A Challenging Journey for the Third CTF Finance Centre. Derry Yu De Ming, Project Director, New World China Land

Transcription

1 A Challenging Journey for the Third CTF Finance Centre Derry Yu De Ming, Project Director, New World China Land

2 Derry YU De Ming Project Director PhD CEng IntPE New World China Land Co Ltd, Hong Kong, China

3 Table of Contents 1.0 Introduction 2.0 Establishment of Major Design Principles 3.0 Key Issues in Structural Scheme Design 4.0 Selection of Structural Schemes 5.0 Summary

4 Table of Contents 1.0 Introduction 2.0 Establishment of Major Design Principles 3.0 Key Issues in Structural Scheme Design 4.0 Selection of Structural Schemes 5.0 Summary

5 1.0 Introduction The 1 st CTF Finance Centre - Guangzhou CTF Finance Centre The 3 rd tallest building completed in China Architectural Height Structural Height Floors Building Functions Construction Start Completion Development GFA 530m 518m 111 (above ground) 5 (underground) Hotel/SA/Office ,288m 2 Office: 221,482m 2 Others: 13,272m 2 Mall + Hotel + SA: 207,021m 2 Basement Carpark: 39,014m 2 Basement ME Room: 27,499m 2

6 1.0 Introduction The 2 nd CTF Finance Centre - Tianjin CTF Finance Centre The 4 th tallest building completed in China Architectural Height Structural Slab Height Floors Building Functions Construction Start Completion Development GFA 530m Topped out on 25/10/ m - Topped out on 25/7/ (above ground) 4 (underground) Hotel/SA/Office ,980m 2 Office: 140,933 m 2 Hotel: 64,096 m 2 SA: 48,465 m 2 Mall: 38,116 m 2 (above ground) Mall: 7,385 m 2 (underground) Basement: 90,985 m 2 (excluding mall)

7 1.0 Introduction The 3 rd CTF Finance Centre - Wuhan CTF Finance Centre Architectural Height Structural Height Floors Building Functions Construction Start Development GFA 648m 584m 121 (above ground) 5 (underground) Office ,000m 2 Office: 327,000 m 2 SA: 80,000 m 2 Mall: 40,000m 2 Basement: 266,000 m 2

8 Table of Contents 1.0 Introduction 2.0 Establishment of Major Design Principles 2.1 Aspect Ratio of Tower 2.2 Aspect Ratio of Core Tube 2.3 External Core Wall Thickness at Low Zone 2.4 Try to Eliminate Outrigger 2.5 Measures to Reduce Wind Load 2.6 Select the Type of Perimeter Columns 3.0 Key Issues in Structural Scheme Design 4.0 Selection of Structural Schemes 5.0 Summary

9 2.1 Aspect Ratio of Tower H/B 9 648m Architectural Height B1 584m Structural Height H = 584m B = min{b1, B2} 65m B2 ±0.0 Ground Floor Plan

10 2.2 Aspect Ratio of Core Tube H/C m Architectural Height 584m H = 584m Structural Height 33.9m C1 33.9m C2 C = min{c1, C2} 32.4m ±0.0 Ground Floor Plan

11 2.3 External Core Wall Thickness at Ground Level Should Not Be Greater Than 1.5m In schematic design stage External shear wall with embedded steel plates as illustrated in table below was adopted. Wall Floor thickness (mm) L1-L L26-L Concrete Grade Steel plate thickness (mm) Steel grade C60 80~25 Q345GJ Ground Floor Core Wall Plan

12 2.4 Try to Eliminate Outrigger Problems caused by outriggers: Complicated and heavy steel members Difficulties in fabrication, transportation and installation Prolong construction period Incur sudden change in tower vertical stiffness Outrigger in Super High-rise Project Our another successful project-tianjin CTF Finance Centre well integrated architectural design, structural design and wind engineering together, and no outrigger was used.

