Manual for Detailing Reinforced Concrete Structures to Ec2

Manual for Detailing Reinforced Concrete Structures to EC2 Detailing is an essential part of the design process. This thorough reference guide for the design of reinforced concrete structures is largely based on Eurocode 2 (EC2), plus other European design standards such as Eurocode 8 (EC8), where appropriate. With its large format, double-page spread layout, this book systematically details 213 structural elements. These have been carefully selected by Jose Calavera to cover relevant elements used in practice. Each element is presented with a whole-page annotated model along with commentary and recommendations for the element concerned, as well as a summary of the appropriate Eurocode legislation with reference to further standards and literature. The book also comes with a CD-ROM containing AutoCAD files of all of the models, which can be directly developed and adapted for specific designs. Its accessible and practical format makes the book an ideal handbook for professional engineers working with reinforced concrete, as well as for students who are training to become designers of concrete structures.

Jose Calavera is Honorary President of the Technical Institute of Materials and Construction (INTEMAC- lnstituto Tecnico de Materiales y Construcciones) and Emeritus Professor, School of Civil Engineering, Polytechnic University of Madrid.

Manual for Detailing Reinforced Concrete Structures to EC2

Jose Calavera

W

~

Span Press an imprint of Taylor & Francis LONDON AND NEW YORK

First published 2012 by Spon Press 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN Simultaneously published in the USA and Canada by Spon Press 711 Third Avenue, New York, NY 10017 Spon Press is an imprint of the Taylor & Francis Group, an informa business

Copyright © 2012 Jose Calavera The right of Jose Calavera to be identified as author of this work has been asserted by him in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers. This publication presents material of a broad scope and applicability. Despite stringent efforts by all concerned in the publishing process, some typographical or editorial errors may occur, and readers are encouraged to bring these to our attention where they represent errors of substance. The publisher and author disclaim any liability, in whole or in part, arising from information contained in this publication. The reader is urged to consult with an appropriate licensed professional prior to taking any action or making any interpretation that is within the realm of a licensed professional practice. Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only tor identification and explanation without intent to infringe. British Library Cataloguing in Publication Data A catalogue record tor this book is available from the British Library Library of Congress Cataloging-in-Publication Data Calavera Ruiz, Jose. Manual tor detailing reinforced concrete structures to EC2 I Jose Calavera. p.cm. Includes bibliographical references and index. 1. Reinforced concrete construction-Details. 2. Reinforced concrete constructionStandards-Europe. I. Title. T A683.28.C35 2012

624.1 '8341-dc22

2011009904

ISBN: 978-0-415-66348-9

Typeset in Helvetica by RefineCatch Ltd, Bungay, Suffolk

"

...,/-u' ~~~

MIX Paper from reeponelble sources

FSC- C004839

Printed and bound in Great Britain by the MPG Books Group

Contents List of tables Foreword The author Author's curriculum vitae Acknowledgements Citations General notes The three golden rules for pouring concrete on site

1 General rules for bending, placing, anchoring and welding reinforcing bars

1. Introduction 1.1 Summary of codes and standards on construction details 1.1.1 Permissible mandrel diameters for bent bars (See EC2, 8.3) 1.1.2 Standard bends, hooks and loops 1.1.3 Cover 1.1.4 Bar spacing 1.1.5 Bundled bars 1.1.6 Surface reinforcement 1.2 Tying bars 1.2.1 Tying method 1.2.2 Tie points 1.3 Spacers and chairs 1.3.1 Types of spacer and chair 1.3.2 Graphic representation 1.3.3 Placement rules 1.4 Welding reinforcing bars 1.4.1 Types of weld 1.4.2 Welded joint details 1.5 Verification of the anchorage limit state 1.5.1 Bond anchorage 1.5.2 Welded transverse bar anchorage 1.6 Anchorage rules for welded transverse bars 1.6.1 Bars where 14 s -- 04

r1

L f

/

v

NO ~: See details @@@and@) in CD-01.03

PLAN - BOTTOM REINFORCEMENT

48

CD-01.07

NOTES

1. RECOMMENDATIONS 1.

The

2.

