3 Recent Innovations for Steel and Composite Steel-Concrete Structures in Australia

8/18/2019 3 Recent Innovations for Steel and Composite Steel-Concrete Structures in Australia

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Recent Innovations for Steel and Composite

Steel-Concrete Structures in Australia

Brian Uy,

Professor of Structural Engineering & Director,

Centre for Infrastructure Engineering & Safety


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Abstract

Structural steel and its use in Australia can be traced back well over a century with its

use in iconic bridge projects and prolific widespread use in general. Its prolific use inbuilding projects has a much shorter history of half a century in multi-storey buildingsof the 1960’s in Sydney when building height restrictions were lifted. This paper willtrace the advancements and achievements in structural steel in bridges and building projects, stadia and transport infrastructure in Australia over the last century. Thedevelopment of Australian Standards for the use of structural steel and compositesteel-concrete structures in buildings and bridges will also be provided. This will

include a review of the current project on the Australian Bridge Design Code AS5100:Part 6 for Steel and composite structures and Part 8 which also includes new aspectsto deal with retrofitting and strengthening to deal with the current challenges facingthe management of ageing infrastructure. The paper will also review aspects of thenew Australia/New Zealand Standard AS/NZS2327 on Composite steel-concretestructures for buildings which incorporates the design of slabs, beams, columns andsystems as well as the mooted development of a Australia/New Zealand Standard onSteel structures AS/NZS 4100. The paper will conclude with an analysis of the future,including a review of existing and future building and infrastructure projects and theuse of structural steel. Future research into structural steel in Australia will also be provided at the conclusion of this paper.


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Structure

•

Introduction• Bridges

• Buildings

• Stadia and special structures

• Transport infrastructure

• Australian standards

• Further research

•Conclusions

• Acknowledgements


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Structure

•


• Buildings





•Conclusions

• Acknowledgements


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Introduction

Major civil engineering projects involvingstructural steel include the 124 year old

rail crossing of the Hawkesbury River

north of Sydney and the 81 year old

Sydney Harbour Bridge. The Hawkesbury

River rail bridge was designed and built

by the Union Bridge Company from NewYork, USA and officially opened in 1889.

The Sydney Harbour Bridge completed in

1932 was based on a general design by

the NSW Department of Public Works

but heavily based on New York’s Hell

Gate Bridge and with detailed design byDorman Long and Co, Middlesborough,

UK through Sir Ralph Freeman and Sir

Douglas Fox.


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Australian buildings using innovative steel constructiondeveloped significantly after the lifting of heightrestrictions in the Sydney Central Business District. Thisperiod saw the design and building of the AMP building

in Alfred Street fronting Circular Quay. This was 45stories in height and was Australia’s tallest buildingwhen completed in 1976. Furthermore, Australia’stallest structure was the Centrepoint Tower now known

as Westfield Tower, completed in 1981 which usedAUSTEN 50 high strength weathering steel of nominalyield stress of 350 MPa in its construction.


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The advantage of the use of composite construction hasbeen less well detailed and probably would date back topost second world war developments. It is assumed thatthe use of composite construction techniques in Australiamay have also been used for well over a century, however

significant iconic structures that can be reported on appearto only be approximately 50 years old, with significantbridges and buildings in New South Wales, possibly the firstto have utilised these techniques. The Hawkesbury RiverRoad Bridge completed in 1977 was designed and

constructed as a steel box girder bridge with shearconnection making the concrete deck composite throughthe top flange.


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The NSW Government Offices completed in 1965 and

demolished in 1997 was Australia’s tallest skyscraperon completion in 1965 reaching 38 levels. This building

relied on innovative methods of construction to

achieve speed of construction and employed many

composite construction methods, namely composite

beams spanning 10 metres, composite slabs utilising

metal decking. Furthermore, this building involved the

first major use of composite construction in columns,

namely encased sections.


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NSW Government Offices,

1965

Demolished in 1997 was

Australia’s tallest skyscraper on

completion in 1965 reaching 38

levels. This building relied on

innovative methods of

construction to achieve speed of

construction and employed manycomposite construction methods,

namely composite beams

spanning 10 metres, composite

slabs utilising metal decking.

Furthermore, this building

involved the first major use of

composite construction in

columns, namely encased

sections.


