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CCTV Building, A Structural Design Overview

The CCTV building is one of the several big Beijing Olympic projects, which houses the headquarters for the Chinese Central Television Network. Its design shows unique style, but great structural engineering challenges to overcome. The following presentation provides an overview of how these challenges were overcome. (Presented at Monash University, Department of Civil Engineering, August 2008).

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CCTV Building, A Structural Design Overview

  1. 1. CCTV Headquarters, Beijing<br />A Structural Design Overview<br />By Peter M. Bach (August, 2008)<br />
  2. 2. Before we start…<br />Will it stand by itself?<br />
  3. 3. Before we start…<br />It can! But the question is: How much effort does it take to make it fall?<br />
  4. 4. Before we start…<br />THIS?!<br />
  5. 5. Topics<br /><ul><li>General Project Details
  6. 6. Architecture
  7. 7. Construction Challenges
  8. 8. Diagrid Framing System
  9. 9. Other Structural Features
  10. 10. Miscellaneous Topics
  11. 11. The Other Buildings
  12. 12. Conclusion</li></li></ul><li>General Project Details<br />
  13. 13. General Project Details <br />Background<br /><ul><li>The new HQ for China’s CCTV
  14. 14. Completion in time for Olympics
  15. 15. Will broadcast the Olympics to the World
  16. 16. Components:
  17. 17. CCTV Building (Headquarters & Broadcasting)
  18. 18. TVCC Wing (Cultural Center, Performing Arts)
  19. 19. Media Park (Social Gathering Place)
  20. 20. First of 300 towers to be constructed in Beijing’s CBD</li></li></ul><li>General Project Details <br />Location<br /><ul><li>In Beijing’s CBD (Third Ring Road)
  21. 21. East of Forbidden City</li></li></ul><li>General Project Details <br />Admin – Site – History <br /><ul><li>Project Manager: Dongmei Yao
  22. 22. Partners in Charge: Ole Sheeren & Rem Koolhaas
  23. 23. Architects: Office for Metropolitan Architecture (OMA)
  24. 24. Structural Engineers: Ove Arup & Partners
  25. 25. 10-hectare site
  26. 26. Two L-Shaped Towers, tallest tower is 230m high
  27. 27. Total Estimated Construction Cost: €600million
  28. 28. Will employ 10,000 people</li></li></ul><li>General Project Details <br />Admin – Site – History (cont.) <br />“…The building is by any conventional definition a Skyscraper…” <br />(UK Telegraph)<br />Comparing Building Heights in Asia<br />Comparing Building Heights in the World<br />
  29. 29. General Project Details <br />Admin – Site – History (cont.)<br /><ul><li>Towers Lean at 60o angles and “kink” at right angles at the top
  30. 30. Cantilever overhang starts after 36 floors and is 13 floors high.
  31. 31. The towers cantilever 75m outwards
  32. 32. History
  33. 33. December 2002 - OMA wins design
  34. 34. March 2003 – Project Start (after review)
  35. 35. September 2004 – Groundbreaking
  36. 36. Mid 2007 – Overhang Construction Underway
  37. 37. Early 2008 – Finalizing Construction</li></li></ul><li>General Project Details <br />Space Usage<br />
  38. 38. General Project Details <br />Space Usage (cont.)<br />Yellow = Canteens<br />Dark Blue = Studios<br />Green = Open Studios<br />Orange = Lobbies (Tower & Sky)<br />Pale Green = Broadcasting<br />Light Blue = Sports & Recreation<br />Red = VIP Areas<br /><ul><li>Lobbies on Ground & Top Floors
  39. 39. Recreation mainly on bottom
  40. 40. Elevators in both towers
  41. 41. Separate Lobby & Elevator for VIPs
  42. 42. Two Ground Floor Lobbies
  43. 43. Continuous Loop through Towers
  44. 44. Studios mainly on the lower Floors</li></li></ul><li>General Project Details <br />Nicknames & Descriptions<br />“Twisted Donut”<br />“The Pants”<br />“Two drunken, upside-down Ls”<br />“Each Tower is a banana, built with a deliberate slight curve…”<br />“Contorted Loop”<br />“Lopsided Colossus”<br />
  45. 45. Architecture<br />
  46. 46. Architecture<br />What do you think “logic” and “beauty” is defined as?<br />
