steel insight 3

7/29/2019 Steel Insight 3

1/9

-

STEEL INSIGHT #03


2/9

h | Ap 2012

The third o the Steel nsight series looks at structural solutions or ofce buildings, and

how steel can rovide advantages in terms o cost, rogramme time and sustainability

steel insightmulti-storey offices

02 | Building 1 ypical business park ofce building

01 | ntroduction and

overview o te study

n ovember 2011 te BCA and

ata teel commissioned ardiner

& eobald (&), Peter Brett

Associates (PBA) and Mace roup

to undertake an impartial study o

current construction practice or

multi-storey ofces to provide cost

and programme guidance or quantity

surveyors and design teams.

e study builds on previous

comparisons to reect developments

in construction tecniques and

canges in prevalence o dierent

structural rame solutions.

As decisions on rame material

and confguration will be based on a

number o actors, not simply cost, te

study also considered te programme

and buildability implications or eac

option and embodied carbon impacts

or Building 2.

PBA identifed and designed

representative raming solutions

or two typical ofce buildings a

business park ofce (Building 1) and

a city centre ofce (Building 2). &

provided cost inormation or eac

rame option and Mace considered

buildability, logistics and programme.

PBA also carried out te cradle to

grave embodied carbon assessment

on Building 2.

e objective o te study is to

provide a compreensive comparison

o two typical ofce buildings acrossa number o aspects or dierent

structural solutions. e confguration

and design o te ofce buildings

is based on te design teams

experience o current practice to

provide an impartial comparison

tat could be used by oters wen

considering te options available

during te design and selection o a

structural rame.

Building 1 is a tyical seculative three-storey

business ark ofce building with a gross

internal area o around 3,200m2.

t is tyical o a low rise building in an

out o town location and is rectangular with

a oor late width o 18m to give an oen

lan sace.

The clear oor-to-ceiling height has been

set at 2.8m and the building contains one

central core, 2nr lits and an external metal

escae stair. The external enveloe has been

assumed to be brick outer skin construction

suorted by a steel angle o the slab

edge with an inner lea o cold rolled metal

studwork built directly o the slab, with an

allowance or windows at 35% o the

acade area.

The building has been assumed to have

mixed mode ventilation and the oor-to-

oor heights include or a 150mm ceiling and

lighting zone and a 150mm raised oor zone.

An architects imression, roduced by

Make Architects, is shown above.

pBA established the structural grid at 7.5m


3/9

POOReD FeAURe | April 2012

03 | Buildin 1 Cost comparison

gardinr & hobald providd th costs

or th study, basd on markt tstin and

rcntly tndrd projcts. Costs ar all at

Q1 2012 prics, xclud s, VA, projct

continncy and urnitur, fxturs and

quipmnt/AV allowancs tc and ar

basd on construction in th City o ondon

to nabl dirct comparison with Buildin

2; howvr thy can b adjustd or dirnt

locations usin BC location actors

(Fiur 7).

h study rconiss th importanc o

considrin all lmnts o th total buildin

cost, not simply th cost o th structur

as som lmnts ar actd mor by th

choic o structural ram than othrs. As

such, th study considrd whol buildin

cost rathr than just structural ram cost.

h substructur, roo and xtrnal claddin

costs wr assssd or ach option rathr

than includin constants across all options.

h ky costs or Buildin 1 xprssd as a

cost pr m2 ross intrnal oor ara (gFA)

ar shown blow (Fiur 1).

h impact o construction proramm

or ach option has bn considrd in th

total buildin costs, with th stl options

bnfttin rom lowr prliminaris

costs du to thir shortr construction

proramms (as rviwd in dtail ovrla).

h stl composit bam and slab option

has both th lowst ram and uppr oors

cost and lowst total buildin cost. his

option has th lowst substructur costs o

all ram options du to th lihtr ram

wiht and th lowst roo cost du to thlihtwiht stl roo dck. h structural

zon and oor-to-oor hiht, whil not th

lowst o all th options, dos not rsult in

lvatd claddin costs as only th concr

post tnsiond at slab option has a notab

lowr oor-to-oor hiht and thror

rducd ara o claddin.

