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Bridge Engineering (9-1) Suspension Bridges

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Title: Bridge Engineering (9-1) A Case Study of Cable-stayed Bridges Author: zhangkr Last modified by: zhangkr Created Date: 5/11/2004 3:59:40 AM – PowerPoint PPT presentation

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Title: Bridge Engineering (9-1) Suspension Bridges


1
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
  •  1 Thursday, December 04, 2014

2
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.
  •  2 Thursday, December 04, 2014

3
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).
  •  3 Thursday, December 04, 2014

4
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.
  •  4 Thursday, December 04, 2014

5
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.
  •  5 Thursday, December 04, 2014

6
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.
  •  6 Thursday, December 04, 2014

7
Bridge Engineering (9-1) Suspension
Bridges
  • III. Anchorage
  • 3.5.2 Cable anchor frames securing the cables to
    the tunnels.
  •  7 Thursday, December 04, 2014

8
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.
  •  8 Thursday, December 04, 2014

9
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

10
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.
  •  10 Thursday, December 04, 2014

11
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
  •  11 Thursday, December 04, 2014

12
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.
  •  12 Thursday, December 04, 2014

13
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.
  •  13 Thursday, December 04, 2014

14
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.
  •  14 Thursday, December 04, 2014

15
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.
  •  15 Thursday, December 04, 2014

16
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.
  •  16 Thursday, December 04, 2014

17
Bridge Engineering (9-1) Suspension
Bridges
  • 5.3.5 Single Rope or Single Strand Cables--These
    are used for small structures.
  •  17 Thursday, December 04, 2014

18
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)
  •  18 Thursday, December 04, 2014

19
Bridge Engineering (9-1) Suspension
Bridges
20
Bridge Engineering (9-1) Suspension
Bridges
  • V. Cables
  • 5.5 Erecting cables
  •  20 Thursday, December 04, 2014

21
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.
  •  21 Thursday, December 04, 2014

22
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.
  •  22 Thursday, December 04, 2014

23
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,
    2014

24
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.
  •  24 Thursday, December 04, 2014

25
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
  •  25 Thursday, December 04, 2014
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