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A survey of 40 office buildings
with long-span concrete floors
P.W. Matthew BE, MSc, MIE(Aust)
and D.F.H. Bennett BSc, MSc, CEng, MICE
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FOREWORDThis publication was commissioned by the Reinforced
Concrete Council.The Group was set up in 1988 to promote better
knowledge and understanding of reinforced concrete designand building technology.
Its members are Co-Steel Sheerness plc and Allied Steel
&Wire, representing the major suppliers of reinforcing steelin the UK; and the British Cement Association, representingthe major manufacturers of Portland cement in the UK.
The authors of this publication are Peter Matthew, partnerwith consulting engineers Powell, Tolner &Associates andDavid Bennett, Senior Engineer in the Marketing Divisionof the British Cement Association.
ACKNOWLEDGEMENTSThe authors wish to thank the following organizations fortheir considerable help in providing the building data for
the survey:Anthony Hunt/YRM PartnershipBeersBison Limited
Bunyan Meyer & PartnersComposite Structures LimitedDGI International plcFerguson &McIlveenFrank Hodgson & Associates
James-Carrington and PartnersJan Bobrowski and PartnersOve Arup & PartnersPowell, Tolner & AssociatesSkidmore, Owings & MerrillWaterman Partnership
Thanks are also due to Brian Dyer of Tower Associatesfor drafting the floor plans.
97.311
First published 1990Reprinted 1994, 1995
ISBN 0 72101386 4
Price Group F
British Cement Association 1990
Published by the British Cement Association on behalf ofthe industry sponsors of the Reinforced Concrete Council.
British Cement AssociationTelford Avenue, CrowthorneBerks RG45 6YSTel (01344) 762676
Fax (01344) 761214
All advice or information from the British Cement Association is intended for those who will evaluate the significance and limitations of
its contents and take responsibility for its use and application. No liability (including that for negligence] for any loss resulting from such
advice or information is accepted. Readers should note that all BCA publications are subject to revision from time to time and should therefore
ensure that they are in possession of the latest version.
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CONTENTS
INTRODUCTION 2
NOTES ON SURVEY
DESIGN FEATURES OF SPECIAL INTEREST
CHOICE OF FLOOR SLAB DESIGN
Solid flat slabs
Ribbed slabs
Waffle slabs
One-way spanning solid slabs and beams
Precast slabs
Composite precast slabs
CONCLUSION
SURVEY DATA
Section 1:
Section 2:
Section 3:
Section 4:
Section 5:
Section 6:
Solid flat slabs
Reinforced -Buildings 1to 7 8-14
Prestressed -Buildings 8 to 12 15-19
Ribbed slabs
Reinforced - Buildings 13 to 15
Prestressed -Buildings 16 to 22
Waffle slabs
Reinforced -Buildings 23 to 25 30-32
Prestressed -Buildings 26 to 28 33-35
One-way spanning solid slabs
and beams
Buildings 29 to 33
Precast slabs
Buildings 34 to 36
Composite precast slabs
Buildings 37 to 40
2
3
4
6
7
20-22
23-29
36-40
41-43
44-47
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INTRODUCTION
Traditional concrete designs for office building have beenassociated with either beam and slab or flat slab floors,typically with 6 to 7.5 m spans. Occasionally, longer-spanfloors have been designed using ribbed or waffle
construction. In recent times, changes in the requirementsof end-users and in developers specifications have led tomore open-plan offices and larger floors. This hasincreased spans from 6 to 9 m, even to 15 m and more.
To verify the competitiveness of concrete long-spanfloors, a survey has been conducted of concrete-framedoffice buildings, the majority constructed in recent years.Forty buildings of in situ, precast and compositeconstruction with long spans have been surveyed. In eachcategory, examples were found of floors designed inreinforced and prestressed concrete to carry similar officefloor loadings.
For in situ structures, solid flat slabs and ribbed slab
designs were common, with spans varying from 6 to 15 m.A number of precast structures with long spans, someover 20 m, are reported, with composite in situ slabs actingwith precast ribs or other precast members.