13 2.5 Measures to Reduce Wind Load OPTION 1 OPTION 2 A B C D Verify through wind tunnel tests different tower crown options different tower crown porosities different tower orientations different radiuses of tower corner Tower Crown Perspective View

14 2.5 Measures to Reduce Wind Load Tower Crown 3D Sketch 50% 40% 30% 20% 60% 50% 40% 30% OPTION 1 OPTION 2 A B C D Verify through wind tunnel tests different tower crown options different tower crown porosities different tower orientations different radiuses of tower corner IMPORTANT: All the obstructions such as M/E equipment inside the tower crown must be accurately simulated during wind tunnel test to ensure the test porosity is in line with real situation.

15 2.5 Measures to Reduce Wind Load OPTION 1 OPTION 2 A B C D Verify through wind tunnel tests different tower crown options different tower crown porosities different tower orientations different radiuses of tower corner

16 2.5 Measures to Reduce Wind Load Verify through wind tunnel tests Typical Floor Plan A B C D different tower crown options different tower crown porosities different tower orientations different radiuses of tower corner OPTION 1 (Base Option) OPTION 2 (Barrel Option)

17 2.6 Select the Type of Perimeter Columns Conduct Comparison by considering the following factors: Finally, SRC columns are adopted. 1. Architectural design requirements 2. Structural construction quality and reliability 3. Structural and maintenance cost 4. Buildability 5. Construction speed 6. Recent completed projects Circular CFT Column (Tianjin CTF Project Low Zone) SRC Column (Tianjin CTF Project High Zone) Rectangular CFT Mega Column (Guangzhou CTF Project)

18 Table of Contents 1.0 Introduction 2.0 Establishment of Major Design Principles 3.0 Key Issues in Structural Scheme Design 3.1 Fundamental Natural Period T 1 of Structure 3.2 Use of High Strength Concrete C Design Spectrum of Seismic Acceleration Response 3.4 Minimum Shear-gravity Ratio λ min 3.5 Overall Stability Check (Stiffness-gravity Ratio) 4.0 Selection of Structural Schemes 5.0 Summary

19 3.1 Fundamental Natural Period 1 T1 of Structure Structural Height, H(m) Relationship between fundamental periods T 1 and heights of structures H>250m The figure is extracted from the following paper : XU, P.F., XIAO, C.Z., & LI, J.H. (2014). Study on relationship between natural vibration periods and heights of structures for high-rise buildings and its reference range. (in Chinese) China Civil Engineering Journal, Volume 47(2), pp Fundamental Natural Period of Structure, T 1 (s)

20 3.2 Use of High Strength Concrete C80 No Project Name Structural Height - Floors Guangzhou International Finance Centre 432m-103 floors Guangzhou CTF Finance Centre 518m-112 floors Guangzhou Leatop Plaza 303m-58 floors Shenzhen KK m-98 floors Shenzhen Hon Kwok City Centre 329m-75 floors Shenzhen Hanking Centre 350m-61 floors Tianjin CTF Finance Centre 530m-94 floors Shenyang Moi Centre 296m-72 floors High Strength Concrete Used in Core Wall C80 (from base slab to L30) Pure RC wall C80 (from base slab to L29) Steel plates embedded in wall C80 (from base slab to L8) Steel columns embedded in wall C80 (from base slab to L39) Steel columns embedded in wall C80 (from base slab to L46) Steel columns embedded in wall High Strength Concrete Used in Perimeter Columns Joint Zone: C90 (from base slab to L38) C80 (from L39 to L82) Non-joint Zone: C70 (from base slab to L38) C60 (other floors) Inclined CFT column C80 (from base slab to L68) CFT column Column concrete Not exceeding C70 CFT column C80 (from base slab to L46) CFT column C80 (from base slab to L46) SRC column No core tube C80 (from base slab to L36) CFT column Wall concrete Not exceeding C60 Steel plates embedded in wall Wall concrete Not exceeding C60 Steel columns embedded in wall C80 (from base slab to L53) CFT column C80 (used in low zone) CFT column Year of Completion Application of C80 and Above High Strength Concrete in Mainland China s 200m+ High-rise Buildings

21 3.2 Use of High Strength Concrete C80 As both the grade and volume of cement for high strength concrete are very large while the core wall is relatively long and with large constrains, it is easy for cracks to be occurred at early stage, and resulting in huge rectification cost and time delay. The construction quality will be greatly affected if the concreting temperature is too high. Concrete with improper slump or mix proportion could block the pump and form cold joints during concreting. IN DESIGN ASPECT Problems exposed in use of high strength concrete: Concrete Grade Design Compressive Strength Allowable Axial Force Ratio Wall Thickness C MPa 0.5 T C MPa T Compared with C60, the thickness of C80 core wall only decreases for about 4.2% PM team decided to apply C60 concrete to core wall and C70 concrete to SRC column respectively.