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Tall building construction in Australia is significantly influenced by thematerial and labour costs involved. Since Australia has a highly skilledlabour force in reinforced concrete construction and more importantlysteel framed construction, labour costs are becoming more significantand thus are a primary consideration in the type of system chosen forconstruction. In Australia in the past it has been shown that about 50% of tall buildings have been constructed in reinforced concrete withsteel structures representing a 30 % share of the tall building marketwith mixed systems representing the remaining 20 % (Uy, 1997). Thesestatistics have been contrast with a list of the tallest 100 buildings inthe world, (Council of Tall Buildings and Urban Habitat, 1996). It is alsoanticipated that this figure has been further skewed toward concretestructures over the last fifteen years as a result of the development ofhigh strength concrete being taken to advantage in multi-storeybuilding systems.


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Type of

Framing

Material

100 Tallest Buildings in the

World (%)

Australian Tall

Buildings(%)

Steel 53 30

Concrete 20 50

Mixed 27 20

Total 100 100


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One of the driving forces for innovation in the design and construction of tall steelbuildings has included the use of composite construction techniques. Some of themore innovative composite construction applications have been confined to a fewiconic buildings of typically multi-storey and tall building structures. Some of thesetypical innovations have included the use of high strength cold formed steel forcomposite slabs. Conventional steel-concrete composite beams have also benefitedfrom some innovations in the use of semi-rigid joint action and pre-cambering of steelbeams in frames. The use of concrete filled steel columns has seen tremendousinnovations, particularly in the use of very thin-walled steel tubes and box columns for

the fabrication of concrete filled columns. Other more specialised innovations incomposite construction have also included the use of post-tensioned compositetrusses.

More recent projects have shown that for specialty structures such as stadia, exhibitioncentres and transport infrastructure, the use of structural steel has promoted theability for reuse. This is seen to be a very important initiative for the future and salient

examples will be provided herein to illustrate some of the technical challenges thatneed addressing in order to ensure that these are made feasible.


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Structure

•


• Buildings





•

Conclusions• Acknowledgements


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Bridges

Structural steel standards have been important inAustralia and date back to the late 19th and early 20th

century when Australia typically imported much of its

steel. The Sydney Harbour Bridge conceived in the late

1800’s, constructed during the 1920’s and completed inthe 1930’s used steel sections imported from Dorman

Long in the United Kingdom, (Lalor, 2006). This bridge

is constantly being maintained and repaired and

currently has a structural health monitoring system toassist in assessing damage to certain critical sections.


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Bridges

One of the most significant bridges in Australia is theWestgate Bridge over the Yarra River in Melbourne,

which li nks the Western Suburbs of Melbourne and

the southern parts of Victoria to its ca pital Melbourne.

This bri dge is a steel box gir der cable stayed bridge

which has a main river span of 336 m a nd has a total

length of more than 2500 metres. This bridge

coll apsed during construction in October 1970, which

resulted in a Royal Commiss ion. This and a number of

other notable colla pses of box girder bridges in the UK

and Germany al so resulted in many important rulesbeing developed by the Merrison Committee in the

United Kingdom. In 2006, the Victori an government

approved plans to refurbi sh the bridge. Some of the

si gnificant factors i ncluded strengthening the box

girders whil st maintaining traffic flow over the entire

works period. These works were compl eted i n June

2011 and incl uded si gnificant work on the box girder.

Much of the work involved the use of blind bolting

techniques to increase plate stiffener thicknesses,

thereby reducing the stress range operating in the

boxes and subsequently the fatigue life of thestructure.


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A major composite bridge was built over the George’s River in Sydney in 1987.This was a parallel bridge to the 1923 Pratt Truss steel bridge which was

completed in 1923. The new bridge consisted of eight 70 m spans involvingthree steel box girders utilising composite action with the concrete deck. Amajor composite-steel concrete bridge was built in Sydney in 2000 at RobertsRoad crossing the Hume Highway and linking northern and southern arterialroads of Sydney. The superstructure of this bridge comprised four steeltrough girders supporting a concrete deck across six continuous spans ranging

from 25-40 metres. The sections adopted 350 MPa (N/mm2

) steel plates with1400 mm depth and 2250 width sections. In addition to some of the moreobvious challenges, some other engineering challenges in the bridge designrealm, will be in the area of urban design. Architects are finding increasinginvolvement in the urban design of bridges. Architectural involvement thenposes unique challenges for structural engineers which need solutions to beavailable. A recent bridge designed in Clifton Hill, Melbourne involved

significant architectural involvement and penetrations were required toachieve the architectural objective.


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Roberts Road, 2000

A major composite-steel concrete

bridge was built in Sydney in 2000

at Roberts Road crossing the

Hume Highway and linking

northern and southern arterial

roads of Sydney. Thesuperstructure of this bridge

comprised four steel trough

girders supporting a concrete

deck across six continuous spans

ranging from 25-40 metres. The

sections adopted 350 MPa(N/mm2 ) steel plate with 1400

mm depth and 2250 width

sections.