L1 is the

3.

AR. The starter bars are diameter 1 bars. L4 should be 2fbd' but length fbd is defined in EC2 for the least favourable case. In this case the side covers for the --

b.::

T

""

\

a

\

6:::

\ " \____

-

"

·1

5cm ,__

"

IMl&l\llWWWWWW

--03 I

Iv _l

•

Ir 1

l

~~+03

; I II II II II 11 11 11 11 II I nl nl nl nl nl i1 i~ i1 -ii , Al nl1

04

4

3 . 2

and

3

reinforcing bars.

distribution steel has a straight extension at the end.

8.

Length L5 should suffice to tie , starter bars to

9.

In this case the column starter bars need ties of the same diameter and maximum spacing as in the column. They differ in size.

2

bars; 20 cm is the suggested length.

10. The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed. 11. In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement. 12. The subgrade is compacted before pouring the blinding for the footing and beam. 13. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 14. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 15. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. 16. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers.

2. STATUTORY LEGISLATION EC2 (5).

53

CD-01.10

COMBINED EDGE FOOTING (VARIATION 1)

Asphalt membrane (if any) LONGITUDINAL SECTION 3~

-

-

'\\

-

--111

((

a

I

I

I I I I I

-- ·:Jr JI:

di I

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-

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lb.. I

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-=i

STIRRUP ARRANGEMENTS

f

]

VARIATION1 Skin reinforcement

r

~o.1Wo cm

on

2.5 cm t=~~~~~~~~~-a-

05 r2

I.. al ~Lb

VARIATION 2 NOTE: See details@@@@and @in CD-01.03

54

-->:.:!ll

10 cm

CD-01.10

NOTES

1. RECOMMENDATIONS 1. The , and

2

bars rest directly on the top of the footing, with no hooks needed.

2.

L, is the lap length in the , bar and L5 is the lap length in the

3.

AR. The starter bars in the inner column are diameter 2 bars. L4 should be 2ebd' but length ebd is defined in EC2 for the least favourable case. In this case the side covers for the 2 bars are very large. See (12), p. 69.

A safe value would be e·bd =~ebd . If L4 3

2

bar.

65 cm. If a> 65 cm, multiple stirrups are needed, except where the concrete absorbs the shear stress entirely. The vertical legs must be spaced at no more than 0.75d : 60cm.

5 . 4

reinforcing bar.

10. If multiple stirrups are used, the horizontal legs must overlap along a distance of at least Lb, where Lb is the 5 bar lap length. (This is required for the horizontal leg of the stirrup to act as transverse bending reinforcement.) 11. The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed. 12. In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement. 13. The subgrade is compacted before pouring the blinding for the footing and beam. 14. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 15. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 16. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. 17. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers.

2. STATUTORY LEGISLATION This type of footing is not addressed in EC2.

55

CD-01.11

COMBINED EDGE FOOTING (VARIATION 2) L

I

Lb

I 1,

,

V1

==

Construction joint

02

== ~

Scm

Scm

--tr

Scm

--tr-tr-

a

PLAN - TOP REINFORCEMENT

See (cf)

-04

~ r.,

11

11 111111

11

11

11

11

II

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,11 IJI.._

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11

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.

-

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a

h

Asphalt :~ ', , '· ', · '· See ~~~~~=~~~~--.10 cm 10 cm.---~~~~~-~~m."",,~~~ detail A Spacer Asphalt membrane (if any) CROSS-SECTION A-A CROSS-SECTION C-C

See@@©

-~~~~-: cj> 1 -

cj>2 •

2. r2 = 7.5 cm if the concrete for the footing is poured directly against the soil. 3.

In beams cast in an excavation width b should be at least 40 cm, for mechanised excavation.

4. L1 is the

cj> 1

bar anchorage length.

5. The top of the beam is floated or smoothed with a power float. 6. The bottom of the excavation is compacted before pouring the blinding. 7. The blinding under the footing is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 8. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 9.

See 1.2 and 1.3 for descriptions of how to tie bars and place spacers.

