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?