22 3.3 Design Spectrum of Seismic Acceleration Response Horizontal seismic influence coefficient Seismic acceleration response spectrum adopted by China National Code Horizontal seismic influence coefficient T Natural period of structure 10.0 Seismic acceleration response spectrum adopted by Shanghai local practice T Natural period of structure

23 3.4 Relationship between Base shear-gravity Ratio & Minimum Shear-gravity Ratio λ λ min = 0.15 α max where α max is the maximum value of horizontal seismic influence coefficient If 0.8λ min base shear-gravity ratio < λ min, then The horizontal seismic shear forces for all floors need to be amplified by multiplying amplification coefficients. It s unnecessary to increase the tower s stiffness. If base shear-gravity ratio < 0.8λ min, then The tower s horizontal stiffness must be increased by adjusting structural framing or members size. Such adjustments will cause significant increment in structural materials quantity. min

24 3.5 Proper Value for Stiffness-gravity Ratio (Must > 1.4) A B C The overall stability check for high-rise buildings is to ensure the gravity second-order effect under wind or seismic loadings will not cause the structural instability or collapse. For this project is located in Wuhan with relatively low seismic and wind loadings, the stiffness-gravity ratio may become a dominant factor for tower stiffness, must be > 1.4. For high-rise building with large variation in floor mass or floor-tofloor height along the building height, the stiffness-gravity ratio should be carefully calculated.

25 Table of Contents 1.0 Introduction 2.0 Establishment of Major Design Principles 3.0 Key Issues in Structural Scheme Design 4.0 Selection of Structural Scheme 4.1 Typical Structural Systems for Super High-rise Building 4.2 Schemes Elimination 4.3 Further Investigation 5.0 Summary Diagrids Mega structures Frame-tubes Tubes

26 4.1 Typical Structural Systems for Super High-rise Building Diagrids Structure Diagrids Perimeter Frame + Core Wall Lateral resistance : HIGH Steel tonnage: LOW Structural Sys: aesthetic integrated Core area at high zone can be freed up Bracing: Low floor efficiency View: obstructed Core wall opening: limited Construction: complicated, long duration Swiss De Building, London (BH= 180m, SH= 167m) Guangzhou IFC, China (BH= 441m, SH= 432m)

27 4.1 Typical Structural Systems for Super High-rise Building - Mega Structure Type A: Mega Columns + Core Wall + Outriggers Lateral resistance : HIGH Interior col. free area: flexible planning View: broad Elevation: simple SRC col.: good fire protection SRC col.: low steel tonnage Mega col.: Low floor efficiency Core wall opening: limited Construction: complicated, long duration CTF col.: high steel tonnage Two IFC, Hong Kong (BH= 412m, SH= 388m) Guangzhou CTF, China (BH= 530m, SH= 518m)

28 Type B: Mega Columns + Core Wall+ Mega Brace 4.1 Typical Structural Systems for Super High-rise Building - Mega Structure Lateral resistance : HIGH Interior col. free area: flexible planning Steel tonnage: LOW Structural efficiency: HIGH SRC col.: good fire protection SRC col.: low steel tonnage Mega elements: Low floor efficiency Core wall opening: limited Construction: complicated, long duration CTF col.: high steel tonnage View: obstructed Elevation design: complicated Beijing China Zun, China (BH= 528m, SH= 522m) Goldin Finance 117, China (BH= 597m, SH= 597m)