  47. 47. Architecture<br />The Skyscraper Concept<br />What do all the above buildings have in common?<br />Height!<br />Human Capabilities<br />
  48. 48. Architecture<br />The CCTV’s Concept<br /><ul><li>Architect: Rem Koolhaas
  49. 49. China willing to try out new ideas
  50. 50. Everything to do with TV Production is within the CCTV Building (“An inter-connected loop of inter-connected activities”)
  51. 51. Iconographic Constellation instead of hopeless race for ultimate height
  52. 52. “…As verticality soars, creativity crashes…”
  53. 53. “…An Expression of Verticality…”
  54. 54. Idea should create buildings that will actively engage the cityscape</li></li></ul><li>Architecture<br />The Architect’s Opinion<br /><ul><li>Community combined as opposed to separate
  55. 55. Concentrate every program into a single system
  56. 56. “It is important to encourage different kind of work of engineering as it is with architecture”
  57. 57. “Experimenting with Engineering liberates imagination and makes other things possible”
  58. 58. The idea links a bit with communism as is still seen in China
  59. 59. “There is a natural affinity between the values of architecture and the values of socialism”
  60. 60. Hopes to spread this new building idea in Europe</li></li></ul><li>Architecture<br />The Basic Geometry<br /><ul><li>Mobius Strip (continuous loop)
  61. 61. Cantilever Overhang
  62. 62. Diagonal Structural Grid System
  63. 63. L-Shaped</li></li></ul><li>Construction Challenges<br />
  64. 64. Construction Challenges<br />What kinds of Challenges will this Project face?<br /><ul><li>A lot steel is used  Weight Issues (instability)
  65. 65. Beijing is an Earthquake Prone Area (need seismic stability)
  66. 66. Every building encounters vertical and lateral loads
  67. 67. Temperature changes, material deformation
  68. 68. Subsoil Conditions:
  69. 69. Shallow foundation not sufficient
  70. 70. Pore Water present in great amounts
  71. 71. High Settlement Risk</li></li></ul><li>Construction Challenges<br />What kinds of Challenges will this Project face?<br /><ul><li>Needs to accommodate 10,000 people, heavy equipment  High service loads
  72. 72. Vulnerable to Natural or Man-Made Disasters
  73. 73. How to design & construct?</li></ul>Performance-based <br />Design Approach<br />
  74. 74. Diagrid Framing System<br />
  75. 75. Diagrid Framing System<br />What is it?<br /><ul><li>Short for Diagonal Grid System
  76. 76. Triangulated structure with diagonal support beams
  77. 77. Similar to a typical moment frame
  78. 78. Triangles connected at Nodes and Rings intersect the nodes
  79. 79. Combines the benefits of a hollow tube with a truss
  80. 80. Loads follow diagonals, gravity and lateral loads can be transferred by the system to the ground</li></ul>Swiss Re, London<br />
  81. 81. Diagrid Framing System<br />What is it? (cont.)<br /><ul><li>Can be constructed of either:
  82. 82. Steel (most common)
  83. 83. Timber
  84. 84. Reinforced Concrete
  85. 85. Steel is typical because of high tensile and compressive strengths
  86. 86. Essentially marrying columns, diagonals and bracings into one system
  87. 87. Not a new technology, used in early aviation and small-scale structures</li></li></ul><li>Diagrid Framing System<br />Load Transfer<br />1.) Vertical Loads<br />2.) Lateral Loads<br />
  88. 88. Diagrid Framing System<br />Load Transfer<br /><ul><li>Load transfer happens primarily through diagrid
  89. 89. Internal Cores will transfer minimal amounts of gravity loads
  90. 90. Floor Slabs do not have to transfer lateral loads
  91. 91. Less internal columns required = more space
  92. 92. Floor plates do not have to be of the same shape on each floor
  93. 93. Continuous and Uninterrupted Load Transfer
  94. 94. Rings help to resist Buckling Loads transforming whole system into one big tube</li></li></ul><li>Diagrid Framing System<br />Advantages of this System<br /><ul><li>Structurally very strong
