TALL BUILDINGS IN KUALA LUMPUR - STEEL, CONCRETE OR BOTH?

Transcription

1 TALL BUILDINGS IN KUALA LUMPUR - STEEL, CONCRETE OR BOTH? Dr. Juneid Qureshi, Director, Meinhardt Singapore Pte. Ltd. Council on Tall Buildings Kuala Lumpur

2 AGENDA 01 The need for Productivity 02 Key Considerations in the design of Tall Buildings 03 Comparison of Material Choice for Tall Buildings Globally 04 Key Issues in Steel & Concrete Construction 05 Cost Comparison of a Concrete & Composite Tall Building 06 Concluding Remarks

3 TALL BUILDINGS

4 STRUCTURAL DESIGN CHALLENGES FOR TALL BUILDINGS Others? Construction Constraints Architectural Vision Developers Requirements Structural Needs

5 TALL BUILDINGS KEY CHALLENGES Key Design Challenges Efficient structural framing systems Drift control Dynamic behavior Differential shortening between vertical elements Foundation settlements Wind & Seismic Engineering Parametric Modeling & Optimization Source: CTBUH

6 TALL BUILDINGS MATERIAL SELECTION Steel or Concrete or Both? There is no universal answer. The choice is dictated by several considerations such as design requirements building s needs industry know-how market rates and conditions Experience is one of the best guides

7 TALLEST BUILDINGS LOCATION Courtesy CTBUH

8 TALLEST BUILDINGS FUNCTION Courtesy CTBUH

9 TALLEST BUILDINGS MATERIAL Courtesy CTBUH

10 TALLEST BUILDINGS USA One World Trade Centre, 541.3m, 2014, COMPOSITE Willis Tower, 442m, 108flrs, 1974, STEEL 432 Park Avenue, 425.5m, 85flrs, 2015, CONCRETE Trump Tower, 423.2m, 98flrs, 2009, CONCRETE Empire State Building, 381m, 102flrs, 1931, STEEL Bank of America Tower, 365.8m, 55flrs, 2009, COMPOSITE Aon Centre, 346.3m, 83flrs, 1973, STEEL John Hancock Centre, 343.7m, 100flrs, 1969, STEEL Chrysler Building, 318.9m, 77flrs, 1930, STEEL New York Times Tower, 318.8m, 52flrs, 2007, STEEL

11 TALLEST BUILDINGS CHINA Shanghai Tower, 632m, 128flrs, 2015, COMPOSITE Shanghai WFC, 492m, 101flrs, 2008, COMPOSITE International Commerce Centre, 484m, 2010, COMPOSITE Zifeng Tower, 450m, 66flrs, 2010, COMPOSITE KK100, 441.8m, 100flrs, 2011, COMPOSITE Guangzhou IFC, 438.6m, 103flrs, 2010, COMPOSITE Jin Mao Tower, 420.5m, 88flrs, 1999, COMPOSITE Hong Kong Two IFC, 412m, 88flrs, 2003, COMPOSITE CITIC Plaza, 390.2m, 80flrs, 1996, CONCRETE Shun Hing Square, 384m, 69flrs, 1996, COMPOSITE

12 TALLEST BUILDINGS EUROPE OKO Tower, Moscow, 353.6m, 2015, CONCRETE Mercury City Tower, Moscow, 338.8m, 2013, CONCRETE Stalnaya Vershina, Moscow, 308.9m, 2015, COMPOSITE The Shard, London, 306m, 73flrs, Yr2013, COMPOSITE Capital City tower, Moscow, 301.8m, 2010, CONCRETE Naberezhnaya Tower, Moscow, 268.4m, 2007, COMPOSITE Triumph Palace, Moscow, 264.1m, 2005, CONCRETE Sapphire Tower, Istanbul, 261m, 2010, CONCRETE Commerzbank Tower, Frankfurt, 259m, 1997, COMPOSITE Capital City Tower, Moscow, 257.2m,2010, CONCRETE

