BS 536STUDIES ON TALL BUILDINGS: DESIGN CONSIDERATIONS

Spring 2013-2014

Case Study: Wuhan Greenland Centerby

Nastaran Deljavan

Submitted to: Assoc.Prof.Dr. Mehmet Halis Günel

MIDDLE EAST TECHNICAL UNIVERSITYDEPARTMENT OF ARCHITECTURE / BUILDING SCIENCE PROGRAM

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BS536GS: DESIGN CONSID2013-2014

Greenland

PROGRAM

General Information [3]

Name: Wuhan Greenland CenterLocation: China, WuhanUsage: Hotel/ Residential/ OfficeHeight (to tip): Architectural:636m/Occupied: 567mFloors: 125 floors above groundConstruction End: 2017Structural Material: CompositeStructural System: Outrigger frame systemClient: Wuhan Greenland Bin Jiang Property Co.Architect: Design: Adrian Smith & Gordon Gill Architecture/ Architect of Record: ECADIStructural Engineer: Thornton Tomasetti

(http://www.skyscrapercenter.com)

Wuhan Greenland Center

Case Study: Wuhan Greenland Center by Nastaran DeljavanSubmitted to: Günel – Spring 2014

METUgrou

20terial: Composite

TUal Syste utrigger framTnt: Wuhan Greenland Bin Ji

EArchi gn: AETArchitecture/ Architetructural Eng

MEBS536

m/Occupied: 567m

Wuhan Greenland Center, Hotel plan (http://www.google.com)

Section of Wuhan Greenland Center(Drawn by Nastaran Deljavan [5])

Plan and Section of Wuhan Greenland Center

Prospective of Wuhan Greenland Center(Drawn by Nastaran Deljavan [4])METU

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Plans of Wuhan Greenland Center(http://www.google.com)

Plan of Wuhan Greenland Center(Drawn by Nastaran Deljavan [5] )

Plans of Wuhan Greenland Center

Core wall

Super ColumnSC1

Super ColumnSC2

Steel Column

MEBS536

el Column

Total Gross Floor Area (GFA): 393.259 m2 [4]

323308 m2 Above Ground[4 ]

70171 m2 5-story Basement[4]

Building Usage [1]

A mixed-use skyscraper including:• Offices up to the 69th floor• Apartments at the 70th to 89th floors• Hotel from the 91th to the top floor• Outrigger trusses and belt are used

for mechanical spaces[1]

(Drawn by Nastaran Deljavan [1])

Entrance of Wuhan Greenland Center[1]

Entrance plan(Drawn by Nastaran Deljavan)

While some mixed-use towers separate users by levels, the triangular floor plan of this building allows for the tenants or visitors to have separate entrances all at Ground Level. [1]

HotelAmenities

Apartment

Office

Parking spaceMETU Flo

U59 m

U323308 m e G70 2 5-story B

OfficeMBS536

orsoor

belt are used es[1]

Entrance of S5uhaSW

Wind Load and Earthquake Load [4]&[5]

Tapering Round Top Soft Corner

TriangularFloor Plan

Wind pressure Relief

Architectural Building Massing Concept [1]&[5]

Lateral loads, wind and seismic, play the important role in design of Wuhan Greenland Center. Therefore, for the structural design of the tower, wind load, seismic load, and seismic load under frequent earthquake, were combined with gravity load.For Wuhan Greenland Center, the base shear and overturning moment under wind load is much larger than the values under the frequent earthquake load. To optimize both the structural and programmatic performance of building, four primary design solutions were implemented. [1]

• A tapered profile• A dome top• Triangular floor plans

with rounded soft corners • Vent slots

OTM: Overturning MomentWind load information is provided by RWDI and dated on February 3, 2012

METUsigismi

e combined w

nd Center, the base shear ament under wind load is much

he values under the frequent ake load

timize both the strucperformance of building, fosolutions were impleme• A tapered profile• A dome top

Triangulawith

BS5362012

Option 1: tapered tower, solid surface [4]

Option 2: tapered tower, opening between the

dome and crown, slotted floor at multiple

elevations [4]

Option 3: wing walls and vertical slots [4]

Tower Wind Load Comparison for Different Massing Options. Based on wind load data from RWDI, February 2011 [1] & [4]

Wind Tunnel Test by RWDI to Study 3 Option [1]&[4]

According to the table:

Option 1 did not show a reduction [1]

Option 2 reduced the overall wind load by 15%and 6.6% along “X” and “Y” respectively [1]

Option 3 did not show a significant wind load reduction [1]

Therefore, second and third option is used for design of Wuhan Greenland Center.METU duction

the overall wind load by 15ng “X” and “Y” respectively [1

n 3 did not show a signification

Therefore, second and design of Wuhan G

BS536Option 1: tapered to

solid su

Based on wind

A Tapered Profile [1]

