steel insight 3
TRANSCRIPT
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STEEL INSIGHT #03
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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
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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.
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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.
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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.
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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
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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
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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
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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.