29 Type A: Perimeter Frame + Core Wall + Outriggers 4.1 Typical Structural Systems for Super High-rise Building - Frame-tube Structure Lateral resistance : MODERATE Interior col. free area: flexible planning Elevation: simple Steel tonnage: High Core wall opening: limited Construction: complicated, long duration Northeast Asia Trade Tower, South Korea (BH= 305m) Chongqing Int l Trade & Commerce Center, China (BH= 468m, SH= 440m)

30 4.1 Typical Structural Systems for Super High-rise Building - Frame-tube Structure Type B: Perimeter Frame + Core Wall Lateral resistance : MODERATE Interior col. free area: flexible planning Elevation: simple Construction: conventional Steel tonnage: High Core wall opening: limited Aon Center, Chicago, USA (BH= 346m, Antenna Tip= 362.5m) Moi Centre, Shenyang China (BH= 311m)

31 4.1 Typical Structural Systems for Super High-rise Building Bundle-tube Structure Bundle-tubes Lateral resistance : HIGH Construction: conventional Layout: restricted by tube modules Interior col. free area: difficult Building profile: Dictated Willis Tower, Chicago, USA (BH= 443m, Antenna tip= 527m)

32 4.1 Typical Structural Systems for Super High-rise Building - Tube-in-tube Structure Tube-in-tube Shear Lag: improved Structural efficiency: improved Interior col. free area: flexible planning Construction: conventional View: congested Core wall opening: limited 181 West Madison, Chicago, USA (BH= 207m) Shenzhen China Resources HQ, China (BH= 400m, SH= 332m)

33 4.2 Schemes Elimination To Further Investigate Design Brief & Client s Requirements - Elegant elevation - Column free internal space - Unblocked comfortable outward view

34 4.3 Further Investigation Computer Modelling Scheme Outrigger 8 COL Scheme Outrigger 8 COL Scheme Outrigger 8 COL = Scheme Bracing 8 COL Scheme Bracing 8 COL Scheme Bracing 8 COL A: Mega-structure B: Frame-tube Scheme Col & Wall Area distribution 24 COL Scheme Col & Wall distribution Area 24 COL Scheme Col & Wall Area distribution 24 COL Scheme Outrigger 24 COL Scheme Outrigger 24 COL Scheme Outrigger 24 COL C: Bracing D: Outrigger E: Column & wall area allocation F: Outer frame G: Core wall types Scheme Col & Wall Area distribution 32 COL Scheme Col & Wall distribution Area 32 COL Scheme Col & Wall Area distribution 32 COL Scheme Outrigger 32 COL Scheme Outrigger 32 COL Scheme Outrigger 32 COL Scheme Col & Wall Area distribution 40/44 COL Scheme Col & Wall Area distribution 40/44 COL Scheme Col & Wall Area distribution 40/44 COL Total More Than 20 Schemes Were Studied!! Scheme Outrigger 40/44 COL Scheme Outrigger 40/44 COL Scheme Outrigger 40/44 COL

35 4.3 Further Investigation Reviewing Mega-structure Type A: Mega Column + Core Wall + Outrigger Column Free Internal Space Comfortable Outward View Highest Steel Tonnage Reviewing Mega-structure Type B: Mega Column + Core Wall + Mega Brace High structural efficiency High lateral resistance Provide column-free internal space Better performance than outrigger Largely reduce steel tonnage from 210kg/m 2 to 187kg/m 2 Major Problem: Bracings are extremely bulky 1.0m width, uncomfortable outward view

36 4.3 Further Investigation Reviewing Mega-structure + Core + Bracing Project Management team proposed innovative design To adopt High-strength Cable Brace to replace conventional steel Mega Brace. Innovative System: China IP Application No X High-strength Cables are composed of strands with the characteristic value of ultimate strength of 1860kPa.