NOTES ON SURVEY
The survey data are presented in the second part of thispublication, beginning on page 7. The information hasbeen arrangedfollows:
Section 1 -
Section 2 -
Section 3 -
Section 4 -
Section 5 -
Section 6 -
according to structural floor types as
Solid flat slabs
Ribbed slabs
Waffle slabs
One-way spanning solid slabs and beams
Precast slabs
Composite precast slabs
The structural information and quantities of materialfor each building surveyed are presented in tabular formand are accompanied by a typical floor plan and floorsection.
For each building studied, quantities of concrete,reinforcement and prestressing steel are expressed inunits/m2 of floor area. All quantities related to verticalcomponents, i.e. columns, walls, etc., have been excluded,thus the effect of storey height and number of storeys iseliminated.
The span/depth ratios given in the tables are based onthe maximum spans.
Notes on the design Code of Practice, concrete gradeand method of achieving frame stability have been addedto provide useful information on the design of thestructure.
The column headed Design loads gives the floorloadings used in the structural design, i.e. imposed load,finishes, partition and service loads: it does not include theself-weight of the floor.
The method of achieving frame stability for eachbuilding is indicated in the column headed Stability byshear walls or frame action. The term shear walls
(Figure 1) indicates a braced structure where the horizontalforces are transmitted to shear walls by the floors acting asdiaphragms. In the case of an unbraced structure [Figure 2),stability is provided from within the frame by theinteraction of columns and floors and referred to as frameaction.
All tables should be read in conjunction with thecorresponding floor plans and section details.
Shear walls
Figure I: Lateral stability provided by shear walls.
Figure 2: Lateral stability provided frame action.
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DESIGN FEATURES
OF SPECIAL
INTERESTNotes on a few of the buildings surveyed are given below tohighlight certain construction and design features thatprovide particular economic advantages for a given floor
tYPe.
Building 5
310 mm reinforced solid flat slab, span 9.5 x 7-3m.
Lightweight aggregate concrete with a compressivestrength of 30N/mm2 was used in order to reduce theself-weight of the floor and the cost of the foundations.
As the span/depth ratio exceeded the guiding limits inthe Code (CPllO), compliance with maximum deflectionin the serviceability limit state was proved by calculation.The floor slab was designed as a beam supporting aone-way spanning flat slab, all within the 310 mm depth ofconstruction. The beam, 2.5 m wide, spans longitudinallyfrom the interior column to the lift core. The one-wayspanning slab is simply supported at the perimeter andcontinuous over the beam.
Building 7
255 mm reinforced solid flat slab, span 9.2 x 6-0m.The deflection of the 255 mm flat slab was checked byfinite element analysis, taking full account of edge
stiffening from the perimeter columns and beams inaddition to the internal columns and frame. A lateralstability check was carried out on a three-dimensionalcomputer model of the structure. The inherent stiffness of
the perimeter beams and columns plus the internal frameeliminated the need for shear walls.
Building 10
300 mm post-tensioned solid flat slab, span 9.4x 9.0m.
Steel cross-bracing, in combination with the floor slabacting as a diaphragm, provided the lateral stability. Droppanels were eliminated by forming shearheads within theslab depth (Figure 3). All external columns were connectedto steel beams, composite with the slab, to cater forpunching shear.
Building 13
450mm reinforced ribbed slab, span 9.0 m.
The wide-rib profile, spaced at 1.5 m centres, providesadequate flexibility to accommodate small and largeservice openings in the floor. The rib profile made itpossible to use table forms with integral grp rib moulds toensure a fast building programme (Figure 4).
Building 14
425 mm reinforced ribbed slab, span 9.0m.
The irregular floor plan of the building and the clientsrequirement for minimum column sizes resulted in it being
Overall to suit column sizec
650J rr
APlan
Section
F i gu re 3 : Detail of steel shearhead.
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Building 26
500mm prestressed/reinforcement waffle slab,span 12.0X12-O m.
