Structure of Skyscrapers

7/27/2019 Structure of Skyscrapers

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Organized by Funded by Research Team

Science Teaching Kit for Senior Secondary Curriculum

[Student notes]

Structure of Skyscrapper

Visit : Central


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Visit: Central - Structure of Skyscrapers

1.1 Itinerary

1.2 Introduction

1.3 Structural System Comparison of Skyscrapers

1.4 Checkpoints

1 Old Supreme Court (Former Legislative Council Building)

2 HSBC Headquarters

3 Cheung Kong Building

4 Bank of China Tower

5 Murray Building

Summary Key words and Further reading

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Contents

Preamble

Teaching plan i

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DesignandAppliedTechnology

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Topic 11Force II: Structure of Skyscrapers

Major Teaching Area

Learning planLesson Contents

Field Trip

Central

Itinerary

Major Structural system in Skyscraper

Spatial arrangement in Skyscraper

Curtain Wall system

On-site Exercise

Physics

Chapter II Force and Motion

Force and Motion

Chapter VIII Energy and Use of Energy

Energy efficiency in building and transportation

Interdisciplinary teaching areasDesign and Applied Technology Strand 2 Technological Principles

Liberal Studies Module 2: Hong Kong Today Module 6: Energy Technology and Environment

Learning Objectives To experience the various form of architectural structure of different times in 1:1 scale and in the city

context

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20 min

Cheung Kong Centre

30 min

Bank of ChinaHSBC HeadquarterCourt of Final Appeal

(Former LegislativeCouncil)

30 min

Murray Building

30 min 30 min

Pre-Trip Introduction (20 min) Structural system, structural element, structural material and spatial arrangement in skyscraper Objectives and on-site exercise introduction

Planned route

Field Trip (approximately 2 hours)

1.1 Itinerary

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Tall buildings are symbolic elements within any city, carrying significant political,

social, cultural and even religious meanings. Today cities compete to produce

the tallest building in the world as a way of showcasing financial and economic

power. Understanding the structures of these buildings, and how they supportthemselves as well as the loads imposed on them by the environment, is a

fascinating way to see the real-life applications of physics.

Core and Outrigger Structural System

Corewall

usually located at the centre or side of building, the reinforced concrete

wall, which is the major structural load bearing element and provide

rigidity to resist deflection caused by strong wind

StructuralSteelExternalFrameseries of steel column located at the building perimeter, with steel beams

connecting the steel columns to core wall

Outrigger

huge braced frame (with height equivalent to 2-3 storey), located at each

20-30 storeys to enhance the rigidity of external frame

Transfertruss

usually adopted to provide spacious ground entrance. Building load from

columns on upper floors is transferred down to fewer main columns (super

/ mega columns) through huge truss system (with height equivalent to 2-3

storey), and then down to the underground foundation.

The International Financial Centre is built using a Core and Outrigger concept.

The core at the centre of the building bears most of the vertical load, while

columns at the perimeter carry less weight and are thus smaller in dimension.

Loads are transferred to the core through steel outriggers that balance the lateral

forces on the whole building.

Steel Structural System

Steel is a common construction material for tall buildings because it has goodperformance in withstanding compressive and tensile forces. Steel bars can be

used to reinforce concrete to add extra structural performance. However, steel is

relatively weak in fire-resistance. An extra layer of fire-resisting coating is often

put onto the steel surface.

Examples of Structure in skyscraper

CoreandOutriggersystem:CheungKongCentre(CKC),IFC2

SteelFramesystem:HSBCHeadquarter,BankofChina

p Core and outrigger system

(IFC2)

p Raised Floor system

p Electricity supply under raised

floor system

Steel Frame

Core Wall

TransferTruss

MegaColumn

Outrigger

p Steel Frame Structure system

(HSBC)

Steel

ExternalFrame

1.2 Introductions


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Completion

Height

Storey

Architect

Structure

HSBC Headquarter

1986

180m

47

Norman Foster

Exoskeleton steel Truss

Cheung Kong Centre

1999

283m

62

Cesar Pelli

Composite structure:Core wall andcomposite columnexternal frame

Bank of China

1990

367m

72

I.M. Pei

Triangular truss incomposite steel andreinforced concrete

Murray Building

1969

89m

25

Former Public WorksDepartment

Composite structure:Core wall and externalreinforced concreteshear wall

1.3 Structural System comparison

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Built in : 1900-1912Architects : Aston Webb and E. Ingress BellStructure : Granite column and Dome structure

Use : 1912-1978: Supreme CourtDuring Japanese occupation in World War II(December 1941 to August 1945), the building wasused as the headquarters of Hong Kong MilitaryPolice.

19852011: Legislative CouncilDue to structural crack discovered during theconstruction works of the Mass Transit RailwayIn 1978, the building was temporarily closed forreinstatement and alteration works. It wasreopened in 1985 as Legislative Council Building.

