Bridge Engineering (9-1) Suspension Bridges

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Bridge Engineering (9-1) Suspension
Bridges

• Components
• Anchorage (blocks or tunnel type),
  towers, main cables, hangers, stiffened (box)
  girder and deck, substructure and foundation
• II. Form an arch upside down or the shape of a
  catenary
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Bridge Engineering (9-1) Suspension
Bridges

• III. Anchorage
• 3.1 The anchorage, constructed as a concrete
  block or by tunneling the ground, forms a giant
  weight to anchor the bridge and transmit the
  tension generated through the cables firmly to
  ground.
• 3.2 The anchorage type is determined by the
  terrain where the anchorage points are
  constructed.
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Bridge Engineering (9-1) Suspension
Bridges

• III. Anchorage
• 3.3 A general type anchorage that supports
  unidirectional forces transmitting through
  cables. (One block for one bridge).
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Bridge Engineering (9-1) Suspension
Bridges

• III. Anchorage
• 3.4 An anchorage of a type that supports
  bi-directional forces transmitting through
  cables. (One block for two bridges)
• __located between two bridges and serving as
  two anchorage points.
• __cable strands crossing each other in the
  air before entering the anchorage.
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Bridge Engineering (9-1) Suspension
Bridges

• III. Anchorage
• 3.4 Bi-directional forces transmitting type
  __The Kurushima Kaikyo Bridge use four
  anchorages for which three types of forms are
  employed.
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Bridge Engineering (9-1) Suspension
Bridges

• III. Anchorage
• 3.5 .1 A tunnel type anchorage which allows
  minimum alterations to be made to the existing
  landform.
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Bridge Engineering (9-1) Suspension
Bridges

• III. Anchorage
• 3.5.2 Cable anchor frames securing the cables to
  the tunnels.
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Bridge Engineering (9-1) Suspension
Bridges

• IV. Tower
• 4.1 The main tower functions to transmit forces
  through the cables and into the main tower
  foundation.
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Bridge Engineering (9-1) Suspension
Bridges

• IV. Tower
• 4.1 The towers can be prefabricated in the
  plants or cast in situ.The blocks for the main
  tower were fabricated at the shop in blocks 6 m
  in length. The blocks are erected in the field
  using a climbing type of tower crane in
  building-block fashion to form the main tower. 9
  Thursday, December 04, 2014

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Bridge Engineering (9-1) Suspension
Bridges

• IV. Tower
• 4.1
• Towers of Kurushima Kaikyo Bridge The blocks
  for the main tower were fabricated at the shop in
  blocks 6 m in length. The blocks are erected in
  the field using a climbing type of tower crane in
  building-block fashion to form the main tower.
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Bridge Engineering (9-1) Suspension
Bridges

• V. Cables
• 5.1 Cables usu. of high tensile steel wires
  support bridge girders and other loads, including
  vehicle loads, and transmit these dead and live
  loads into the anchorage points.
• 5.2 Wires, strands, and ropes
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Bridge Engineering (9-1) Suspension
Bridges

• V. Cables
• 5.2 Wires, strands, and ropes
• 5.2.1Galvanized bridge wire for parallel wire
  bridge cables. Recommended diameter .196 inch.
• 5.2.2 Galvanized bridge strand--consists of
  several bridge wires, of various
  diameterstwisted together.
• 5.2.3Galvanized bridge rope--consists of six
  strands twisted around a strand core.
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Bridge Engineering (9-1) Suspension
Bridges

• 5.3 Types of Cables
• 5.3.1 Parallel wire cables This type of
  cable is made up of a large number of individual
  wires parallel to one another. Neither the cables
  nor the wires are twisted in any manner. The wire
  is shipped to the site of the bridge on reels and
  the individual wires are installed or' "spun" on
  the bridge and later compacted together to form a
  round crosssection. Cables of this type are used
  on monumental structures, such as the Golden Gate
  Bridge and the George Washington Bridge.
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Bridge Engineering (9-1) Suspension
Bridges

• 5.3.2 Parallel Strand Cables, Closed
  Construction--These consist of several
  prefabricated Galvanized Bridge Strands, all laid
  parallel and in contact with one another. Wood or
  aluminum fillers are used to bring the cable to a
  circular cross-section, after which the whole
  cable is wrapped with wire for protection. The
  cable may contain 7, 19 37, 61, 91 or 127
  strands.
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Bridge Engineering (9-1) Suspension
Bridges

• 5.3.3 Parallel Strand Cables, Open
  Construction--This type of cable consists of
  several prefabricated galvanized bridge Strands
  which are all laid parallel to one another and
  not in contact. The strands are usually arranged
  in the form of a rectangle and the cable may
  contain 2, 4, 6, 9, 12, 16, 20, 24 or 30 strands.
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Bridge Engineering (9-1) Suspension
Bridges

• 5.3.4 Parallel Rope Cables, Open
  Construction--These are the same as Parallel
  Strand Cables except that Galvanized Bridge Rope
  is used in place of Bridge Strand.
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Bridge Engineering (9-1) Suspension
Bridges

• 5.3.5 Single Rope or Single Strand Cables--These
  are used for small structures.
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Bridge Engineering (9-1) Suspension
Bridges

• 5.4 A single-stranded cable with a hexagonal in
  cross section is formed by tying together 127
  high-tension galvanized steel wires each about 5
  mm in diameter. (as used for Kurushima Kaikyo
  Bridge)
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Bridge Engineering (9-1) Suspension
Bridges
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Bridge Engineering (9-1) Suspension
Bridges

• V. Cables
• 5.5 Erecting cables
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Bridge Engineering (9-1) Suspension
Bridges

• 5.6 Squeezing the cables
• __After all the strands are laid, they are
  squeezed to form one single cable with a circular
  cross section.
• __The strands are first tapped manually
  using a wooden maul to form a cable roughly
  circular and then squeezed using a hydraulic
  squeezing machine to form a circular cross
  section.
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Bridge Engineering (9-1) Suspension
Bridges

• 5.7 Cable strength
• 5.7.1 Strength of cables One single steel
  wire (about 5 mm in diameter) is strong enough to
  hoist three passenger cars (1.2 tons each), and
  one stranded cable (consisting of 127 steel
  strands) is strong enough to hoist six space
  shuttles (74 tons each). 5.7.2 Length of cables
  The main cables for the Kurushima Kaikyo
  Bridges weigh 16,000 tons, and the strands are
  long enough to run round the earth two and one
  half times.
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Bridge Engineering (9-1) Suspension
Bridges

• VI. Stiffening Girder
• 6.1 The stiffening girder functions as a driveway
  for vehicles. The girder was designed with a
  cross section in the shape of a slim box to
  reduce vibrations in strong winds to a
  minimum. 23 Thursday, December 04,
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Bridge Engineering (9-1) Suspension
Bridges

• VI. Stiffening Girder
• 6.2 Erecting box girder with barge
• Stiffening girder sections, each 36m in
  length, are prefabricated in the plant and loaded
  on a self-propelled barge for transport to a site
  directly below each erection points. There they
  are lifted into position by a lifting beam and
  secured to hanger ropes.
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Bridge Engineering (9-1) Suspension
Bridges

• VII. Features of suspension bridges
• 7.1. Aesthetic, light, and strong
• 7.2 Span range 2,000 to 7,000 feet -- far longer
  than any other kind of bridge
• 7.3 Most expensive to build
• 7.4 Complicated in force bearing and
  distribution
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