The solid beam strips were post-tensioned, with the wafflesection reinforced. This allowed the waffle section to bereinforced independently of the beams, thus speeding upconstruction, whilst maintaining an economical floordepth.
Building 31
335mm one-way spanning prestressed solid slab,span 12.6 m.
The frame was designed as a stacked portal, with 160 mmprecast per imeter walls support ing a 335 mmpost-tensioned solid slab. An important benefit inpost-tensioning the slab was that the end momentstransferred to the precast walls, due to dead load, werenegligible. This in turn led to manageable transfermoments in the wall under ultimate load conditions.
The structural solution proved both economic and fastto build, with a maximum net to gross floor area.
Building 36
200 mm precast floor slab, span 7.7 m.
The precast columns were designed as vertical cantilevers
CHOICE OF FLOOR
fixed at the base to provide frame stability. The precast lfloor beams were simply supported and designed as pinjoint connections to the columns.
Building 37
560 mm double-T floor units with in situ topping,span 14.5m. Stability was achieved by a combination of shear walls atthe ends of the building and frame action developed fromthe precast perimeter H frames. The H sections are formedby adjacent perimeter columns and the perimeter edgebeam (Figure 5a). The precast column joints are positionedat mid-storey height, i.e. the point of contra-flexure, so afull moment connection to the double-T floor beam waspossible (Figure 5b). The precast frame was erected in just
The need for long spans to provide floor spaceuninterrupted by cores and columns.
A maximum floor-to-floor height which allowsadequate space for services and ducts, balanced againstplanning pressure to limit overall building height.
An adaptable floor structure which can accommodatefuture tenant alterations with maximum speed and
minimum disruption.The wide range of floor construction in both
reinforced and prestressed concrete, highlighted in thissurvey, demonstrates that concrete floors can be designedeconomically to meet these requirements.
The types of floors and the reasons for choosing them
SLAB DESIGN
In assessing the structural cost of a multi-storey building, itis evident that the bulk of the cost is often for the floor slabconstruction. Therefore, the overall economy of a structuremay depend on the efficiency and economy of the floorslab system. While quantities of materials reflect theefficiency of the design and structural layout, the actualcost of the structure may also depend on such factors asspeed of construction, loc al mark et cond iti ons,competitive tendering, availability of labour andequipment and cost of construction finance. Consequentlya structural design that has proved to be competitive in oneregion may not always be competitive in another.
For a building to meet the needs of major financialoccupiers in todays market, the choice of floor design isoften determined by one or more of the followingconsiderations:
under ten weeks. are given opposite.
2400 4800 2400 II I I
(a) Elevation (b) Section
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Solid flat slabs (with or withoutdrops)The principal feature of the dropless floor is its flush soffitwhich requires only simple formwork and is easy toconstruct (Figure 6a). The overall depth of this floor is aminimum and it allows great flexibility for locating
horizontal services. However, the economical span range
of a reinforced floor is limited by shear in the vicinity of thecolumn supports and the need to control long-termdeflection.
The provision of drop panels at the column supports(Figure 6b) avoids the need for shear reinforcement andincreases the stiffness of the slab and the economical spanrange. Alternatively, a structural steel shearhead can beincorporated to maintain a flush soffit to allow for easyconstruction and efficient use of large forming systems(Figure 6c).
Ribbed slabs
Providing ribs to the soffit of the floor slab can reduce thequantity of concrete and reinforcement, and thus theweight of the floor. The deeper, stiffer floor permits longer
spans to be used. Formwork complexity can be minimizedby the use of standard modular, re-usable formwork. Whenflying form panels are used, the ribs should be positionedaway from the column lines. Ribbed slab floors are veryadaptable for accommodating a range of service openings(Figure 7).
Waffle slabs
Waffle slab floors are commonly used when buildings aresubjected to heavy imposed loading. They are veryefficient in the use of materials and provide veryeconomical long spans, but the additional complexity offormwork can often slow the construction. Where speed ofconstruction is critical, a ribbed slab or a shallow beamsolution is often preferred.