• Reduce overall tower lateral load • Resolve different floor plate size

requirements for varied program elements without using a traditional step profile

Triangular floor plans with rounded soft corners [1]

• create unique public spaces that attract visitors to the building

• reduce the tower wind load• Separated entrances at ground level

distinguish each type of user and control access

alternation of floor plans in wuhan Greenland Center

Opening Between the Dome and Crown[1]

• An opening at the tower top would separate the whole tower top into an upper crown and a lower dome

• Reducing the wind load• Top opening is a unique architectural feature • It is as a building maintenance unit in which

window cleaning machine is concealed in the crown to clean the dome surface. [1]

alternation of slotted floor plans in Wuhan Greenland Center

Opening Between the Dome and Crown slotted floor(http://www.skyscrapercenter.com)

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Structure System

Structural Elements:[4]

• Outrigger • Core• Super Column • Belt Truss• Horizantal Braced Frame

Outrigger frame system

Structural Plan od Wuhan Greenland Center(Drawn by Nastaran Deljavan [1] & [4])

Features of Core and Super Column [1]

• “Y” shape plan make maximize the structural stiffness and it is more efficient than rectangle core

• At the tip of each tower wing a pair of massive super columns (SC1) are located

• Two additional super columns (SC2) are spaced at approximately one-third points along each face and serve to reduce the spans of perimeter structural members.

• The super columns are Steel Reinforced Concrete (SRC)

• SC1 columns are up to 3.3x4.6m in first levels

The core was organized to provide multiple benefits across different disciplines: separating office, hotel and apartment operational functions, providing significant structural stiffness and strength for the tower to resist lateral and gravity loads, and accommodating the mechanical system floor and riser space requirements.

Core wall

PerimeterBelt Truss

HorizontalFloor Braces

Super ColumnSC1

Outrigger Truss

Super ColumnSC2

Steel Column

METU mize thit is more ef

ach tower wing a pair of uper columns (SC1) a

dditional super columns (Sed at approximately one-thi

each face and serve spans of perimeter struc

• The super columnsConcrete (SRCSC1 colum

vels

36uss

mnuper ColumC2

B5353Steel Col

Outrigger Truss and Belt Truss Location [4]

Outrigger Truss Location:[4]

3 Outrigger Truss FloorsLevel 36 to 39Level 67 to 70Level 101 to 103

1 Header Truss FloorLevel 121 to 123

Outrigger Truss and Belt Truss Location(Drawn by Nastaran Deljavan [4])

Belt Truss Location:[4]

10 Belt Truss FloorLevel 3 to 5Level 14 to 15Level 24 to 25Level 48 to 49Level 59 to 60Level 90 to 91

METU 15

4 to 25l 48 t

Level 59 to 60Level 90 to 9

BS536

Prospective of Structural System of Wuhan Greenland Center(Drawn by Nastaran Deljavan [4])

“Y” Shape Core

Super ColumnSC2

Super ColumnSC2

PerimeterBelt Truss

Prospective of Structural System & Belt Truss

Steel Column

BS5Super ColuSC

ColuSC2

BS6 “Y” Shape Core Super Column

SC2

Super ColumnSC2

Outrigger Truss

PerimeterBelt Truss

HorizontalFloor Braces

Prospective of Outrigger Frame System of Wuhan Greenland Center

(Drawn by Nastaran Deljavan [4])

Prospective of Outrigger Frame System

MU BS536rimeter

elt T uss

3ontal

aces

Prospective of Structural System & Belt Truss

Prospective of Structural System of Wuhan Greenland Center in first 39 levels(Drawn by Nastaran Deljavan [4])

366Level 91

Level 70

Core plan of Wuhan Greenland Center from level 1 to level 70(Drawn by Nastaran Deljavan [1])

Core plan of Wuhan Greenland Centerfrom level 70 to level 91(Drawn by Nastaran Deljavan[1])

Core plan of Wuhan Greenland Center from level 91 to level 125(Drawn by Nastaran Deljavan [1])

Set Back of Core in Wuhan Greenland Center [1]

The central “Y” plan, concrete core extends 31.3m in plan from the tower center to its far ends at lower zones, and sets back twice at Levels 70 and 91. [1]

Level 125

M

S536terto level 125

by Nastaran Deljavan

Wuhan Greenland Center Main Tower’s unique architectural shape evolved from a classic tapered tower with “Y” plan shape into an elegant curvilinear figure. By locally omitting portions of floorsand perimeter framing at different elevations, “slots” are created in the building envelope to provide a distinctive architectural personalitywhile reducing wind loads on the structure from vortex shedding. [1]

Plan of Slotted Floor in 3 levels(Drawn by Nastaran Deljavan) Source: google

Slotted Floor in Wuhan Greenland Center [1]

