Construction of Bridges

Transcription

1 Construction of Bridges

2 Materials suitable for the Construction of Long-span Bridges 1. Stone in arch masonry 2. Steel in girder or box-section constructed in steel plates and standard sections 3. Steel truss constructed of standard sections 4. Reinforced Concrete in arch or spanned forms 5. Tensioned RC in various forms 6. Precast mainly in box-section girder

3 Common Bridge Forms

4 Simple Supported span effective from 10m to 60m Actual example Route 3 Interchange at Au Tau, Yuen Long

5 Continuous Span from 10m to 100m Actual example construction of a span of continual section of elevated highway bridge at Route 3, Kwai Chung

6 Balanced Cantilever span from 25m to 200m Actual example balanced cantilever bridge series forming the approach to the Ting Kau Bridge

7 Balanced cantilever bridge for viaduct of West Rail at Au Tau Interchange

8 Balanced Cantilever Suspended Span span from 50m to 300m

9 Steel Truss 50m to 100m Actual example 5-span steel truss bridge in western part of Pearl River, Guangzhou

10 Steel Arch (framed or trussed) from 150m to 500m

11 The Sydney Harbour Bridge and its approach

12 Cable suspension from 400m to 1500m The 1377m span Tsing Ma Bridge

13 Concrete Arch (ribbed or unribbed) from 50m to 300m

14 Steel Arch from 100m to 500m

15 Cable stayed (multi-spanned) from 50 to 500m per span The 3-span cable-stayed Ting Kau Bridge

16 Cable stayed span from 200m to 800m Actual example the connecting bridge from Macau Mainland to the Island of Taipa in Macau

17 Example of box-sectioned steel girder bridge

18 Structural Elements for Typical Bridges 1. Foundation for bridge towers, portal frames or piers 2. Bridge Tower the vertical supporting structure for cable suspension or cable-stayed bridges 3. Portal frame or pier the vertical supporting structure for usual spanned bridges 4. Bridge deck the horizontal part of a bridge that support pedestrian or traffic activities 5. Bridge anchor required only for suspension bridges to counter resist the pull from the suspension cable 6. Suspension cable for suspension and cable-stayed bridges for the hanging, support or counter-balancing of the bridge deck

19 The foundation of the bridge tower of Ting Kau Bridge on Tsing Yi side

20 The foundation for the Bridge Tower of Tsing Ma Bridge on the Tsing Yi side

21 Forming the foundation for piers of elevated highway bridges

22 Pier supports for an elevated roadway A portal frame serving also as a transfer beam in the Route 3/Airport Railway at Kwai Chung

23 Bridge tower for Tsing Ma Bridge and Kap Shiu Mun Bridge Tsing Ma Tower

24 The forming of the cable anchor of Tsing Ma Bridge on Ma Wan side

25 The forming of the cable anchor of Tsing Ma Bridge on Tsing Yi side

26 Forming the deck of the approach section of Tsing Ma Bridge on Ma Wan side using erection and hoisting approach

27 Forming the deck of the approach section of Tsing Ma Bridge on Tsing Yi side

28 Completing the deck of Tsing Ma Bridge (abutting section at Tsing Yi side) by erecting of the steel truss at spot

29 Hoisting and erecting of the modulated bridge deck for the Tsing Ma Bridge

30 Forming the bridge deck of Ting Kau Bridge using modulated steel girder frames

31 Laying the precast deck of the steel girder frame

32 Other methods to form the deck of bridges 1. Balanced cantilever method 2. Construct in-situ 3. Construct using precast beam 4. Construct using precast girder section and erected by a launching machine (viaduct) 5. Construct using incremental launching method

33 Forming the deck of the Ting Kau Bridge approach section using a special balancedcantilever traveling formwork system

34 The Ting Kau Bridge approach section

35 Construction of a section of elevated railway track in the KCR Ma On Shan Line using in-situ method

36 The laying of precast beams to form the deck of the Route 3 elevated roadway at Kwai Chung

37 Hoisting of the precast beams using a special launching gantry

38 Construction of an elevated highway bridge using precast girder erected by the use of a launching machine

39 Launching gantry used to erect precast girders to form a span of an elevated bridge (viaduct)

40 A bridge in the Fo Tan Road Improvement Project making use of Incremental Launching method to span across the servicing KCR rail line Alignment of servicing rail line