One-way spanning solid slabsand beamsA wide, shallow beam profile is often preferred in order toreduce the overall depth of the floor, whilst permitting
longer spans. The one-way spanning solid slab betweenthe beams facilitates the use of table forms for fastconstruction (Figure 8).
(b)
2 :::r ~~ ~~ l - : : - ~J - - : - ; : - : : - r -F i g u r e Ribbed slab for flexibility to accommodate openings.
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Precast slabs Composite precast slabsComposite precast slabs combine precast floor elementswith in situ concrete in an economical way, eliminatingtraditional formwork for floor construction, and providinglong-span floors. Thin precast concrete floor plates can becombined with an in situ topping to form compositeone-way spanning floors up to 6 m long, or, in combinationwith precast beams, to form a composite ribbed slab
(Figure lOa). For extremely long spans, double-T precastbeams and a composite in situ topping is preferred(Figure 10b).
Precast slabs offer the advantage of off-site manufacture,with a reduction in site labour and site formwork. Whenthe slabs are prestressed there are additional benefits oflonger spans and higher load capacity. A popular type ofprecast floor is the hollow core slab (Figure 9). Therelatively lightweight units form a flush soffit whenplaced. A shear key between units ensures load sharingand the construction is commonly capable of developingdiaphragm action without the need for a structuraltopping. The precast units are easy to remove and can
accommodate a wide range of floor openings.
Figure 9: Precast hollow core planks:flexibility for alterations.
CONCLUSION
The buildings surveyed in this publication demonstratethat reinforced and prestressed concrete floors with spansranging from 6 to 20 m, are technically feasible and
economically competitive.This is a direct consequence of improved design and
analysis techniques, higher strength materials, better
construction methods and finally, more construction-leddesign.
Figure IO: C it fl ( ) t ibb d fl
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SURVEY DATA
Section 1: Solid flat slabs
Reinforced-
Buildings 1to 7
Prestressed -Buildings 8 to 12
Section 2: Ribbed slabs
Reinforced -Buildings 13to 15
Prestressed -Buildings 16 to 22
Section 3: Waffle slabs
Reinforced -Buildings 23 to 25
Prestressed -Buildings 26 to 28
Section 4: One-way spanning solid slabs and beams
Buildings 29 to 33
Section 5: Precast slabs
Buildings 34 to 36
Section 6: Composite precast slabs
Buildings 37 to 40
7
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SECTION 1
SOLID FLAT SLABSSolid flat slab -reinforced
m m m ratio m3 kgI I I I I I
2 7. 2x7. 2 300 24 0. 30 30. 0 6-O r~~~~ GradeC40rameacti on Code BS 8110
J r 3600 J i 3600 1 7200 i 3600 1 3600
7J
7 _I
n
n
300 sl ab
I-
n
8
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Solid flat slab -reinforced
No. SlabMaterials per m2
of floor area Designof l o a d Notes
floors Span Depth Span/depth Conc;ete Rebar kN/,, Stabilitym m m ratio kg
10 7.5x6.1 3 0 0 25 0.30 45.0 6-O Shear Grade C35walls Code BS 8110
300 slab
I - I I I I I I
I
I
I
I
8
I
I
I
I
Typical floor plan
A
9
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Solid flat slab -reinforced
82Emi
1
I
3000A
i
5 i J 7500 3000
n
400 slab
n
1 / _Li
40 0slab
Typical floor plan
10
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Solid flat slab -reinforced
No.of -
Spanfloors m
SlabMaterials per m*
of floor area Designload NotesStability
Depth Span/depth Conc;ete Rebar kN/,-,-,*mm ratio kg
7 6 5 x 4 5 250 26 0.25 29.0 5 0 Shear Grade C35walls Code BS 8110