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Clifton Hill, 2009Clifton Hill, Melbourne

involved significant

architectural involvement

and penetrations were

required to achieve thearchitectural objective.

This structure required

significant finite element

analysis carried out to

justify the designs and thiswill be a continuing trend

in future bridge designs.


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Structure

•


• Buildings





•



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Grosvenor Place, 1988The innovative use of structural steel in this

building included quite a few firsts in

Australia. The building involved the use of

high strength cold formed profiled steel

sheets for the decking with a yield stress of

550 MPa (N/mm2). The beams which span

approximately 16 metres from the reinforced

concrete core to perimeter frame were

designed for serviceability as semi-

continuous, with a semi-rigid joint assumed

between the beam and core. The columns in

the lower levels of the buildings are quite

unique and involve three perimeter columns

being grouped at the ground level in a single

column, with the key objective being the

savings in space made for car parking in thebasement. This involved the use of high

strength quenched and tempered structural

steel of yield stress of 690 MPa (N/mm2 )

being used for encased sections in this zone.


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Grosvenor Place, Sydney (Cont’d)Piloti Column Encased

• Heavy steel fabricated

section prior to and

following encasement

• (shear studs provided

for composite action)


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Forrest Plaza

The Forrest Plaza building is in the

central business district of Perth and thebuilding was completed in 1988. Thebuilding was designed by structuralengineers Ove Arup and Partners andconstruction was completed by buildersMultiplex, (Gillett and Watson, 1987).The building has a total height of 110

metres over 28 storeys. This building isunique in that it was the first steelbuilding built in Perth in a decade. Someof the novel features which were used inthe design and construction of thisbuilding included the use of concrete filled steel box columns. Furthermore,

profiled steel sheeting fixed over twofloors was used in the constructionphase. Composite action for the slabsand beams were used throughout theheight of the building.


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Casselden Place, Melbourne

The Casselden Place building is in the

central business district of Melbourneand the building was completed in 1992.The building was designed by structuralengineers Connell Wagner andconstruction was completed by buildersBaulderstone Hornibrook. The buildinghas a total height of 166 metres over 43

storeys. This building is unique in that itwas the first building in Melbourne toutilize concrete filled steel tubes.Concrete filled steel tubes of twin cross-sections of 950 mm diameter have beenused in the upper levels and thesetransition to a single 1350 mm diameter

thin-walled steel tubular column at thelower levels. These columns were then filled with high strength concrete of 80MPa compressive strength, Webb andPeyton (1990).


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Central Park, Perth

The Central Park building is the tallest building inthe central business district of Perth (Figure 8)and the building was completed in 1992. Thebuilding was designed by structural engineersBruechle, Gilchrist and Evans and constructionwas completed by builders Multiplex. Thebuilding has a total height of 249 metres over 52storeys. This building incorporates some unique

features for steel construction, which include theuse of precast concrete floor panels on steelcomposite beams. The columns used in thedesign and construction are also unique in thatthey include fabricated cruciform high strengthsteel sections utilizing 32-60 mm high strengthsteel plate (f y =690 MPa) at the base of thebuilding, with mild steel (f y =250 MPa) at theupper section of the building, (Structural Steel

Development Group, 1989).


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Star City, 1995

The building comprised a number of

innovative composite construction and

high strength steel applications.Firstly, in the main gaming areas of thecasino, large span composite beams ofapproximately 16 metres were

designed and constructed. In thebasement levels of the building, high

strength steel fabricated sections were

used to miminise the cross-sections ofthe columns. Due to constraints with

site access for craneage, the trussesfor the roofs had to be constructed

with minimal weight. This required

the design of 36 metre spanningtrusses made composite with a

topping slab and utilising high strength

structural steel for the sections. Post-tensioning of the trusses was also usedto help alleviate long-termserviceability concerns.


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Latitude, 2005

The beams in the floor system

span a total of 14 metres from

core to perimeter frame and in

order to achieve this the beam’s

were pre-cambered by 40 mm to

overcome estimated long term

deflections of 60 mm. The

building also uses twin composite

columns on the perimeter frame,

using 508 mm diameter steeltubes filled with 80 MPa concrete.

The building has required the

design of 7 metre deep transfer

trusses using large diameter steel

tubes filled with concrete and

large high strength steel boxes

filled with concrete.


