CTBUH Journal
Tall buildings: design, construction and operation | 2009 Issue II
Nakheel Harbour & Tower - The Vertical City Condenser Typology Seismic Evaluation: Nanjing Greenland Tower 40 years of the CTBUH: Publications World's Tallest 50 Urban Agglomerations SEI/ASCE Structures Congress 2009 Report Fire & Safety Working Group Meeting Report Inside
News and Events Features
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Architecture !>A43>67E;9@BD35F;57/AA6E 39AFI7D7 David Scott, CTBUH Chairman Feedback and Comments 3BBA;@F763EF:7D5:;F75FE8ADF:7&3=:77> ,AI7D3@6%3EF7DB>3@@7D8ADF:7:3D4AGD ' # BD75;@5F;@ " G;>6;@9A@F:7F:7AD;7EA8B3EFH;E;A@3D;7E EG5:3E$7 AD4GE;7D D3@=$>AK6/D;9:F3@6 %3D=%;F5:7EA@ $AI (3A>A+A>7D; F:7&3=:77>,AI7D;EF:78;DEF FDG7 D73>;E3F;A@A83H7DF;53>5;FK 'H7D ;@:34;F3@FEI;>>>;H7 IAD=3@6EA5;3>;E73>> & I;F:;@38AAFBD;@FE?3>>7DF:3@3&7I0AD= ;FK 05 CTBUH News and Events 48 Tall Buildings in Numbers 4>A5= /;F:F:77H7D 5:3@9;@99>A43> 7@H;DA@?7@F3>5>;?3F738875F;@9@AFA@>K G43; 4GFF:7IAD>63E3I:A>7 ,:7&3=:77> ,AI7DE77=EFAD76G57F:7:G?3@;?B35FA@ :?36*3:;?;3@ 7@@;E'M D;7@ Nakheel Harbour & Tower, Dubai’s new experience centre and observation F:77@H;DA@?7@F4K47;@934735A@A8B3EE;H7 Antony Wood, World's Tallest 50 Urban capital, will be a beacon of inspiration for facilities along with a special sky Authors the region and the world, incorporating function space – creating a vertical 1Mark Mitcheson-Low, *79;A@3>%3@39;@9 ;D75FAD elements from Islamic culture. Encom- community of over 15,000 people (see Figure 2. Nakheel Harbour & Tower Plan /AA6E 39AF %;66>7 3EF 2 passing more than 270 hectares, this Figure 1). Ahmad Rahimian, (: ( + (D7E;67@F /+( 3@FAD +7;@G= -+ mixed-use development will be located 3 The lessons learned from the Nakheel Dennis O'Brien, *79;A@3> ;D75FAD &AD?3@ ;E@7K in the heart of New Dubai, and will + ;@;F;3F;H7E EFD;H;@9FA5AG@F7D35F3@6 I;@68AD57E #@5A@FD3EF F:7&3=:77>,AI7D CTBUH Executive Director Agglomerations 0AG@9 %;66>7 3EF Harbour Tower hold implications for include the world’s tallest building, a ?;@;?;E7;FE53D4A@8AAFBD;@F4K;@F7>>;97@F 673>EI;F:F:7;EEG7EA8I;@64K3>>AI;@9F:7 future buildings of this magnitude. /AA6E 39AF harbour, cultural podium and residential 67E;9@EA>GF;A@E3@6D76G5;@9GD43@EBD3I> I;@6FAB3EEF:DAG9:F:7FAI7D D3F:7DF:3@ $7H7> +G;F7 Although the technical difficulties districts. Nakheel Tower in itself will be a E77 ;9GD7 3DAG@6;F ,:;E;E35:;7H764K;@5ADBAD3F;@9 +:7;=:13K76*A36 associated with such a large project are G43; - vertical city, accommodating residents *735:;@9:7;9:FEA8AH7DA@7=;>A?7F7DI3E FIAE>AFEF:DAG9:F:7:7;9:FA8F:7FAI7D 7%3D= %;F5:7EA@ $AIIAA6E439AF 37 many, none are insurmountable. This I:;5:78875F;H7>K5D73F7E8AGDE7B3D3F7FAI7DE in an efficient LEED rated, sustainable ?367BAEE;4>74K;?B>7?7@F;@9367E;9@ provides optimism for the future of tall /+( 3@FAD+7;@G= &AD?3@ ;E@7K0AG@9 building. This is the world’s first true, 5A@57BFF:3F6;H;676F:7,AI7D;@FA8AGD 735:I;F:F:7;DAI@5AD73@6EFDG5FGD3>>K F:+FD77F (' AJ building design and demonstrates the >;@=763F7H7DK>7H7>E4KE=K4D;697E 35: &7I0AD= &0 -+ G43; - very tall mixed use development E7B3D3F7FAI7DE ,KB;53>F3>>4G;>6;@9E3D7 possibilities in building towers that 7D3:;?;3@IEB5E 5A? 76 AM4D;7@@6K 5A? combining offices, a 5 star hotel, luxury GEG3>>KB>3@@763DAG@63E;@9>7 57@FD3>5AD7 A8F:7E7E=K4D;697E35FE3E3BA6;G?8AD735: reach higher than any that have come Mark Mitcheson-Low residential and serviced apartments, an A8F:7FAI7DE75F;A@E34AH7;F ,:77@6D7EG>F;E before. 3@6F3B7DFAI3D6EF:7FABFA?;F;93F7F:7 05 What’s on the Web 52 Exhibit Review %3D=:3E3@7JB3@E;H7BADF8A>;AA8?3 What's coming up? Condenser Typology: open envelope vertical 10 Global News 26 farming, the extremes of tower urbanism "In a hybrid vertical farm, harvests would Highlights from the CTBUH inevitably cause ‘delirium’, as crops, people, and services would necessitate a 24-hour cycle global news archive CTBUH of events" Rem Koolhaas, (1994). Delirious New York. NY. Monacelli. Matthew Wilson Can humidity-harvesting experiments inform tower urbanism in arid coastal environments? Author The finding of this study includes how the ‘Condenser’ tower typology deviates from other Matthew Wilson methods of vertical farming, climate control, and tower urbanism for the Dubai region. It Vectorfield.org includes an overview of the Condenser’s rationale, precedence, technical workings, Figure 1. Condensation Graph - Relative Humidity , Dubai, 1st Floor United Arab Emirates 364 Garratt Lane organization, incentives, and limitations. London, SW18 4ES, UK t: +44 077 9465 1691 e: [email protected] Foundations homes and workplaces are constructed as Project Overview ‘keno-urban’ tower typology (Dear, 2000). Its uninhabited masonry tower on a hill in rural hermetic boxes of synthetic materials that are uncertainty of events derogates from modern France, called Knapen’s air well (Nelson, 2003). Order, control, and purity are key attributes of This study introduces the Condenser tower 50 Fire & Safety Working Group Matthew Wilson sealed and controlled by oversized ducts and aspirations and moves towards a postmodern Knapen built the large-scale masonry structure the utopian socialist projects of the modern typology and an uncommon vertical Matthew is an independent researcher living and era. From within these modern visions, many advanced mechanical systems. To exacerbate eco-tourism that is specific to Dubai’s arid utopianism. as a labyrinth of internalized cavities. He was working in London. He is currently researching the keen on combining wind flows, diurnal extremes of sustainability focusing on environmental academics have argued that ‘high-technology’ the issue, some academics are promoting the coastal environment. As one of Dubai’s sociology, utopianism, and social ecology. use of hyper-elite and advanced mechanical temperature variations, and the structure’s will conquer nature to save us from impending contemporary modes of urbanism, the Humidity Harvesting Precedence Inaugural meeting report doom. These anthropomorphically centered technologies to germinate plants in closed- ecologic tower could enhance the city’s green thermal mass to trap and condense Case Study desires have led us away from working with loop environments. Their manifestos depict credentials (Yeang 2008). The rationale for this Humidity harvesting can be traced into the atmospheric vapors (see Figure 2). Although natural resources and into unfamiliar worlds towers as space ships that produce food for project is that the tower’s inherent nature is to depths of antiquity. Literature cites a wide, he anticipated his air well to collect 90L (23.7 (McHarg, 1992). The common side effects are the entire city. Paradoxically, their proposals ‘condense’ development. As it does so, it gains geographical gamut of these experiments, Gal) of water per meter of its surface per night, feelings of alienation from the natural imply that humankind should seek subsistence more access to greater amounts of sunlight taking place in various regions of the world the well’s 3.7m (12ft) height and 2.7m (9 ft) environment, and detachment from the city in detached environments to deter an and fresh air than any other building type. By throughout time. This lineage ranges from the thick walls produced