Slots are located at mechanical levels, and are carefully coordinated to avoid causing structural discontinuities. A Vierendeel truss system could be used at slotted floors, since the lack of diagonals would allow the most air flow. However, Vierendeel truss systems’ structural efficiency is much less than for traditional truss systems with diagonal members; additionally, as they serve as transfer trusses supporting perimeter columns in one zone bounded by adjacent belt truss levels, the trusses are critical to prevent progressive collapse by carrying additional load from columns above in the event of failure of a perimeter column below. [1]

Section of Slotted Floor of Wuhan Greenland Center

(Drawn by Nastaran Deljavan [4])

Slotted Floor (http://www.skyscrapercenter.com)METU

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A Vierendeel trd at slotted floors, since the

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6Progressive Collapse Analysis of Exterior Frame [1]

Slotted Floor (http://www.skyscrapercenter.com)

After discussions between the architect and structural engineer, the slotted floors were located below the belt truss floors; and the continuous perimeter belt trusses are of conventional design, reducing construction costs compared to Vierendeels. In the progressive collapse analysis, floor beams can span loads normally carried by those columns if the discontinuous perimeter steel column below the floor slots fails. Those loads would then be redirected to adjacent columns. [1]

Slotted Floor in Wuhan Greenland Center [1]

Prospective of Slotted Floor of Wuhan Greenland Center(Drawn by Nastaran Deljavan [4])Mospe

The top of the Wuhan Greenland Center Main Tower is an expression of the project design philosophy. As the tower reaches into the sky, the cladding splits at the line between two architectural components known as the body and the shield. This separation was created to help alleviate tower top wind forces and thus significantly improve building behavior. This simple but powerful statement about the effectiveness of coordinating architecture and structure in super tall building design has become the building’s most iconic feature and is certain to create a landmark on the city skyline.Rising from gently tapering tower wing tips, the taper steadily and continuously increases to the point that the tips converge on the tower centerline to form a unique 61m tall crown. Tapering of other building surfaces defines a 35m tall dome.

Integrating the Architecture and Structure [1]

Prospective of Dome and Crown(http://www.skyscrapercenter.com)

Prospective and Section of Dome and Crown(http://www. google.com)METU U

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dome.

Dome Structure [1]

• Dome cladding is transparent but substantial cladding support framing is required at long spans and high wind pressures.

• Dome structural framing will be visible to visitors so a dramatic sculptural appearance is desired.

• Multiple structural schemes were proposed by the structural engineer for consideration by the architect. Systems included support framing distributed along all faces, framing concentrated at discrete locations, horizontal spanning schemes and vertically spanning schemes. For each scheme the relative hierarchy of framing sizes and functions was considered for aesthetic intent, structural efficiency and constructability.

• The selected system has horizontal curved pipe girts to support the tower skin. To minimize girt pipe diameter, gravity load pans are reduced by suspending the girts from steel hangar rods.

Tower Dome Structure [1]

Interior prospective of Dome [4]METU che

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for aesthetic intent, and constructabili

tem has horizontal curved pipeport the tower skin. To minimize

meter, gravity load pans aending the girts from steel han

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6 Tower Crown Structure [1]

• Cladding of the outer crown is supported by a special tripod structural system. Because crown tripod leg framing is concealed within opaque cladding, support structural design was based on material efficiency and constructability.

• Each crown tripod leg, a half-arch in profile, is trapezoidal in cross-section or plan. The four faces of each leg are trusses following simple surfaces.

• Pipes up to 500 mm diameter are used for truss chords and smaller diameter pipes are used for web members and braces.

• The side trusses taper nearly to a point at the crown base, landing on the super columns at wing tips and connecting directly to the embedded steel columns in the super column for secure load transfer.

• The legs stop before the peak, and plane trusses are added at leg truss top panels to tie the three Tripod legs together.

• Cleaning of the dome glass will be performed by equipment suspended from the crown above. Tower Crown Structure [1]METU

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egs stop before the peak, and padded at leg truss top panellegs together.Cleaning of the domequipment suspen

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536References

1. Fu, Guoyong; Poon, Dennis & Dannettel, Mark1 Betancur, Juan. Wuhan Greenland Center Main Tower: Seamlessly Integrating Structure and Architecture, CTBUH 9th World Congress Shanghai, 2012

2. Viise, John; Zhao; Yantong & Halvorson; Development of Innovative Structures for Supertall and Unique Towers, CTBUH 9th World Congress Shanghai , 2012

3. http://www.skyscrapercenter.com/4. Video,

http://ctbuh.org/TallBuildings/VideoLibrary/ConferenceVideos/2012ShanghaiT14Fu/tabid/4071/language/en-GB/Default.aspx/

5. Presentation of CTBUH’ movie

METU son;World Congres

center.com/

TUorg/TallBuildings/VideoLibrary/e/en-GB/Default.aspx

ntation of CTBUH’ movi

BS536k1 Betancur, Juan. Wuhan G

Architecture, CTBUH 9th Wo

pment of Innhai , 20