Download Design Hybrid Concrete Buildings PDF

TitleDesign Hybrid Concrete Buildings
Tags Beam (Structure) Column Precast Concrete Prestressed Concrete
File Size4.2 MB
Total Pages116
Document Text Contents
Page 1

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IP
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3
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D
esign

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C

o
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crete B
u

ild
in

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R

. W
h

ittle M
A

(C
antab) C

Eng M
IC

E H
. Tay

lo
r FR

Eng, BSc, PhD
, C

Eng, FIC
E, FIStructE



Design of Hybrid Concrete Buildings

This design guide is intended to provide the structural
engineer with essential guidance for the design of structures
that combine precast and in-situ concrete in a hybrid
concrete structure. It introduces the options available for
hybrid concrete structures, and goes on to explain the key
considerations in the design of this type of structure.

Bearings, interface details, consideration of movement, composite
action, robustness and the effects of prestressing are all explained in
this guide and design examples are included where appropriate. The
importance of overall responsibility and construction aspects are also
described.

CCIP-030
Published January 2009
ISBN 978-1-904482-55-0
Price Group P

© The Concrete Centre

Riverside House, 4 Meadows Business Park,
Station Approach, Blackwater, Camberley, Surrey, GU17 9AB
Tel: +44 (0)1276 606 800
www.concretecentre.com

CI/Sfb

UDC
624.072.33:624.012.3/.4

Robin Whittle has extensive knowledge and experience of designing
all types of concrete buildings. He regular contributes to concrete
industry publications and is a consultant to Arup. He was a member
of the project team which drafted Eurocode 2.

Howard Taylor has extensive knowledge and experience of
designing precast concrete elements and buildings, including
developing alternative production methods. He is a past president
of the Institution of Structural Engineers and is currently chairman
of the British Standards Institution Building and civil engineering
structures Technical Committee B/525.

Design of Hybrid
Concrete Buildings
A guide to the design of buildings combining in-situ
and precast concrete

A cement and concrete industry publication

R. Whittle MA (Cantab) CEng MICE
H. Taylor FREng, BSc, PhD, CEng, FICE, FIStructE

Hybrid cov-.indd 1Hybrid cov-.indd 1 29/01/2009 16:43:3729/01/2009 16:43:37

Page 2

Schematic Graphic 5.eps


A cement and concrete industry publication

Published by The Concrete Centre
Riverside House, 4 Meadows Business Park, Station Approach, Blackwater, Camberley, Surrey GU17 9AB
Tel: +44 (0)1276 606800 Fax: +44 (0)1276 606801
www.concretecentre.com

CCIP-030
Published January 2009
ISBN 978-1-904482-55-0
Price Group P
© The Concrete Centre

Cement and Concrete Industry Publications (CCIP) are produced through an industry initiative to
publish technical guidance in support of concrete design and construction.

CCIP publications are available from the Concrete Bookshop at www.concretebookshop.com
Tel: +44 (0)7004 607777

All advice or information from The Concrete Centre is only intended for use in the UK by those who will evaluate the signifi cance
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 by The Concrete Centre or their subcontractors, suppliers or advisors.
Readers should note that the publications from The Concrete Centre are subject to revision from time to time and should
therefore ensure that they are in possession of the latest version.

Cover photo: Courtesy of Outinord International Ltd.
Printed by Information Press Ltd, Eynsham, UK

Acknowledgements
The authors would particularly like to thank the following people for their support in the development of this
design guide:

Tony Jones Arup
Ian Feltham Arup

The contributions and comments from the Concrete Society Design Group and also from the following
people are gratefully acknowledged:

John Stehle Laing O’Rourke
Graham Hardwick John Doyle Construction Ltd
Peter Kelly Bison Concrete Products Ltd
Alex Davie Consultant
David Appleton Hanson Concrete Products
Kevin Laney Strongforce Engineering Plc
Norman Brown British Precast Concrete Federation Ltd

Type 1
Precast twin wall and lattice girder slab with

in-situ concrete

Type 2
Precast column and edge beam with in-situ

fl oor slab

Type 3
Precast column and fl oor units with cast in-situ

beams

Type 4
In-situ columns or walls and beams with precast

fl oor units

Type 5
In-situ column and structural topping with precast

beams and fl oor units

Type 6
In-situ columns with lattice girder slabs with

optional spherical void formers

Typical hybrid concrete options.
Please note this diagram is a repeat of Figure 2.1, page 8.