an average of 22L (5.8 and the places we live. Our contemporaneous apocalyptic future. Preemptively, these vertical reorganizing the tower, and exposing its inner collection of dew in ancient Greece, taking the Gal) of water by each sunrise. urban conditions are inspired in part by these farm designers cite NASA-like, closed- core to Dubai’s environment, we could collect form of constructed dew ponds. It includes fog visions, from the hinterlands, to the flat share ecological systems as the answer before or condense humidity to germinate plants for water collection from coastal mountain ridges (Pinder 2005). At the urban regional scale these considering contemporaneous bespoke sustenance and climate control (see Figure 1). in Hawaii and Chile, 51 Report: SEI/ASCE Structures solutions. Herein lies an opportunity to and extends to ideologies are realized short of their social In this light, the Condenser situates itself as an aspirations, leading to the erasure of local ‘re-territorialize’, or open, the tower typology to alternative to many vertical farm proposals. On explorations on how to 16 Nakheel Harbour & Tower - cultures, climatic ways of living, and the dialectics with the city and its resources another front, the Condenser itself is a collect advection fog uniqueness of everyday life. Our modernized (Guattari, 1987). We could use our common postmodern utopian project. It is situated to to settle nomadic Congress 2009 hopes and desires for changing space in weave environmental, social cultural, and tribes in Namibia relation to life’s fluxes. We could germinate perceptive ecologies (Guattari, 2000). To foster (Beysens, 1998). The plants in towers for climate control and food these relations several of the Condenser’s materials and methods The Vertical City, Dubai ...20 years to recover production and make towers that are that are employed to floors are designated for ‘seasonal crop responsive to the local culture, climate, and the rotation’, or ‘flux-farming’. These are deceptive collect atmospheric Latest advances in the field of urban fabric (Abalos, 2003) (Wood, 2008). In terms as these spaces are not dedicated to vapors have varied in a If a major project has not started in the city already, it is the following sections, I will speculate on the manner that is unlikely“ to start… I’m not thinking years, I’m thinking decades… only growing crops. The function of these ‘flux’ Mark Mitcheson-Low & technological concepts of this ‘open source’ spaces changes depending on seasonal significant to both time After the Wall Street crash, it took 20 years to recover. alternative, the Condenser tower typology. I natural resources, demand for crops, and region. This ” will overview its precedence, technical antiquated idea communal space, and finance. These variations the seismic design of tall Peter Rees, the London city’s planning officer, admitting that the gloom among developers and investors application, and internal organization. entered the modern create different social groupings within the is so great it could be a generation before another tall building planning application is received by his Following these sketches is a discussion on the tower. Together these space, seasonality, and era with the department. From ‘Decades till City’s next tall building’, Building Design, March 6, 2009 Dennis O'Brien incentives, limitations, and implications of this communal living aspects introduce a rekindled construction of an buildings and other methods of vertical farming. Figure 2. Knapen's Air well 26 | Condenser Typology CTBUH Journal | 2009 Issue II CTBUH Journal | 2009 Issue II Condenser Typology | 27 Research 54 Profile: Gordon Gill CTBUH Awards Committee Chairman Performance-Based Evaluation for the 450m 26 Condenser Typology: open 36 Nanjing Greenland Financial Center Main Tower Structural System for the Main Tower The Main Tower consists of a composite envelope vertical farming, system utilizing both structural steel and "SOM has completed numerous projects in reinforced concrete elements to resist both China which were super-tall and beyond the gravity and lateral loads. Typical floor-to-floor 54 Profile: Israel David heights are 6m to 7m in the podium zone, limits of the Chinese code, beginning with the 4.2m in the office zone and 3.8m in the hotel the extremes of tower zone. Mechanical floors are generally double-height spaces at 8.4m tall. Charles M. Besjak Jin Mao Tower in Shanghai in the mid-1990's. The lateral-load resisting structural system CTBUH Country Representative, Additional design and analysis measures are provides resistance to both seismic and wind urbanism always required on these projects to prove their loading. Refer to Figure 2 for a graphic of the overall lateral system. The primary lateral behavior and gain approval from seismic review system is comprised of an interior reinforced Israel concrete “super-core” shear wall system and panels and building authorities." exterior composite columns. Shear wall thicknesses range from 300mm to 1500mm Matt Wilson Brian J. McElhatten Preetam Biswas over the height of the building with reinforced In order to obtain seismic review approval for the Nanjing State-Owned Assets & Greenland Authors concrete link beams joining adjacent sections Financial Center’s Main Tower, one of tallest structures in the world to date, enhanced design of shear wall around door openings and 1Charles M. Besjak, SE. PE. Director, Skidmore, Owings and Merrill, LLP measures and performance-based evaluations were utilized. The critical parts of the lateral 2Brian J. McElhatten, SE, PE. Associate, Skidmore, system were designed for earthquake forces between two and six times that typically required Figure 1. Nanjing Financial Center Main Tower; Left: Architectural Rendering; Right: Construction Photograph Owings and Merrill, LLP 3Preetam Biswas, PE. Skidmore, Owings and Merrill, LLP by Chinese code. In addition a full 3-Dimensional Non-Linear Elasto-Plastic analysis for a 2500-year earthquake was completed to determine the structures response and serviceability. Skidmore, Owings & Merrill LLP A multi-stage axial shortening, creep and shrinkage analysis was also performed to evaluate Across the street from the A1 Site is the for the A1 Site were completed by SOM by the 55 CTBUH Organizational 24th Floor, 14 Wall Street, New York, NY the long-term load sharing between the central core and the perimeter of the Tower via the Nanjing Greenland International Commercial middle part of 2005 and then turned over to Center Project (A2 Site), which is a thirteen- the Local Design Institute (LDI), East China 36 Performance-Based t: +1 212 298 9300 outrigger truss system. f: +1 212 298 9500 story multi-use building containing office, Architectural Design and Research Institute Introduction Overview retail, dining and parking facilities. Surface (ECADI), for completion of the construction 1Charles M. Besjak parking is contained at basement Level B2. documents and construction administration Structure + Member Listings As the Director in charge of Structural Engineering for In order to obtain seismic review approval for The Nanjing State-Owned Assets & Greenland SOM New York, Charles Besjak leads the structural Financial Center Project (A1 Site) is a