1 1 IABSE CONFERENCE 2007, WEIMAR, GERMANY EVOLUTION OF BRIDGE TECHNOLOGY BY MAN-CHUNG TANG Chairman of the Board, T.Y. LIN International Keynote Lecture - IABSE Conference - Weimar 2007 2 1. What has been the most important factor in the evolution of bridge technology? 2. Would the Romans and the Egyptians be able to build our bridges if they had the construction materials of today? 3 Evolution: Human beings started building bridges many thousand years ago. What made our bridges different from theirs? 4 First of all, What are our bridges made up of? Let us look at the bridges we have today.
Transcript
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IABSE CONFERENCE 2007, WEIMAR, GERMANY
EVOLUTION OF BRIDGE TECHNOLOGY
BYMAN-CHUNG TANG
Chairman of the Board, T.Y. LIN International
Keynote Lecture - IABSE Conference - Weimar 2007
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1. What has been the most important factor in the evolution of bridge technology?
2. Would the Romans and the Egyptians be able to build our bridges if they had the construction materials of today?
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Evolution:Human beings started building bridges many thousand years ago.
What made our bridges different from theirs?
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First of all,
What are our bridges made up of?
Let us look at the bridges we have today.
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In the several thousand years since we started building bridges, we have built only
FOUR TYPES OF BRIDGES
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In the several thousand years since we started building bridges, we have built only
FOUR TYPES OF BRIDGES
Girder bridgesArch bridges
Suspension bridgesCable-stayed bridges
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Extradosed Bridge is a combination of girder bridge and cable-stayed bridge
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We can have other combinations too
Partially cable-supported girder bridges.
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Franz Dishcinger proposed this combination of
cable-stayed and suspension bridge
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But, still only these four basic types.
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All four types of bridges have existed for millenniums!
SUSPENSION
GIRDER
CABLE-STAYED
STRESS RIBBONCONT. BEAM
They were not as sophisticated.
But, conceptually correct nevertheless!
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All four types of bridge have existed for millenniums!
SUSPENSION
GIRDER
CABLE-STAYED
STRESS RIBBONCONT. BEAM
They were not as sophisticated. But, conceptually correct nevertheless!
They build them
IntuitivelyEven before
we gave them a name.
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All four types of bridge have existed for millenniums!
SUSPENSION
GIRDER
CABLE-STAYED
STRESS RIBBONCONT. BEAM
They were not as sophisticated. But, conceptually correct nevertheless!
They used Construction materials
available naturally!Wood, vines, stone, ropes,
etc.
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Sad to admit, In the last few thousand years,
We have NOT invented any new bridge type.
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Because we have not invented anything
It is an evolutionNot any revolution.
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Because we have not invented anything
It is an evolutionNot any revolution.
But, our bridges today are
Bigger, stronger, more sophisticated, more durableand, more predictable.
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Today’s bridges
Bigger, stronger,
more sophisticated,
and
more durable
CRAIGELLACHIE, 1815
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What affects the evolution of bridge technology?
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What affect the evolution of bridge technology?
Science - structural theoriesConstruction equipmentConstruction material
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Look at these old, old structures
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What affect the evolution of bridge technology?
Structural theoriesConstruction equipmentConstruction material
?
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What affect the evolution of bridge technology?
Structural theoriesConstruction equipmentConstruction material ?
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They did it empirically!
Structural theoriesConstruction equipmentConstruction material
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They did it empirically!
Structural theoriesConstruction equipmentConstruction material
They made it work, somehow!
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Material has been the most important factor in the evolution!
Structural theoriesConstruction equipmentConstruction material
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Creation of a bridge - A Flow Chart
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A Flow Chart
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Two Dominating Materials in the History of Bridge Construction:
Stone
Steel
Dominating influence
&
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Two main eras in bridge evolution:
Arch Era2000BC– 1850ADAlmost 4000 years
Contemporary Era1850AD - now Only about 160 years
Stone
Steel
&
2000
BC
Rom
an
Em
pire
Con
tem
pora
ry E
ra18
50 A
D
2007
AD
Arch Era
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ARCH ERAStone
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Two thousand years ago, the only construction material available was STONE.
STONE can take high compression,but very little tension.
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Arch is the only bridge type that does not require tensile capacity of the material
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Arch is the only bridge type that does not require tensile capacity of the material
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The Romans built many spectacular
arch bridges
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The Romans built many spectacular
arch bridges
Over 2000 years ago!