13 TALLEST BUILDINGS UAE Burj Khalifa, Dubai, 828m, 163flrs, 2010, STEEL / CONCRETE Princess Tower, Dubai, 413.4m, 101flrs, 2012, STEEL / CONCRETE 23 Marina, Dubai, 392.4m, 88flrs, 2012, CONCRETE Elite Residence, Dubai, 380.5m, 87flrs, 2012, CONCRETE Almas Tower, Dubai, 360m, 68flrs, 2008, CONCRETE JW Marriott Dubai, 355.4m, 82flrs, 2012/13, CONCRETE Emirates Tower 1, Dubai, 354.6m, 2000, COMPOSITE The Torch, Dubai, 352m, 86flrs, 2011, CONCRETE Rose Rayhaan, Dubai, 333m, 71flrs, 2007, COMPOSITE Al Yaqoub Tower, Dubai, 328m, 2013, CONCRETE

14 TALLEST BUILDINGS SINGAPORE UOB Bank Plaza One, 280m, 66flrs, 1992, STEEL OUB Centre, 277.8m, 63flrs, 1986, STEEL Republic Plaza, 276.3m, 66flrs, 1996 COMPOSITE Capital Tower, 255.4m, 52flrs, 2000, COMPOSITE Anson, 250m, 2014, CONCRETE Enggor St., 250m, 62flrs, 2014, CONCRETE The Marina Bay, 245m, 70flrs, 2008, CONCRETE MBFC Office Tower II, 245m, 50flrs, 2010, CONCRETE ORQ North Tower, 245m, 50flrs, 2006, COMPOSITE Ocean Financial Centre, 245m, 43flrs, 2011, CONCRETE

15 TALLEST BUILDINGS MATERIAL Reasons for this trend? Concrete is perceived to be cheaper than steel Developing countries have more concrete technological expertise than steel More tall residential and mixed-use developments favor some use of concrete Increased performance requirement can be better addressed by composite construction rather than one material alone

16 STEEL OR CONCRETE KEY ISSUES Concrete Steel Floor Construction, Spans & Services Integration Range of floor types beam & slab, flat slab, ribbed, banded, coffered with options for insitu, pre-cast, RC and PT. For short to moderate spans of up to 10m, possible to achieve very shallow floors with PT flat plates. PT Banded Beams can span economically up to around 16m. Generally uni-directionally spanning steel beams with concrete slabs on metal decks acting compositely. Rolled Sections are generally most economical for spans up to 15m. Fabricated sections can span economically up to 25m. Castellated, cell-form, truss-girder construction can span even longer & allows integration of building services within the structure to minimize floor to floor depths. One Raffles Link, Singapore

17 STEEL OR CONCRETE KEY ISSUES Concrete Steel Columns Generally much larger than steel or composite columns. Much smaller column sizes possible. CFT s allow smaller column size & reduced labour & construction time due to simplified connections and elimination of formwork SRC columns offer flexibility a) large steel section to maximize capacity, or b) nominal section for erection only

18 STEEL OR CONCRETE KEY ISSUES Concrete Seismic Loads Concrete buildings are heavier thereby attracting higher seismic loads, Steel Lower seismic forces due to lesser mass. Steel is also more ductile which is beneficial for seismic force resistance.

19 STEEL OR CONCRETE KEY ISSUES Concrete Lateral Load Resistance Concrete buildings generally provide better lateral stiffness & coupled with the extra damping (mass) provides better dynamic performance. Steel The lower lateral stiffness of steel construction is one of the reasons for adoption of composite tall buildings utilizing a concrete core with steel floor framing. Outriggers are added for taller buildings for enhanced stability & stiffness. NDIA, Doha

20 STEEL OR CONCRETE KEY ISSUES Concrete Steel Foundations Concrete buildings are heavier & therefore require larger foundations. Transfer Structures The low strength-to-area ratio and low shear strength is a significant disadvantage. Foundations can be lighter by 30% to 40% lighter. This is a significant advantage in poor soil conditions or to protect existing below ground structures. Higher strength-to-area ratio makes steel the preferred choice for transfer structures. One Raffles Quay, Singapore

21 STEEL OR CONCRETE KEY ISSUES Concrete Steel Deflections Variable material properties & time dependent creep & shrinkage effects make precise deflection predictions difficult. Vibrations The mass of concrete construction generally mitigates vibration concerns except for very long spans. No time dependent change in properties making long term movement control simpler. Lighter steel framed construction Dynamic needs to be designed specifically property to limit vibration. Dynamic property Signature Towers, Dubai Floor response Floor response

22 STEEL OR CONCRETE KEY ISSUES Concrete Steel Fire Protection Provides inherent fire resistance. With enhanced detailing, resistance in excess of four hours can be achieved. Standardization Buildable design & detailing helps but is less critical than steel construction. Bare steel has low fire resistance. Conventional protection provided by intumescent paint, spray coatings or wrappings. CFT s allow moderate fire resistance without protection. Standardisation is key for economy and speed. Particularly in selection of element types and connections.