mixed- Retail, dining and atrium spaces occur from phases. Schematic design for the A2 Site was engineering team to develop a diverse array of projects. the Nanjing State-Owned Assets & Greenland Level B1 to Level 3. Following are nine floors of completed by SOM in January 2005, and then Evaluation for the 450m As a licensed structural and professional engineer and use development consisting of a 450-meter tall Financial Center's Main Tower, one of tallest licensed architect, he brings over 20 years of experience in (1476'), 70-story office and hotel Main Tower; a office space with a partial mechanical floor and turned over to ECADI to complete the the design and construction industry. He has supervised structures in the world to date, enhanced atrium at the top. Typical floor-to-floor remainder of the design phases. ECADI is the structural engineering for some of SOM’s tallest building design measures and performance-based 100-meter tall (328'), 22-story Accessory Office projects, including the 555-meter tall Lotte Super Tower in Tower; and a 7-story podium building linking heights are 6.3m at the retail floors and 4.2m at engineer of record for both the A1 and A2 Seoul, Korea and zero energy 71 story Pearl River Tower in evaluations were utilized. The critical parts of the office floors. The overall height of the sites. Guangzhou as well as Airports such as Terminal T3, Changi the lateral system were designed for the two towers and containing retail space, Nanjing Greenland Financial International Airport, Singapore and the 5 million sq. ft. building is 66.2m (217') above grade with a cinemas and hotel conference center. The Integrated Terminal at Chhatrapati Shivaji International earthquake forces between two and six times Given the height of the Main Tower and the total area of 46,000 square meters (495,000 Airport in Mumbai, India. that typically required by Chinese code. In total area above grade is approximately requirements for super-tall buildings which are 197,000 square meters (2.1 million square feet). square feet). 2Brian J. McElhatten addition a full 3-Dimensional Non-Linear well beyond the limits of the Chinese code, an As an Associate, Brian McElhatten leads the development Elasto-Plastic analysis for a 2500-year The 450-meter tower contains approximately Structural topping-out of the Main Tower was extensive performance-based evaluation of the entire structural design for individual projects in 65,000 square meters of office space on levels completed in September 2008. Cladding approach was employed. Particular emphasis Center Main Tower coordination with the architectural and building services earthquake was completed to determine the teams and incorporates the structural engineering design structures response and serviceability. A 11 through 34 and 60,000 square meters of installation has been completed and interior and effort was put into the seismic design, concepts within project requirements. The projects he has hotel, club, and restaurant space on levels 36 been involved with include Pearl River Tower, Lotte Super multi-stage axial shortening, creep and fit-out is currently underway. When finished analysis and review process including an Tower and Terminal T3, Changi International Airport. shrinkage analysis was also performed to through 65. The project has 4 below-grade the Main Tower will be the 5th tallest building elasto-plastic analysis on one of the tallest levels under the entire site with a partial 3Preetam Biswas evaluate the long-term load sharing between in the world according to the CTBUH criteria. buildings in the world to date. The steps taken Charles M. Besjak, Brian J. As senior structural engineer, Preetam Biswas develops mezzanine between the first basement floor for the seismic design and approval of the the central core and the perimeter of the The overall project was a competition that was the structural design for individual projects in and the ground floor. Total below-grade area is Main Tower will be the primary focus of this coordination with the architectural and building services Tower via the outrigger truss system. awarded to the Chicago office of Skidmore, approximately 64,000 square meters. These teams and incorporates the structural engineering design Owings and Merrill (SOM) in 2004. The paper. concepts within project requirements. The projects he has floors contain retail, mechanical systems, hotel been involved with include Lotte Super Tower and the schematic design and design development support, loading docks, car parking, and bike Integrated Terminal at Chhatrapati Shivaji International phases along with the seismic review process McElhatten & Preetam Biswas Airport. parking (see Figure 1.) Figure 2. Main Tower Lateral System 36 | Nanjing Greenland Financial Center Main Tower CTBUH Journal | 2009 Issue II CTBUH Journal | 2009 Issue II Nanjing Greenland Financial Center Main Tower | 37 “This cumulative seismic design effort has resulted in one of the tallest structures in the world to date and represents the state-of-the-art in performance-based evaluation.” Charles M. Besjak, page 36 Visit www.ctbuh.org for more on the global tall building industry and the Council on Tall Buildings and Urban Habitat CTBUH Journal | 2009 Issue II Content | 3 Case Study: Nakheel Tower – The Vertical City "The Nakheel Tower is a feat of design intelligence on all levels and across all disciplines – it truly is a mark of the epoch. It is an example of the resilience of the human spirit Mark Mitcheson-Low to overcome the forces of nature to create a monument dedicated to past, present and future generations of the Gulf.” Ahmad Rahimian Dennis O'Brien Nakheel Harbour & Tower, Dubai’s new experience centre and observation capital, will be a beacon of inspiration for facilities along with a special sky Authors the region and the world, incorporating function space – creating a vertical 1Mark Mitcheson-Low, Regional Managing Director, elements from Islamic culture. Encom- community of over 15,000 people (see Woods Bagot, Middle East passing more than 270 hectares, this 2Ahmad Rahimian, Ph.D., P.E., S.E., President, WSP Cantor Figure 1). Seinuk, USA mixed-use development will be located 3 The lessons learned from the Nakheel Dennis O'Brien, Regional Director, Norman Disney & in the heart of New Dubai, and will Young, Middle East Harbour Tower hold implications for include the world’s tallest building, a future buildings of this magnitude. 