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  1. 1. Prefabricated Construction Systems for Building and Civil works adopted in Hong Kong Presented by Raymond W M WongDivision of Building Science & Technology City University of Hong Kong
  2. 2. The presentation is based on a paper prepared by Raymond Wong for the World Congress on Housing Process & Product,Organized by the International Association for Housing Science and hosted by the Concordia University, Montreal, Canada, June 2003
  3. 3. Development and Application of Prefabricated Technology in Building Construction in HK1. Had been used once in early 1970s in a pilot project to construct a series of 17-storey public houses2. Used in a broader scale in the mid/late 1980s in the construction of public houses where all the façades of the flats were constructed in precast in a after-fixed manner3. Improvement to public houses by introducing in-situ joined façade and broader use of other precast elements in early/mid 1990s.4. A few private developments pioneered in the use of prefabricated system in the construction of buildings of various nature since early 1990s
  4. 4. Development and Application (continue)5. Packaged projects introduced from late 1990 onward by the Hong Kong government for the construction of a series of schools using semi-prefabricated method6. A series of government quarter buildings using similar construction techniques were introduced in 20007. A few special buildings such as bus depot or train station podium employed large amount of prefabricated elements of which some were primary structural members (1997 onward)8. Popular use of prefabricated external wall from 2002 onward in residential buildings due to the introduction of a new guideline encouraging the use of precast façades as a form of green elements in construction (exemption of Gross Floor Area)
  5. 5. Generations of Public Houses (Harmony Block) constructedusing semi-prefabricated concept
  6. 6. First generation of Harmony Block using after-fix façadeLater version of Harmony Block using inisitufaçade cast at the same time with structural walls
  7. 7. Precasting yard was set up toproduce precast elements for publichousing projects in early to mid 1990
  8. 8. After-fix façade system requiredthe formation of small amount ofin-situ joint and grouting thateasily caused leaking problem
  9. 9. Detail of façade installationusing in-situ jointingarrangement in the later versionof Harmony Block Construction
  10. 10. Forming the floor slab in theHarmony Block constructionusing semi-slab (right) andaluminium formwork (above)
  11. 11. Introduction of mechanicalformwork systems incorporatingthe standard precast elements inthe construction of latest versionof public houses in the late 1990
  12. 12. Public houses using Concorddesign with special emphasison the use of mechanicalisedconstruction system
  13. 13. Layout of the ConcordBlock showing theposition of the cast-in-situ core wall, shearwalls and precast façade
  14. 14. Other pioneered projects in the early 1990 constructed using semi-prefabricated concept
  15. 15. The construction of the Headquarter and MembersFacilities Complex for the Hong Kong Jockey Club
  16. 16. Forming the floor slab using precastsecondary beams and semi-slab for the mainbuilding (above) and members’ complex (right)
  17. 17. Detail of the floor system with thecast in-situ main beams and theplace-in precast secondary beams
  18. 18. Introduction of prefabricatedconcept to construct government quarters in 2000
  19. 19. Government quartersin West Kowloon
  20. 20. Layout of the quarter building showing typcial phasing arrangement of work
  21. 21. Features in the construction –extensive use of precastfaçade and lintel beams,precast cast-in-situ internalpartitions are also introduced
  22. 22. Detail of the façade andthe lintel beam installation
  23. 23. Installation of the cast-in-situprecast internal partition
  24. 24. Construction of special buildingsusing high proportion of precast since 1998
  25. 25. Kowloon Canton Railway Station podium/deckConstruction of the KowloonCanton Rail podium deck –cargo handling bay on theground level and on top for alarge-scale residentialdevelopment afterward
  26. 26. Forming of the cast-in-situ main beams
  27. 27. Jointing detail of themain beam and precastsecondary beams
  28. 28. Semi-slab with RCtopping to form thecomposite podium deck
  29. 29. Kowloon Motor BusMaintenance Depot- 3-level depot buildingwith columns, main andsecondary beams all inprecast
  30. 30. Erecting of the building frameusing precast columns and beams
  31. 31. Connecting the precast column to thefoundation cap with a base plate
  32. 32. Placing the secondary beamsonto the main beam
  33. 33. Connecting beams to columns bystitching, a means to provide anin-situ joints with rigid RC links
  34. 34. Detail of the beam/columnand beam/beam joints
  35. 35. Recent Residential/CommercialDevelopments using prefabricated concept to construct
  36. 36. Residential developmentat Cyber Port
  37. 37. Façade and general installation details
  38. 38. Features in the construction –large amount of external wallsare constructed in precastfaçade untis, with majorstructural links tie back to theinner shear walls and floorslab
  39. 39. Incorporation of other sophisticated formwork in construction – steel gang form for walls and table form for floor
  40. 40. Residential Developmentat Taikoo ValleyConstruction features –the use of large amountof precast units both ofstructural or architecturalnature. This includes thebalcony, façade units,loss-form for externalwalls and some shadingfins.