23 STEEL OR CONCRETE KEY ISSUES Concrete Steel Adaptability The continuous nature of concrete makes it more challenging to modify or strengthen. Propping during Construction In-situ concrete requires propping constraining fast erection. Precast concrete can eliminate this constraint. Discrete nature facilitates removal, additions or strengthening. No propping required with secondary beams spaced to suit metal deck spanning capability. NDIA, Doha

24 STEEL OR CONCRETE KEY ISSUES Concrete Steel Construction Accuracy Less accurate because of onsite activities. Sustainability The difference of embodied CO2 of concrete & steel buildings is insignificant compared to a building s operational CO2 emissions. Late Changes More amenable to late changes. More accurate due to off-site controlled manufacturing. Steel has the added benefit of having potential to be reused and recycled repeatedly, Changes are disruptive.

25 STEEL OR CONCRETE KEY ISSUES Concrete Steel Speed Requires less lead-in time (superficial attraction) Is labour-intensive. Cost Requires greater lead-in time & fabrication speed is important. Higher potential for faster construction due to prefabrication. One Raffles Quay, Singapore

26 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Building Description GFA: 85,000 m 2 Height: 130m No. of Floors: 30 Typ. Floor Height: 4.3m Typ. Floor Area: 2800 m 2 Clear Span: up to 15.5m Lateral System: Dual System - RC Core + Frames RC Building Steel-Concrete Composite Building

27 TYPICAL TALL BUILDING COMPARATIVE COST STUDY 13.5m 12.5m 15.5m Framing 9m Systems Considered Floor Framing Graphics 13.5m 12.5m 15.5m RC Building Typical Parameters Composite Building - Typical Parameters Long Span PT Band Beam: 2400x 600 Deep Long Span Steel Beams: UB610 x 229 x 92 Short Span PT Band Beam: 2400x 550 Deep Short Span Steel Beams: UB610 x 229 x 113 Edge Beam: 500x600 Deep Edge Steel Beams: UB533 x 210 x 66 PT Slab Thickness: 200 Typical Slab: 130 on Re-Entrant Deck Primary Core Wall Thickness: 350 Primary Core Wall Thickness: 300 Secondary Core Wall Thickness: 250 Secondary Core Wall Thickness: 250 Columns : 1.0m x 1.0m Columns : 0.8m dia. CHS 9m

28 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Design Criteria Gravity Loading: Dead Load (DL) Superimposed Dead Load (SDL) Live Load (LL) Cladding (SDL) Lateral Loading: Wind Speed Wind Load Pressure Seismic : Self-weight of elements : 1.5 kpa : 3.5 kpa + 1 kpa for Partitions : 1.0 kpa (on elevation) : 22m/s Mean Hourly, 50-year Return Period : Max Pressure ~ 1.3 kpa : SS-EN , BC3, q=1.5, Ground Type D Deflections & Drift Parameters: Interior Beams, Live Load : L / 250, 20 mm maximum Interior Beams, Incremental Deflection : L / 350 Perimeter Beams, Live Load : L /500, 10 mm maximum Wind Inter-story Drift : H / 500 Floor Vibrations and Acceleration: : Acceleration 0.5%g

29 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Building Dynamic Characteristics T 1 = 3.5 s RC Building T 2 = 3.1 s T 1 = 3.2 s Composite Building T 2 = 2.9 s