Typical floor plan
I17 ccc 45 1
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Solid flat slab -reinforced
No. SlabMaterials per m*
of floor area Design Notesof load Stability
floors Spanm
Depth Span/depth Conc;ete Rebar kNirn2 (See page 3)m m rat io kg
4 9-5x 7.3 310 30.6 0.31 41.5 5.0Shear C30 lightweightwalls Code CP 110
Typical floor plan
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Solid flat slab -reinforced
No. SlabMaterials per m2
o fof floor area Design
loadfloors Span
mDepth Span/depth Co;;ete Rebar kN/r- Stability Notes
mm ratio kg13 8 0x7.2 275 29 0.28 40.7 5-o Shear Grade C35
walls Code BS 81 10
5800 3 irr 7200 5800
275 slab
Typical floor plan
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Solid flat slab -reinforced
-
I I I I I II I I I7 9.2x6. 0 255 36
I I0.26 I24. 0 5. 2I I I I I
Stability Notes
(See page 3)
6200h 4 5 (( I 6000
255 sl ab
Typical floor plan
14
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Solid flat slab -prestressed
No. SlabMaterials per m2
of floor area Designof load Notes
floors Span Depth Span/depth Con$ete Rebar Strand kN/r-$ Stabilitym mm ratio kg kg
2 8.0x8-0 275 29.1 0,275 10-2 4 8 10..0Shear Grade C40walls Code BS 8110
Gl P
,.~- I tx x : x x x x
I m
Atrium
.j----
X
xx
xX
xX
X
m m PI m m m m P1 JFirst-floor plan
0Eico0
Column head detail I
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Solid flat slab -prestressed
a 7.2x 7.2 240 30.0 0.240 2.4 4.7 6.5
Stability
Shearwalls
Notes
* See Concrete Society TechnIcal Reports No 17 and No 25
3 I 7200 4800
00cuP-
Typical floor plan
950
n
n c :iI
24 0 50i 25 0
Column head detail c 475
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Solid flat slab -prestressed
No.of
floors
SlabMaterials per m
of floor area Design
l o a d Stability NotesSpanm
Depth Span/depth Conx$ete Rebar Strand kN/mzm m ratlo kg kg
(See page 3)
Grade C40
Stee l Code BS 81109 9 4x 9- o 30 0 31 3 0 300 14-l 78 50 bracing t o CS TR 17 &25*
columns Steel col um nswithshearheads
*See Concrete Society TechnIcal Reports No 17 and No 25
45000
P m B
aI m
Typical floor plan Cross-bracing
17
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Solid flat slab -prestressed
No SlabMaterials per m*
of floor area Designof load
floors Span Depth Span/depth Concrete Rebar Strand kN/mzm m m ratio m3 kg kg
7 11 5 x 7 5 325 35 4 O-325 11 1 6 5 5 0See Concrete Society TechnIcal Reports No 17 and No 25
Stability Notes
FrameGrade C40
actionCode BS8110CSTR 17&25*
Typical floor plan
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Slab
Solid flat slab - prestressed
Stability Notes
7200 3600 7200 2400 7200 3600 7200r c J
Typical floor plan
Typical column head detail
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SECTION 2
RIBBED SLABSRibbed slab -reinforced
No. Rib BeamMaterials per m*
of floor area Desof
,__floors Span Depth Span/depth Span B x D Span/depth Concrc
m mm ratio m mm ratio m3
ignwad Stability
Notes
?te Rebar kN/m* (See page 3)kg
10 9.0 450 20.0 8.0 1200 13.3 0.23 39.5 7.5 Frame Grade C35x 450 action Code BS 8110
7 1 90001 I
Typical floor plan
Typidal rib section Typical beam section
20
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Ribbed slab -reinforced
Rib BeamMaterials per m2
No. of floor area f Stability Notesof (See page 3)
floors Span Depth Span/depth Span B x D Span/depth ConcJete Rebar kN/m*m m m ratio m m m ratio kg
11 9.0 4 2 5 21 .l 9.0 1800
x42521.1 0.27 38.5 5.0
Shear Grade C35walls Code BS 8110
1500_~~ __~125
9000 6750 4 @ 7500 6750 9000i 1
Typical floor plan
5 u,9000
L -t 425 Il l i 1800250
Typical rib section Typical beam section