1O. Care should be taken to avoid beam breakage when compacting fill over tie beams. 11. If the footing is cast in forms, footing and tie beams may be cast separately as shown. L2 is the cj> 1 bar anchorage length.

2. STATUTORY LEGISLATION See EC2, 9.8.3 (5).

69

CD-01.17

FOUNDATION BEAM (VARIATION 1)

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I•

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r1--l f---

-1

Construction joint

f Skin reinforcement (if any)

f 0 '1

L-l L-l so.IM/ ~75d

s60 cm

2.5 cm:j=~~~~s:g~~~H---. 09-~I

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r2b~~~~~~~fil < ... ~~

S60 cm VARIATION - 2

01or08

Blinding

NOTE: See details @@©@® in CD-01.03

CROSS-SECTION

70

10 cm

CD-01.17

NOTES

1. RECOMMENDATIONS 1. The

1 , 2

and

3

bars rest directly on the top of the footing, with no hooks needed.

2.

L, is the lap length in the

3.

The starter bars are diameter 1 bars, except where L4 < L1 • If L4 < L1 , often a more suitable solution than increasing the depth of the footing is to use two starter bars for every 1 bar in the column. The sum of the cross-sections of these two bars should not be less than the 1 bar cross-section, but their diameter should be such that Lb< L4 , where Lb is the anchorage length. The arrangement detail is as in alternative (d). For the inner columns, see CD - 01.03.

4.

L8 is the lap length in the larger of the the 7 or 8 bars.

5.

r1 and r3 are equal to 7.5 cm if the concrete for the footing is poured directly against the soil.

6.

r2 = 2.5 cm ;:::

7.

See 1.5 to determine when to use anchor type a, b or c as end anchors.

8.

Length L2 shall suffice to tie 1 , 2 or 3 starter bars to two 2s, where s is the space between 7 or 8 bars.)

1

bar, L5 is the lap length in the

4

2

bar and L6 is the lap length in the

or 5 bars, L9 in the larger of the

5

3

bar.

or 6 bars and L10 in the larger of

9 •

7

or

8

transverse bars. (It may not be less than

9. The edge column starter bars need ties of the same diameter and maximum spacing as in the column. For the inner column starter bars, see CD - 01.03. 10. The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed. 11. In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement. 12. The subgrade is compacted before pouring the blinding for the footing and beam. 13. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 14. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 15. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. 16. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers.

2. STATUTORY LEGISLATION This type of footing is not addressed in EC2 (5).

71

CD - 01.18 La

1

.._

FOUNDATION BEAM (VARIATION 2) lti

1

~~ ~

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NOTE: See details@@@@and@ in CD-01.03

72

I

/

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PLAN - BOTTOM REINFORCEMENT

a

I I

L

CD - 01.18

NOTES

1. RECOMMENDATIONS 1. The $1 , $2 and $3 bars rest directly on the top of the footing, with no hooks needed. 2.

L1 is the lap length in the $1 bar, Ls is the lap length in the $2 bar and L6 is the lap length in the $3 bar.

3. The starter bars are diameter $1 bars, except where L4 < L 1. If L4 < L1 , often a more suitable solution than increasing the depth of the footing is to use two starter bars for every $1 bar in the column. The sum of the cross-sections of these two bars should not be less than the $1 bar cross-section, but their diameter should be such that Lb< L4 , where Lb is the anchorage length. The arrangement detail is as in alternative (d). For the inner columns, see CD - 01.03. (If the side cover on the web in the $2 bars is greater than or equal to ten times their diameter, or more than 10 cm, the condition is L 4 > ~ Ls . If it is less, L4 > Ls.) The same applies to $3 . 4.

L8 is the lap length in the larger of the $4 or $s bars, L9 is the lap length in the larger of the $s or $6 bars and L10 is the lap length in the larger of the $7 or $8 bars. (Anchorages need not be used if the commercial length of the bars suffices.)

5.

r1 = 7.5 cm if the concrete for the footing is poured directly against the soil.

6.

r2

7.

See 1.5 to determine when to use anchor type a, b or c as end anchors.

8.

