1. Engineering design is a form of problem-solving.
2. The first step of the design process is to define the problem.
3. A truss is an arrangement of structural members that are connected together to form a rigid framework.
4. Trusses are able to span long distances with a minimum of material.
5. Trusses have been used extensively since the 19th century.
6. The classic American covered bridges are all trusses, though wooden components are covered for protection from the elements.
7. Later trusses were made of cast iron and wrought iron.
8. Modern trusses are made of structural steel.
9. Some other types of bridges include arch, suspension, cable-swayed, and beam.
10. Dunlap’s Creek Bridge was the first iron bridge built in the United States.
11. The bridge was a vital link in the newly constructed National Road, which was the first important road built with Government funds.
12. Dunlap’s Creek Bridge consisted of five parallel cast iron tubes spanning 80 feet.
13. Dunlap’s Creek Bridge was built by Captain Richard Delafield of the Corps of Engineering.
14. Dunlap’s Creek was designated a National Historic Civil Engineering Landmark in 1978.
15. Truss bridges are usually categorized in two ways depending on the location of the deck and orientation of diagonal and vertical members.
16. The deck truss has its deck located at the top chord.
17. A through truss has its deck located at the bottom chord.
18. A pony truss is like a through truss, but not as high and has no lateral bracing.
19. Truss configurations are based on orientation of members.
20. A number of standard truss configurations are commonly used in bridge structures.
21. These configurations are defined primarily by the geometry of their members.
22. Three of the most common standard configurations are Howe, Pratt, and Warren trusses.
23. These trusses are named after the 19th century engineers who developed them.
24. The major components of a typical truss are verticals, chords, diagonals, floor beams, deck, pinned support, roller support, and abutment.
25. Loads include the weight of a bridge and vehicles that are on them.
26. Loads can also include weather, such as snow.
27. These forces must all be considered when developing a bridge.
28. Yield stress is the strength of a metal.
29. The strength of a metal must be determined before building a bridge.
30. Supporting structures, such as beams and wires, are used commonly in bridges.