  95. 95. Less material required (~20% reduction in steel as opposed to typical moment frame method)
  96. 96. Aesthetically Pleasing – Blends in together with façade
  97. 97. Floor plan becomes open and free – more internal space
  98. 98. Most forms can be created with a triangulated form – architectural freedom
  99. 99. Self-reliant structure, simple in shape</li></li></ul><li>Diagrid Framing System<br />Advantages of this System (cont.)<br /><ul><li>Simple Construction Technique
  100. 100. Skyscraper Structural Failure minimized by diagrid construction
  101. 101. Better ability to redistribute loads than a moment frame (Failure of one portion does not mean complete structural failure)</li></li></ul><li>Diagrid Framing System<br />Disadvantages of this System<br /><ul><li>Not thoroughly explored for skyscraper construction yet
  102. 102. Inexperienced construction crews
  103. 103. A diagrid structure will definitely show in the aesthetics, very difficult to hide
  104. 104. Difficult to create a consistent window design
  105. 105. Heavy-handed if not executed properly
  106. 106. Material usage can be very excessive if loads are not high</li></li></ul><li>Other Structural Features<br />
  107. 107. Other Structural Features<br />Connections – Butterfly Plates<br /><ul><li>Critical Members in the Structural System
  108. 108. Must ensure a “strong joint-weak member” system
  109. 109. Must resist maximum probable load from braces with minimum yielding and stress concentration
  110. 110. Butterfly plates used to assist smooth load transfer
  111. 111. Finite Element Analysis of Connection</li></li></ul><li>Other Structural Features<br />Connections – Butterfly Plates<br />
  112. 112. Other Structural Features<br />Foundation – Piled Raft <br /><ul><li>Total Settlement estimated as <100mm
  113. 113. Differential Settlement kept to 1:500
  114. 114. Piles are 1.2m diameter and 35m long
  115. 115. Piled Raft is 7m thick and has a footprint greater than the towers
  116. 116. Tension piles used away from towers to resist uplift pressures</li></li></ul><li>Other Structural Features<br />Load Transfer Assistance - Trusses<br /><ul><li>Hidden from view for architectural purposes inside
  117. 117. Link up external columns with internal steel core via pin-joints
  118. 118. Trusses span the bottom two floors of the overhang, loads above are transferred to these trusses, which subsequently transfer loads to the diagrid system
  119. 119. Major trusses located at building base (podium) to support the above loads</li></li></ul><li>Other Structural Features<br />Load Transfer Assistance - Trusses<br />
  120. 120. Other Structural Features<br />Building Internal Cores<br /><ul><li>Three main cores accommodating elevators
  121. 121. Cores remain vertical despite Tower Slope (shifted against floor plates)
  122. 122. One core dedicated to “Grandness” (Administrative), the other to “Newness” (News & Technology)</li></li></ul><li>Miscellaneous Topics<br />
  123. 123. Miscellaneous Topics<br />Construction Procedure<br />
  124. 124. Miscellaneous Topics<br />Seismic Stability Design Approach<br /><ul><li>CCTV Performance-based Design for Seismic Stability well outside National Building Codes
  125. 125. Analysis for different seismic events
  126. 126. Level 1: Frequent Earthquake  No structural damage
  127. 127. Level 2: Intermediate Earthquake  Repairable Structural Damage
  128. 128. Level 3: Rare Earthquake  Severe Structural Damage permitted, must not collapse</li></li></ul><li>Miscellaneous Topics<br />Seismic Stability Design Approach<br /><ul><li>Other Research shows test results depicting Overhang vertical displacement with time during an Earthquake
  129. 129. Tests also show that some braces go into plastic buckling during the Earthquake  Dissipate seismic energy (GOOD)</li></ul>Maximum downward displacement = 700mm<br />
  130. 130. Miscellaneous Topics<br />Dealing with Wind<br /><ul><li>Wind Tunnel Experiments had to be carried out to assess the severity of Wind Loads