Hybrid cov-.indd 2Hybrid cov-.indd 2 29/01/2009 16:43:5429/01/2009 16:43:54

Page 58

56

Project details

Worked example 6
Vertical tie

Calculated by Job No.

Checked by Sheet No.

Client Date

Consider a 9 m x 9 m flat slab floor 300 mm thick with imposed variable load of 3 kN/m2 and
finishes of 1 kN/m2.

Actions
The total design force in vertical tie
FEd = Gk + Ad
= 9 x 9 x {(25 x 0.3 + 1.0) + (0.5 x 4) = 851 kN.

Resistance
Using a column shoe system: 4 No 25 mm bars will provide a resistance of
FRd = �s fyk As
= 1.0 x 500 x 252 x 4 x π/4/1000 = 981 kN
FRd > FEd → OK

Use 4 No 25 mm bars

Eurocode, Table NA.A1.3

RW

OB

TCC

CCIP-030

WE 6/1

April 08

Initial sizing can be determined from manufacturers literature. The manufacturer literature
will also advise the size of the spheres available, the spacing requirements and the general
confi guration of the slab.

The benefi t of the reduced self-weight should be taken into account in the design. The
design may assume a fl at slab model, which has been demonstrated as appropriate through
testing of the slabs. A check should be carried out to ensure that the concrete compression
zone remains outside of the depth of spherical void formers. Where this is not the case, as
in heavily loaded slabs, the manufacturers will be able to offer appropriate guidance on
determining the permissible compression zone that can be used in the calculation of the
fl exural strength.

Testing has been carried out to determine the shear strength of this type of slab, alongside a
theoretical assessment of the reduction in the shear plane due to the inclusion of the voids.
The manufacturers recommend that shear strength of a solid slab of the same depth should
be reduced by a factor of between 0.55 and 0.6 to obtain the design shear resistance for
the voided slab, see Figure 5.16.

For punching shear it is recommended that the void formers are left out where the design
shear stress exceeds the reduced shear resistance of a voided slab, see Figure 5.16. Punching
shear checks may then be carried out on the solid slab areas around the columns.

5.3.1 Slab geometry

5.3.2 Flexural design

5.3.3 Shear design

5 Structural elements and connections

Design of Hybrid Concrete Buildi56 56Design of Hybrid Concrete Buildi56 56 29/01/2009 16:48:2329/01/2009 16:48:23

Page 59

57

Figure 5.16
Typical layout with fi nal reinforcement in

place.
Photo: Cobiax Technologies Ltd

Manufacturers have carried out testing to determine the reduced stiffness of the slabs due
to the voids. Conservatively, the stiffness of the voided slab may be taken as 0.87 times
the stiffness of a solid slab, although in some confi gurations the factor may be increased
to 0.96. The manufacturers have data available to take advantage of these situations.

When using a fi nite element analysis, the stiffness of the slab (by adjusting the modulus
elasticity) can be reduced accordingly. The use of the span-to-effective depth rules of
Eurocode 2 is not valid for this form of construction since it is not clear how the slab
stiffness is incorporated in the manufacturers design expressions.

Splice bars are used across the panel joints so that the slab may be designed as a continuous
member. Figure 5.16 shows a typical layout including the fi nal reinforcement.

Buoyancy of voids
Whilst the concrete is being place and vibrated, the buoyancy force can reach the displaced
weight. The void formers are held in place by:

firm tying of the void former to the lower and upper reinforcement
casting of concrete in several stages (normally two, but three may be required where

the voids are larger than 360 mm).

Slab edges
Voids are not normally provided near slab edges to ensure a robust and continuous edge
detail.