1Woods Bagot harbour, cultural podium and residential Level 3, Suite 313 Although the technical difficulties Sheikh Zayed Road districts. Nakheel Tower in itself will be a associated with such a large project are Dubai, UAE vertical city, accommodating residents e: [email protected] many, none are insurmountable. This in an efficient LEED rated, sustainable provides optimism for the future of tall 2WSP Cantor Seinuk 3Norman Disney & Young building. This is the world’s first true, 228 E 45th Street PO Box 212828 building design and demonstrates the New York, NY 10016, USA Dubai, UAE very tall mixed use development possibilities in building towers that e:[email protected] e: d.o'[email protected] combining offices, a 5 star hotel, luxury reach higher than any that have come Mark Mitcheson-Low residential and serviced apartments, an Mark has an expansive portfolio of major projects in all before. sectors of design across the world in his 30 years of experience in Architecture. Projects include mixed use developments of commercial, retail, hospitality and Figure 1. Nakheel Harbour & Tower residential sectors and major projects in transportation, education, and infrastructure developments. Mark has been a director since 1998 and joined Woods Bagot in 1986. His role has included the development of new markets and the procurement and design management of a diverse range of projects across the globe. Ahmad Rahimian With over 28 years of experience, Ahmad, an internationally recognized expert in tall buildings, is president of WSP Cantor Seinuk, a leading structural engineering firm based in New York and part of WSP Group PLC. He is the recipient of 2007 AISC Special Achievement Award, 2005 ASCE-CERF Charles Pankow Award and ENR -Top 25 Newsmakers Award of 2003. Among many notable projects, he directed the structural engineering of the Trump World Tower and Hearst Tower, New York; and Torre Mayor, Mexico City. Dennis O'Brien Dennis O’Brien is the Deputy CEO for the International Group and Regional Director for Middle East. Dennis established the office in Dubai following NDY, appointment as Building Services Consultants for the Nakheel Tall Tower. In addition to roles on the Board of the Company, he is responsible for areas of Quality Assurance and Risk Management for the International Group. He is also active in assisting international offices in concept design and design reviews for major projects. 16 | Nakheel Harbour & Tower CTBUH Journal | 2009 Issue II Architecture Global design practice Woods Bagot were appointed as the Architects for the Nakheel Tower and Masterplanner for the harbour precinct in 2006. Building on the theories of past visionaries such as Le Corbusier, Frank Lloyd Wright and Paolo Soleri, the Nakheel Tower is the first, true realisation of a vertical city. Over 15,000 inhabitants will live, work and socialise all within a footprint smaller than a New York City block. With the ever-changing global environmental climate affecting not only Dubai, but the world as a whole - The Nakheel Tower seeks to reduce the human impact on the environment by being a beacon of passive Figure 2. Nakheel Harbour & Tower Plan ESD initiatives, striving to counteract and wind forces. In contrast, the Nakheel Tower minimise its carbon footprint by intelligent deals with the issues of wind by allowing the design solutions and reducing urban sprawl wind to pass through the tower, rather than (see Figure 2). around it. This is achieved by incorporating Reaching heights of over one kilometer was two slots through the height of the tower made possible by implementing a design which effectively creates four separate towers, concept that divided the Tower into four each with their own core and structurally separate towers. Typical tall buildings are linked at every 25 levels by "skybridges". Each usually planned around a single, central core of these skybridges acts as a "podium" for each and taper towards the top to mitigate the of the tower sections above it. The end result is large floor plates at high levels as the tower does not taper as it gets taller (see Figures 3a+b). Figure 3a. Tower Components Figure 3b. Slots through Nakheel Tower allow wind to pass through CTBUH Journal | 2009 Issue II Nakheel Harbour & Tower | 17 Figure 4a. Arabic Pattern Base Figure 4b. Concentric Circles Figure 4c. 16 points is a regular geometric shape that symbolises circle of the plan they created crescents, and equal radiation in all directions from a single the intersection of these crescents, in turn, form In the concept stages point. This is a fitting symbol for the spread of the shape of the columns. As they fan out from of“ the design, the architects the teachings and influence of Islam the base of the tower, these larger circles searched for cultural and throughout history. When the star motif is inform the geometry of the surrounding areas, replicated and radiated, it creates junctions at reinforcing the importance of the tower’s regional inspiration. A key the points where they meet. This, in turn, geometry and the way it sits in its context (see element that came up time and defines further points of a circle, creating a Figure 5). time again from an engineering series of concentric circles all emanating from There are many buildings that claim to offer perspective was that a building the centre point, again reinforcing Islamic vertical communities. However, the Nakheel that was symmetrical would principles (see Figures 4a-c). Tower will far exceed the existing paradigm of evenly distribute the massive In developing the Nakheel Tower, the circle has vertical living with the inclusion of ‘sky bridges’ loads. This was keyed into been adopted as the essential form of the plan. in the proper sense of the term. The sky bridges The locations of the columns supporting the perform multiple roles, offering community Arabic pattern-making, which tower represent the points of a 16-point star. and public spaces where visitors and residents is the same notion about Instead of forming the star from straight lines, alike can interact - the Village Squares for the symmetry, harmony and the circles were used. As these circles crossed the building inhabitants. They will also serve centre point. From a cultural point of view and from an engineering point of view there is an overlap that basically tells the same story.” Alf Seeling, Principal, Woods Bagot The design essence of the Tower is thus deeply routed in the regional influences of pattern- making and geometry, stemming from the harmony, unity, order and balance of the radiating circle and 16 pointed star often seen in regional designs. The 16-pointed star, from which the Nakheel Tower draws its inspiration, Figure 5. Pattern informing tower plan 18 | Nakheel Harbour & Tower CTBUH Journal | 2009 Issue II Figure 6a. Skybridge section Figure 6b. Skybridge link Figure 6c. View to Skybridge dome from glass elevator Figure 7. Diagram of the planning and stacking of the 156 tower lifts functionally as the transfer point between lifts, The express lifts use the highest lift technology the refuge zones in an emergency, and the available to reach the 560m high sky lobby and structural link between the four tower legs, transfer floors. From the sky bridges, residents, acting as a ‘belt truss’ that binds the tower tenants and guests can commute in local lifts together (see Figure 6a-c). for the 25-level community above. All 156 lifts Fire and life safety design is paramount in tall can be used for fire evacuation to refuge zones building design. The design team made a on sky bridges or complete evacuation. priority of incorporating multiple levels of Delivery to the tower is also via remote loading in-built redundancy within the Nakheel Tower’s and docking with a logistics handling system design. The concept of four legs means that not unlike an airport terminal (see Figure 7). there are four separate towers that offer four Due to the sheer scale of the Nakheel Tower distinct means of exiting in an emergency. For and the time projected to build it, a key Figure 