  41. 41. Detail of the precast balcony unit
  42. 42. Detail of the loss-form
  43. 43. Residential developmentat Ma Tau Wai
  44. 44. Overview of the precastinstallation arrangement
  45. 45. Façade installation detailas seen on the floor deck
  46. 46. Cambridge House – a 42-storeyOffice Building at Quarry Bay
  47. 47. Features in construction –precast beam trough andprecast sub-slab with RCtopping forming the floor system
  48. 48. Placing of the precast beam troughto form the floor layout
  49. 49. Recent Achievements of Hong Kong’s Prefabricated Technology• Previous defects such as leakage problems have been improved• Application diversified to other forms of construction• Capable to apply to rather complicate-shaped buildings• Incorporation of other advanced technology in the construction (such as use with mechanical form/ tensioned elements)• Generally mastering of skill and growing popular
  50. 50. Future Trend in the application of Prefabricated Technology in Hong Kong1. To increase the use of prefabrication for more structural elements such as for beam, column or load bearing wall2. Use more modulated elements or plug-in units3. Use more for architectural or decorative elements4. Incorporation of other composite elements in the design such as using at the same time with structural steel5. Apply prefabrication more to medium-rise buildings with more standardized structural items6. Improve the supply chain management to make production more efficient and economical
  51. 51. Practical Constraints1. Tighter coordination to allow for structural design, construction planning, procurement & approval procedure2. Required a critical amount of precast items before work can be economically used3. Huge work space for handling precast elements especially in congested urban environment in Hong Kong4. Congested site environment makes access and delivery of heavy precast units to the work spot becomes difficult5. Quality assurance become critical especially where large amount of precast components are used as structural nature
  52. 52. Examples of very congestedconstruction environmentwhere prefabrication approachis adopted
  53. 53. Example of Innovative Project (Local) The Integer
  54. 54. The Integer Houseat Admiralty
  55. 55. Floor plan of the experimental house
  56. 56. The working concept
  57. 57. Typical connection details
  58. 58. Assembly of the 3-D modules
  59. 59. Possible future development for high-rise structures using similar concept
  60. 60. Example of Innovative Project (overseas) The Habitat 67 in Montreal, Canada
  61. 61. Building SectionHabitat 67 as seen along the bank of St Lawrence River
  62. 62. Habitat 67 as seen along the bank of St Lawrence River
  63. 63. Close up look of themodulated dwelling units
  64. 64. Close up look of the modulated dwellingunits and the linking structure in theform of a access corridor
  65. 65. View as seen onthe deck level
  66. 66. Forming and Installation ofthe modulated units
  67. 67. Installation of the modulated units and the associated structure
  68. 68. BuildingSection
  69. 69. Floor plan
  70. 70. Connecting the modules
  71. 71. Prefabricated Construction Application in Civil Works
  72. 72. Examples of application of prefabricated techniques in civil construction works1. Used in highway projects such as cantilevered deck of elevated bridge, parapets of expressway and road curb2. Precast girder units or beams for elevated roadway (viaduct)3. Precast beams or decks for elevated pedestrian footbridges4. Tunnel lining especially for tunnel formed by tunnel boring machine5. Decks for long span bridges
  73. 73. Examples of application (continue)6. Marine work such as seawall and deck of terminal berth7. Soil retaining element such as for earth-balanced type retaining structure8. Platform for railway station9. Parapets and noise barrier panels10. Overhanging ducts or services channels for underground facilities11. Nullah section for storm water discharge
