bridges: past, present, and future dr. lisa spainhour dept. of civil and environmental eng. famu-fsu...
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Bridges: Past, Present, and FutureBridges: Past, Present, and Future
Dr. Lisa SpainhourDept. of Civil and Environmental Eng.
FAMU-FSU College of Engineering
What Defines a Bridge?What Defines a Bridge?
Four main factors define a bridgeSpan (simple, continuous, cantilever)Travel surface (deck, pony, through)Form (beam, arch, truss, etc.)Material (timber, concrete, steel)
Bridge Basics—Span TypesBridge Basics—Span Types
Bridge Basics—Travel Surface
Bridge Basics—Travel Surface
Bridge Basics—TypesBridge Basics—Types
Five main types of bridgesBeam bridgeTruss bridgeArch bridgeCable-stayed bridgeSuspension bridge
Bridges may combine different types
Beam BridgesBeam 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
Beam Bridges—TypesBeam Bridges—Types
Beam Bridges—ExamplesBeam Bridges—Examples
Pony plate girder bridge
Stone footbridges
Beam Bridges—ExamplesBeam Bridges—Examples
I-44, 16th St. Overpass, OK
I-540/I-70 Interchange, NC
Lincove Viaduct, NC
Truss BridgesTruss Bridges
Overall behavior like a beam with less material in the middleEach member either in tension (e.g. bottom chord) or
compression (e.g. top chord)Rigid because bar ends pinned into trianglesBest for spans < 2000’.
Simple truss Cantilever truss
Truss Bridges—TypesTruss Bridges—Types
Truss Bridges—ExamplesTruss Bridges—Examples
Stillwater Bridge, MN
Smithfield Street Bridge, PABridge No. 1482, MN
Baihe Bridge, China
Covered Truss BridgesCovered Truss Bridges
Town lattice truss (1830’s)
Germantown Covered Bridge, OHInverted bowstring truss (1870’s)
Stone Mt. Covered Bridge, GA
Cantilever Truss BridgesCantilever Truss Bridges
Firth of Forth, Scotland (1890)
Kingston-Rhinecliff Bridge, NY
Arch BridgesArch 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’.
Arch Bridges—TypesArch Bridges—Types
Arch Bridges—ExamplesArch Bridges—Examples
The Pont du GardAqueduct,
France(Ca. 100 AD)
Thomas Aqueduct, MD (1835)
Rio Cobre Bridge,Jamaica (1800)
Wrought-Iron Ties,Cast-Iron Deck
Arch Bridges—Construction
Arch Bridges—Construction
New River Bridge, WV Natchez Trace Arch, TN
Tied Arch Bridges—Examples
Tied Arch Bridges—Examples
Bayonne Bridge, NJ
I-64 Ohio River Bridge, IN
Willamette River Bridge, OR
Suspension BridgesSuspension Bridges
Cables (thousands of steel wires) under tensionTowers under compressionRequire anchorages at ends to resist span
deflection, bending of towersBest for spans of > 3000’.
Suspension Bridges—Examples
Suspension Bridges—Examples
Luding Iron-chain Bridge,Over Dadu River, China(1705-06)
Menai Suspension Bridge,United Kingdom (1826),Removed from service in 1940
Suspension Bridges—Examples
Suspension Bridges—Examples
Humber Bridge,England
Golden Gate Bridge,CA Brooklyn Bridge, NY
Tacoma Narrows Bridge Failure
Tacoma Narrows Bridge Failure
After Failure“Galloping Gertie”
Approach Span, After Failure Replacement Bridge
Cable-Stayed BridgesCable-Stayed Bridges
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’.
Cable-Stayed Bridges—Examples
Cable-Stayed Bridges—Examples
Clark Bridge, ILSunshine Skyway, FL
Normandy Bridge, FrancePuente del V Centerario
Seville, Spain
Cable-Stayed Bridges—Examples
Cable-Stayed Bridges—Examples
Footbridge, Aarhus, Denmark
Salzburg, Austria
Santarem-AlmeirimBridge, Portugal
Cable-Stayed Bridges—Examples
Cable-Stayed Bridges—Examples
Leonard P. Zakim Bunker Hill Bridge,
Over Charles RiverBoston, MA
Bridge Basics—MaterialsBridge Basics—Materials
PastStoneTimber*Iron
PresentSteel*Steel-Reinforced ConcretePrestressed Concrete*
FutureThose with asterisksFiber-Reinforced
Polymers (FRP’s)???
Bridge Materials—FRPBridge Materials—FRP
Wickwire Run Bridge, West Virginia“No-Name Creek”
Bridge, Kansas
Footbridges—Entirely FRPFootbridges—Entirely FRP
Aberfeldy Footbridge, Scotland
Fiberline Bridge, Denmark
Parson’s Bridge, Wales
Modern Timber BridgesModern Timber Bridges
Keystone Wye Bridge, South Dakota, 1968
Gluelam Beams & ArchesShort lengths of treated wood bonded with epoxy
– Stiff, strong components– Custom designed off-site– Natural, aesthetic appearance
Unknown
Modern Timber BridgesModern Timber Bridges
Stress-Laminated Bridge Decks
Short lengths of treated wood run lengthwiseSteel or FRP rods crosswise through holes in deckStressing the rods puts steel in tension, timber in compression. Creates strong, stiff deck.
Wisconsin River Bridge
Steelrodanchorage
Summary/QuestionsSummary/Questions
Four main factors define a bridgeSpan (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?