8. Facade Panelisation example, if one of the tower cores were consideration during the design process has disabled due to an emergency, it is possible to been to maximise the repetition of façade whilst providing shading co-efficiencies and travel either up or down to the nearest sky elements, to keep construction time and cost U-Values to withstand direct sunlight and high bridge and safely cross to an unaffected tower down as much as possible. The curtain wall and humidity levels. The Titanium panels proposed and exit from there. titanium cladding follow a modulation that are 100% recyclable – including all fixing plates The logistics of servicing a population of over panelises the entire façade – essentially making and connections. The panels are manufactured 15,000 people vertically requires innovative the panels used on every level exactly the same in a process similar to that utilised by the design solutions. The tower is serviced by 156 (see Figure 8). aerospace industry. lifts using the latest technology of double-deck The façade incorporates the very latest in glass In a region such as the Middle East with its and express lifts - the equivalent of a vertical technology, including advanced nanotech- harsh climate, sustainability is of the upmost mass transit system. nology, to allow maximum light transmission importance. The design teams are working CTBUH Journal | 2009 Issue II Nakheel Harbour & Tower | 19 to achieve LEED Gold rating for the Nakheel Tower. Also, original and forward-thinking ...super-talls sustainability initiatives are being developed and incorporated in parallel to contemporary standards to ensure that it is ‘future proofed’. The primary difference between a super-tall tower and two When holistically considered, all these efforts towers“ half its size is not the cost per square meter – it is the time it will offer ‘green’ capability above and beyond takes to build the tall one versus two shorter ones, and the loss of the existing advisory standards. The current revenue through lost rent. This makes most super-tall buildings sustainability model for super tall buildings is being challenged at every level on a financially unfeasible.” continuous basis, the physical example becoming the Nakheel Tower . Many forms of Adrian Smith, Principal, Adrian Smith + Gordon Gill Architecture on why most super-tall buildings environmental strategies have been applied to are financially unfeasible for developers. From ‘The Sky’s the Limit’ Cityscape. February/March 2009 the building design. These include everything from the use of high-performance facades to low energy-use servicing. traditionally that broad footprint would taper systems of all kinds – structural, mechanical, and narrow at higher elevations. Generally, electrical, fire egress, life safety, etc… this approach has the beneficial effect of And of course, this design maximizes the most Structure reducing the lateral wind and seismic loads on valuable real estate at the top of the building. the building. Unfortunately, the tapering WSP Group has been appointed as structural reduces the most valuable real estate that the consultant for the Tall tower. Structural building possesses – the area towards the top. Structural Form engineering of the Tall Tower were managed by WSP Cantor Seinuk as lead structural To gain an adequate footprint for stability, the Beyond practically a constant form from top to engineer in collaboration with LERA and VDM tower extends to nearly 100m in diameter, bottom, the tower is also characterized by its Group. resulting in an approximately 10:1 aspect ratio. symmetry. This provides two very important Still, despite being quite a slender tower, the benefits for the structure. Firstly, there are no transfers of vertical elements through the main Building Form central area of such a floor plate cannot be reasonably utilized as lettable area, as it is too body of the tower. Secondly, it allows for a The building form steps forward beyond the far from the natural light of the façade. uniform distribution of gravity forces through traditional approach to high-rise construction, the structure. These characteristics allow for a This fact led to creating a central void space in and does so in a holistic way that harmonizes more efficient structure. Further, they address the tower, which pushed all of the usable area the structure and architecture. For any an important design consideration for to the perimeter. This in turn afforded the high-rise building, a broad footprint gives the super-tall buildings – axial shortening. opportunity to create vertical slots in the structure the stability that it needs; and tower, allowing wind to pass directly through Maintaining a uniform distribution of load the center of the throughout the structure was one of the building. In effect, driving forces in developing the structural the tower essentially systems, given that the building would likely tapers from the shorten more than 400mm at its observation inside out to dramat- level. However, the structural characteristics ically reduce the that address this issue are one in the same as overturning wind those that address the core issues of efficiency, forces on the redundancy, and economy. structure. There is no separation between the gravity system and the lateral system, as can often be the case in high-rises. The vertical structure is The 4 quadrant organized in such a way that the elements are approach also all sized based on strength considerations, provided the while at the same time providing sufficient opportunity for lateral stiffness. Every element of the structure independent and is interconnected as will be described below. redundant building This creates an extremely efficient structure Figure 9. Typical Wall Layout 20 | Nakheel Harbour & Tower CTBUH Journal | 2009 Issue II where the materials perform double-duty be constructed with structural steel. (gravity and lateral support). Multiple load Outrigger trusses at the special function paths are created to give added redundancy levels will provide support to the floor and by placing material only where it is systems as well as stabilize the spire by required for strength. This structure creates a engaging the arch elements. uniform distribution of load, so as not to have The last main element is the floor system, differential shortening. which is a conventional concrete on metal Though the building may function architec- deck supported by composite steel beams. turally as several groups of 25-story buildings, With 10 million square feet of area, the floor structurally it functions as a single entity. designs are meant to reduce complication. Given that there is a tremendous amount of repetition and that its erection can run Primary Structural Elements independently of the concrete operation, the Figure 10. Isometric View of Belt Trusses All of the vertical elements of the building are system is easily erected. cast-in-place reinforced concrete. The wall system consists of a Drum Wall, which is essentially analogous with a typical building’s Structural Materials central core wall. From the Drum, Hammer As important as the simplicity of the floor Walls spring outwards to engage the structure framing is, its weight is equally as important. at