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7/28/2019 Costing WEB

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C ng u y c nf m c nc 'c m v g

concrete conceptsL o w - c o s t / / L o w - r i s k / / H i g H - s p e e d / / H i g H - r i s e

c o s t i n g s t u d y

ex v mm

A recent independent study o the relativeconstructed costs o structural raming solutions

or medium- and high-rise construction conductedby WT Partnership con rms concretes competitive

edge in Australia over other construction systems.The study was completed or Sydney, Melbourne,Brisbane, Adelaide and Perth and is summarisedbelow.

n Concrete ramed structures with post-tensionedfoors on permanent metal deck ormwork are themost cost e ective solutions or the medium-risebuildings studied. In comparison, the cost premium

or a steel ramed structure ranged rom 26%(Adelaide) to 85% (Sydney), s g s 1 to 5 .

n Concrete ramed structures with post-tensionedfoors on conventional ormwork are the most cost

e ective solutions or the high-rise buildingstudied. In comparison, the cost premium or asteel ramed structure ranged rom 22%(Adelaide) to 65% (Sydney), s g 6 .

n Concrete ramed structures remain morecompetitive than steel ramed structuresacross all spans studied 8.4 m to 16.8 m.

n Depending on site-speci c requirements, thereare no construction programme disadvantageswith concrete ramed structures whencompared with steel ramed structures.

i

The Australian commercial construction industry isrenowned or its e ciency and innovation, leadingthe world with its use o innovative concrete rameconstruction, design and technologies. Concrete

ramed designs have consistently delivered low cost,low risk, high speed and high quality medium- andhigh-rise buildings in a highly competitive market.

Cement Concrete & Aggregates Australia (CCAA)set out to gain a complete understanding o theAustralian commercial building industry, in order tosee how the concrete industry might add urthervalue to this sector. CCAA identi ed a range o

multi-rise building projects across Australia, andinterviewed all members o the supply chain builders, engineers, architects and suppliers inregards to the major value points relevant to thebuilding structure. A ter examination o the resultso these interviews, CCAA identi ed that a betterunderstanding o the comparative costs o di erent

raming solutions was required.


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Table 1 St uctu g id o tions *

Four structural grid options or a 10-storey medium-rise building8.40 x 8.40 m

10.80 x 8.40 m12.60 x 8.40 m16.20 x 8.40 m

One structural grid or a 30-storey high-rise building16.80 x 7.20 m

*All grids suited to typical car-park layouts

Table 2 D sign o tions

10-sto y m dium- is ui ding

Structural raming systems

1 Rein orced concrete (RC) rame with permanent metal so t ormwork2 RC rame with conventional so t ormwork3 RC columns, post tensioned (PT) foors with permanent metal so t ormwork4 RC columns, PT foors with conventional so t ormwork5 Steel rame, RC topping slab on permanent metal so t ormwork

30-sto y ig - is ui ding

Structural raming systems1 RC rame with conventional so t ormwork2 RC columns, PT foors with conventional so t ormwork3 Steel rame, RC topping slab on permanent metal so t ormwork

Table 3 F oo zon o c st uctu g id o tion

10-sto y m dium- is ui ding

Grid size Area per foor Total suspended foor area(m) (m 2) (m 2)

16.20 x 8.40 1,201 12,01012.60 x 8.40 947 9,47010.80 x 8.40 819 8,1908.40 x 8.40 649 6,490

30-sto y ig - is ui ding

Grid size Area per foor Total suspended foor area(m) (m 2) (m 2)

16.80 x 7.20 2,669 80,070


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0

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8.40 x 8.4010.80 x 8.4012.60 x 8.4016.20 x 8.40

$ / m 2

o f s u s p e n

d e

d s l a b

Grid size (m)

G 1 10-storey medium-rise building sydney

GraphS 15 10-storey medium-rise building

RC rame; metal so t ormwork

RC rame; conventional so t ormwork

RC columns; PT foors; metal so t ormwork

RC columns; PT foors; conventional so t ormworkSteel rame; RC toppings on metal so t ormwork