Convrsly, th rinorcd concrt at

slab option has both th hihst ram

and uppr oors cost and hihst ovrall

buildin cost. h ram and oors cost is

ovr 10% hihr than th stl composit

and th total buildin cost is about

6% hihr. his option has th hihst

substructur costs du to th havir ram

wiht, th hihst roo and prliminaris

costs du to th lonst proramm.

A rviw o th stl and prcast concr

slab and post tnsiond at slab concrt

options also hihlihts th importanc o

considrin total buildin cost rathr than

just ram and oor costs whn analysin

and slctin th structural ram matria

durin th dsin stas. h post tnsion

option has a marinally lowr ram and

oor cost than th stl and prcast optio

(150/m2 compard with 151/m2), howv

on a total buildin basis, th stl and

prcast slab option has a lowr cost (1,56

m2 compard with 1,610m2), du to both

a lowr roo cost and lowr prliminaris

rsultin rom th shortr proramm.

hror, on comparison o all our

options, it is vidnt that on a lik or lik

basis th stl composit bam and slab

ram has th lowst ram and oor and

ovrall buildin cost, ollowd by th

stl and prcast concrt oor slaboption with th two concrt options

bin hihr.

tl Composit tl and Prcast Rinorcd Concrt Post nsiond Concrt

Concrt labs Flat lab Flat lab

bstrctre 52/m2 gifA 55/m2 gifA 67/m2 gifA 62/m2 gifA

frame and upper floors 140/m2 gifA 151/m2 gifA 155/m2 gifA 150/m2 gifA

Total Building 1,535/m2 GIFA 1,561/m2 GIFA 1,631/m2 GIFA 1,610/m2 GIFA

FiGur 1: coSTS For BuildinG 1 BASd on GroSS inTrnAl Floor ArA (GiFA)

x 9m base a tmm g f a tya

bsess ak fe t tate by ste

stats a ths was se f a fame

tyes, whh sste f the fwg

f ts:

1) Stee mste beams a mste sab

2) Stee fame a east ete sabs

3) refe ete at sab

4) i st ete fame wth st

tese sab

F a ts the fats have bee

esge as efe mass ete

as, the e stt s steewk

ss bae famg wth a mem esty

bkwk f the stee ts a

ete shea was f the ete ts.

F bth stee ts, the 30 mte e

esstae s ve thgh tmeset

atg t beams a bag membes a

bag t ms, whe f the ete

ts, t s assme that the tea

ms ae astee a ate f

aesthet ses.

Awaes have bee mae f a ts

f a at e a at ese f at

aea a ft mt m. i tems f f

stt, the tw stee fame ts

have a ghtweght stee ek f, whe the

ete ts te the ete sab

stt f the we s.

The -t- heghts f the stee

ts e a 800mm seve ze

bew the meta ek (300mm ea

beeath the beams) a the etets aw f a 600mm seves ze

beeath the sab.


4/9

A 2012

o inform the programmes, Mace

undertook a logistics analysis for each

o t e rame opt ons an t s as een

reected in total building costs through

the preliminaries analysis.

For both steel options, construction

is assumed to be phased, with the

excavat on, oun at ons, ra nage an

service ducts, ground oor slab anderection of the steel frame and steel or

precast decks occurring in four phases.