the perimeter of the building and Fin Walls Reducing the overall weight of super-tall spring inward primarily to support the core buildings is always a principal goal, since the area (see Figure 9). weight and costs tend to compound themselves in the vertical elements. In this case, nearly half of the vertical structure’s The Hammer Walls connect directly to eight capacity went towards simply supporting its Mega-Columns situated at the perimeter. own self-weight. Therefore, a lightweight At each skybridge, the balance of the floor system is key. Mega-Columns are interconnected to the Of course high strength concrete is imper- Hammers by means of the 3 story high steel ative in achieving a building of such Belt Trusses (see Figure 10). In addition to unprecedented height. Although there is a increased lateral stiffness, the Belt provides a ready supply of concrete in Dubai, placing level of redundancy and added robustness to concrete above an 80MPa strength is not the structure by creating alternate load paths. believed to have been attempted. For the Also at each skybridge are Link Walls, which Nakheel Tower, concrete in excess of 100MPa tie the Drum Wall segments together. This strength is required with Young’s Modulus of produces a completely interconnected nearly 50,000MPa. structural system that behaves as a single Again, beyond simply the strength of the tower rather than separate quadrants. To material, constructability is at the forefront of transfer the tremendous shear forces, steel the design approach. The concrete must be plate shear walls, up to 80mm thick encased workable in a very hot environment, with up to 1300mm of concrete, are used. pumpable to great heights, and above all Figure 11. Finite Element Model of Spire and Crown The top of the building is characterized by a reliable. series of 8 arches that extend upward to a To this end the design team worked together center spire that supports several special with concrete technologists, Ancon Beton of function levels (see Figure 11). To put this Australia, developing design mixes. This was portion of the tower in perspective, the seen as a crucial element in the structural arches are taller than the Eiffel Tower. design of the building and work on the The spire itself is a cylindrical concrete form concrete design was undertaken during that is supported from the 7th skybridge with schematic design. a series of concrete walls. The arches are to CTBUH Journal | 2009 Issue II Nakheel Harbour & Tower | 21 to wind. Aeroelastic model testing, high frequency pressure integration studies, and large-scale tests at high Reynolds Number (Re) were also performed to provide additional pieces to the puzzle (see Figure 14). The strategy for addressing lateral accelera- tions of the tower was always to look for an aerodynamic solution first. This required a very good understanding of the wind behavior and extensive testing (as intimated above). The wind engineering is substantially completed at present. The building’s performance in terms of lateral accelerations is good and no supplemental damping is Figure 12. CFD Analysis necessary. However, provisions for a liquid mass damper has been included in the Wind Engineering With a constant cylindrical form, the tower design to account for possible variations in Wind was perhaps the single greatest was susceptible to vortex shedding, which is the building’s as-built stiffness and inherent adversary for the engineers on this project. why the slots are such a crucial design damping. Rowan Davies Williams & Irwin (RWDI) are the element. The slots serve to mitigate the wind engineers for the project with peer vortex-shedding phenomenon and reduce the overall wind load on the building by review work being performed by the Alan G. Building Services Davenport Wind Engineering Group of the three fold. One lesson learned in the design University of Western Ontario and MEL was that very subtle changes in the slot or Norman Disney & Young has been appointed Consultants. The wind engineering, structural internal void geometry can substantially to design Mechanical, Electrical, Hydraulic engineering and the architecture of the tower impact the aerodynamic behavior. and Fire Services for the Nakheel Harbour were very closely intertwined in the devel- Computational fluid dynamics (CFD) were Tower. A significant amount of research and opment of the project. Numerous building used to study many small variations in development has been undertaken for this forms were studied throughout the tower’s geometry (see Figure 12) together with project. The product of this effort has development. Ultimately, many of the dozens of high frequency force balance significant implications for the engineering of refinements to the tower’s architectural (HFFB) tests (see Figure 13). However, the other tall towers. concept were driven by aerodynamics. CFD modeling and HFFB tests were only initial indicators as to the building’s response Figure 13. High Frequency Force Balance Test Figure 14. Large Scale High Re Test 22 | Nakheel Harbour & Tower CTBUH Journal | 2009 Issue II Stack Effect impossible or dangerous to open. Stack effect is one the main difficulties Measures being considered to mitigate the ...retrofit associated with tall tower design. The problems created by stack effect include: problem has traditionally been encountered t Use of revolving doors at pedestrian in cold climates in North America, during They’re showing the entries. rest“ of the city that existing winter, where temperature differences approaching 40°C are common. Many of the t Providing multiple stages to entries. buildings, no matter how tall world’s early tall towers were constructed t Isolating loading docks from goods lifts. they are, no matter how old there. tProviding an anti-room with sequenced they are, can take steps to A warm building in a cold climate behaves operation of doors and pressure control significantly reduce their like a chimney, with warm air rising to the top for goods access. energy consumption. of the building. This results in the internal A similar use of anti-rooms is proposed for ” pressure at high level becoming well above maintenance access at the top of the Mayor Michael R. Bloomberg, New York City, atmospheric and at low level becoming well building. who has made sustainability a theme of his below atmospheric. Somewhere near the In general, stair shafts serve from skybridge to administration, quoted on the middle of the building there will be a neutral environmental retrofit plans for the Empire skybridge only, opening onto safe havens at point, where the internal and external State Building. From ‘Empire State Building pressures are equal. each skybridge. Likewise, lifts serving limited Plans Environmental Retrofit’ The New York parts of the tower do not present major In the past decade, the world’s new breed of Times, April 6, 2009 problems. high rise towers has been built in the hotter climates of Asia and the Middle East. High rise lift shafts will be temperature the tower. The concern with this arrangement Problems occur during hot weather, with the controlled to align pressure differentials to is the very high pressures in the system. pressure gradient operating in reverse. The those existing