What Kind of Bridge?

Important WordsSpan: the distance between two bridge

supports (column, tower, canyon walls…)Abutment: a. The part of a structure that

bears the weight or pressure of an arch.

b. A structure that supports the end of a bridge.c. A structure that anchors the

cables of a suspension bridge.Girder: a beam, made of steel, wood, or

reinforced concrete, used as a main horizontal support in a building or bridge – can be a box girder or truss girder

Girders

http://www.fhwa.dot.gov/bridge/steel/pubs/if12052/volume05.pdf

More Important WordsCompression: a force that compresses or

shortens the thing it is acting on. Pushing together force.

Tension: a force that expands or lengthens the thing it is acting on. Pulling apart force.

http://www.howstuffworks.com/bridge.htm

Beam BridgeA rigid horizontal structure that is resting on two piers, one on each side.

LoadCompression

Tension

Reaction Force Reaction ForceCompression

Beam BridgeTypical Span Lengths: 10m - 200m (can be up to 300m +)World's Longest: Shipanpo Bridge, China (restressed Concrete Girder)

Center Span: 330m

Ponte Costa e Silva (Rio-Niteroi Bridge), Brazil (Steel Box/Plate Girder)

Center Span: 300m

http://brasiliabsb.com/tabfotos.htm

http://wikipedia.com

Continuous Span Beam Bridge

Several Beam Bridges linked togetherWorld’s Longest (over water): Lake Ponchartrain Bridge in Louisiana – 38.4 km (nearly 24 miles) long

http://worldslongestbridges.blogspot.com/2009/12/worlds-longest-bridges.html

More Continuous SpanWorld’s Longest (high speed railroad): Danyang – Kunshan Grand Bridge between Beijing and Shanghai – 164.8 km (about 120 miles) long (longest span 80 meters)

World’s Longest (over water & land): Jiaozhou Bay Bridge in China – 42.5 km (about 26 miles) long (longest span 260 m)

Cantilever BridgeCantilever bridges are a modified form of beam bridge, with the support being placed not at the end, but somewhere in the middle of the span. A cantilever is a structure or beam that is unsupported at one end but supported at the other, like diving boards. 

Queensboro (59th St) Bridge over the East River

http://www.richmangalleries.com/cantilever_bridges.htm

Cantilever Bridge

Cantilever BridgeTypical Span Lengths: 40m - 500mWorld's Longest: Pont de QuebecTotal Length: 863mCenter Span: 549m

www.sepaq.com/Photos/J380/batPontQuebecC.jpg

Firth of Forth Bridge Under Construction

(1890)

http://www.nas.gov.uk/about/071004.asphttp://www.rsgs.org/ifa/gems/bridgegap.html

Firth of Forth Bridge - Scotland

http://www.edinburgh-scotland.net/images/ForthBridge11L.jpg

Basic Spans

http://www.slideshare.net/illpa/bridge-1403689

TrussSupporting structure - lattice work added to many types of bridges. Trusses are skeletal structures made up of many small beams (normally in the shape of triangles). As the size of a beam bridge increases, so must the size of the truss

Forces in a Bridge with Trusses

load

tension

Compression

Reaction force

http://www.britannica.com/EBchecked/topic/79272/bridge

Arch BridgeAn arch bridge is a semicircular structure with abutments on each end. The arch naturally brings the weight (a force) of the load from the roadway to the abutments. Used by the ancient Romans. Can be made out of brick or stone.

Load

Compression

Reaction Force

http://www.matsuo-bridge.co.jp/english/bridges/index.shtm

Arch BridgeTypical Span Lengths: 40m – 150m (can be 500m +)World's Longest: Chaotianmen Bridge, Chongqing, ChinaTotal Length: 1741 mCenter Span: 552 m http://mainbridge.co.cc/?p=74

Arch BridgeUSA’s Longest: New River Gorge Bridge, U.S.A. Total Length: 924mCenter Span: 518m

http://cs101.wvu.edu/wvscenes

http://www.post-gazette.com/pg/06251/719452-37.stm

Suspension BridgeThe deck of the bridge is held up by cables. main cables strung over two towers and anchored

on either end vertical (or hanging) cables connect to the main

cables and connect to the road (called suspenders)

towers support most of the road deck’s weight.

http://www.brantacan.co.uk/starterpages.htm

Tension LoadCompression

Reaction Force

Anchorage

SuspensionTypical Span Lengths: 70m -

1,000m+ (can be close to 2000 m)World's Longest: Akashi Kaikyo

Bridge, JapanTotal Length: 3,911mCenter Span: 1,991m

www.bergen.org/.../2002/wp_bridge/akashi.jpg

Longest U.S. Suspension BridgesRank Name Location Feet Complete

d1. Verrazano-Narrows Lower New York Bay 4,260 19642. Golden Gate San Francisco Bay 4,200 19373. Mackinac Mackinac Straits, Mich. 3,800 19574. George Washington Hudson River at New York

City 3,500 1931

5. Tacoma Narrows II Puget Sound at Tacoma, Wash.

2,800 1950

6. San Francisco–Oakland Bay

San Francisco Bay 2,310 1936

7. Bronx–Whitestone East River, New York City 2,300 19398. Delaware Memorial Delaware River near

Wilmington, Del. 2,150 1951,

19689. Seaway Skyway St. Lawrence River at

Ogdensburg, N.Y.2,150 1960

10. Walt Whitman Delaware River at Philadelphia

2,000 1957http://www.infoplease.com/toptens/

Cable Stayed BridgeA continuous beam with one or more towers built above piers. From these towers, cables stretch down diagonally (usually to both sides) and attach to the girder to support the bridge deck.

LoadTension

Reaction Forcehttp://www.brantacan.co.uk/starterpages.htm

Compression

Cable StayedTypical Span Lengths: 110m - 480m (can be 1000m +)World's Longest: Russky Bridge, RussiaTotal Length: 3,100 mCenter Span: 1,104 m www.veooz.com 

http://trimet.org/pdfs/pm/general_docs/HNTB_July15_Low_Res.pdf

122 - 366 m

45 - 137 m

229 - 610 m

152 – 914+ m

Every 100 ft = about 30.5 m

Summary of Forces on Bridges

Summary of Forces on Bridges