A single mobile crane (about 50 tonnes)

s use or mater a str ut on an

loading as full perimeter access to the

building is available and the placing of

concrete or structural screed to oors

would utilise a concrete pump.

or ot concrete opt ons,

construction is assumed to occur

across two zones, each consisting of

three phases. h sequence includes

the excavation, concrete foundations,

drainage and service ducts, ground

oor slab, reinforced concrete columns,

formwork and propping for slabs,

re n orcement o post tens one

strands and placing of insitu concrete

slabs using a concrete pump. Atower crane located centrally on the

building perimeter is assumed to be

t e most pro uct ve means o mater a

str ut on as mater a can t en e

distributed between both construction

zones. he cost of the tower crane base

has been included in the preliminaries

costs owever t s ou e note t at

t ere may e oversa ng ssues w t a

saddle jib crane.

05 | Bu ng 1 og st cs an u a ty06 | u ng 1

The cost and programme analysis of

all four frame options for Building 1

has shown that the steel composite

eam an oor op on as o

the lowest cost and the shortest

programme, followed by the steel and

precast concrete oor slab option.

The frame and oor cost for the

s ee rame op ons are up o

lower than for concrete and theoverall building cost is up to 6%

lower than for concrete. ven taking

an average of the two steel options

an an average o e wo concre e

options, the steel option costs are

over 4% lower for both frame cost and

total building cost.

Furthermore, both steel framed

op ons can a so e cons ruc e n

a shorter time frame than for the

concrete buildings, on average over

5% quicker.

04 | u ng 1 Programme compar son

ost s un ou te y a e y r ver n

decision making when comparing

alternative frame materials and

congurations. wever for many

projects, the comparative programme

an u a ty mpacts are argua y as

important and should also be considered

when selecting the frame material.

Mace undertook the programming

analysis for each option and to ensure

a ro ust compar son, prece ng an

succeeding trades to the frame elements

were included to ensure a holistic

approach to the study.

he programme durations for

construction of the ground oor slab

(two weeks four days), external facade

(15 weeks) and internal works to a CA A

nish (18 weeks per oor) were assumed

to be the same in overall duration for

eac opt on. stu y assumes t at t e

internal t out commences on the ground

oor and progresses up the building

with a lag of three weeks between the

commencement o t e next oor, g v ng

an overall duration of 24 weeks for

each option.

e su structure urat on was a so

considered in detail for each option. Both

steel options required nine weeks due

to the similar quantity of work, however

onger urat ons o wee s t ree ays

for the reinforced concrete at slab and

10 weeks for the post tensioned option

were required to reect the higher volume

of groundworks.

e programmes or t e rame an

upper oor construction are similar for

both steel options. he precast slab

requires slightly larger foundations than

the composite option, but this is largely

o set y t e re uce num er o s tee

members in the precast option, giving an

overall very similar programme.

ikewise, it is quicker to lay the steel

decking for the steel composite option

ue to t e a ty to oa out mu t p e

numbers of decks at any time while the

precast planks are limited to one per lift,

but this time advantage is offset due to

the time required to stud weld each of

t e ec s, w c s a s ower process t an

grout lling between the precast planks

and both then require a concrete topping.

Ultimately, the advantages and

isadvantages of each steel option largely

ancel each other out providing very

similar programme periods for both the

rame an overa construct on. stee

omposite option however, due to the

speed of laying and distributing the steel

ecks provides the quickest frame and

verall duration by one week.

e programmes or t e rame an

upper oor construction are also similar

for both concrete options as the processes

involved in constructing the structure

re fundamentally the same. he main

var ant s w t n t e s a construct on,

with the post tensioned option providing

slightly quicker duration overall due to

the lower quantity of reinforcement to

place. he foundations duration for the

post tens one opt on s a so qu c er as

the structure is lighter and therefore the

xtent of excavation and concrete pouring

to the foundations is less.

a our opt ons, t e stee compos te

frame provides the fastest method of

frame construction and overall programme

for Building 1.


5/9

s sh A 2012

Building 2 is a typical eight-storey speculative

city centre ofce building with a gross

internal area o around 16,500m . is

s ape w a ou e e g recep on area,

central core and internal secondary escape

stair. The clear oor-to-ceiling height has

been set at 3m.

