suspension bridges - Florida International University

SUSPENSION BRIDGES
Dalila Fernandez
Marisol Salas
Yamilet Senespleda
Florida International University
EGN 1033 TECHNOLOGY HUMANS AND SOCIETY
Prof: Dr. Sabri Tosunoglu
Anatomy of a Suspension Bridge
Deck - For pedestrian, train, and/or automobile traffic.
Supports - The towers are the supports.
Span - Describes the distance between towers.
Foundations - The supports rest on the foundations.
Approaches - The approaches are the roads leading up to the bridge.
Long wire cables - are strung over the towers and secured to the
anchors on land.
Hangers - run from the cables to the deck hold it up.
Suspension Bridge
ƒ It is a bridge that consists of two or more towers (or
pylons) one on either end of the central span.
ƒ It has two or more cables slung between them.
ƒ The bridge deck is suspended from vertical cables
or rods attached to the main cables.
ƒ The bridge will usually have two smaller spans,
running between either pair of towers and the land.
History of Suspension Bridges
Origins
ƒ The primitive suspension
bridge are found in South
America, Africa, and
Asia.
ƒ These simple crossing
devices were just ropes
thrown across a narrow
canyon or river
ƒ Later, wooden footways
were added between the
ropes.
Origins
Many of the rope
suspension bridges
have been repaired
and rebuilt over the
centuries using the
same natural materials
and traditional
techniques. They
remain in constant use
to this day.
Origins
Suspension bridges were constructed with iron chain cables over
2000 years ago in China and India.
Ancient Tibetan Iron Chain Bridge
Evolution of Modern Suspension
Bridges
Beginning of the Modern Suspension Bridges
Progress of the Center Span Length in the United
States
New Trends in Structures in Europe after the 1960s
Developments in Asia since the 1970s
Beginning of Modern Suspension Bridges
The world's first wire-cable suspension bridge was a 124m
temporary walkway built in 1816 for the workers of wire
manufacturers Josiah White and Erskine Hazard over the
Schuylkill in Philadelphia.
The world's first permanent wire-cable suspension bridge,
designed by Séguin and Guillaume-Henri Dufour, was
opened to the public in Geneva in 1823.
Beginning of Modern Suspension Bridges
The British preferred to use chains. They achieved light and
beautiful spans that contrasted with colossal suspension towers.
The United Kingdom's first large-scale suspension bridge was the
Menai Bridge (1826 ) on the London to Holyhead road over the Strait
in North Wales.
Progress of the Center Span Length in the Second Half of
the 19th Century in the United States
In 1867, John A Roebling began with the design of the Brooklyn
Bridge. It took two years to plan and check every detail, and 14
more years to build the bridge. The Brooklyn Bridge was
completed in 1883 with a span of 486 m, across New York’s East
River, where steel wires were first used.
Brooklyn Bridge
Progress of the Center Span Length in the First Half of
the 20th Century in the United States
In 1903, the Manhattan Bridge, with a center span of 448 m, and in 1909 the
Williamsburg Bridge, with a center span of 488 m, were constructed on the upper
reaches of New York’s East River.
Manhattan Bridge
Williamsburg Bridge
Progress of the Center Span Length in the First Half of the
20h Century in the United States
The first center span longer than 1000 m was the George Washington Bridge
across the Hudson River in New York.
It was completed in 1931 with a center span of 1067 m.
George Washington Bridge
Progress of the Center Span Length in the First Half of the
20th Century in the United States
In 1936, the San Francisco-Oakland Bay Bridge, which was twin suspension
bridge with a center span of 704 m, and in 1937, the Golden Gate Bridge with a
center span of 1280 m were constructed in the San Francisco Bay area.
San Francisco-Oakland Bay Bridge
Golden Gate Bridge
Progress of the Center Span Length the First Half of the 20th Century
in the United States
The Tacoma Narrows Bridge, with a center span of 853 m, opened to traffic on
1st July 1940 .
4 months after its completion it finally collapsed under just 19 m/s wind.
New Trends in structures in Europe after the 1960s
In the United Kingdom
The Severn Bridge(1977), with a center span of 988 m, the Humber Bridge, with
a third longest center span of 1410 m, were both constructed with a box girder
and diagonal hanger ropes simultaneously .