Length L2 shall suffice to tie $1 , $2 or $3 starter bars to two $7 or $8 transverse bars. (It may not be less than 2s, where s is the space between $7 or $8 bars.)

= 2.5 cm but not less than $9 ; r3 = 2.5 cm but not less than $10 •

9. The edge column starter bars need ties of the same diameter and maximum spacing as in the column. The starter bars on the inner columns need ties of the same diameter and maximum spacing as in the column if the side cover over the T-section web is less than ten times their diameter, or less than 10 cm. Otherwise two ties suffice (see CD - 01.03) across depth h1 and two along the height of the web. 10. The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed. The flange-to-web joint is treated similarly. 11. In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement. 12. The subgrade is compacted before pouring the blinding. 13. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 14. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 15. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. The flange-to-web joint should be treated similarly. 16. See 1.2 and 1 .3 for descriptions of how to tie bars and place spacers.

2. STATUTORY LEGISLATION This type of footing is not addressed in EC2 (5).

73

CD- 01.19

GRID FOUNDATION (VARIATION 1) (1 of2)

/\-

-

1

I

+ +-

-

\

T

1 ,~

t

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/

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2

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3

03

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5cm I 15 cm 0 14

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Asphalt membrane (if any)

74

018

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-

____,

-· "

9

7

09

CD - 01.19

NOTES

1. RECOMMENDATIONS 1.

r, = 2.5 cm ~ $, - $3 •

2.

r2 = 2.5 cm.

3.

r4 and r5 are equal to 7.5 cm if the concrete for the footing is poured directly against the soil.

4. The $w $13 and $16 bars lie on the $1 , $4 and $7 bars, respectively. 5. The $11 , $14 and $17 bars lie on the $2 , $5 and $8 bars, respectively. 6.

If the shear stress cannot be entirely absorbed by the concrete, the stirrups must be arranged in such a way that their vertical legs are not separated by more than 60 cm or 0.75d. Cross-ties, as shown, or multiple stirrups (see CD - 01.17) may be used.

7.

If multiple stirrups are used, the horizontal legs must be lapped along a distance of at least Lb, where Lb is the stirrup anchorage length. (This is required for the horizontal arm of the stirrup to act as transverse bending reinforcement; see CD - 01.17.)

8. The corner column starter bars need ties of the same diameter and maximum spacing as in the column. Two stirrups suffice for the inner column starter bars (see CD - 01.03). 9. The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed. 10. In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement. 11. The subgrade is compacted before pouring the blinding. 12. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 13. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 14. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. 15. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers.

2. STATUTORY LEGISLATION This type of footing is not addressed in EC2 (5).

75

CD - 01.19

1

GRID FOUNDATION (VARIATION 1) (2 of2) La 0 1 /\:~ 3

-

I

Le

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PLAN - BOTTOM REINFORCEMENT

010 DETAIL3

76

CD- 01.19

NOTES

1. RECOMMENDATIONS 1.

r, = 2.5 cm

2.

r2 = 2.5 cm.

3.

r4 and r5 are equal to 7.5 cm if the concrete for the footing is poured directly against the soil.

2 cji, - cji3 .

4. The cjiw cji, 3 and cji 16 bars lie on the cji,, cji4 and cji 7 bars, respectively. 5. The cji,,, cji, 4 and cji 17 bars lie on the cji2 , cji 5 and cji 8 bars, respectively. 6.

If the shear stress cannot be entirely absorbed by the concrete, the stirrups must be arranged in such a way that their vertical legs are not separated by more than 60 cm or 0.75d. Cross-ties, as shown, or multiple stirrups (see CD - 01.17) may be used.

7.

If multiple stirrups are used, the horizontal legs must be lapped along a distance of at least Lb, where Lb is the stirrup anchorage length. (This is required for the horizontal arm of the stirrup to act as transverse bending reinforcement; see CD - 01.17.)

8. The corner column starter bars need ties of the same diameter and maximum spacing as in the column. Two stirrups suffice for the inner column starter bars (see CD - 01.03). 9. The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed. 10. In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement. 11. The subgrade is compacted before pouring the blinding. 12. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 13. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 14. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. 15. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers.