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Grid size (m)

G 2 10-storey medium-rise building Melbourne


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G 4 10-storey medium-rise building adelaide





RC columns; PT foors; conventional so t ormworkSteel rame; RC toppings on metal so t ormwork

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G 3 10-storey medium-rise building brisbane


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RC columns; PT foors; conventional so t ormwork

Steel rame; RC toppings on metal so t ormwork

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G 5 10-storey medium-rise building pertH

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PERTHADELAIDEBRISBANEMELBOURNESYDNEY

$ / m 2

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Grid size16.80 x 7.20 m

G 6 30-storey high-rise building all cities, one grid

Graph 6 30-storey high-rise building


RC columns; PT foors; conventional so t ormwork

Steel rame; RC toppings on metal so t ormwork


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s m h j v

CCAA commissioned a detailed independent studyby internationally respected quantity surveyors andconstruction cost consultants, WT Partnership, withstructural engineering designs by Irwinconsult. Thestudy, believed to be the rst o its kind in Australia,comprised two parts. Firstly, it compared ve di erentstructural raming systems across our structural gridlayouts in ve mainland capital cities or a prototypemedium-rise (10 storeys) commercial building.

In the second part it compares three di erentstructural raming systems across one long-spanstructural grid layout in ve mainland capital cities

or a prototype high-rise (30 storeys) commercialbuilding. Full details o the prototype designs areshown in T s 1, 2 nd 3 . All costs are basedon March 2007 construction tender prices or thedi erent locations.

The analysis aimed rstly to independently quanti ythe comparative costs o typical, contemporarycommercial raming systems used by constructionproject teams in Australia. A second objectivewas to identi y any short alls or barriers thatcurrently prevent the maximum value o concreteconstruction being delivered, and how CCAAmight work in partnership with the constructionsector to address them through the developmento improved concrete solutions in the uture.

a m

The analysis ocuses on the constructed cost o theootings, columns, and suspended upper foors o

a typical prototype building or the di erent ramingsystem options. Variables and other structuralelements common to all designs, such as: sitepreparation and bulk earthworks; ground slab/ basements; structural cores/stairs/li t wells/risers;roo ; and builders preliminaries were excluded romthe analysis. Qualitative analysis and considerationwas also provided on a range o other variablessuch as: sensitivity to market-place fuctuations;construction programme; cash fow; net lettable areaand risk actors or the alternate designs.

s mm f

In their detailed analysis and report or the designsunder consideration, WT Partnership ound as

ollows:

Costn Concrete ramed structures are more competitive

than steel ramed structures in the medium- andhigh-rise commercial o ce markets in Sydney,Melbourne, Brisbane, Adelaide and Perth.

n In medium-rise (10-storey) buildings, the costpremium or a steel ramed structure ranged

rom 26% (Adelaide) to 85% (Sydney), relativeto a concrete ramed structure with PT foors onpermanent metal so t ormwork ( g s 1 to 5 ).

n For high-rise (30-storey) buildings, the costpremium or a steel ramed structure ranged

rom 22% (Adelaide) to 65% (Sydney) relativeto a concrete ramed structure with PT foors onconventional ormwork ( g 6).

n A cost premium or steel ramed structures isconsistently evident across both short and longspans up to 16.80 m.

n RC columns with PT concrete foors are the mostcost e ective raming design.

n Structural steel prices ($/t) in place would needto drop by 35% to 65% (with all other actorsheld constant) or the steel ramed design to becompetitive with a concrete ramed structurewith PT foors on permanent metal ormwork.The variance depends on grid size and locality.

n Permanent metal deck orm-work is more coste ective than conventional so t ormwork inmedium-rise buildings.

n Conventional ormwork prices ($/m 2) would needto increase by 40% to 250% (with all other actorsheld constant) be ore concrete ramed structureswith PT foors on conventional ormwork becamecost neutral with steel ramed structures. Thevariance depends on grid size and locality.

n Steel ramed structures can have 100 mm to 300mm greater foor-to-foor height which increases

acade costs plus all vertical structural andvertical services costs. (These additional costs arenot accounted or in this study).

n Fire rating (2 hour) adds 510% to the cost othe steel structure depending on re protectionrequirements, grid size, locality and concretedesign.


