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

Chiew Sing-Ping School of Civil and Environmental Engineering Nanyang Technological University, Singapore 6 August 2014

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Intensification of Low-Density Developments:

Functional Bridging Buildings

MNDRF SUL Project 2013-4

More Ancient Functional Bridges

The Ponte Vecchio, Florence, Italy

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Pinnacle @ Duxton – Skybridges, Singapore

҉ Paradigm Shift ҉ 2-D and Parallel Intensification ҉ Enhancing Livability

More Recent Functional Bridges

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Fusionopolis, Singapore

Reflections at Keppel Bay, Singapore

Going beyond Functional Bridges ….

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҉ 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.

Marina Bay Sands (MBS)

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Weight of steel per m2 = (3500 T x 1000 kg) / (120 m x 40 m) = 730 kg/m2 (S355)

Source: Arup (Singapore)

Podium Block over Orchard MRT Station

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12 mega transfer trusses (66 m - 80 m span) Spacing = 11.4 m c/c; Height = 15 m Weight/m2= 600 kg/m2 (S355)

Source: RSP / Parsons Brinkerhoff / Yongnam (Singapore)

Novena Medical Centre

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8 mega transfer trusses (45 m span) Spacing = 9 m c/c; Height = 4.9 m Weight/m2= 570 kg/m2 (Grade Q345)

Source: KTP Consultants / 22MCC (Singapore)

Background

80 m 8

Source: The Straits Times (2 April 2014)

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Technical Challenges & Difficulties !

Construction Structural Material

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Modular, Safe and Innovative Lifting & Assembly with shortest downtime, to facilitate Stage Construction Instrumentation & Monitoring Deflection Vibration Control to enhance Livability HSS Performance: Welding + Heat Affected Zones + Post-Weld Heat Treatment

Strength Ductility Toughness Weldability

Proposed Structural System for FBB

Proposed Structural System

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x y z x y z x y z x y z x y z x y z x y z x y z x y z

Front View of Megatruss 3-D Model Joint Megatruss Main Girder Tendons

Why Megatruss with Post Tension?

• 1. Provide High Carrying Capacity
• 2. Real time adjustment & monitoring
• 3. Easy Prefabrication & Installation

low depth-span ratio + buildings on bridge stack-up buildings to be erected in stages later very limited window for construction

Control deflection Fully utilize material strength and keep

• verall member size

and weight down Provide a flat “Land” Post Tension Truss Bridge Post Tension

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‘Land’ Usage & Planning

Simplified 3D Model

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Plot Ratio: 1.79

Load Distributions

Upper Deck

Building 4-Floor Park Park Pass Way Bridge Span Direction Drive Way Car Park Bridge Span Direction M & E

Basement

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Design Load Values

Location Section gk (KN/m2) (DL) qk (KN/m2) (LL) Above Deck Stack-up Building 8.6 7.5 Side Walk 3.84 5.0 Green Belt 30 5.0 Deck & Driveway s/w calculated directly in software traffic loads selected directly in software Below Deck Truss s/w calculated directly in software M & E 1.5 Car Park s/w calculated directly in software 2.5

Design Loads

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Structural Model

FBB Structural Model

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21 mega transfer trusses (spaced along 100 m transverse dir, each 80 m span). Spacing = 5 m c/c; Height = 5.0 m Weight/m2= 311 kg/m2 (Grade S690) + 150 kg/m2 (Grade S355) + 22 kg/m2 (Y1860S7 15mm)

Spacing = 5 m c/c between trusses

Member Dimensions

Megatruss Front View

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Material Utilization factor: 85%

Member under Stack-up Building under Green Belt under Drive Way 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

Preliminary Results – Bending Stresses

Stress Condition under ULS (MPa)

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Bending Stress (MPa)

20 40 60 80 100 120 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Number of Strands Tendon number

Number of Strands

Preliminary Results – Number of Strands

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Strand type VSL Y1860S7 (Ø 15mm) Tendon type 6-37 (Ø 137mm)

1

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Stack-up building

1 strand made up of 7 wires twisted together A tendon with 7 strands

Preliminary Results – Stress & Deflection

ULS member stress and stability -- satisfactory strand maximum stress : 1531MPa (＜ 1569MPa) SLS maximum deflection: 272mm strand maximum stress : 157MPa

Summary of Results

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Vertical Deflection under SLS (mm)

Material Comparison

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Podium Block over Orchard MRT Station Novena Medical Centre

8 mega transfer trusses (45 m span) Spacing = 9 m c/c; Height = 4.9 m Weight/m2= 570 kg/m2 (Grade Q345) 12 mega transfer trusses (66 m - 80 m span) Spacing = 11.4 m c/c; Height = 15 m Weight/m2= 600 kg/m2 (Grade S355) Weight/m2= 311 kg/m2 (Grade S690) + 150 kg/m2 (Grade S355) + 22 kg/m2 (Y1860S7 15mm)

Functional Bridging Megatrusses (Preliminary Analysis)

21 mega transfer trusses (80 m span) Spacing = 5 m c/c; Height = 5.0 m

S690 + S355

Weight/m2= + 896 kg/m2 (Grade S355) + 22 kg/m2 (Y1860S7 15mm)

• nly S355

Future Work

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Research Team

NTU

A/Prof Chiew Sing-Ping, NTU A/Prof Lee Chi-King, NTU

Public Agency

Er Lau Joo-Ming, HDB Er Wong Swee-Khian, HDB Er Koh Chwee, JTC Er Ng Kian-Wee, JTC

Industry

Dr Ng Yiaw-Heong

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NTU Research Group

• Dr. Cheng Kwok-Wah
• Ms. Cai Yan-Qing
• Mr. Gan Bing-Zheng
• Dr. Jiang Jin
• Mr. Chen Cheng
• Mr. Zeng Peng-Gang
• Mr. Jin Yan-Fei
• Mr. Zhao Ming-Shan
• Ms. Zuo Fei

Acknowledgement

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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!