Prefabricated

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  • 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. 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. 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. 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. Generations of Public Houses (Harmony Block) constructedusing semi-prefabricated concept
  • 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. Precasting yard was set up toproduce precast elements for publichousing projects in early to mid 1990
  • 8. After-fix façade system requiredthe formation of small amount ofin-situ joint and grouting thateasily caused leaking problem
  • 9. Detail of façade installationusing in-situ jointingarrangement in the later versionof Harmony Block Construction
  • 10. Forming the floor slab in theHarmony Block constructionusing semi-slab (right) andaluminium formwork (above)
  • 11. Introduction of mechanicalformwork systems incorporatingthe standard precast elements inthe construction of latest versionof public houses in the late 1990
  • 12. Public houses using Concorddesign with special emphasison the use of mechanicalisedconstruction system
  • 13. Layout of the ConcordBlock showing theposition of the cast-in-situ core wall, shearwalls and precast façade
  • 14. Other pioneered projects in the early 1990 constructed using semi-prefabricated concept
  • 15. The construction of the Headquarter and MembersFacilities Complex for the Hong Kong Jockey Club
  • 16. Forming the floor slab using precastsecondary beams and semi-slab for the mainbuilding (above) and members’ complex (right)
  • 17. Detail of the floor system with thecast in-situ main beams and theplace-in precast secondary beams
  • 18. Introduction of prefabricatedconcept to construct government quarters in 2000
  • 19. Government quartersin West Kowloon
  • 20. Layout of the quarter building showing typcial phasing arrangement of work
  • 21. Features in the construction –extensive use of precastfaçade and lintel beams,precast cast-in-situ internalpartitions are also introduced
  • 22. Detail of the façade andthe lintel beam installation
  • 23. Installation of the cast-in-situprecast internal partition
  • 24. Construction of special buildingsusing high proportion of precast since 1998
  • 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. Forming of the cast-in-situ main beams
  • 27. Jointing detail of themain beam and precastsecondary beams
  • 28. Semi-slab with RCtopping to form thecomposite podium deck
  • 29. Kowloon Motor BusMaintenance Depot- 3-level depot buildingwith columns, main andsecondary beams all inprecast
  • 30. Erecting of the building frameusing precast columns and beams
  • 31. Connecting the precast column to thefoundation cap with a base plate
  • 32. Placing the secondary beamsonto the main beam
  • 33. Connecting beams to columns bystitching, a means to provide anin-situ joints with rigid RC links
  • 34. Detail of the beam/columnand beam/beam joints
  • 35. Recent Residential/CommercialDevelopments using prefabricated concept to construct
  • 36. Residential developmentat Cyber Port
  • 37. Façade and general installation details
  • 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. Incorporation of other sophisticated formwork in construction – steel gang form for walls and table form for floor
  • 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. Detail of the precast balcony unit
  • 42. Detail of the loss-form
  • 43. Residential developmentat Ma Tau Wai
  • 44. Overview of the precastinstallation arrangement
  • 45. Façade installation detailas seen on the floor deck
  • 46. Cambridge House – a 42-storeyOffice Building at Quarry Bay
  • 47. Features in construction –precast beam trough andprecast sub-slab with RCtopping forming the floor system
  • 48. Placing of the precast beam troughto form the floor layout
  • 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. 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. 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. Examples of very congestedconstruction environmentwhere prefabrication approachis adopted
  • 53. Example of Innovative Project (Local) The Integer
  • 54. The Integer Houseat Admiralty
  • 55. Floor plan of the experimental house
  • 56. The working concept
  • 57. Typical connection details
  • 58. Assembly of the 3-D modules
  • 59. Possible future development for high-rise structures using similar concept
  • 60. Example of Innovative Project (overseas) The Habitat 67 in Montreal, Canada
  • 61. Building SectionHabitat 67 as seen along the bank of St Lawrence River
  • 62. Habitat 67 as seen along the bank of St Lawrence River
  • 63. Close up look of themodulated dwelling units
  • 64. Close up look of the modulated dwellingunits and the linking structure in theform of a access corridor
  • 65. View as seen onthe deck level
  • 66. Forming and Installation ofthe modulated units
  • 67. Installation of the modulated units and the associated structure
  • 68. BuildingSection
  • 69. Floor plan
  • 70. Connecting the modules
  • 71. Prefabricated Construction Application in Civil Works
  • 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. 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. Elevated pedestrianfootbridge in Mong Kok
  • 75. Piers formed usingprecast column
  • 76. Precast girder erectedon top of the piers toform the main span ofthe footbridge
  • 77. Extending precast plank toform the deck of the footbridge
  • 78. Structural arrangementof the footbridge
  • 79. Precast V-shape beam for the Route 3 elevated expressway at Kwai ChungPrecast V-shape beambeing lifted to pier headby launching gantry
  • 80. Precast box-girder for the RamblerStrait Bridge of Route 3
  • 81. Forming the elevated bridge of the West Kowloon Expressway
  • 82. West Kowloon Expressway –installing the precast box girder using balanced cantilever method with the help of track mounted gantry crane
  • 83. Forming the elevated trackof the West Rail using theslung launching girder
  • 84. Forming the elevated trackof the West Rail using thelongitudinal steel supportbeam
  • 85. Forming the elevated track ofthe KCR Ma On Shan Lineby precast girder and lifted todeck level for erection usingmobile crane
  • 86. Placing the precastgirder in position
  • 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. Construction of highway bridge using precast box-girder (viaduct) – Road T7 in Ma On Shan
  • 89. Early stage of the project –formation and forming thepiers for the viaduct
  • 90. Overall layout of the precasting yard
  • 91. Forming the box-girder units
  • 92. Formwork to form the innervoid of the box-girder units
  • 93. Overview of thelaunching machine
  • 94. Drawing provided by China Harbour Engg. Co. (Group)Launching sequence of the box-girder units using launching machine
  • 95. Installation of the box-girders
  • 96. Installation of the box-girders
  • 97. Other example of application in civil engineering works
  • 98. Precast parapet unit for the highwayand railway road/track way
  • 99. Precast floating slab forthe laying of railway track
  • 100. Tunnel lining formedby precast segments
  • 101. Detail of the lining asseen inside the tunnel tube
  • 102. Forming the station platformusing precast curb and plank(KCR Tsim Sha Tsui Station)
  • 103. Forming the cable hood
  • 104. Delivery of the precast units
  • 105. Forming the deck of the berth for the Container Terminal No. 9Forming the deck of the Ting KauBridge using precast concrete plank
  • 106. Precast concrete plankas cover to podium deck
  • 107. Precast vertical panelforming an earth-reinforcedtype retaining structure
  • 108. Forming storm water discharge culvert – Tseung Kwan O Reclamation
  • 109. Delivery and storage along the temporary seawallPrepare for the foundationto support the culvert
  • 110. Precast units to form the 4mhigh 5-cell culvert system inTseung Kwan O
  • 111. Positioning the Precast unitsonto the culvert alignment
  • 112. Precast culvert in the formof semi-submerged tube –Tsuen Wan WestReclamation as advancedwork for the West RailTsuen Wan Station
  • 113. Sinking of the precastculvert section
  • 114. Positioning of the culvertsection onto to formed bed
  • 115. Connecting the culvertfrom the precast sectionto the in-situ section
  • 116. Precast box as footing to bridgetower – Tsing Ma Bridge toweron Ma Wan side
  • 117. Precast box as pump housefor water cooling system inthe Central Reclamation
  • 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 athttp://personal.cityu.edu.hk/~bswmwong/