elsewhere in the building. Option 1 is favoured, with the most signif- result is high pressures at ground level and Shafts will be required to be warmer in icant concern being the potential for a leak in low pressures at high level. The tallest towers summer than the general space temperature, the heat exchangers between stages. This in Asia have been approximately to provide the same pressure gradient. would result in a doubling of pressure in the 500m high. Temperature differences tend to lower parts of the stages and subsequent be no more than 15°C (say 36°C ambient and Pressure Staging failure of all heat exchangers below these 21°C internal). The Nakheel Harbour Tower is stages. Resultant damage would be over 1,000m high and the temperature Tall buildings create the need to pump water enormous, and the potential for injury difference in summer is 25°C (46°C ambient in stages up the building, to limit the pressure significant. less 21°C internal). This results in a pressure in any part of the pipework to the pressure difference between the top and bottom of an rating of the available pipework, valves and This is likely to be overcome by the use of an open shaft of 780 Pa. This is expected to result equipment. oversized venting system. Whilst this seems likely to prevent a rapid pressure build up, in a positive pressure on the order of 390Pa at In the case of chilled water, this issue computer modeling is to be undertaken to the ground and a negative pressure of 390 Pa becomes more complicated. The number of ensure the design can cope with any at the high level. To put this into perspective, stages is limited by the practicalities of transient pressures due to a sudden failure. most fire codes limit the pressure difference permissible temperature rise in the chilled across a fire escape door, due to stair water to the top of the tower. pressurisation, to 50 Pa. This is due to the Environmental Initiatives Two broad options presented themselves. force needed to open the door. Option 1 had a pressure stage at each The project brief requires high standards of The pressure created by stack effect causes air skybridge. This kept the pressure ratings low environmental performance. Most initiatives, infiltration into the building at the high level, but resulted in unacceptably high chilled which are widely considered best practice in resulting in energy loss and loss of capacity of water temperatures at the top of the tower. modern buildings, are being incorporated as HVAC systems. At the bottom of the tower, Air-cooled chillers would be required at high a matter of course and are not covered in this the high pressure will cause high loss of levels in the tower. paper. conditioned air to the outside. Option 2 had a pressure stage at every The project has a high component of The pressures will result in high air velocities second skybridge. This limited the stages to 5 residential and hotel space and therefore a across doors connecting to the outside. This (including a stage at the basement chiller high need for hot water on a continual basis. will cause lift doors to jam and subsequent level) and eliminated the need for chillers in The Dubai climate creates the need for loss of lift service. It will make doors either cooling, even during the winter months. CTBUH Journal | 2009 Issue II Nakheel Harbour & Tower | 23 Several alternative cogeneration strategies handlers complete with mounting frames, thoughts and innovations behind the design are being considered. valves, electrical panels and control panels.All involves becoming a futurist and not The project requires its own District Cooling will be pretested offsite and will use propri- accepting current norms. Research into future Plant. This provides the opportunity to gain etary-bolted assembly pipework. trends and means of providing for them has the advantages of efficient operation from a Replacement of system components, during been an important part of the design teams’ large chiller plant. It also enables the design the life of the building, includes equipment approach. of the load side (air handling plant) to be that can be broken down to components and In these uncertain financial times, Dubai and optimised to increase chiller efficiency and catered for in a goods lift. Where this is not the Nakheel Tower have not been immune to reduce pumping needs. feasible, the dimensions of the component the effects of the Global Financial Crisis. Water conservation is by means of black must be within the dimensions of the lift Currently, the design team have completed a water treatment, storm water harvesting, and shaft, which can be temporarily used for substantial portion of the project design and reuse of fire test water. hoisting. documentation, enabling extensive Services risers must be planned, to allow foundation work to be completed at the site. Phase change material is being considered The decision by the developer to temporarily for thermal storage in chilled water and hot replacement and additional services to be run. This requires spatial planning not only for suspend site-work has not impacted the water systems as well as in building enthusiasm of the team, who are still excited construction, where an increase in thermal the riser but also for access during instal- lation. about the day this boundary-pushing tower mass can contribute to either energy savings will rise out of the sand. or reduction in peak demand. Facing the Future Naming all the professionals involved and The use of high voltage power distribution instrumental in advancing a project of this scale enables reduced transmission losses. In order to develop a tower of this scale and requires more space than available here. distinction, the design team has had to However, this article will not be complete project its design strategies without acknowledging the contribution and Logistics forward into the future by dedication of the following individuals: During construction, the time taken to hoist using the latest design Cris Johansen, Peter Read and Neil Woodcock, equipment to such heights is considerable. techniques of today and Nakheel. Alf Seeling, Garry Marshall, Richard The time taken for labour to go to and from creating flexibility to Marshall, Nik Karalis, Peter Miglis and Matthew the upper parts of the building is also embrace the trends and Gaal, Woods Bagot; Kamran Moazami, Bart considerable. This dictates the need to look technology of the future. Sullivan, Samer Wattar, Andy Veall and Patrick closely at prefabrication offsite. Children of the Emirates will see this tower constructed Chan WSP cantor Seinuk; Leslie Robertson and Internal lift shafts are to be used for and will be the future SawTeen See, LERA; Anil Hira, VDM; Kevin construction lifts, to reduce the reliance on occupiers, tenants and Winward, Winward Structure; Peter Irwin and external cranes. Therefore, components that guests of the building. The Derek Kelly, RWDI; Nick Isyumov and Peter Case, fit in the lift shaft and can be quickly team has been designing BLWTL; Bill Melbourne, MEL Consultant. Max assembled onsite are preferred. this tower for future Ervin & Chris Haberfield, Golder Associates; Ian Examples of preassembly include prewired generations and future Ullah, Fugro; Harry Poulos, Coffey Geotechnics. electrical and communication systems with vertical communities. Soletanche-Bachy / Intrafor JV Michel Percak plug-in connections, fan coil units and air Future-proofing the Khalil Ibrahim; Rick Barker and Paul Bennett, Barker Mohandas. 