The external envelope is a unitised curtain

wa sys em cons ruc e n s orey e g

panels 1.5m wide with eature fns solarcontrol. Solid areas are lined with cold rolled

metal studwork, insulation and plasterboard.

The building has been assumed to have

our p pe an co a r con on ng w ou

natural ventilation.

An architects impression and indicative

cutaway, produced by Make Architects, are

shown above and overlea.

es a s e e s ruc ura gr a . m

x 15m based on experience o similar city

centre schemes, and this was used or both o

the ollowing rame options:

07 | uilding 2 pical city centre ofce building

) ellular composite beams and

composite slab

2) ost tensioned band beams and slab,

n s u co umns

Both options adopt A piles and there

are typically three to our piles per column

pile cap. The core construction is steel cross

race ram ng w a me um ens y

blockwork infll or the steel option andconcrete shear walls or the concrete option.

t is noted that buildings o this type would

normally include a basement; however or

con nu y e ween e op ons, e u ngs

are assumed structurally to start rom ground

oor with no impact rom any basement

construction as the basement will be the

same construction or all options.

e m nu e re res s ance s prov e o

he steel ramed option through intumescent

coating to beams and bracing members

and boarding to columns, while the internal

columns o the concrete option are plastere

and painted or aesthetic reasons.

Allowances have been made to both

op ons or a par open an par enc ose

roo plant area and lit motor room. The pla

area is a abricated steelwork portal rame

with composite metal panel cladding and th

roo decks or both options continue the o

cons ruc on o e ower oors.

The overall oor-to-oor height or thesteel option is 4.18m, which includes a

700mm zone or services distribution throu

the beams with 400mm diameter holes

a owe a mm cen res.

The overall oor-to-oor height or the

concrete option is 4.375m, which includes a

475mm clear zone below the concrete band

beams or services distribution.

o op ons a s o nc u e a owances

within the oor-to-oor heights or a 150mm

ceiling and lighting zone and a 200mm

raised oor zone.


6/9

h Apr 2012

08 | Building 2 Cost comparison

09 | Bu ng 2 Programme

compar son

Mace also undertook te programming

analysis or Building 2, analysing bot

te rame and te wole building

construction durations (see Figures 3

an ).

e substructure works commence

wit te CFA piling, ollowed by

excavation or te pile caps and

lit pits. For te steel option, te

structura rame s erecte on a

foor by foor basis wit te steel

decking installation, stud welding and

concrete foor toppings ollowing on

progressively.

or t e concrete opt on,

te columns and walls progress as

soon as te ground foor slab is cast,

and eac foor slab is constructed in

two pours, wit te concrete sear

wa s comp ete progress ve y w t

eac foor.

e durations or construction o

te ground foor slab (our weeks

t ree ays), externa aca e

wee s) an nterna wor s to a

A nis (21 weeks per foor) were

assumed to be te same or eac

option. e internal t out is assumed

to commence on t e groun oor

an progress up t e u ng w t

a lag o two weeks between te

commencement o te next foor,

giving an overall duration o 39 weeks

or eac opt on.

e t e su structure an groun

slab construction ave te same

programme period (20 weeks) or

eac option, te steel rame as

a s gn cant y s orter rame an

foor construction period (16 weeks

compared wit 28 weeks or teconcrete option), wic enables te

internal t out works to start earlier.

s resu ts n t e ce u ar stee

option providing a signicantly

sorter period o bot rame

construction and overall programme

or Building 2 compared wit te post

tensone concrete opt on, w t a

saving o 12 weeks demonstrated or

te rame and eigt weeks across te

overall programme.

eel Cellular Composite Post ensioned Concrete

B nd Beam and lab

s rc re 56 m2 60 m2

ame and l 194 m2 210 m2

otal Bilding 1,861 m G ,922 m G

G re 2: STS G 2 AS G SS r (G )

tnsiond conct band bam otion. n a

total bilding basis, th stl otion bnfts

om ow s s c cos s o

light am wight and a low oo cost

d to th cost o th stl dck comad

with th ost tnsiond slab.