: 42 5
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Ribbed slab -reinforced
No. Rib BeamMaterials per m2
of floor area Dri,n Stabilityfloors Span Depth Span/depthSpan B x D Span/depth Conc;ete Rc??rkN/mz
m mm ratio m mm ratio
5 9.0 3 0 0 30.01800
7-2 x 4 0 018.0 0.32 29.0 5.0 Shear
walls
Notes
Grade C35Code BS 8110
6 I 7200 9000 7200I i i
1800
Typical rib section Typical beam section
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Ribbed slab -prestressed
No. Rib BeamMaterials per m*
Designof
of floor areal o a d Notes
floors Span Depth Spacing Span/depth Span B x D Span/depth Type Concrete Rebar Strand kN/ Stabilitym m m m m ratio m m m ratio kg kg
3 9.0 3 2 5 1200 27-71800
6.0 x32518-5 Pt 0 194 12 6 3.65 6.0 Frame Grade C35
action Code BS 8110
Prestressed
Typical floor plan
Typical rib section ki
100
325
23
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Ribbed slab -prestressed
No.of
floors-I22*Prestressed
Rib BeamMaterials per m*
of floor area Designload
Span Depth Spacing Span/depth Span B x D Span/depth Type Con;;ete Rebar Strand kN/t-$m m m m m ratio m m m ratio kg kg
9.0 2 5 0 750 36.0 22007.5 x 2 5 0
30.0 Pt 0.186 7 . 0 3 5 .79 5.0
Stability
Shearwalls
Notes
Grade C40Code CP 110
10 @ 7500i
Typical floor plan
750
125
A - ,-r .250 250
2200
I-s \
175
Typical rib section Column head detail
24
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Ribbed slab -prestressed
NO. Rib BeamMaterials per m2
of floor area Designof load Stability Notes
floors Span Depth Spacing Span/depth Span B x D Span/depth Type Con;;ete Rebar Strand kN/m*m m m m m ratio m m m ratio kg kg
8 9. 8 400 725 24.5 1 9 4 1200 Shear Grade C40x 800
24.2 Pt 0.354 16.9 9.76 6.0walls Code CP 110
Prestressed
I I I I13000 9350 9350 10000
Typical floor plan
725c 725 725P75Typical rib section
25
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Ribbed slab -prestressed
No. Rib BeamMaterials per m2
Designo f
of floor areaload Notes
floors Span Depth Spacing Span/depth Span B x D Span/depth Type Concrete Rebar Strand kN/r-$ Stabilitym m m m m ratio m m m ratio m3 kg kg
5 10.85 450 850 24.1 12.5 1500x 4 5 0
28.0 Pt* 0.280 8.3 6-63 5.0 Shear Grade C40wallsL L Code CP 110
Prestressed
Typical floor plan
Typical section
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Ribbed slab -prestressed
No. Rib BeamMaterials per m
of floor area Design
of load Stability Notesfloors Span Depth Spacing Span/depth Span B x D Span/depth Type Concrete Rebar Strand kN/m
m mm mm ratio m m m ratio kg kg
4 16.3 525 850 31 .0 6.3275
X10006.3 R.C.* 0.225 9.8 5.66 6.0 Shear Grade C40
walls Code CP 110
i7 @ 6300_ t
Typical floor plan
I 850 8 5 0 850 i100Typical section
Reinforced
29
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SECTION 3
WAFFLE SLABSWaffle slab -reinforced
No. ColumnMaterials per m*
of floor area Design
of spacing Depth Span/depth l o a d Stability Notesfloors m mm ratio Con-v$ete Rebar Strand kN/m2
kg kg
5 6.6 X 7.43 350 21.2 0.245 24.0 - 6-O Frame Grade C35action Code BS 8110
5835 7425 3 @4950
I ---
Typical floor plan
Ribs at 900 crs
125
4;7I
1600
Section at column head
3 0
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Waffle slab -reinforced
No. ColumnMaterials per m2
of floor area Designof spacing Depth Span/depth load Stability Notes
floors m mm ratio Con;;ete Rebar Strand kN/m2kg kg3 7.5x10 5 525 20.0 0.450 67.0 - 6-O Frame Grade C35
action Code BS 8110
, 7500 typical ,
Typical floor plan
Typical section
31
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Waffle slab re i n f o rced
No. ColumnMaterials per m*
Depth Span/depth _ of floor area Designof spacingratio