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www. c on cr e t e.n e t . a u / c on cr e t e c on c e p t s

Sydney [61 2 ] 9437 9711BriSBane [61 7] 3831 3288MelBourne [61 3] 9825 0200

adelaide [61 8] 8274 3758 Perth [61 8] 9389 4452

taSMania [61 3] 9825 0200

Since the in ormation provided is intended or general guidanceonly and in no way replaces the services o pro essionalconsultants on particular projects, no legal liability can be acceptedby Cement Concrete & Aggregates Australia or its use.

Cement Concrete & Aggregates Australia

: [email protected]

speed

n There does not appear to be any programmeadvantages in the steel structure to o set thecurrent cost premium.

n Each structural system has advantages which maylend themselves to speci c project constraintsand needs. For example:

Labour orce to site ratio is greater in concretestructures.

Steel has a longer lead time (shop drawings/ o site abrication).

risk

n Steel structures have an accelerated cashfow draw down and arguably greater contractdisruption and nancial risk in the event osubcontractor/supplier de ault.

n Price volatility between locations is high or steelramed structures.

n The expertise in high-rise steel structures isviewed as more limited than in concrete high-risestructures.

o h

n acoustics: The greater mass o the concretestructure provides better acoustic per ormance

or both impact and transmitted noise whencompared to the steel solutions.

n D f ction imit tions nd vi tions: Long-termdefections have been limited to 1/300 th o thespan o element (slab or beam).

n T sus nd d u foo s or steel ramedstructures have an 11%85% ( or 10-storeybuildings) and 6%45% ( or 30-storey buildings)cost premium when compared to a concretestructure with PT foors. The variance depends ongrid size and locality.

n F oo -to-foo ig t: The steel ramed optionadds between 100 mm and 200 mm ( or 10-storey

buildings) and between 200 mm and 300 mm( or 30-storey buildings) to the foor-to-foor heightwhen compared to the concrete ramed structurewith PT foors. This would increase the cost oother vertical elements which are not accounted

or in this study. The cost o acades wouldincrease by approximately:

2.4% or a 100 mm increase in foor-to-foorheight (based on the 16.20 x 8.40 m grid option

or 10-storey buildings) and

5.4% or a 200 mm increase in foor-to-foorheight (based on the 16.80 x 7.20 m grid option

or 30-storey buildings).

n Su st uctu : Savings in ooting cost or thelighter steel structure amounted to between1% and 5% on total cost o the structure whencompared with concrete ramed structures.

n Co umns: Concrete columns are more coste ective than steel columns. Steel columnsaccount or 5% to 15% ( or 10-storey buildings)and 5% to 11% ( or 30-storey buildings) o thecost premium or a steel structure when comparedto a concrete structure with PT foors.

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In their report, WT Partnership have noted thatpricing levels in the construction market are volatile,with costs varying greatly between the ve mainlandcapital cities surveyed, particularly in relation to the

steel design options. Over time, these pricing levelswill vary with each city being driven by the supply-and-demand actors o the market. However, eachproject has its own commercial drivers which cansee large shi ts in the pricing structure.

Nevertheless, within the parameters o this report,WT Partnership note that alternative designs orprice fuctuations would need to be considerableto alter the act that, or commercial constructionin Australia, concrete ramed construction utilisingpost tensioned foors on permanent metal ormworkis a signi cant 26% to 85% cheaper than steel

ramed solutions. Combine the actors o lower costwith no construction programme disadvantagesand concretes competitive edge in Australia isundeniably con rmed.

WT Partnership con rms thatthe ndings o the article areconsistent with the High- and Medium-rise Building Structural Design Option Studies undertaken

or the Irwinconsult engineeringsolutions.

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