Intensification of Low-Density Developments: Functional Bridging - PowerPoint PPT Presentation

Intensification of Low-Density Developments: Functional Bridging Buildings MNDRF SUL Project 2013-4 Chiew Sing-Ping School of Civil and Environmental Engineering Nanyang Technological University, Singapore 6 August 2014 1

More Ancient Functional Bridges The Ponte Vecchio, Florence, Italy 2

More Recent Functional Bridges ҉ Paradigm Shift ҉ 2-D and Parallel Intensification ҉ Enhancing Livability Fusionopolis, Singapore Pinnacle @ Duxton – Skybridges, Singapore 3

Going beyond Functional Bridges …. ҉ Intensify and optimize land use among existing buildings and across existing infrastructures (e.g. roads/expressways, car parks, drain/tunnel reserves & services, etc); ҉ Support greater economic activities while enhancing community living, increasing connectivity and reducing transportation cost & travelling time within and between buildings; ҉ Impact construction industrial practice, enhancing technological image and expertise of our building and construction industry. Reflections at Keppel Bay, Singapore 4

Marina Bay Sands (MBS) Weight of steel per m 2 = (3500 T x 1000 kg) / (120 m x 40 m) = 730 kg/m 2 (S355) Source: Arup (Singapore) 5

Podium Block over Orchard MRT Station 12 mega transfer trusses (66 m - 80 m span) Spacing = 11.4 m c/c; Height = 15 m Weight/m 2 = 600 kg/m 2 (S355) Source: RSP / Parsons Brinkerhoff / Yongnam (Singapore) 6

Novena Medical Centre 8 mega transfer trusses (45 m span) Spacing = 9 m c/c; Height = 4.9 m Weight/m 2 = 570 kg/m 2 (Grade Q345) Source: KTP Consultants / 22MCC (Singapore) 7

Background 80 m Source: The Straits Times (2 April 2014) 8

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Technical Challenges & Difficulties ! Modular, Safe and Innovative Lifting & Assembly with shortest downtime, to facilitate Stage Construction Ductility Toughness Instrumentation & Monitoring Strength Weldability Construction HSS Performance: Deflection Welding + Vibration Control to Heat Affected Zones + enhance Livability Post-Weld Heat Treatment Structural Material 10

Proposed Structural System for FBB Joint 3-D Model Megatruss Main Girder x x x x x x x x x y z y z y z y z y z y z y z y z y z Front View of Megatruss Tendons Proposed Structural System 11

Why Megatruss with Post Tension? stack-up buildings to be erected in stages later very limited low depth-span ratio window for + buildings on bridge construction 1. Provide High Carrying Capacity Post Tension 2. Real time adjustment & monitoring 3. Easy Prefabrication & Installation Truss Bridge Provide a flat “ Land ” Control deflection Fully utilize material Post Tension strength and keep overall member size and weight down 12

‘Land’ Usage & Planning Plot Ratio : 1.79 Simplified 3D Model 13

Load Distributions Park M & E Building 4-Floor Pass Way Car Park Park Drive Way Bridge Span Direction Bridge Span Direction Upper Deck Basement 14

Design Loads Design Load Values g k (KN/m 2 ) (DL) q k (KN/m 2 ) (LL) Location Section Stack-up Building 8.6 7.5 Side Walk 3.84 5.0 Above Deck Green Belt 30 5.0 s/w calculated traffic loads selected Deck & Driveway directly in software directly in software s/w calculated Truss 0 directly in software Below Deck M & E 0 1.5 s/w calculated Car Park 2.5 directly in software 15

Structural Model 21 mega transfer trusses (spaced along 100 m transverse dir, each 80 m span). Spacing = 5 m c/c; Height = 5.0 m Weight/m 2 = 311 kg/m 2 (Grade S690) + 150 kg/m 2 (Grade S355) + 22 kg/m 2 (Y1860S7  15mm) Spacing = 5 m c/c between trusses FBB Structural Model 16

Member Dimensions Megatruss Front View under Stack-up Building under Green Belt under Drive Way Member Top Chord SHS 750*750*50 SHS 500*500*40 SHS 500*300*20 Bottom Chord SHS 500*500*36 SHS 400*400*36 SHS 300*300*10 Diagonal Web Member SHS 400*400*26 SHS 400*400*20 SHS 300*300*16 Vertical Web Member SHS 450*450*32 SHS 500*500*40 SHS 500*300*16 Stiffened Top Chord (red) SHS 900*900*64 SHS 550*550*54 SHS 400*400*34 Stiffened Bottom Chord (red) SHS 550*550*60 SHS 500*500*38 SHS 400*400*12.5 Stiffened Web Member (red) SHS 500*500*46 SHS 400*400*34 SHS 350*350*12.5 Material Utilization factor:  85% 17

Preliminary Results – Bending Stresses Bending Stress (MPa) Stress Condition under ULS (MPa) 18

Preliminary Results – Number of Strands Strand type VSL Y1860S7 (Ø 15mm) Tendon type 6-37 (Ø 137mm) Stack-up building Number of Strands 120 100 Number of Strands 1 strand made up of 7 wires twisted together 80 60 40 20 A tendon with 7 strands 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Tendon number 21 1 19

Preliminary Results – Stress & Deflection Summary of Results member stress and stability -- satisfactory ULS strand maximum stress : 1531MPa ( ＜ 1569MPa) maximum deflection: 272mm SLS strand maximum stress : 157MPa Vertical Deflection under SLS (mm) 20

Material Comparison Podium Block over Orchard MRT Station Novena Medical Centre 12 mega transfer trusses (66 m - 80 m span) 8 mega transfer trusses (45 m span) Spacing = 11.4 m c/c; Height = 15 m Spacing = 9 m c/c; Height = 4.9 m Weight/m2= 600 kg/m 2 (Grade S355) Weight/m2= 570 kg/m 2 (Grade Q345) Functional Bridging Megatrusses (Preliminary Analysis) 21 mega transfer trusses (80 m span) Spacing = 5 m c/c; Height = 5.0 m S690 + S355 only S355 Weight/m 2 = 311 kg/m 2 (Grade S690) Weight/m 2 = + 150 kg/m 2 (Grade S355) + 896 kg/m 2 (Grade S355) + 22 kg/m 2 (Y1860S7  15mm) + 22 kg/m 2 (Y1860S7  15mm) 21

Future Work 22

Research Team NTU Public Agency Industry A/Prof Chiew Sing-Ping, NTU Er Lau Joo-Ming, HDB Dr Ng Yiaw-Heong A/Prof Lee Chi-King, NTU Er Wong Swee-Khian, HDB Er Koh Chwee, JTC Er Ng Kian-Wee, JTC NTU Research Group Dr. Jiang Jin Mr. Jin Yan-Fei Dr. Cheng Kwok-Wah Mr. Chen Cheng Mr. Zhao Ming-Shan Ms. Cai Yan-Qing Mr. Zeng Peng-Gang Ms. Zuo Fei Mr. Gan Bing-Zheng 23

Acknowledgement Ministry of National Development Research Fund on Sustainable Urban Living (MNDRF SUL) for award of this research grant to carry out this project. (January 2014 – January 2017) THANK YOU! 24