Th stl otion has a low oo-to-

oo g . m coma w . m

which slts in abot a 5% low xtnal

nvlo cost d to th small aa o

cladding and also has low liminais

costs d to its shot ogamm, which

con s o s ows ova cos .

all, th am and oo cost o thstl otion is ov 8% low than th

conct otion and ov 3% low on a

whol bilding basis.

Th Bilding 2 cost stdy also considd

whol bilding cost alongsid am and

oo cos s, w s s c , oo a n

xtnal nvlo viwd in dtail, howv

basmnt costs hav bn xcldd om

th stdy. As th am matial choic also

mac s on ogamm, s s o

ac ogamm an ogs cs ana yss

w also incldd whn dtmining

liminais costs.

All costs a at Q1 2012 ics and a

as on cons c on n y o n on.

Th ky costs o Bilding 2 xssd as a

cos m A a shown blow.As shown, th cllla stl comosit

otion has both a low am and oo cost

and low total bilding cost than th ost


7/9

| A 2012

10 | Building 2 ogistics and buildability

he assumed logistics for both the

cellular steel and post tensioned concrete

options are similar, with the substructure

works progressing from the main core

pile caps working out in two directions

for both options.

Both frames would also utilise a lufng

jib tower crane (about 50m radius)

situated outside of the building footprint,

used for distribution of the steel frame

and oor decking for the steel option

and for reinforcement and formwork

distribution for the concrete option.

he lufng jib also helps to overcome

oversailing issues common in city

centres.

he superstructure works for the

concrete option were assumed to

progress in two phases with two or

three pours required for the oor slabs.

Pumps would be used for the placing

of the oor slab concrete for the post

tensioned option and for the lightweight

concrete topping for the steel option and

both options utilise an external hoist for

t out material vertical distribution.

11 | Building 2 mbodied carbo

comparison

While cost and programme are key criteria

assessing design options for many projects

the comparative environmental credentials

are also important. BA therefore carried

ot an embodied carbon assessment for

both frame options for Bilding 2.

mbodied carbon is considered to be

the cradle to grave carbon dioxide (2)

emissions occrring over the whole life

cycle of the bilding, inclding end of life

considerations bt exclding the operation

carbon occrring dring the bilding se.

The stdy adopts a similar approach to

the cost stdy by considering the whole

bilding rather than jst the strctral fram

for each option; however it focses on the

emissions from the strctral elements as

they represent the main differences in term

of carbon between the options.

To ensre a balanced approach, readily

available indstry data on materials

emissions from Target Zero pblications fo

steel and from oncrete entre pblication

for concrete have been adopted. on-

strctral embodied carbon emissions hav

been based on benchmark information and

are consistent across both frame options.

Transport emissions are based on the

epartment for Transport statistics for the

average length of hal per commodity and

on oncrete entre data on the average

delivery distance of ready-mixed concrete

constrction sites.

n assessing the emissions from the

constrction and demolition activities on

site, uK nvironment Agency data, the Mac

constrction programming information and

an estimated period for demolition have

been considered.

n considering cradle to grave emissions

for each option, end of life scenarios have

been selected to reect crrent practice,where 99% of the strctral steel and 82%

of the concrete reinforcement are recycled

and 100% of the concrete is down-cycled t

provide granlar ll material.

The reslts of the stdy are shown in

Figre 5 overleaf.

