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Bridges: Past, Present, and Future

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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?                                                                   

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