41 elevated roadway constructed in the form of viaduct

42 Route 3 Kwai Chung Section

43 Route 3 Country Park Section at Au Tau Interchange

44 Hung Hom Bypass

45 Tsing Yi North Coastal Roadway

46 Highway project in Ma On Shan

47 Launching gantry used in the Hung Hom Bypass

48 Launching gantry used in Route 3 at Au Tau Interchange

49 Launching gantry used in Tsing Yi North Coastal Roadway

50 Launching gantry used in the Ma On Shan highway project (T7)

51 Launching Gantry used in the Route 3 Kwai Chung section

52 A review of other highway and railway bridges construction of the viaduct systems for the West Rail projects

53 Viaduct for railway track of the Kowloon Canton Railway West Rail at the northwestern part of the New Territory, Hong Kong

54 Some sections of viaduct spanning more than 40m at Au Tau Interchange

55 Forming the viaduct for railway track using the underslung girder and longitudinal beam supported method

56 Erection of the viaduct using balanced cantilever arrangement with temporary anchor before completion of a span

57 Precast box girders used for the viaduct

58 A section of viaduct with provision for an extension to the future northern link

59 Construction of some sections of elevated railway track using in-situ method

60 Constructing the linking bridge between Tung Chung and Chek lap Kok (the Airport Railway) using Incremental Launching method

61 Principle of viaduct construction using segmental launching (by Launching Machine)

62 (SWL = 105 T) Slave winch Main Truss 116m long (For end span and 1st pair segment erection) Hangers Front support (SWL = 120T) Master winch Rear leg Rear support Front leg Elevation of the Launching Machine

63 Typical installation of the precast box-girder to form the viaduct: Install the 1st Pair Segment By The Launching Machine with Hangers

64 1st pair segment preassembled on ground, ready to be lifted up by master winches. a) Stitching platform and rebar cage b) Hanger frame c) Stressing Platform

65 FIRST PAIR SEGMENTS LIFTING (WITH FORMWORK AND STRESSING PLATFORM)

66 Hang the 1st pair segments to launching girder After fine adjustment, cast the stitch concrete

67 FIRST PAIR SEGMENTS IN PLACE

68 Perform the tendon stressing, load transfer from LG to Portal Pier Remove the platforms

69 FORMWORK REMOVAL

70 FIRST PAIR SEGMENTS STITCHING COMPLETED

71 Typical installation of the precast box-girder to form the viaduct: Continue to erect the segments pairs by pairs Using balanced cantilever principle

72 LIFT SEGMENT FROM GROUND TO ERECTING POSITION

73 Lift and erect the next precast segment Apply epoxy glue to the match cast face and temporary stressing.

74 Erect the conjugate segment pair; After application of cantilever tendon, load transfer to pier completed;

75 A section of viaduct erected in a balanced cantilever manner

76 Continue the segment erection for the rest segment pairs

77 Typical Span Completion of a span Hang the end span segments with hanger frame Adjust the geometry of the hanging segments Concrete the stitch joints Perform the span tendon stressing when concrete has developed the required strength,. Load transfer to pier or portal completed, released the hangers

78 End-span erection with the use of hanger to support the precast box from the launching girder

79 Trends in the Construction of Bridges in HK Construction of large and long-span bridges is of no doubt a part of the major infrastructure development for a city, which is, again, a reflection of the economical climate and development strategy of the area. On the construction side, the limited land reserve in Hong Kong does imposes stringent conditions especially where the options and cost effectiveness of constructing a bridge is concerned. To cope with these considerations, a few world-class bridges over 1000m span are yet scheduled for completion in the coming decade, in view of keeping Hong Kong to be competitive in particular within the highly economic-active region in the southern part of China. The construction of these bridges is, without much choice, in the form of either cable-stayed or suspension bridges.

80 The construction of other medium to short-span bridges are becoming much popular recently as part of the highway improvement strategy in Hong Kong. The shortage of space for highway improvement works, the involvement of complicated interchanging provisions, the familiarization of bridge construction techniques in catering various local constraints with acceptable cost, are factors that made bridges of this type becoming popular. Some inherited difficulties such as the requirement of large amount of working spaces for the forming, transporting and storing of the roomy precast elements; the operation of the launching works, or arrangement for traffic diversion within existing busy roadway, still makes roadwork under urban environments complicated and costly. Needless to mention working in environmental sensitive locations such as where protection to natural habitats or rural culture is required; or where waste, noise and dust problems are of ultimate concern.

81 The cost for constructing bridges are unavoidably high in particular working within congested and complicated urban environment like Hong Kong. As a tradition, bridges and elevated highway structures in Hong Kong are mainly constructed in concrete. As a cost saving option, steel bridge, say, in hollow section, box-girder or any other feasible design, may be alternative choices for highway bridges, like those commonly used in Mainland China or Japan. The saving in initial cost and construction time of using such alternatives may provide surplus capitals and expedite the ongoing infrastructure projects, this is essential especially in the forthcoming years when the economic situation is expected to be less favourable than before.

82 The end of the presentation