24 | Nakheel Harbour & Tower CTBUH Journal | 2009 Issue II CTBUH Organizational Members http://membership.ctbuh.org SUPPORTING CONTRIBUTORS Rosenwasser/Grossman Consulting CPP Inc. Arup Engineers, PC CS Associates CTL Group W. S. Atkins & Partners Overseas Rowan Williams Davies & Irwin Inc. Solomon Cordwell Buenz & Associates, Inc. Dagher Engineering Bovis Lend Lease S.r.l. Dar Al-Handasah (Shair and Partners) Buro Happold Ltd. Studio Gang Architects Dennis Lau & Ng Chun Man Architects & CB Richard Ellis Ltd Thornton Tomasetti Inc. Engineers (HK) Ltd. Davis Langdon LLP Walter P Moore Dunbar & Boardman Edgett Williams Consulting Group, Inc. DeSimone Consulting Engineers Winward Structures Pty. Ltd. Woods Bagot Emirates Specialities Co. LLC Emaar Properties PJSC Epstein Gale International CONTRIBUTORS Faithful + Gould Illinois Institute of Technology, College of Fortune Consultants Ltd. AECOM Architecture FXFOWLE Architects P.C. AKF Engineers Kohn Pedersen Fox Gold Coast City Council American Iron and Steel Institute Gorproject (Urban Planning Inst. of Residential and KONE Oyj Broadway Malyan Public Buildings) Mori Building Co., Ltd. Canary Wharf Group Guangzhou Scientific Computing Consultant NBBJ CB Engineers Gulf Glass Industries. Remaking of Mumbai Federation Continental Automated Buildings GVK–ECS, Inc. Samsung Corporation (Engineering & Haynes Whaley Associates, Inc. Association (CABA) Heller Manus Architects Construction) C.S. Structural Engineering Hilson Moran Partnership Ltd. Schindler Elevator Corporation DeStefano + Partners Ltd. Hoerr Schaudt Landscape Architects Skidmore Owings & Merrill LLP DHV Bouwen Industrie HOK,Inc. Turner Dong Yang Structural Engineers Hong Kong Housing Authority Viracon (Apogee) Goettsch Partners Horvath Reich CDC Inc. Halvorson and Partners International Union of Bricklayers and INTEMAC Allied Craftworkers PATRONS Irwinconsult Pty. Ltd. American Institute of Steel Construction, Inc. JCE Structural Engineering Group, Inc. JBA Consulting Engineers, Inc. Blume Foundation KHP Konig, Heunisch und Partner John Portman & Associates BMT Fluid Mechanics Ltd. Lobby Agency Lerch Bates Inc. DLA Piper UK LLP MulvannyG2 Architecture Limitless LLC The Durst Organization Nakheel Lucien Lagrange Architects Hongkong Land Ltd. NFPA Magnetek, Inc Norman Disney & Young Margolin Bros. Engineering & Consulting Ltd. KLCC Property Holdings Berhad McNamara/Salvia, Inc. Kuwait Foundation for the Advancement of Perkins+Will MechoShade Systems Sciences Riggio / Boron, Ltd. Middlebrook & Louie Saudi Ogers Ltd. The Steel Institute of New York Murphy/Jahn Tishman Speyer Properties Structal-Heavy Steel Construction Nikken Sekkei Ltd. Webcor Builders Studio Daniel Libeskind, Architect LLC Nishkian Menninger T.R. Hamzah & Yeang Sdn. Bhd. Arkitek O’Connor Sutton Cronin Weidlinger Associates, Inc. Option One International W.L.L. Zuhair Fayez Partnership Tekla Corporation TSNIIEP for Residential and Public Buildings Otis Elevator Company Palafox Associates WSP Group DONORS Pelli Clarke Pelli Architects Adrian Smith + Gordon Gill Architecture Perkins Eastman Architects Boundary Layer Wind Tunnel Laboratory PARTICIPANTS Plannungsgruppe Droge Baade Nagaraj Aedas Limited PPG Industries (U. Western Ontario) Al Jazera Consultants Ramboll Whitbybird Built Form Allford Hall Monaghan Morris LLP Stanley D. Lindsey & Associates Gensler APH Capital Partners Syska Hennessy Group, Inc. Halcrow Yolles Arabian Aluminum Co. LLC Taylor Thomson Whitting Pty Ltd Hughes Associates, Inc. ARC Studio Architecture + Urbanism TFP Farrells Limited. Hyder Consulting Archstudia P.M. TPS Consult Ltd Centre Architectural Institute of Korea Larsen & Toubro Limited Traynor O’Toole Architects Arquitectonica United States Gypsum Company Leslie E. Robertson Associates BG&E Pty Limited University of Nottingham Magnusson Klemencic Associates Bouygues Construction Vanguard Realty Pvt. Ltd. W. L. Meinhardt Group P/L Building Design International Vipac Engineers & Scientists Ltd. Nabih Youssef & Associates Callison LLP Walsh Construction Company Pan Arab Consulting Engineers The Calvin Group, LLC Werner Sobek Stuttgart GmbH & Co. KG Canderel Management, Inc. Pickard Chilton Architects WOHA Architects Pte. Ltd. CBM Engineers Wong & Ouyang (HK) Ltd. RISE International Chicago Committee on High-Rise Buildings World Academy of Sciences for Complex Security RMJM Hillier Code Consultants, Inc. WSP Cantor Seinuk Group Inc. Rolf Jensen & Associates, Inc. Contract Glaziers Inc. WSP Flack + Kurtz COWI A/S Y. A. Yashar Architects Supporting Contributors are those who contribute $10,000; Patrons: $6,000; Donors: $3,000; Contributors: $1,500; Participants: $750. CTBUH Journal | 2009 Issue II CTBUH Organizational Members | 55 About the Council The Council on Tall Buildings and Urban Habitat, based at the Illinois Institute of Technology in Chicago, is an international not-for-profit organization supported by architecture, engineering, planning, development and construction professionals. Founded in 1969, the Council’s mission is to disseminate multi-disciplinary information on tall buildings and sustainable urban environments, to maximize the international interaction of professionals involved in creating the built environment, and to make the latest knowledge available to professionals in a useful form. The CTBUH disseminates its findings, and facilitates business exchange, through: the publication of books, monographs, proceedings and reports; the organization of world congresses, international, regional and specialty conferences and workshops; the maintaining of an extensive website and tall building databases of built, under construction and proposed buildings; the distribution of a monthly international tall building e-newsletter; the maintaining of an international resource center; the bestowing of annual awards for design and construction excellence and individual lifetime achievement; the management of special task forces / working groups; the hosting of technical forums; and the publication of the CTBUH Journal, a professional journal containing refereed papers written by researchers, scholars and practicing professionals. The Council actively undertakes research into relevant fields in conjunction with its members and industrial partners, and has in place an international ‘Country Representative’ network, with regional CTBUH representatives promoting the mission of the Council across the globe. The Council is the arbiter of the criteria upon which tall building height is measured, and thus the title of ‘The World’s Tallest Building’ determined. CTBUH is the world’s leading body dedicated to the field of tall buildings and urban habitat and the recognized international source for information in these fields. Council on Tall Buildings and Urban Habitat Illinois Institute of Technology S. R. Crown Hall 3360 South State Street Chicago, IL, 60616 Phone: +1 (312) 909 0253 Fax: +1 (610) 419 0014 Email: [email protected] http://www.ctbuh.org ISSN: 1946 - 1186