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Latitude, Sydney


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One Shelley Street, 2010The building is best known for

utilising an extremely efficient

steel diagrid perimeter structure

to eliminate the need for internal

columns and to minimise the use

of internal structural cores. Thediagrid members were formed

from 310 UC sections and welded

steel sections with 70 mm plate

thicknesses of nominal yield

stress, 450 MPa (N/mm2). The

beams typically spanned up to 14

m at 3.2 m centres and used a

610 UB made composite with a

120 mm deep composite slab.


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Column Free Floor Plate


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Exoskeleton


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Floor and external frame integration


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Perth Tower, 2012

Whilst technical challenges will

continue to be important in the

design of composite steel-

concrete buildings, issues relating

to project management,

procurement and quantity

surveying may be of increasing

importance. The builders of the

recently completed Perth Tower,the tallest tower in Perth chose to

adopt a concrete filled steel

column solution. In order to

secure this type of solution the

builder pre-ordered and stored all

steel tubes in the columns to

ensure steel cost fluctuations

were minimized and construction

costs able to be controlled.


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Perth Tower, 2012


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Structure

• Introduction

• Bridges

• Buildings


• Transport infrastructure• Australian standards


•



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Stadia

Probably the best example of a

structure which has been madedemountable in Australia is the

Olympic Stadium built for the Sydney

Olympics in 2000. The structure wasdesigned to seat 110,000 people

during the Olympics with two largeend stands. These end stands were

then removed after the Olympics andthereby reducing the capacity to80,000. These end stands were then

transported to Wollongong, 80 kmsouth of Sydney and used in the

reconstruction of the WIN stadium. Tofacilitate the concept of

deconstruction a special blind bolting

technique was utilised.


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Blind bolting


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Post Olympics Mode


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Exhibition and Convention Centre, Sydney

The original Sydney Exhibition and ConventionCentre was completed in 1988 for the AustralianBicentennial celebrations in the Darling Harbourprecinct, Sydney. The New South WalesGovernment has chosen Lend Lease to completea $2.5 billion project which includes world classhotel facilities. The $1 billion redevelopment ofthe Sydney Exhibition and Convention Centre willinclude over 40,000 square metres of exhibitionspace, making it the largest in Australia. Theproject will be completed by December 2016.One of the significant aspects of this projectinvolves the reuse of the concrete plinth for thefoundations and carpark. The use of structuralsteel in the redevelopment has allowed thissustainable approach to be used for theredevelopment of this world class facility.


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Exhibition and Convention Centre, Sydney


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Royal Randwick Racecourse

Royal Randwick Racecourse in Sydneyhas recently been refurbished. Theoriginal Queen Elizabeth II stand wascompleted in 1969 and was constructedin reinforced concrete, with the roofbeing designed and constructed in post-tensioned concrete. In 2011, safety

concerns regarding the roof beamsclosed the stadium and this forced manyraces away from one of Australia’s finesthorse racing venues. The stadium wasredesigned and rebuilt, using the lower part of the concrete stadium, with thenew roof involving the use of structural

steel in a $150 million redevelopment.The stadium was completed and openedfor use in the Autumn racing carnival in2013.


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Structure

• Introduction

• Bridges

• Buildings




•



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Transport infrastructure

A significant application of transportinfrastructure which is being mooted

for reuse in Australia is the Sydney

monorail. The monorail which linksthe Darling Harbour area with theSydney Central Business District. The

plans are to dismantle this and torelocate to Hobart, which is the Capitol

of the Australian island state ofTasmania, (Sydney Morning Herald,

2012).


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AS4100-1998 Steel Structures

This Australian Standard was producedby committee BD1, (Standards Australia,1998). This Australian Standard is aprimary reference standard for theBuilding Code of Australia and deals withthe design of bare steel structures. Thestandard was firstly released in 1990 in

limit states format, (Standards Australia,1990). One of the major innovations inthis standard is the ability to allow theuse of advanced analysis.The standardlimits the yield stress of the material to450 MPa (N/mm2 ); however a newamendment was released in 2012 to

increase the yield stress to 690 MPa(N/mm2 ), (Standards Australia, 2012).


