Suspension Bridges - University of California, Berkeley
Transcription
Suspension Bridges - University of California, Berkeley
Suspension Bridges Professor Filip C. Filippou Department of Civil and Environmental Engineering University of California, Berkeley Verantius’ Pons Ferreus (Iron Bridge ca. 1600 AD) Verantius’ Suspension Bridge (ca 1600 AD) Interesting web sites and some references • http://www.firebirdz.net/tnb/, The Complete Tacoma Narrows Info Center • http://www.iti.nwu.edu/links/bridges/disasters.html, Bridge Disasters • http://www.ketchum.org/wind.html, Bridge Aerodynamics • Why Buildings Fall Down by Matthys Levy and Mario Salvadori, paperback, WW Norton and Company • Why Buildings Stand Up, The Strength of Architecture by Mario Salvadori paperback, WW Norton and Company Menai Straits (1826) 579 ft Clifton bridge (1830-1864), Bristol, England 702 ft Brooklyn Bridge (1863), New York 1595 ft = 486 m Brooklyn Bridge (1863), New York Manhattan Bridge (1909), New York 1470 ft = 448 m Manhattan Bridge (1909) 1470 ft = 448 m Benjamin Franklin Bridge (Philadelphia) 1922-1926 1750 ft = 535 m Golden Gate Bridge (1933-1937) Deck depth = 7.6 m Depth/Span = 1/168 4200 ft = 1280 m Tower height: 748 ft (228 m) Deck width = 27 m Width/Span = 1/47 First Tacoma Narrows Bridge (opened July 1, 1940) Main span: 2,800 ft (840 m) Tower height: 420 ft (126 m) Stiffening girder depth: 8 ft (2.4 m) Deck width: 39 ft Ratio of girder width to span: 1/72 Depth/Span = 1/350 Tacoma Narrows Bridge (economic constraints) So the state scrapped its first design - $11 million - and turned to Leon Moisseiff. Moisseiff, a well-regarded designer and researcher, calculated that a considerably lighter deck -stiffened only by a thin plate girder, not a deep truss - would do, thus cutting the cost to only $6.4 million. Tacoma Narrows (spinning the suspesion cable) First Tacoma Narrows (spinning the suspension cable) The disaster strikes on November 7, 1940 Franklin D. Roosevelt had just returned to the White House from Hyde Park having just won an unprecedented third term as president of the United States. At 10 am PST the wind velocity at the bridge was 42 mph. The bridge center rose and fell 38 times a minute with a 3 ft amplitude. Suddenly, the bridge started twisting violently ... Galloping Gertie Second Tacoma Narrows Bridge (1950) Third Tacoma Narrows Bridge (2001-2005) Third Tacoma Narrows Bridge 2800 ft Severn Bridge (England) (1961-1966) First suspension bridge with hollow box girder with aerodynamic profile 988 m Humber Bridge (England) Main Span 1410 m Deck width 28.5 m 1/47 Deck depth 4.5 m Great Belt Suspension Bridge (Denmark) (1996) Main Span 1624 m Akashi-Kaikyo Bridge (Kobe Japan) (1988-1998) Main span: 6,527 ft (1991 m) Tower height: 927 ft (283 m) Longest Suspension Bridge in the World Name Span Year Akashi Kaikyo Great Belt East Humber Jangyn Tsing Ma 1991 1624 1410 1385 1377 1998 1998 1981 1999 1999 Verrazano Narrows Golden Gate Hoga Kusten Mackinac 1298 1964 1280 1210 1158 1937 1997 1957 Minami (South) 1100 Bisan-Seto 1988 Location Kobe-Naruto Route Halsskov-Sprogoe Kingston-upon-Hull Jiangsu (Yangtze river) Hong Kong (Lantau Island) New York City Japan Denmark U.K. China Hong Kong San Francisco Veda Mackinaw City, Michigan Kojima-Sakaide Route U.S.A. Sweden U.S.A. U.S.A. Japan Next: the Straits of Messina Main Span: 3300 m = 10082 ft Deck width/span 1/55 Straits of Messina: Scylla and Charibde 3300 m