BA rstly assessed the bildings in

line with the cost stdy and sing only

ortland ement for the concrete mix, whi

demonstrated that the embodied carbon

was signicantly lower for the steel frame

than that for the concrete frame; with the

FGu 3: BuG 2 uA ST MST FAM GAMM

Grondworks and Slab

Steel Frame and ecks

Slab ors

oof Works

xternal Facade

nternal Works

elllar Steel omposite

0 10 20 30 40 50 60 70 80

72.4

20.4

16.4

16

39.2

12

5

FGu 4: BuG 2 ST TS BA BAM FAM GAMM

Grondworks and Slab

oncrete Frame and Slabs

oof Works

xternal Facade

nternal Works

T oncrete Band Beam

0 10 20 30 40 50 60 70 80 90

80.3

20.4

16

39.3

28.3

5


8/9

| A 2012

12 | ummary and conclusion

he study illustrates that or both

typical ofce building types, on

a like or like basis steel ramed

solutions are highly competitive,

with the rame and upper oor costs

or the steel ramed options being

potentially up to 9% lower than

or concrete.

he study has also highlighted

the importance o considering total

building cost not just structural rame

cost, as the choice o the structural

rame material and confguration

will have associated impacts on

many other elements, including

the substructure, roo and external

cladding. he total building cost

or the steel options are on average

around 5% lower than the concrete

options as a result o the rame and

upper oor costs noted above and

smaller oundations, lightweight

roos, lower storey heights reducing

cladding costs and reduced

preliminaries costs.

Furthermore, the construction

durations o the steel ramed

solutions are also shorter than the

concrete ramed buildings (up to 13%

or Building 1 and 11% or Building 2).

he study also considers embodied

carbon, which is projected to become

an increasingly important criterion

or design options moving orward.

he study shows that in this area as

well, steel ramed solutions have

a noticeably reduced embodied

carbon compared with the concrete

solutions, with an 18-30% lower

embodied carbon total or the

cellular steel option than the post

tensioned band beam option orBuilding 2.

Over three key assessment

criteria, the study has illustrated

that steel ramed solutions in current

construction practice can outperorm

concrete options and provide

lower cost, shorter programmes

and lower embodied carbon.

More detail on the study can be

ound at www.steelconstruction.org

steel option having over 23% less embodied

carbon than the concrete option.

However, refecting the common practice

o sing cement replacement to redce

sstainability impacts, the embodied

carbon was also assessed sing 30% cement

replacement with fy ash and grond

granlated blast rnace slag. This level

o cement replacement is considered to

be a reasonable replacement withot

having a signicantly adverse impact on

constrction programme de to increased

cring time.

n this case, the embodied carbon redced

to 184kg2/m2 or the steel option and

to 204kg2/m2 or the post tensioned

concrete option. Thogh the dierence

between the steel and concrete options

was redced, it was still signicant with

the steel rame having arond 11% less

embodied carbon than the post tensioned

concrete rame.

Finally, the impact o sing steel bearing

piles on the embodied carbon or both

rame options was also assessed based on

alternative sbstrctre soltions developed

by BA and Tata Steel which tilised 356 x

368 x 152 uKB in lie o FA piles.

The se o steel bearing piles reslts in

an increased nmber and length o piles or

both rame options, rom 147nr (2,490m) to

190nr (3,984m) or the steel rame and rom

150nr (3,225m) to 241nr (5,400m) or the

concrete option; however, there are osets

in terms o a signicant redction in the size

o pile caps and associated redctions to

excavation and disposal or both options.

The steel bearing piles can also be

extracted at end o lie and recycled or

re-sed elsewhere.

While the se o steel bearing piles

does have a cost implication, with the

sbstrctre costs or the steel option

increasing rom 56/m2 to 71/m2 and rom

60/m2 to 90/m2 GFA or the concrete

option, some o this will be oset throgh

programme benets and they can also

deliver embodied carbon benets. n a

sbstrctre only basis, the embodied

carbon redces by 15% or the steel ramed

option and by 5% or the concrete option

and across the whole bilding, the

embodied carbon redces to 195kg2/m2

or the steel option and to 250kg/2/m2

or the post tensioned concrete option in

the base case scenario. This demonstrates

that where sstainability is a key driver,

signicant benets cold be realised by

the consideration o a steel bearing pile

sbstrctre soltion.