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The Romans built many spectacular
arch bridges
The Roman arches are all semi-circular
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Anji Bridge, Zhaozhou, ChinaSpan 37m, Rise 7m. Built 600AD
18.5m
37m
37m
7m
A Roman ArchZhaozhou Bridge
The first non-semi-circular arch bridge.
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Semi-circular vs Segmental
7m
18.5m
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The Romans were really masters on stone arches!
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The Romans were really masters on stone arches!
But, for almost one and a half millennia after the Romans,
nothing new happened!
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Contemporary EraFrom 1850 until now
Then came the
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Contemporary EraFrom 1850 until now
Only about 160 years. But there were more bridges built in these 160 years
than the 4000 years before it.
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Contemporary EraFrom 1850 until now
Steel
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There was a transition period that we had IRON as construction material.
Iron is much stronger than stone, but its tensile capacity is still very limited.
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There was a transition period that we had IRON as construction material.
Iron is much stronger than stone, but its tensile capacity is still very limited.
We may categorize iron as a primitive form of steel, as far as construction material is concerned.
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The Chinese started building iron chain suspension bridges around 600 AD
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A suspension bridge in Tibet
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A bridge in Tibet
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A bridge in Tibet
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Coalbrookdale Bridge,Span 30.5mBy Thomas Pritchard, 1779
Dom Luis I BridgeBy Gustav Eiffel and Th. Seyrig,
1885, span = 172m
Iron arch bridges was popular for a period of time
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Menai Bridge – the first major suspension Bridge
Designed by Thomas Telford, span = 176mbased on a patent by James Findley, completed in 1826.
With iron eye bar chains as main cable.
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Menai Bridge – the first major suspension Bridge
Designed by Thomas Telford, span = 176mbased on a patent by James Findley, completed in 1826.
With iron eye bar chains as main cable.
B
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SteelMass production processes were introduced in the mid 1850s
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SteelMass production processes were introduced in the mid 1850s
It changed the entire landscape of bridge construction
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SteelMass production processes were introduced in the mid 1850s
It changed the entire landscape of bridge construction
Steel used for girders – boxes and trussesSteel bars for concrete reinforcement
Steel cold drawn wires for cablesSteel wires for prestressing
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SteelMass production processes were introduced in the mid 1850s
Three landmark steel bridge structures before the 20th century:
1. St. Louis Bridge by James Eads, 1874 2. Brooklyn Bridge by the Roeblings, 1883
3. Firth of Forth Bridge by John Fowler and Benj. Baker, 1889
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The St Louis Bridge over the Mississippi.Completed 1874, Spans 153m + 158.5m + 153mDesigned by James Eads
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The Brooklyn Bridge, New York CityCompleted 1883, Span 486m.Designed by John and Washington Roebling
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The Firth of Forth Rail Bridge, Scotland.Completed 1889, Span 521m.Designed by John Fowler and Benjamin Baker
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Then came
A tale of three bridges, in early 1900s……………………
Hellgate Bridge, Sydney Harbor BridgeBayonne Bridge
The Hellgate Bridge in New York by Gustav Lindenthal. Span = 298m.
Completed in 1916.
Sydney Harbor Bridge. Span = 503m by Ralph Freemann, Const. 1924 - 1932.
Bayonne Bridge in NY. By Othmar Ammann
Span = 503.6m Constr. 1928 - 1931
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New River Gorge, USA, 1978Span = 518.3m
Lupu, China, 2004Span = 550m
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Competition of Span LengthsSpan Year
Hellgate, NY Gustav Lindenthal 298. 1916.Sydney Harbor Ralph Freemann 503 1932. Bayonne, NY Othmar Amman 503.6 1931 New River Gorge, WV Michael Bakers 518.3 1978Lupu, Shanghai Lin Yuan Pui 550 2004Caotienmen, Chongqing 552 2008
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Competition of Arch Span Length
0
100
200
300
400
500
600
1850 1900 1950 2000 2050
Year
Spa
n Le
ngth
s (m
)
Hel
lgat
e
Sydn
ey H
arbo
rBa
yonn
e
New
Riv
er G
orge Lu
puC
aotie
nmen
Pia
Mar
iaG
arab
it
St. L
ouis
Luis
I
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Long span suspension bridges
became possible only after high strength wire was available.
Evolution:1. What was the most important factor in
the evolution in bridges?
2. Would the Romans and the Egyptians be able to build our bridges if they had the construction materials we have?
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Evolution:1. What was the most important factor in
the evolution in bridges?
2. Would the Romans and the Egyptians be able to build our bridges if they had the construction materials we have?
Obviously, no one knows. But let us take an example.