  74. 74. Elevated pedestrianfootbridge in Mong Kok
  75. 75. Piers formed usingprecast column
  76. 76. Precast girder erectedon top of the piers toform the main span ofthe footbridge
  77. 77. Extending precast plank toform the deck of the footbridge
  78. 78. Structural arrangementof the footbridge
  79. 79. Precast V-shape beam for the Route 3 elevated expressway at Kwai ChungPrecast V-shape beambeing lifted to pier headby launching gantry
  80. 80. Precast box-girder for the RamblerStrait Bridge of Route 3
  81. 81. Forming the elevated bridge of the West Kowloon Expressway
  82. 82. West Kowloon Expressway –installing the precast box girder using balanced cantilever method with the help of track mounted gantry crane
  83. 83. Forming the elevated trackof the West Rail using theslung launching girder
  84. 84. Forming the elevated trackof the West Rail using thelongitudinal steel supportbeam
  85. 85. Forming the elevated track ofthe KCR Ma On Shan Lineby precast girder and lifted todeck level for erection usingmobile crane
  86. 86. Placing the precastgirder in position
  87. 87. Project example – Road T7 in Ma On Shan (TTD project)Technical Features1. Total length of viaduct – 2200m (approx.)2. Span length – Average 40m3. Total nos. of segment used – 790 nos.4. No. of segment per span – average 14 nos.5. Weight of segment – ranging from 50 to 98 tons6. Weight of the launching machine – 310 tons7. Max. weight of machine with segments – 1300 tons8. Length of launching machine – 85m9. Casting of the box-girder segment – match-cast
  88. 88. Construction of highway bridge using precast box-girder (viaduct) – Road T7 in Ma On Shan
  89. 89. Early stage of the project –formation and forming thepiers for the viaduct
  90. 90. Overall layout of the precasting yard
  91. 91. Forming the box-girder units
  92. 92. Formwork to form the innervoid of the box-girder units
  93. 93. Overview of thelaunching machine
  94. 94. Drawing provided by China Harbour Engg. Co. (Group)Launching sequence of the box-girder units using launching machine
  95. 95. Installation of the box-girders
  96. 96. Installation of the box-girders
  97. 97. Other example of application in civil engineering works
  98. 98. Precast parapet unit for the highwayand railway road/track way
  99. 99. Precast floating slab forthe laying of railway track
  100. 100. Tunnel lining formedby precast segments
  101. 101. Detail of the lining asseen inside the tunnel tube
  102. 102. Forming the station platformusing precast curb and plank(KCR Tsim Sha Tsui Station)
  103. 103. Forming the cable hood
  104. 104. Delivery of the precast units
  105. 105. Forming the deck of the berth for the Container Terminal No. 9Forming the deck of the Ting KauBridge using precast concrete plank
  106. 106. Precast concrete plankas cover to podium deck
  107. 107. Precast vertical panelforming an earth-reinforcedtype retaining structure
  108. 108. Forming storm water discharge culvert – Tseung Kwan O Reclamation
  109. 109. Delivery and storage along the temporary seawallPrepare for the foundationto support the culvert
  110. 110. Precast units to form the 4mhigh 5-cell culvert system inTseung Kwan O
  111. 111. Positioning the Precast unitsonto the culvert alignment
  112. 112. Precast culvert in the formof semi-submerged tube –Tsuen Wan WestReclamation as advancedwork for the West RailTsuen Wan Station
  113. 113. Sinking of the precastculvert section
  114. 114. Positioning of the culvertsection onto to formed bed
  115. 115. Connecting the culvertfrom the precast sectionto the in-situ section
  116. 116. Precast box as footing to bridgetower – Tsing Ma Bridge toweron Ma Wan side
  117. 117. Precast box as pump housefor water cooling system inthe Central Reclamation
  118. 118. End of Presentation and Thank youIf you require more information about the Author’s recent work on various technology topics, you can enter his homepage at