elllar Steel omposite ost Tensioned Band Beam oncrete

FGu 5: BuG 2 A T GA MB AB MAS

300

250

200

150

100

50

0

k

gco

2/m2

253

205

184

204195

250

ost Stdy 30% ementeplacement

Steel Bearing iles


9/9

g | A 2012

his article was produced by Rachel

Oldham (associate) and Alastair

Wolstenholme (partner) of gardiner &

heobald. t is the third in a series that

provides uidance on the realistic costin

of structural steelwork. he next teel

nsiht will appear on 27 July 2012. f you

are considerin usin structural steelwor

for your buildin, bride or structure,

we recommend an early dialoue witha specialist steelwork contractor. hey

can offer a rane of support and advice,

includin budet estimates and value

enineerin. teelwork contractors can

be sourced accordin to project size and

technical competency. his searchable

function is available at

TH ST SGHT SS

WWW.CORUCO.ORg

13 | ost update

The results of the comparison study are

reected in the latest structural steelwork

cost table ranges in Figure 6.

The cost range for the low rise, short span

building (Building 1) has remained constant

across Q1 2012, which reects the continuing

difcult market conditions throughout the

construction industry generally.

Following the production of typical designs

for the two building types, the description

and rate range for the high rise, long span

frame noted in the table has been updated

to align with Building 2. However, it should

be noted that for high rise or long span

structures with more complex elements or an

irregular grid the rate range would need to

be adjusted accordingly, and could be 15-20%

higher than those noted for Building 2. To

address this, a further frame type has been

included within Figure 6.

Similarly, the ranges for oor costs and

re protection have been adjusted to align

with the results of the cost study and market

testing, with the oor costs for both the

metal deck and precast options reducing by

around 15%.

The continual forecasts of difcult

economic conditions across 2012 continues

to suggest that structural steelwork tender

returns will remain stable well into 2012,

ocation BC ndex ocation BC ndex

ity of odo 114 eeds 100

nottigham 97 newcastle 94

Birmigham 99 lasgow 102

achester 94 Belfast 61

iverpool 90 ardiff 94

FG 7: BS AT FATS, AS AT 23 MAH 2012

FG 6: AT ST AGS BAS GSS TA F AA

P

Frame - low rise, short spans, repetitive

rid / sections, easy access (Buildin 1)

Frame - hih rise, lon spans, easy access,

repetitive rid (Buildin 2)

Frame - hih rise, lon spans, complex

access, irreular rid, complex elements

Floor - metal deckin and lihtweiht

concrete toppin

Floor precast concrete composite oor

and toppin

Fire protection (60 min resistance)

Portal frames low eaves (6-8m)

Portal frames hih eaves (10-13m)

gFA Rate ()

City of ondon

90 - 120/m2

140 - 170/m2

165 - 190/m2

45 - 65/m2

50 - 70/m2

8 - 16/m2

55 - 75/m2

65 - 90/m2

gFA Rate ()

BC ndex 100

75 - 100/m2

125 - 150/m2

145 - 170/m2

40 - 58/m2

45 - 60/m2

7 - 14/m2

45 - 65/m2

55 - 75/m2

and the rates in Figure 6 can be considered

suitable for the cost planning of projects

where the structural works will commence i

Q2 and Q3 2012.

To use the table a) identify which frame

type most closely relates to the project und

consideration b) select and add the oor

type under consideration c) add re

protection if required.

As highlighted in previous Steel nsights,

before using such standard ranges it is

important to conrm the anticipated frame

weight and variables such as the oor-to-o

heights with the design team to determine

whether they are above or below the averag

and to adjust the rate used accordingly.

Similarly, all of the other key cost drivers o

complexity, site conditions, location, functio

logistics, programme and procurement

strategy should be considered in turn.

steel insight 3

Documents