37 4.3 Further Investigation Mega-structure + Core + High-strength Cable Brace Either Or : 2 sets of φ300mm cables : 1 set of φ425mm cable Structural Efficiency Cable is fixing HIGH at MEP floor However There exist potential usable area loss due to cable braces need to be fixed at the center of megacolumns for better structural efficiency Elevation treatment may be difficult Scheme is NOT adopted Performance: Equivalent or better than a 1000mm width structural steel bracing

38 4.3 Further Investigation Structural Steel Tonnage Reviewing Frame-tube System 24 Col. (9m grid) 32 Col. Steel (benchmark) Comfortable Outward C/C (7.5m grid) Steel (-8%) Col. too C/C 44 Col. (4.5m grid) Steel (-13%) Number of Columns at outer frame Col. too C/C

39 4.3 Further Investigation Reviewing Frame-tube System Testing Different Column Area Allocation - Increase Column to Floor Area Ratio from 2.7% to approx. 5% - Reduce core wall thickness - Try for UNIFORM column sections - Try for LARGER corner columns Analysis shows - Try for LARGER side columns structurally the most effective Selected 24 nos. of C/C

40 4.3 Further Investigation Reviewing Frame-tube System Effects of Outrigger Started With NO Outrigger Bench mark By considering construction complexity, time & cost implications comprehensively 3 sets of outriggers are adopted Try for 1 SET of Outrigger Steel Tonage Steel Tonage - 5% Try for 3 SETS of Outriggers Steel Tonage - 12%

41 4.3 Further Investigation Reviewing Frame-tube System Core Wall selection CORE TYPES STIFFNESS CORE WEIGHT USABLE AREA STEEL TONAGE SLOPING TELESCOPIC SLOPING CORE TELESCOPIC CORE 175kg/m 2 205kg/m 2 OVERALL PERFORMANCE RECESSED CORE PREFERABLE OPTION RECESSED 222kg/m 2

42 4.3 Further Investigation Projects Adopted Sloping Core-wall Constructability???!!! 328m Tall Zhuhai Center, Zhuhai, China 393m Tall CRC Headquarter Office Tower, Shenzhen, China

43 4.3 Further Investigation Summary of the Selected Structural Scheme 24 nos. of C/C Wall Thickness: 1300mm C60 Core-wall Slopes at 4 portions LARGER side columns SRC columns (D x B, C70) Corner : 2400x2250 Side : 2900x SETS of outriggers RECENT STEEL TONNAGE 175kg/m 2 (excluding connections) FLOOR EFFICIENCY 76%

44 Table of Contents 1.0 Introduction 2.0 Establishment of Major Design Principles 3.0 Key Issues in Structural Scheme Design 4.0 Selection of Structural Schemes 5.0 Summary

45 5.0 Conclusions According to CTBUH, by the end of September 2017, there are 11 nos. of 500m+ high-rise buildings had been completed or structurally / architecturally topped out globally. Guangzhou and Tianjin CTF Finance Centres ranks as the 8 th and 9 th tallest building respectively. 6 nos. of 500m+ buildings (i.e. 55%) are located in Mainland China. 500m+ High-rise Buildings Completed or Topped out

46 5.0 Conclusions If including the projects under construction and under design, there will be 41 nos. of 500m+ high-rise buildings in the future. Wuhan CTF Finance Centre will be the 5 th tallest building in the world. 22 nos. of 500m+ buildings (i.e. 54%) are located in Mainland China. 500m+ High-rise Buildings Completed, Topped out, Under Construction or Proposed

47 5.0 Conclusions Based on our design management experiences for 3 nos. of CTF Finance Centres, super high-rise project will definitely be a landmark not only connecting but also reshaping the City. To create a heritage for the future, all of the developer, operators & potential users of the building have very high standards and requirements in the aspects of building profile, outward view, functions, comfort level, cost, sustainability and environmental concerns etc., therefore, the followings are very critical in the early stage for selecting structural scheme: 1. It s necessary to consider not only the structural efficiency, but also the functional requirements & voice of customers very carefully with good foresights for bespoke design; 2. It s important to conduct comprehensive coordination among the design teams, operators and other stakeholders, so as to realize optimal design with excellent craftsmanship and fulfil special requirements from different disciplines & stakeholders; 3. It s indispensable to keep innovative thinking and open mind to explore all kinds of feasible structural schemes, so as to maximize the structural efficiency with good constructability while secure structural safety.

48 Sincere Thanks 谢谢! from