In 2012, the building was closed and planned toopen as the Court of Final Appeal by 2015.

p The Old Supreme Court was declared as aGrade I monument by the Antiquities andMonuments Office and is protected legally

under the Antiquities and MonumentsOrdinance

Court of Final Appeal (Former Legislative Council Building)

Stylobate

Columns

Architrave EntablatureFrieze

Pediment

p Various parts of a classical Greek faade, composed mainly ofstylobate, colonnade, entablature and pediment. Some of thesefeatures are also used in the Neoclassical Old Supreme CourtBuilding.

Ionic Column

Pediment

Dome

Structure under Western Classicisms Influence

The three storey granite structure containsdesign features of Roman and Greekarchitecture, with Ionic style columns and domeelegantly proportioned. The wide arcade onground floor and balcony above is designedto responded to sub-tropical climate of HongKong. It acts as a buffer zone to prevent directsunlight from entering to the building.

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Arch structureThe dome is a form seen in many old structure, e.g. Pantheon

(Italy), Taj Mahal (India).

It is a spherical surface structure having a circular plan,constructed in rigid material like granite or reinforcedconcrete.

[Do you know...]Under the rule of the British colonial government, the OldSupreme Court was built in a Western architectural style inthe Eastern city of Hong Kong. This is Neoclassical style, withfeatures of classical Greek and Roman architecture (850 BC-476AD), but constructed after 18th century. However, because ofclimatic and geographical differences, architectural featureswere altered to fit local conditions. This mixed, adaptivedesign is what we call the Colonial Style.

Chinese hip roof

DomeA dome is a hemispheric roof structure. Structurally, it can beanalysed as an arch that has been rotated around a centralaxis. Like an arch, a dome enables large spaces withoutinterior support. Tension rings can be used to withstand theoutward pushing forces of the dome.

Section across domeof Pantheon

Force on the domeCompression in eachstructural piece

Arcade

Force on the arch


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Structural Features1. The structure can be dissembled into kits-of-part and

resemble in another site

2. Column free floor areaThe 8 steel masts carry all the structural loads and allowsthe creation of column-free floor area. It maximizes theflexibility to adopt to different spatial arrangement.

4. Clear and unobstructed circulationall lift and escalator located at the side of the building.

5. Unobstructed view within the building and towards externalarea.

6. Sustainable design 40mhighatriumwithabankofgiantmirrorsonits

top, which reflects the sunlight from a light scoopdown through the atrium to the public plaza.

exteriorreflectorreflectsnaturalsunlightintothe atrium space

buildingservicesarelaidunderraisedfloortoallowthe most efficient air-conditioning control and flexibleuse of electrical supply

HSBC Headquaters

Built in : 1983-1985Style :Architect : Lord Norman Foster, Pritzker Prize-

winning architect

History of the HSBC Main Building

First generation : 1865-1886Second generation : 1886-1935 (Victorian style)Third generation : 1935-1978 (mixed Art Deco and Stripped

Classical Style i.e. classical elementssimplified to show only structural orproportional systems)

Current building : 1986 (High-tech architecture)

p Contrasting architectural styles in Central Old Supreme Court in Neoclassical style andthe nearby HSBC Main Building in High-techstyle (Source: Ian Lambot)

Structural Mast

Hanger

p The atrium and the free plan office space

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[Do you know...]The HSBC Headquarters is surrounded by tallbuildings and a hill at the south. In order tointroduce natural light into the atrium, a solarreflector was installed to reflect sunlight from higherlevel into the 40 m atrium space. This approach wasrelatively new in the 1980s. Although people doubtthe performance of this sun reflector, the goodwill

behind the idea should be appreciated.

Phototaking TipsPhotography not allowed anywhere in thebuilding except in the atrium


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07t Simplified diagram of the structural system ofthe HSBC Headquarters

Pivot point

MomentMoment

Truss

Structural mastW/2 W/2

W

pt The structural system of the HSBCHeadquarters is called ExoskeletonTruss Frame. Floor slabs are suspendedby pairs of trusses. The trusses aresupported by the structural mastswhich transfer all vertical forces to theunderground structure.p The structural system of the HSBC Headquarters

Plan

[Exercise]How are different loads on the building transferred to the underground structure?

In the following diagram, it is given that the distance between two structural masts = d ; and weight of thefloor slab = W. Assume the weight of each floor is acting in the middle of the floor slab.