2. STATUTORY LEGISLATION This type of footing is not addressed in EC2 (5).

77

CD-01.20

GRID FOUNDATION (VARIATION 2) (1 of2)

1

Le 020

021

I~

D

____j'-

I

10347

5cm 5cm

L_~

4c

035

PLAN - TOP REINFORCEMENT r5

Construction (Joint

--011

Construction joint

h

r1 f==i,~~~~~~~$W

'/'>n*'7>7'7h~"""~7777'77-J.~-+10cm

01

Blinding

CROSS-SECTION A-A

°26

022

CROSS-SECTION E-E

78

CD-01.20

NOTES

1. RECOMMENDATIONS 1. r1 = 2.5 cm. 2.

r2 = 2.5 cm.

3. r3 = 2.5 cm. 4.

r4 and r6 are equal to 7.5 cm if the concrete for the footing is poured directly against the soil.

5.

r5 = 2.5 cm.

6. The

17 , 22

7. The

w 23 and 29 bars lie on the 2 , 7 and 13 bars,

8. The

20 , 25

9.

L2

and

and

28

31

bars lie on the

bars lie on the

1 , 6

4 , 9

and

and

12

15

bars, respectively. respectively.

bars, respectively.

=20 cm.

10. The corner and edge column starter bars need ties of the same diameter and maximum spacing as in the column. The starter bars on the inner columns need ties of the same diameter and maximum spacing as in the column if the side cover over the T-section web is less than ten times their diameter, or less than 1O cm. Otherwise two ties suffice (see CD - 01.03) across depth h1 and two along the height of the web. 11. The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed. 12. In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement. 13. The subgrade is compacted before pouring the blinding. 14. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 15. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 16. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. The flange-to-web joint should be treated similarly 17. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers.

2. STATUTORY LEGISLATION This type of footing is not addressed in EC2 (5).

79

CD-01.20

GRID FOUNDATION (VARIATION 2) (2 of2) La

1

1-1+-++-11+-+11,__1_1 _, _, -- -7

--~-

v \

1_ I I 1-1

5c"T

I

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_tE

\

: 5cm

r--026

~ 5cm

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;

022

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I

:

:

I I I

I

:

:

I>- /detail 2

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032

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I L

' ....

r -

-

-

-

-- -- -

-

See

028

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-

-

-:::--

See detail 3

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--

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-

I

021~

Le

Vi I

i

I

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017

-

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-

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-

I

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I

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-~- ·-1±:+~,··:~H±::±±:±ll::~l. . .*=±::±~±:'±1-:±~fdiffi:l±:!~~::±~±::±!:I-:±±1~·ffim~;-:::±!*l!::f:~~~~ 7 I 012 ~016 8 I 012- ~016 9 I 012 \L_016

c

PLAN - BOTTOM REINFORCEMENT

See@@® in CD-01.03

0a 07~f-ff--~-tt-~-tt-~it-'N

010---10rt1t----tttt----tt1r----t1

Skin reinforcement

See@@® in CD-01.03

&110270,, n-050~~60~:1032

lb

n

034 035 035-u

STIRRUP ARRANGEMENT

spacer

NOTES:

~

90° BEND

FOR SIMILAR STARTER BAR LAYOUT AND COLUMN ANCHORAGE SEE CD-01.08.

DETAIL 4

80

BARS WITH SUBSCRIPTS 2, 3, 7, 8, 13, 14, 18, 19, 23, 24, 29 AND 30 CONSTITUTE SKIN REINFORCEMENT AND ARE PLACED CONTINUOUSLY ALONG THE ENTIRE SECTION.

CD-01.20

NOTES

1. RECOMMENDATIONS 1.

r1 = 2.5 cm.

2.

r2 = 2.5 cm.

3. r3 = 2.5 cm. 4.

r4 and r6 are equal to 7.5 cm if the concrete for the footing is poured directly against the soil.

5.

r5

=2.5 cm.

6. The

17 , 22

and

28

bars lie on the

1 , 6

and

12

bars, respectively.