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AS2327.1-2003

Composite structures: simply supported beamsThe development of an Australian Standard inlimits states form resulted in the standardAS2327.1 which was first released in 1996 andfurther amendments were produced for a furtherrevision in 2003, Standards Australia, (1996 and2003). The Australian Standard deals with thedesign of simply supported composite-steelconcrete beams. The major innovations in thisstandard are the ability to allow the use of partial

shear connection. The standard also requiresdesigners to pay close attention to the variousstages of loading, namely construction, serviceand ultimate loading stages. The document doesnot cover continuous or semi-continuous beambehaviour and currently does not allow for theuse of precast or hollowcore slabs to be madecomposite with steel beams. Designers wantingto take advantage of continuity have often availed

themselves of European Standards, (BritishStandards Institution, (1994)). Further progressover the next few years should see progress onthis new standard which is ongoing in the AS/NZS2327 project, (Standards Australia, 2014a).


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AS5100.6-2004 Bridge design,

Part 6 Steel and composite construction

It has been suggested that the design of composite columns may besatisfactory using the existing steel and concrete standards,Standards Australia (1998) and Standards Australia (2001), howeverthis has some serious drawbacks. The benefits of this type ofcolumn are through savings made during the construction phaseand thus these need to be considered. The Australian steelstandard allows one to use a rational local buckling method todetermine the local buckling coefficient however and this is useful.However the concrete standard wil l not allow for confinement if itis required to be taken into account for large plate thicknesses. Thedeficiencies of these codes have been resolved in the AS5100Bridge design series which was produced by committee BD90 which

was a partnership between Standards Australia, the AustralasianRailway Association and AUSTROADS. The Standard deals with thedesign of members in steel and composite construction (StandardsAustralia, 2004). The standard draws heavily on the AustralianStandards, AS4100-1998 and AS2327.1-2003 (Standards Australia,1998 and Standards Australia, 2003) for beam and column design.The standard is also however also able to deal with compositeconstruction members which may prove to be a forerunner to thedevelopment of a standard for composite columns produced byBD32 for buildings. This standard is currently being revised and in

particular will take into account the changes in steel and concretestrengths that AS4100 and AS3600 have respectively proposed,

(Standards Australia 2014b).


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Reduction factor for the use of high strength steel

f i l d f i


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Manufacturing tolerances used for capacity

reduction factor calibration


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Capacity factor versus reliability index for compact

sections using products complying with

manufacturing tolerances given in (a) EN 10034/KS D

3502 (b) JIS G 3192/JIS A 5526



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sections using products complying with

manufacturing tolerances given in (c) ASTM A

6/A6M (d) AS 5100.6

AS5100 Part 8: Rehabilitation and strengthening of


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AS5100 Part 8: Rehabilitation and strengthening of

bridges

In addition to revisions of theexisting steel and compositebridges standard a newstandard dealing withrehabilitation and

strengthening of existingbridges is also being prepared.Some of the salient featuresfor the steel and compositeparts include the use of post-

tensioning and the use of post-installed anchors, (StandardsAustralia, 2014c).


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Structure

• Introduction

• Bridges

• Buildings




•



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Deconstructability

Following on from recent practical examples, such as thedeconstruction of the end stands of the Sydney OlympicStadium, recent research has been carried out ondeconstruction of steel and steel-concrete composite beamsystems. Initial research has illustrated that for both

stiffness and strength purposes, bolted shear connectorscan provide the same or improved performance forcomposite beam behaviour when compared with headedshear studs. The following figures show the type of boltedshear connectors and how they have been shown to allowdemountability in composite beams, (Mirza et al, 2010andPathirana et al, 2012).


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Deconstructability


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Schematic of Kowari Strain Scanner at

ANSTO, Sydney

S h i f K i S i S ANSTO


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Schematic of Kowari Strain Scanner at ANSTO,

Sydney

Th h thi k l it di l id l t


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Through thickness longitudinal residual stress

distribution

-300

-200

-100

0

100

200

300

400

500

600

0 5 10 15 20 25 30

L o n g i t u d i o n a l r e s i d u a l s t r e s s [ M P a ]

Distance from the weld centre line [mm]

4 mm

1 mm

2.5 mm

Representative stress strain diagrams for


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Representative stress-strain diagrams for

concrete and steel


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Ratio of column/cylinder concrete strength

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

10 15 20 25 30 35

R a t i o o f C o l u m n / C y l i n d e r

c o n c r e t e s t r e n g

t h

b/t


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Acknowledgements


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Acknowledgements

The author would like to thank all the students, staffand collaborators at the University of Western Sydney

and the University of New South Wales for their work in

some of the elements presented in this paper.

Furthermore, a special mention to Drs Hicks and Kang

from Heavy Engineering Research Australia, New

Zealand and University of Western Sydney respectively

for the work that has been carried out to develop newcalibration factors for steel beams in Australia.


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3 Recent Innovations for Steel and Composite Steel-Concrete Structures in Australia

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