load Stability Notesfloors m mm Conc;ete Rebar Strand kN/m2
kg kg
310.18
x10.18550 18-5 0.396 37.0 - 9.0
Shear Grade C35walls Code BS 8110
kTypical floor plan
3 @10180
Typical section125 14
32
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Waffle slab -prestr essed
Materials per m2No. Column of floor area Design
of spacing Depth Span/depthratio
load StabilityNotes
floors m mm Compete Rebar Strand kN/m2 (See page 4)kg kg1 12.0x12.0 500 24.0 0.349 15.9 2.52 6.0
Shear Grade C40walls Code BS 6110
4 @ 12000 6000
q CIOOOOOOOrlnnnnnnrin
Typical floor plan
125Typical section
33
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Waffle slab -prestressed
No. ColumnMaterials per m*
Depth Span/depthof floor area Design
of spacingratio
load Stability Notesfloors m mm Cor?$ete Rebar Strand kN/m*
kg kg
2 12.7x12.7 500 25.4 0.341 12.2 5.60 6.0Shear Grade C35walls Code BS 8110
12700
Typical floor plan
Typical section
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SECTION 4
ONE-WAY SPANNING
SOLID SLABS&BEAMS
One-way spanning
solid slab and beam
No. Slab BeamMaterials per m2
of floor area Designof . load
floors Span Depth Span/depth Type Span B x D Span/depth Type Concrete Rebar Strand kN/+ Stability Notesm m m ratio m m m ratio m3 kg kg
4 7. 43 20 0 37.2 Pt* 9.0 1 5 0 0x 500
18.0 Pt* 0.261 1 4 . 0 4.11 4.0 Shear Grade C35walls Code BS 8110
Prestressed
Typical floor plan
Typical beam section
3 6
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One-way spanning
solid slab and beam
No. Slab BeamMaterials per m2
of floor area Designo f load Stability Notes
floors Span Depth Span/depth Type Span BxD Span/depth Type Conc;ete Rebar Strand kN/m*m m m ratio m m m ratlo kg kg
6 10.30 250 41.2 Pt*1500
6.0 x 4 5 013.3 R.C.+ 0.298 13.9 3.93 6.8
Shear Grade C30walls Code CP 110t
Prestressed +ReInforced
250 slab
Typical floor plan
Typical beam section
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One-way spanningsolid slab and beam
No. Slab BeamMaterials per m2
of floor area Design
of load StabilityNotes
floors Span Depth Span/depth Type Span BxD Span/depth Type Concrete Rebar Strand kN/m2(See page 4)
m m m ratio m mm ratio m3 kg kg7 12.6 3 3 5 37.6 Pt* Precast perimeter wall support 0 335 11 .8 8.25 6.8 Shear C40 lightweight
walls Code BS 8110
Prestressed
335 slab
Typical floor plan
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One-way spanning
solid slab and beam
No. Slab BeamMaterials pe rm2
of floor area Design
of load Stability Notesfloors Span Depth Span/dept Tyee Spnn BxD Span/depth Type Conc;et e %??r StFgndkN/m2
m m m ratio m m m ratio
10 6 75 220 30 7600x
R.C.* 10 0 6oo 16.7 R.C.* 0.26 42-O - 5 0 Shear C40 lightweightwalls Code CP 110
*ReInforced
Typical floor plan
Main beam section
E0
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One-way spanning
solid slab and beam
No. Slab BeamMaterials per m2
ofof floor area Design
load Notesfloors Span Depth Span/depth Type Span B x D Span/depth Type Con-$ete Rebar Strand kN/& Stability
m mm ratio m mm ratio kg kg
5 6.0 175 34.31500
R.C.* 9.0 x425 21.2 R.C.* 0.25 52.0 - 5.0 Shear Grade C40walls Code BS 8110
Reinforced
Typical floor plan
:425
Typical section
40
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SECTION 5Precast slab
PRECAST SLABS
SlabMaterials per m2of floor area
No. Beam Design
ofPrecast In situ
load Stabilityfloors Span Section Span/depth Span B x D Span/depth Conc;ete Rebar Strand Conc;ete Rebar kN/r-$
m m m ratio m m m ratio kg kg kg
12 7.0 203 34.5 3006.0 x600
10.0 0.145 4.8 40 0,011 0.4 7.0Shearwalls
Notes
C50, BS 8110
7% in situHollow coreplanksNo topping
6 @ 6000
.