7. The 18'

23

and

29

bars lie on the

2 , 7

and

13

bars, respectively.

8. The 20'

25

and

31

bars lie on the

4 , 9

and

15

bars, respectively.

9. L2

=20 cm.

10. The corner and edge column starter bars need ties of the same diameter and maximum spacing as in the column. The starter bars on the inner columns need ties of the same diameter and maximum spacing as in the column if the side cover over the T-section web is less than ten times their diameter, or less than 10 cm. Otherwise two ties suffice (see CD - 01.03) across depth h1 and two along the height of the web. 11. The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed. 12. In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement. 13. The subgrade is compacted before pouring the blinding. 14. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 15. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 16. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. The flange-to-web joint should be treated similarly. 17. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers.

2. STATUTORY LEGISLATION This type of footing is not addressed in EC2 (5).

81

CD- 01.21

FOUNDATION SLAB (1 of 2) La rl» B

2 ---f ;;;+-+

3 - --C~t- -

I

I

I

- --fe¥+- ·:o..r··

-

-{~j---t~··

Le 0b1(Top) 0b2(Bottom)

A

A 1 +-+--+-+-+-+-+--+-+--+-+---+-+-+--+--+---+----+---+-+---+-+----+---+->--+-+-+-+-+--+-+---+-+~

t

t 7 i

0b3(Top) 9i 0b4(8ottom) PLAN - GENERAL TOP AND BOTTOM REINFORCEMENT

48

8

i

5

6

----+-+---+--ll---+----+-+-----1--4-

Le

PLAN - SUPPLEMENTARY BOTTOM REINFORCEMENT

82

CD - 01.21

NOTES

1. RECOMMENDATIONS 1.

r1 = 7.5 cm if the concrete for the footing is poured directly against the soil.

2.

r2 = 2.5 cm. (The cover over the main reinforcement should not be smaller than its diameter.)

3.

L1 is the lap length in the larger of the

b 3

or

b 4

bars.

4.

L2 is the lap length in the larger of the

b 1

or

b2

bars.

5.

The corner and edge column starter bars need ties of the same diameter and maximum spacing as in the column. Two stirrups suffice for the inner column starter bars (see CD - 01.03).

6. The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed. 7.

In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement.

8. The subgrade is compacted before pouring the blinding. 9. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 10. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 11. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. 12. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers. 13. Placement of a polyethylene membrane over the blinding may be advisable to prevent thermal contraction and shrinkage-induced tensile stress generated by the bond between the slab and the blinding concrete.

2. STATUTORY LEGISLATION This type of footing is not addressed in EC2 (5).

3. SPECIFIC REFERENCES See (18), (20) and (23).

83

n Construction JOint

r

Standee

0b3

0b1

0b3

0

Construction joint

10c:Ilt;'i ::c.: ~ .; . ::c:.·: !:·J:;.~ : :·'. r, :;: '.':·.:

I 0

End

'.>;

.;;e;E;~~~~~

......... N ........

CROSS-SECTION A-A

Construction joint _0 b1

~ ;; n ~j'L / (5,

10 cm

cle ' '

9

9

.. .

/ y/;;/····;· /

Standee

e

e

e

s

1

?.

r

h

,

c II a

,

e

c

a

p\lc

,\

I(

a

i

I

4

Q

Q

Q

(

8

8

0

Q~ 2 .5 cm !\~

I' // ,

b2

/

. 0, \c:O;;.Paci;.; End spacer

'Tj

Construction joint

'

2

~sphalt

subgrade

membrane

(if any) CROSS-SECTION B-B

~tl

~

-~

\/).

l"

~

,,-..__

NOTES: Anchorage in columns 7 and 8: for similar details see CD-01.12. Anchorage in columns 2, 3, 4, 8 and 9: for similar details see CD-01.08. Anchorage in columns 5 and 6: for similar details see CD-01.03. (See the respective recommendations).

N 0

.-+i

N __,

CD- 01.21

NOTES

1. RECOMMENDATIONS 1.

r1 = 7.5 cm if the concrete for the footing is poured directly against the soil.

