1. Bridges: Past, Present, and Future
Dr. Lisa Spainhour
Dept. of Civil and Environmental Eng.
FAMU-FSU College of Engineering

2. What Defines a Bridge? Four main factors define a bridge
Span (simple, continuous, cantilever)
Travel surface (deck, pony, through)
Form (beam, arch, truss, etc.)
Material (timber, concrete, steel)

3. Bridge Basics—Span Types

4. Bridge Basics—Travel Surface

5. Bridge Basics—Types Five main types of bridges
Beam bridge
Truss bridge
Arch bridge
Cable-stayed bridge
Suspension bridge
Bridges may combine different types

6. Beam Bridges
Simple span: top surface in compression, bottom in tension
Cantilever span: top in tension, bottom in compression
Best for spans < 1000’, requires many supports to cross a long distance

7. Beam Bridges—Types

8. Beam Bridges—Examples
Pony plate girder bridge
Stone footbridges

9. Beam Bridges—Examples
I-540/I-70 Interchange, NC
Lincove Viaduct, NC
I-44, 16th St. Overpass, OK

10. Truss Bridges
Simple truss
Cantilever truss
Overall behavior like a beam with less material in the middle
Each member either in tension (e.g. bottom chord) or compression (e.g. top chord)
Rigid because bar ends pinned into triangles
Best for spans < 2000’.

11. Truss Bridges—Types

12. Truss Bridges—Examples
Stillwater Bridge, MN
Baihe Bridge, China
Bridge No. 1482, MN
Smithfield Street Bridge, PA

13. Covered Truss Bridges Stone Mt. Covered Bridge, GA
Germantown Covered Bridge, OH
Inverted bowstring truss (1870’s)
Town lattice truss (1830’s)

14. Cantilever Truss Bridges
Kingston-Rhinecliff Bridge, NY
Firth of Forth, Scotland
(1890)

15. Arch Bridges
Under load, ends try to move outward, require strong abutments or ties to resist spreading
When supported at ends, arch is in compression
Best for spans of 1000’ to 2000’.

16. Arch Bridges—Types

17. Arch Bridges—Examples
The Pont du Gard
Aqueduct,
France
(Ca. 100 AD)
Thomas Aqueduct,
MD (1835)
Rio Cobre Bridge,
Jamaica (1800)
Wrought-Iron Ties,
Cast-Iron Deck

18. Arch Bridges—Construction
New River Bridge, WV
Natchez Trace Arch, TN

19. Tied Arch Bridges—Examples
Bayonne Bridge, NJ
Willamette River Bridge, OR
I-64 Ohio River Bridge, IN

20. Suspension Bridges Cables (thousands of steel wires) under tension
Towers under compression
Require anchorages at ends to resist span deflection, bending of towers
Best for spans of > 3000’.

21. Suspension Bridges—Examples
Menai Suspension Bridge,
United Kingdom (1826),
Removed from service in 1940
Luding Iron-chain Bridge,
Over Dadu River, China
( )

22. Suspension Bridges—Examples
Humber Bridge,
England
Brooklyn Bridge, NY
Golden Gate Bridge,CA

23. Tacoma Narrows Bridge Failure
“Galloping Gertie”
After Failure
Approach Span, After Failure
Replacement Bridge

24. Cable-Stayed Bridges Cables under tension
                                                                                            
                                                                                            
Cables under tension
Towers, deck under compression (w/post-tensioning)
No end anchorages, require less cable, and are faster to build than suspension bridges
Best for spans of 1000’ to 3000’.

25. Cable-Stayed Bridges—Examples
                                                                  
Sunshine Skyway, FL
Clark Bridge, IL
Puente del V Centerario
Seville, Spain
Normandy Bridge, France

26. Cable-Stayed Bridges—Examples
Footbridge, Aarhus, Denmark
Santarem-Almeirim
Bridge, Portugal
Salzburg, Austria

27. Cable-Stayed Bridges—Examples
                                                                  
Leonard P. Zakim Bunker Hill
Bridge,
Over Charles River
Boston, MA

28. Bridge Basics—Materials
Past
Stone
Timber*
Iron
Present
Steel*
Steel-Reinforced Concrete
Prestressed Concrete*
Future
Those with asterisks
Fiber-Reinforced Polymers (FRP’s)
???

29. Bridge Materials—FRP Wickwire Run Bridge, West Virginia
“No-Name Creek”
Bridge, Kansas

30. Footbridges—Entirely FRP
Fiberline
Bridge,
Denmark
Parson’s Bridge,
Wales
Aberfeldy
Footbridge,
Scotland

31. Modern Timber Bridges Gluelam Beams & Arches
Short lengths of treated wood bonded with epoxy
Stiff, strong components
Custom designed off-site
Natural, aesthetic appearance
Keystone Wye Bridge,
South Dakota, 1968
Unknown

32. Modern Timber Bridges Stress-Laminated Bridge Decks
Short lengths of treated wood run lengthwise
Steel or FRP rods crosswise through holes in deck
Stressing the rods puts steel in tension, timber in compression. Creates strong, stiff deck.
Wisconsin River Bridge
Steel
rod
anchorage

33. Summary/Questions Four main factors define a bridge
Span (simple, continuous, cantilever)
Travel surface (deck, pony, through)
Form (beam, arch, truss, etc.)
Material (timber, concrete, steel)
Each is suitable for different sites/conditions
What factors affect the selection/design of a bridge?