Typical floor plan
PrecastyqFy=300
Centre beam section
41
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Precast slab
Materials per mof floor areaNo. Slab Beam Precast In situ
Design
of loadfloors Span Section Span/depth Span BxD Span/depth Concrete Rebar Strand Conc$ete Rebar kN/m2
m mm ratio m mm ratio m3 kg kg kg
4 7.2 200 36.0600
7.2 x60012.0 o-193 7.9 3.0 - - 7.0
I I I I I I I I I
Stability
Shear
Notes
Grade C50Code BS 8110Hollow coreplanksNo topping
7200 7200 5400 7200 7200 54007200 7200
1 1 1 1 1
Typical floor plan
Typical section
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Precast slab
SlabMaterials per m2of floor area
No. Beam - Designof
Precast In situload Stability
Notes
floors Span Sectlon Span/depth Span B x D Span/depth Concrete Rebar Strand Con ete Rebar kN/m* (See page 4)m m m ratio m m m ratio m3 kg kg kg
Grade C50
3 7 7 200 38.5 7 . 4 3 , ;o 1 2 . 4 0.157 10.5 2.55 - - 6.5 Frame Code BS 6110action Hollow core
planksNo topplng
Typical floor plan
Typical section
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SECTION 6
COMPOSITE
PRECAST SLABS
Composite precast slab
No. Rib BeamMaterials per m2of floor area
of . Precast In situ Designload Stability Notesfloors Span Depth Span/depth Span
ratioDepth Span/depth Concrete Rebar Strand Concrete Rebar kN/m2
(See page 4)
m mm m mm ratio m3 kg kg m3 kg
500x FrameGrade C60Code CP 110
9 14.5 560 25.9 4.8 1000 4.8 0.150 5.75 6.3 0.080 2.2 5.0(Perimeter)
any$$arDouble Tees, wrthwalls
In situ toppingPrecast H frame
4800 typical
14500. I
Typical floor plan
I47600
1200i , I n s i t u t opp n
- /
Typical section Precast double-T beams
44
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Composite precast slab
No. Rib BeamMaterials per m2of floor area
ofPrecast In situ Design
floors Span Depth Span/depth Span. load
m mm ratioDepth Span/depth Concrete Rebar Strand Concrete Rebar kN m
m mm ratio m3 kg kg m3 kg
750x
6 / 12.0 1 610 / 19.7 j 9.0 ,in;FU, 14.8 0.134 (13,751 - 0.111 110 721 5.7
Stability Notes
In situ C35Frame Precast C45action Code BS 8110
55% In situ
I II II II I
r iririr i r i r i r irir ir iririr irwirlir irII II II II II II II II II II II II II
I II II II II II II II II II II II II II II II II
I II II II II II II II II II II II II II II II II II II II II II II II
Typical floor plan
55 precast soffit plankPrecast rib
Typical rib section Typical in situ beam section
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Economic long-span concrete floors
P.W. Matthew and D.F.H. Bennett
BRITISH CEMENT ASSOCIATION PUBLICATION 9 7.3 11
CI/SfB
I (13) I q4 I (Y6
UDC
624.073.012.4.003.1
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