Training

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Concrete 99Sydney May 1999
Arch Structures - Spanning Past Present and
Future Doug Jenkins Reinforced Earth Engineering
Manager
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The Sydney Opera House and Harbour Bridge
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Gladesville Bridge
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Why Arches?
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Arches are efficient in use of materials
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Arch behaviour is now well understood
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Arches are now economical to construct
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Early Arch Bridges
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The Landscape Arch, Utah
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The Industrial Revolution
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Telfords Proposal for London Bridge
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Theories of Arch Design
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Robert Hooke, 1676

• "The true mathematical and mechanical form of all
  manner of arches for building, with the true
  butment necessary to each of them. A problem
  which no architectonick writer hath ever yet
  attemted, much less performed
• "As hangs the flexible line, so but inverted will
  stand the rigid arch."

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David Gregory

• "When an arch of any other figure is supported,
  it is because in its thickness some catenaria is
  included"

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Parabolic arch enclosing a catenary
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An old photograph of Pontypridd Bridge
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An-Ji Bridge
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The Blackfriars Committee

• Eight gentlemen of the most approved knowledge
  in building geometry and mechanics
• A clergyman
• The Astronomer Royal
• A Teacher of medicine
• A lawyer
• Two professors

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Samuel Johnson

• "If the elliptical arch be equally strong with
  the semicircular, that is, if an arch, by
  approaching to a straight line, looses none of
  its stability, it will follow that all arcuation
  is useless
• But if a straight line will bear no weight, which
  is evident to the first view, it is plain like
  wise that an ellipsis will bear very little, and
  that as an arch is more curved its strength is
  increased."

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Publicus (believed to be Robert Mylne himself)

• "so that, if I understand it right, all from the
  haunches of the arch downward becomes a pier or
  abutment, to support a small part of the arch in
  the middle as a segment of a circle.
• This middle part, if built like other arches
  would make a lateral pressure against these
  abutments, but to take that away he has placed
  cubical stones, which he calls joggles, in the
  joints of the arch so that every stone tends to
  fall perpendicularly by its being carried along
  with the one above it, and nor shoved aside as in
  other arches, which is the cause of the lateral
  pressure."

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The Twentieth Century
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A Monier Arch Bridge
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Grafton Road Bridge, Auckland
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Salginatobel Bridge
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Floating Formwork for Plougastel Bridge
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Today and the Future
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Shin Hamadera Bridge, Japan
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Properties of the ideal arch material

• High compressive strength at comparatively low
  cost.
• The ability to form any desired shape cheaply and
  accurately.
• Erection without elaborate formwork.
• Low maintenance and excellent durability,
  particularly under compression.

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