London’s Bridges
Are Not Falling
By Ricky Smetana
Basic Bridge Types
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Girder
Truss
Rigid Frame
Arch
Cable Stayed
Suspension
Girder
• A girder bridge is
perhaps the most
common and most
basic bridge.
• Typical Span Lengths:
10m - 200m
• World's Longest: Ponte
Costa e Silva, Brazil
Total Length: 700m
Center Span: 300m
Truss
• The truss is a simple skeletal
structure.
• Trusses are comprised of many
small beams that together can
support a large amount of weight
and span great distances.
• The most representative trusses
are the Warren truss, the Pratt
truss, and the Howe truss.
• Typical Span Lengths: 40m - 500m
• World's Longest: Pont de Quebec
Total Length: 863m Center Span:
549m
Rigid Frame
• A rigid frame bridge is one in
which the piers and girder are
one solid structure.
• Though there are many
possible shapes, the styles
used almost exclusively these
days are the pi-shaped frame,
the batter post frame, and the
V shaped frame.
Arch
• Arches use a curved structure
which provides a high resistance
to bending forces.
• arches can only be used where
the ground or foundation is solid
and stable.
• Structurally there are four basic
arch types: hinge-less, twohinged, three hinged and tied
arches.
• Typical Span Lengths: 40m - 150m
• World's Longest: New River Gorge
Bridge, U.S.A.
Total Length: 924m Center Span:
518m
Cable Stayed
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A typical cable stayed bridge is a
continuous girder with one or more
towers erected above piers in the middle
of the span. From these towers, cables
stretch down diagonally (usually to both
sides) and support the girder.
Though only a few cables are strong
enough to support the entire bridge, their
flexibility makes them weak to a force we
rarely consider: the wind.
Typical towers used are single, double,
portal, or even A-shaped towers
Cable arrangements also vary greatly.
Some typical varieties are mono, harp,
fan, and star arrangements
Typical Span Lengths: 110m - 480m
World's Longest: Tatara Bridge, Japan
Total Length: 1,480m Center Span: 890m
Suspension
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The suspension bridge allows for the longest
spans.
A typical suspension bridge is a continuous
girder with one or more towers erected above
piers in the middle of the span.
The girder itself it usually a truss or box girder
though in shorter spans, plate girders are not
uncommon. At both ends of the bridge large
anchors or counter weights are placed to hold
the ends of the cables.
The cables pass over a special structure known
as a saddle. The saddle allows the cables to slide
as loads pull from one side or the other and to
smoothly transfer the load from the cables to
the tower.
Typical Span Lengths: 70m - 1,000m+
World's Longest: Akashi Kaikyo Bridge, Japan
Total Length: 3,911m Center Span: 1,991m
Movie with Bridges:
Jumping Off Bridges
-Inspired by invincible friendships, junior high journal entries, heart breaking crushes and
the complexities of losing loved ones, jumping off bridges follows a carefree, adventurous
group of four best friends deep in the trenches of adolescence.
-Throughout the movie the characters had jumped off several different types of bridges.
-And yes the movie is revolved around bridges
Bridge in Book
• The book switches between
three main protagonists,
John Orr, Alex, and the
Barbarian, who turn out to
be different levels of the
psyche of a man who is in a
coma after crashing his car
on the Forth Road Bridge.
• By Iain Banks
Bridge Disasters
• Tay Rail Bridge:
• girder bridge;
• Dundee, United Kingdom;
• Faulty design, construction and
maintenance, collapsed because
of structural deterioration and
wind load exceeding estimate
• Bridge unusable, girders partly
reused, train damaged
• Upper Steel Arch Bridge
• Also known as Honeymoon
Bridge and Falls View Bridge
• Niagara Falls, NY– Niagara Falls,
ON; U.S. and Canada
• Steel arch road bridge
• Ice jam in gorge pushed bridge off
foundations
• Bridge completely destroyed
• Replaced in 1941 by the Rainbow
Bridge.
More Bridge Disasters
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Tacoma Narrows Bridge
Tacoma, WA U.S.
Road bridge, cable suspension with
plate girder deck
Aerodynamically poor form
resulted in aeroelastic flutter.
Bridge partially destroyed, one car
lost, and one dog killed
Became known as "Galloping
Gertie", in the first 4 months after
opening up until its collapse under
aeroelastic flutter.. Since that time
all new bridges have been modeled
in wind tunnels. Rebuilt in 1950;
parallel span opened in 2007.
Famous Bridges
• Akashi-Kaikyo
• Bayonne
• Connecting Kobe on the mainland
with Awaji on Awaji Island (Japan)
• three-span cable-stayed bridge
some 3910 meters in total length
with a center span of 1990
meters.
• The bridge has a wind-proof and
earthquake-resistant
construction, withstanding winds
up to 80 meters per second and
earthquakes reaching 8.5 on the
Richter scale.
• New Jersey/New York, USA
• Steel Arch
• Awarded the prize for Most
Beautiful Steel Arch Bridge of
1931 be the American Institute of
steel construction.
• span: 1,652 feet
More Famous Bridges
• Sydney Harbor
• Steel arch
• Sydney, Australia
• The world's third largest steel
arch bridge.
• span: 1,650 feet
The Physics Involved
• Stress: is produced by forces
• Strain: as a load as applied to an object, that object deforms
just the right amount to produce the required opposing
force. Such a change, expressed as a fraction of the original
size.
• Tension: act or process of stretching something tight.
• Compression: act or process of bending something stiff, or
make smaller