1 Identify how the weight of each floor transferred through the structure.

2 Can you identify the pivot points of the structure?

3 Calculate the moments of force (torque) at each pivot point of the structure.

ColumnDesignandAppliedTechnology

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Cheung Kong Centre ()

p Construction photo

p Interior view of Transfer Truss on 2/Fp Exterior view of Transfer Truss on 2/F

1 Transfer truss structure (see photo on right) used about ground level entrance. Suggest the functionof it.

Composite Column:Steel post encased inside concrete

Core

Core

Composite ColumnExternal Frame

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[Exercise]

Built in : 1999Structure : Composite structure - Core wall and

composite column external frameArchitect : Cesar PelliUse and Facts : the headquarters of Cheung Kong

(Holdings) Limited, and is owned and

managed by its associated companyHutchison Whampoa Limited, whileother tenants include severalmultinational banking firms.

It sits on the combined sites of theformer Hong Kong Hilton, which wasdemolished in 1995/6, and BeaconsfieldHouse, sold by the Government in 1996.

Baycrest


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1 Draw the load path to show how the loads on the building being transferred to the earth.

2 Why do you think the architect choose to use triangle as the composition of the structure?

[Exercise]

Bank of China Tower ()4

Built in : 1985-1990Structure : Triangular truss in composite steel and

reinforced concreteArchitect : I. M. Pei, Pritzker Prize-winning architect

Use : Headquarters of Bank of China Hong Kong.Part of the storeys are leased out. The sitewas the former address of the MurrayHouse, which had been dismantled in 1982and relocated to Stanley in 2000s.

u With a striking angular form, the Bank of China is aniconic piece of Structural Expressionism. The idea for theform came from bamboo, a symbol of growth and prosperityin Chinese Culture. However, there have been comments onthe poor Feng Shui the buildings causes to the surroundingdue to the triangular form and the many crosses (X) of itsstructural frame.


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Murray building ()

p Murray Building was awarded the Certificate ofMerit of the Energy Efficient Building Award in 1994,for its successful design in environmental concern.

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[Exercise]

1 Identify the direction where solar glare comes from during morning and late afternoon.2 Suggest the advantages of the design of perimeter shear wall and angular oriented windows.

p All windows are meticulously oriented to avoid

excessive direct sunlight from entering the office.

p Floor Plan - The envelope is the key structure

holding the building space inside Force is from insidetransferred outward to the ground

Built in : 1969Structure : Composite structure - Core wall and

external reinforced concrete shear wallArchitect : Public Works Department of the time

Historical Facts : Upon its completion, it was the tallest

government building at that time

The site was the former address ofthe Murray House, which had beendismantled in 1982 and relocated toStanley in 2000s.

Murray Building became vacant uponrelocation of its current offices to thenew Central Government Complex atTamar by end-2011.


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Organized by Funded by Research Team


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1. h t tp : / /www.grea tbu i ld ings .com/bu i ld ings/Hongkong_and_Shangha i_Ban .h tml2. h t tp : / /www.arch .hku .hk/ teach ing/case .h tm#Stud ies%20on%20Bu i ld ings%20in%20Hong%20

Kong

3. h t tp : / / skysc raperpage .com/d iagrams/?member ID=6314. h t tp : / /b log .yahoo .com/arch t rave l l e r / ca tegory /%E5%BB%BA%E7%AF%89%E9%81%8A%E8

%A8%98-%E9%A6%99%E6%B8%AF%2C%E6%BE%B3%E9%96%80%2C%E6%B7%B1%E5%9

C%B3/page/7?deta i l

5 . HSBC Headquatersh t tp : / /www.arup .com/Pro jec ts/HSBC_Headquar te r s_1_Quee ns_Road_Cent ra l .aspx

6 . Bank of China

h t tp : / /www.a l l abou tskysc raper s .com/proper t y /bank-o f - ch ina- tower -2

www. le ra .com/ f i l es/Bank%20of%20Ch ina .pd f -

7. Construction of Super High-rise Composite structures in Hong Kong, Raymond W.M. Wong, Divisionof Building Science and Tecnhology, City University of Hong Kongbst1 .c i t yu .edu .hk/e - learn ing/bu i ld ing_ in fo_pack/ ta l l_bu i ld ing / i f c2 .pd f

h t tp : / /persona l . c i t yu .edu .hk/~bswmwong/pho to_ l ib / i f c / i f c i ndex .h tml

h t tp : / /en .w i k iped ia .o rg /w ik i / In te rna t iona l_F inance_Cen t re

8. Murray Buildingh t tp : / /www.devb .gov .hk/en/ i ssues_ in_ focus/conserv ing_cen t ra l /Mur ray_Bu i ld ing / index .h tml

Key Words

Composite StructureStructural FrameCoreSteelReinforced Concrete

References

Summary

The field trip introduces typical structural systems used in skyscrapers in Hong Kong, and explains howthey support themselves as well as the loads imposed on them by the environment. They are the real-life applications of physics. Skyscrapers in Central are not only aesthetically pleasing, but also showcaseinnovations in building materials and technology and influence the identity of the city. Some even showenvironmental concerns that have been a hot global issue in recent years.

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Documents

Structure of Skyscrapers