Humber Bridge
Severn Bridge
Developments in Asia since the 1970s
In Japan, the Akashi Kaikyo Bridge, completed in 1998 with the
world longest center span of 1991 m, represents the accumulation of
bridge construction technology to this day.
Akashi Kaikyo Bridge
Advantages Over Other Types of
Bridges
ƒ The center span can be made very long in proportion to
the amount of materials required, allowing the bridge to
economically span a very wide canyon or waterway.
ƒ It can be built high over water to allow the passage of
very tall ships.
ƒ Neither temporary central supports nor access from
beneath is required for construction.
ƒ Being relatively flexible it can flex under severe wind
and seismic conditions, where a more rigid bridge
would have to be made much stronger and so also
heavier.
Disadvantages Over Other Types of
Bridges
ƒ
Lack of stiffness and the bridge may become unstable in
turbulent and strong wind conditions and so require temporary
closure to traffic.
ƒ
Being flexible in response to concentrated loads the structure is
generally not used for regional rail crossings, which concentrate
the maximum "live" loading at the location of the locomotives.
ƒ
Under severe wind loading the towers apply a large torque force
in the ground, and thus require very expensive foundations.
Longest Suspension Bridges in the
World
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Akashi-Kaikyo Bridge (Japan) 1,991 metres - 1998
Izmit Bay Bridge (Marmara Sea, Turkey) 1,668 metres 2004
Great Belt Bridge (Denmark) 1,624 metres - 1998
Humber Bridge (England) 1,410 metres - 1981 (The largest from 1981 until
1998.)
Jangyn Bridge (China, Yangtze River) 1,385 metres - 1997
Tsing Ma Bridge (Hong Kong) 1,377 metres - 1997 (with road and metro)
Verrazano Narrows Bridge (USA) 1,298 metres - 1964 (The largest from
1964 until 1981.)
Golden Gate Bridge (USA) 1,280 metres - 1937 (The largest from 1937
until 1964.)
Höga Kusten Bridge (Sweden) - 1,210 metres - 1997
Mackinac Bridge (USA) 1,158 metres - 1958
Tacoma Bridge
Tacoma Bridge
ƒ
Third Longest at that time (1940)
ƒ Structural Failure
ƒ Collapse with only 42 mph (designed for 120 mph)
ƒ Wind motion created Resonance
Tacoma Bridge
ƒ Video
Tacoma Bridge
ƒ Reconstruction
ƒ Scale models
ƒ Wind tunnel testing
Tacoma Bridge
ƒ 1950 Reopening
ƒ New second span
Akashi Kaikyo
In Japan, the Akashi Kaikyo Bridge, completed in 1998 with the world longest
center span of 1991 m, represents the accumulation of bridge construction
technology to this day.
Akashi Kaikyo
ƒ Facts
ƒ Location: Kobe and Awaji-shima, Japan
ƒ Completion Date: 1998
ƒ Cost: $4.3 Billion
ƒ Length: 12,828 feet
ƒ Type: Suspension
ƒ Purpose: Roadway
ƒ Materials: Steel
ƒ Longest Single Span: 6,527 feet
ƒ Engineer(s): Honshu-Shikoku Bridge Authority
Akashi Kaikyo
ƒ The Akashi Kaiko Bridge was designed to
support hurricanes, tsunamis, and earthquakes
that affect the island almost annually.
ƒ tuned mass dampers (TMDs)
ƒ the Akashi Kaikyo can handle 180 mph winds,
and it can withstand an earthquake with a
magnitude of up to 8.5 on the Richter scale.
Akashi Kaikyo
ƒ Length comparison
Akashi Kaikyo
w Length bridge: 8 Sears Towers.
w
cables total length:circle the earth 7.5 times.
w The Great Hanshin Earthquake stretched the bridge an
additional three feet.
w The bridge holds three records: it is the longest, tallest,
and most expensive suspension bridge ever built.
Conclusion
ƒ Impact in Society
ƒ Engineering ethical concerns of pushing limits
of technology versus the risks that this can carry
generates a debate that is going to be always
present in the mind of engineers and society in
general.
QUESTIONS?