5.3.4 Defl ection control

5.3.5 General considerations

Structural elements and connections 5

Design of Hybrid Concrete Buildi57 57Design of Hybrid Concrete Buildi57 57 29/01/2009 16:48:2429/01/2009 16:48:24

Page 115

Schematic Graphic 5.eps


A cement and concrete industry publication

Published by The Concrete Centre
Riverside House, 4 Meadows Business Park, Station Approach, Blackwater, Camberley, Surrey GU17 9AB
Tel: +44 (0)1276 606800 Fax: +44 (0)1276 606801
www.concretecentre.com

CCIP-030
Published January 2009
ISBN 978-1-904482-55-0
Price Group P
© The Concrete Centre

Cement and Concrete Industry Publications (CCIP) are produced through an industry initiative to
publish technical guidance in support of concrete design and construction.

CCIP publications are available from the Concrete Bookshop at www.concretebookshop.com
Tel: +44 (0)7004 607777

All advice or information from The Concrete Centre is only intended for use in the UK by those who will evaluate the signifi cance
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 by The Concrete Centre or their subcontractors, suppliers or advisors.
Readers should note that the publications from The Concrete Centre are subject to revision from time to time and should
therefore ensure that they are in possession of the latest version.

Cover photo: Courtesy of Outinord International Ltd.
Printed by Information Press Ltd, Eynsham, UK

Acknowledgements
The authors would particularly like to thank the following people for their support in the development of this
design guide:

Tony Jones Arup
Ian Feltham Arup

The contributions and comments from the Concrete Society Design Group and also from the following
people are gratefully acknowledged:

John Stehle Laing O’Rourke
Graham Hardwick John Doyle Construction Ltd
Peter Kelly Bison Concrete Products Ltd
Alex Davie Consultant
David Appleton Hanson Concrete Products
Kevin Laney Strongforce Engineering Plc
Norman Brown British Precast Concrete Federation Ltd

Type 1
Precast twin wall and lattice girder slab with

in-situ concrete

Type 2
Precast column and edge beam with in-situ

fl oor slab

Type 3
Precast column and fl oor units with cast in-situ

beams

Type 4
In-situ columns or walls and beams with precast

fl oor units

Type 5
In-situ column and structural topping with precast

beams and fl oor units

Type 6
In-situ columns with lattice girder slabs with

optional spherical void formers

Typical hybrid concrete options.
Please note this diagram is a repeat of Figure 2.1, page 8.

Hybrid cov-.indd 2Hybrid cov-.indd 2 29/01/2009 16:43:5429/01/2009 16:43:54

Page 116

C
C

IP
-0

3
0

D
esign

o
f H

y
b

rid
C

o
n

crete B
u

ild
in

gs
R

. W
h

ittle M
A

(C
antab) C

Eng M
IC

E H
. Tay

lo
r FR

Eng, BSc, PhD
, C

Eng, FIC
E, FIStructE



Design of Hybrid Concrete Buildings

This design guide is intended to provide the structural
engineer with essential guidance for the design of structures
that combine precast and in-situ concrete in a hybrid
concrete structure. It introduces the options available for
hybrid concrete structures, and goes on to explain the key
considerations in the design of this type of structure.

Bearings, interface details, consideration of movement, composite
action, robustness and the effects of prestressing are all explained in
this guide and design examples are included where appropriate. The
importance of overall responsibility and construction aspects are also
described.

CCIP-030
Published January 2009
ISBN 978-1-904482-55-0
Price Group P

© The Concrete Centre

Riverside House, 4 Meadows Business Park,
Station Approach, Blackwater, Camberley, Surrey, GU17 9AB
Tel: +44 (0)1276 606 800
www.concretecentre.com

CI/Sfb

UDC
624.072.33:624.012.3/.4

Robin Whittle has extensive knowledge and experience of designing
all types of concrete buildings. He regular contributes to concrete
industry publications and is a consultant to Arup. He was a member
of the project team which drafted Eurocode 2.

Howard Taylor has extensive knowledge and experience of
designing precast concrete elements and buildings, including
developing alternative production methods. He is a past president
of the Institution of Structural Engineers and is currently chairman
of the British Standards Institution Building and civil engineering
structures Technical Committee B/525.

Design of Hybrid
Concrete Buildings
A guide to the design of buildings combining in-situ
and precast concrete

A cement and concrete industry publication

R. Whittle MA (Cantab) CEng MICE
H. Taylor FREng, BSc, PhD, CEng, FICE, FIStructE

Hybrid cov-.indd 1Hybrid cov-.indd 1 29/01/2009 16:43:3729/01/2009 16:43:37

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