend to resist tensile forces the same as hollow tubes with the same cross-sectional area Tend to be less expensive than hollow tubes, in cost per kilogram (Usually most economical to use solid bars for members primarily under tension)

25 Basic Principles of a Truss bridge Other factors to consider: Load Dynamic - Vehicle and/or pedestrian weights Static Deck and structural member weights

26 Basic Principles of a Truss bridge Other factors to consider: Properties of structural members Size Diameter and thickness of the tube or bar Material type Strength vs. cost

27 Summary Definition of a bridge Different types of bridges Basic principles of a Truss bridge

28 Conclusion There are many factors that go into a successful bridge design.

29 Conclusion A successfully designed bridge safely transports pedestrians / vehicles over an obstacle from point A to point B.

30 Conclusion With some engineering know how, you can design a successful bridge

31 Design failure is Epulu, Congo (Nov 2009) NOT an option!!!