  131. 131. Building strength against a 100-year Wind was assessed
  132. 132. Method: Dynamic Analysis using High-Frequency Pressure Integration Method
  133. 133. 285 Pressure Taps installed on 1:500 Scale Model
  134. 134. North and West Winds Critical
  135. 135. Southwest Wind worst for Vertical Loads</li></li></ul><li>Miscellaneous Topics<br />Emergency Scenarios<br /><ul><li>In the event of a fire or a major disaster (natural or man-made) that causes major structural damage, what are the possible escape routes and how long will it take?</li></li></ul><li>Miscellaneous Topics<br />Emergency Scenarios (cont.)<br /><ul><li>Numerous Escape Routes
  136. 136. Looped Structure an Advantage
  137. 137. Reduced Escape Time
  138. 138. Better Safety</li></li></ul><li>The Other Buildings<br />
  139. 139. The Other Buildings<br />The TVCC Building<br /><ul><li>Hotels, Theaters, Cultural Center for Performing Arts</li></li></ul><li>The Other Buildings<br />Service Building & Media Park<br /><ul><li>Service Building: Energy Center, Guards Dormitories, Major Broadcasting Vehicle Garages, Fire Control Center
  140. 140. Media Park: Social Gathering place, filming options</li></li></ul><li>Construction Progress<br />Latest Pictures of the Building<br />Dated June 2008<br />
  141. 141. Conclusion<br />
  142. 142. Conclusion<br /><ul><li>Building is to become an icon of Beijing’s Cityscape once completed and will play an important role for the 2008 Olympics
  143. 143. Architecture looks at iconography rather than the race for height – engineering creativity is better than height
  144. 144. Many structural challenges to overcome in realizing the project  Performance-based design needed
  145. 145. Diagrid System, Butterfly Plates, Piled Raft Foundations, Load Transfer Trusses all deemed good solutions
  146. 146. Seismic and Wind Stability ensured through rigorous analysis
  147. 147. Emergency Escape Routes are effective
  148. 148. Other buildings on-site serve unique functions</li></li></ul><li>References<br />[1] Carroll, C., Xiaonian, D., Gibbons, C., Lawson, R., Lee, A., Luong, A., Megowan, R., Pope, C., (2006), “China Central Television Headquarters – Structural Design”, Steel Structures 6<br />[2] CB Richard Ellis, (2007), “The CCTV Tower: Central Icon of Post-Urban Beijing?”, CBRE Research – Asia 2007 Issue 1<br />[3] “CCTV Address”, China Academic Journal Electronic Publishing House, http://www.ckni.net, Last Accessed 25th May 2008<br />[4] “CCTV by OMA”, A+U Architecture & Urbanism July 2005 Special Issue, Tokyo, Japan<br />[5] “China Central Television (CCTV) Headquarters”, Design Build Network, http://www.designbuild-network.com/projects/cctv/, Last Accessed 25th May 2008<br />[6] Koolhaas, R., (2004), “Beijing Manifesto”, Wired Issue 8 2004<br />[7] Lee, S., “Nonlinear Dynamic Earthquake Analysis of Skyscrapers”, CTBUH 8th World Congress, Dubai 3-5 March 2008<br />[8] McCain, I., “DiaGrid: Structural Efficiency & Increasing Popularity”, http:// daapspace4.daap.uc.edu/~larsongr/Larsonline/SkyCaseStu_files/Diagrid.pdf, Last accessed 25th May 2008<br />[9] “OMA – New Head Quarters – Central Chinese Television”, arcSpace.com, http://www.arcspace.com/architects/koolhaas/chinese_television/, Last Accessed 25th May 2008<br />[10] Telegraph.co.uk, “2008 Olympics: New Towers for a New Superpower”, UK Telegraph, http://www.telegraph.co.uk/arts/main.jhtml?xml=/arts/2007/12/29/babeijing129.xml, Last Accessed 25th May 2008<br />[11] Telegraph.co.uk, “China’s ambitious building passes key test”, UK Telegraph, http://www.telegraph.co.uk/news/uknews/1572347/China%27s-ambitious-building-passes-key-test.html, Last Accessed 25th May 2008<br />[12] Xie, J. , To, A., “Design-Oriented Wind Engineering Studies New China Central Television Headquarters”, Technotes Issue No. 26, RWDI Consulting Engineers & Scientists<br />
  149. 149. Questions<br />

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