30 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Storey Building Performance Comparison S d (T) = S e (T). γ l q [ γ l = 1.0, q=1.5] Wind RC/Composite Seismic Composite Seismic RC RC Building: V eq1 = 3.41%*W = 35.9 MN V eq2 = 3.95%*W = 41.6 MN Lateral Storey Forces Wind 5 RC/Composite Seismic- Composite Overturning Moment Composite Building: V eq1 = 3.81%*W = 24.9 MN V eq2 = 4.05%*W = 26.5 MN Seismic-RC Storey 35 Wind-RC Wind Composite 5 Δ = h / 500 Seismic-RC Seismic Composite Inter-storey Drift Δ = h / (200.v.q)

31 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Member Force Envelopes RC Building Composite Building

32 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Costing Data Pricing information was obtained from Langdon & Seah & verified through a combination of local sources Baseline Unit Costs ( All-in, incl. labour) Concrete Grade (f cu ) Cost (S$/m3) 40 S$ S$ S$ 165 Rebar Cost (S$/T) S$ 1,350 Post-tensioning (S$/T) S$ 6,250 Formwork (S$/m2) S$ 45 Structural Steel incl. studs (S$/T) S$ 5,000 Metal Deck (S$/m2) S$ 50 Steel Fireproofing (S$/m2) S$ 25 Foundation Costs (S$/ ton / m ) S$ 0.60

33 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Building Weight (normalized) Normalized Building Weight RC Building Steel-Concrete Composite Building

34 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Concrete Costs (normalized; excluding rebar & PT) Normalized Concrete Costs RC Building 0.5 Steel-Concrete Composite Building

35 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Rebar & PT Costs (normalized) Normalized Rebar & PT Costs RC Building Steel-Concrete Composite Building

36 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Structural Steel Costs (normalized; including decking & FP) Normalized Steel Costs RC Building Steel-Concrete Composite Building

37 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Foundation Costs (normalized) Foundation Costs RC Building Steel-Concrete Composite Building

38 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Total Structural Material Costs (normalized) Normalized Structural Costs RC Building Steel-Concrete Composite Building

39 COMPARATIVE COST STUDY THE BIG PICTURE

40 COMPARATIVE COST STUDY THE BIG PICTURE

41 TYPICAL TALL BUILDING COMPARATIVE COST STUDY Total Project Construction Costs (normalized) Normalized Structural Costs RC Building Steel-Concrete Composite Building

42 COMPARATIVE COST STUDY THE BIG PICTURE Other Costs & Revenues Project Costs GFA = 85,000 sq-m Land Cost = $19,000 per sq-m of GFA Legal Fee & Stamp Duty = 4% of land cost Total Project Duration= 33 months Property Tax = 0.5% x land cost x duration Associated Costs (Prof. & Site Supervision Fee) = ~ 8% of Total Construction Cost Marketing & Advertisement = ~ 5% of Total Construction Cost GST = 7% of Construction & Assoc. Costs Interest of Financing Cost for Land = 5% of Land Cost, Legal Fee & Property Tax Interest of Financing During Construction = 5% of Construction & Associated Costs x 0.5 Rental Return + Preliminaries Net Efficiency= 80% Occupancy Rate= 80% Rental Rate $$/sq-ft/month= $10 per sq-ft per month (net floor area) Preliminaries / month = 10% of Total Construction Cost

43 COMPARATIVE COST STUDY THE BIG PICTURE Total Development Construction Costs (normalized) Normalized Structural Costs RC Building Steel-Concrete Composite Building

44 COMPARATIVE COST STUDY THE BIG PICTURE

45 COMPARATIVE COST STUDY THE BIG PICTURE Total Project Construction Costs with One Month Lesser Construction Time for Composite Building (normalized) Normalized Structural Costs RC Building Steel-Concrete Composite Building

46 COMPARATIVE COST STUDY THE BIG PICTURE Total Project Construction Costs with Two Month Lesser Construction Time for Composite Building (normalized) Normalized Structural Costs RC Building Steel-Concrete Composite Building

47 CONCLUDING REMARKS FUTURE TRENDS As Singapore develops, labour costs will continue to rise. Productivity will continue to be the key driver Project cost is dictated by completion period not material cost. The perception that steel means higher cost must be seen in perspective In addition to performance benefits, composite buildings offer far higher potential for greater productivity & hence lower costs What do you think will be the material of choice for these future buildings?