9 Beam Bridges—Examples I-540/I-70 Interchange, NCLincove Viaduct, NCI-44, 16th St. Overpass, OK
10 Truss BridgesSimple trussCantilever trussOverall 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’.
24 Cable-Stayed Bridges Cables under tension Cables under tensionTowers, deck under compression (w/post-tensioning)No end anchorages, require less cable, and are faster to build than suspension bridgesBest for spans of 1000’ to 3000’.
25 Cable-Stayed Bridges—Examples Sunshine Skyway, FLClark Bridge, ILPuente del V CenterarioSeville, SpainNormandy Bridge, France
26 Cable-Stayed Bridges—Examples Footbridge, Aarhus, DenmarkSantarem-AlmeirimBridge, PortugalSalzburg, Austria
27 Cable-Stayed Bridges—Examples Leonard P. Zakim Bunker HillBridge,Over Charles RiverBoston, MA
28 Bridge Basics—Materials PastStoneTimber*IronPresentSteel*Steel-Reinforced ConcretePrestressed Concrete*FutureThose with asterisksFiber-Reinforced Polymers (FRP’s)???
29 Bridge Materials—FRP Wickwire Run Bridge, West Virginia “No-Name Creek”Bridge, Kansas
31 Modern Timber Bridges Gluelam Beams & Arches Short lengths of treated wood bonded with epoxyStiff, strong componentsCustom designed off-siteNatural, aesthetic appearanceKeystone Wye Bridge,South Dakota, 1968Unknown
32 Modern 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 BridgeSteelrodanchorage
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/conditionsWhat factors affect the selection/design of a bridge?