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Aerodynamics
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Most early suspension bridges were failed by wind.
Around 1800, James Findley patented the stiffened suspension bridge.
Most of those bridges were destroyed by wind.
Aerodynamics
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Most early suspension bridges were failed by wind.
Around 1800, James Findley patented the stiffened suspension bridge.
Most of those bridges were destroyed by wind.
Around 1870, John Roebling installed inclined cables in Wheeling Bridge to help mitigate wind vibration problems. It worked!
He found a solution in less than 70 years
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Aerodynamics
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Most early suspension bridges were failed by wind.
Around 1800, James Findley patented the stiffened suspension bridge.
Most of those bridges were destroyed by wind.
Around 1870, John Roebling installed inclined cables in Wheeling Bridge to help mitigate wind vibration problems. It worked!
He found a solution in less than 70 years
.
Aerodynamics
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Most engineering solutions came before the theory.Engineering is an art, not a science!
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Most engineering solutions came before the theory.Engineering is an art, not a science!
And,
Looking at how the Egyptians, the Romans and the Chinese built their spectacular structures,
Structural theories and modern equipments do not seem that important.
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Most engineering solutions came before the theory.Engineering is an art, not a science!
To answer my second question, I may dare say that given the materials we have today,
The Romans and the Egyptians would most probably be able to build our bridges too!
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ButEvolution of bridge technology can only happen if we have the opportunity to build bridges.
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ButEvolution of bridge technology can only happen if we have the opportunity to build bridges.
Two pre-requisites determine if a bridge will be built:
1. Affordability2. Necessity
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ButEvolution of bridge technology can only happen if we have the opportunity to build bridges.
Two pre-requisites determine if a bridge will be built:
1. Affordability2. Necessity
Cost vs. Value
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COSTS:
Planning
Right of Way
Construction
Maintenance
Others
VALUE:
Functional value
Community Value
Political Value
Aesthetic Value
Others
<=>
NO!
YES!
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COSTS:
Planning
Right of Way
Construction
Maintenance
Others
VALUE:
Functional value
Community Value
Political Value
Aesthetic Value
Others
<=
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COSTS:
Planning
Right of Way
Construction
Maintenance
Others
VALUE:
Functional value
Community Value
Political Value
Aesthetic Value
Others
<=
Related to the Living Standard.
Related to Construction cost index.
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COSTS:
Planning
Right of Way
Construction
Maintenance
Others
VALUE:
Functional value
Community Value
Political Value
Aesthetic Value
Others
<=
Related to the Living Standard.
Related to Construction cost index.
As our society progresses,
the living standard usually increases faster than the construction costs.
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That means, some bridges we can not afford today may become affordable tomorrow.
As our society progresses,
the living standard usually increases faster than the construction costs.
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That means, some bridges we can not afford today may become affordable tomorrow.
That means, we will be building bigger and bigger bridges, as time goes by!
As our society progresses,
the living standard usually increases faster than the construction costs.
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That means, some bridges we can not afford today may become affordable tomorrow.
That means, we will be building bigger and bigger bridges, as time goes by!
As our society progresses,
the living standard usually increases faster than the construction costs.
Good news for us bridge engineers!
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ButEvolution of bridge technology can only happen if we have the opportunity to build bridges.
Two pre-requisites determine if a bridge will be built:
1. Affordability2. Necessity
When do we need a new bridge?
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Periods with Great Opportunities: The expansion of the Roman EmpireThe industrial revolutionThe re-construction after World War IICurrently, in China, India and other developing countries.
ButEvolution of bridge technology can only happen if we have the opportunity to build bridges.
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ButEvolution of bridge technology can only happen if we have the opportunity to build bridges.
Periods with Great Opportunities: The expansion of the Roman Empire - Stone Arch BridgesThe industrial revolution - Steel productionThe re-construction after World War IICurrently, in China, India and other developing countries.
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ButEvolution of bridge technology can only happen if we have the opportunity to build bridges.
The Expansion of the Roman Empire - Stone Arch BridgesThe industrial revolution - Steel productionThe re-construction after World War II -
ButEvolution of bridge technology can only happen if we have the opportunity to build bridges.
Periods with Great Opportunities:The Expansion of the Roman Empire - Stone Arch BridgesThe industrial revolution - Steel productionThe re-construction after World War II -
Currently, in China, India and other developing countries.?
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ButEvolution of bridge technology can only happen if we have the opportunity to build bridges.
Periods with Great Opportunities:The Expansion of the Roman Empire - Stone Arch BridgesThe industrial revolution - Steel productionThe re-construction after World War II -
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