2.

r2 = 2.5 cm. (The cover over the main reinforcement should not be smaller than its diameter.)

3.

L1 is the lap length in the larger of the

cpb3

or cpb4 bars.

4.

L2 is the lap length in the larger of the

cpb 1

or

5.

The corner and edge column starter bars need ties of the same diameter and maximum spacing as in the column. Two stirrups suffice for the inner column starter bars (see CD - 01.03).

6.

The top of the footing is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed.

7.

In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement.

cpb 2

bars.

8. The subgrade is compacted before pouring the blinding. 9. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 10. Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified. 11. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. 12. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers. 13. Placement of a polyethylene membrane over the blinding may be advisable to prevent thermal contraction and shrinkage-induced tensile stress generated by the bond between the slab and the blinding concrete.

2. STATUTORY LEGISLATION This type of footing is not addressed in EC2 (5).

3. SPECIFIC REFERENCES See (18), (20) and (23).

85

CD-01.22

CAISSON

See detail A

Construction joint

Structural concrete

Construction joint _____, for placing the starter bars

C 5/6 concrete

ELEVATION

DETAIL A

86

CD-01.22

NOTES

1. RECOMMENDATIONS 1. The

1

bars in the column rest directly on the top of the foundation shaft.

2.

L1 is the

3.

L2 is the

1 1

bar lap length. bar anchorage length.

4.

The starter bar ties are supports whose sole purpose is to keep the starter bar assembly firmly in place while the concrete is cast in the foundations. These are not the same ties as in the column.

5.

The 1 diameter starter bars should be positioned as shown in Detail A. Stability should be monitored during concrete pouring.

6.

In soft soils, the bottom 35 cm should not be excavated until shortly before placing the concrete to ensure that the soil is not softened by rainfall immediately before pouring the blinding.

7.

The foundation shaft subgrade must be compacted before the blinding is poured.

8.

The top surface of the C 5/6 concrete should not be smoothed. (The last layer should be vibrated.)

9.

The top surface of the foundation is smoothed with a float or power float except in the contact area with the future column, where a rough surface such as is generated by the vibrator is needed.

10. Before pouring the column concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until it dries. 11. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers. 12. Where calculations are very tight, the mid plane in pairs of lapped bars should be perpendicular to the direction of the greatest bending moment acting on the column springing.

2. STATUTORY LEGISLATION None, to the author's knowledge.

87

CD-01.23

WALL FOOTING a f3

STIRRUP ARRANGEMENT

03

D

~

ijtA;00

06

h 2.5 cm

f

04

) 05

h1 04

10 cm (Blinding)

0 HOOK

~

90° BEND

Spacer

Asphalt membrane (if any)

b

100 ;::::70 mm

I.

f.:

CROSS-SECTION

DETAIL A

See detail A

01

01

'

I

. r--

I

~·

4

~

1

2

~

0---t-

It--~

~

15 I :::m

-~

I

0

I

·1~.

L04

-5cm H_§cm

04 02+0J

04

I

I

' CORNER DETAIL - PLAN

88

t---

-

1~5cm

I

I

CD - 01.23

NOTES

1. RECOMMENDATIONS 1.

r1

=2.5 cm.

2. r2 = 7.5 cm if the concrete for the footing is poured directly against the soil. 3. r3 = 2.5 cm.

=2.5 cm.

4.

r4

5.

The top of the stem and base are smoothed with a float or power float except at the joint, where a rough surface such as is generated by the vibrator is needed.

6.

In soft soils, the 25 cm over the level of the future blinding should not be excavated until shortly before pouring the concrete to ensure that the soil is not softened by rainfall immediately before placement.

7. The foundation subgrade must be compacted before the blinding is poured. 8. The blinding is floated or smoothed with a power float. Its standard 10-cm thickness may be varied to absorb tolerances in foundation subgrade levelling. 9.

Where the footing is to be poured on soils that constitute an aggressive medium, it should be protected by an asphalt membrane as specified.

10. Before casting the concrete, the joint surface should be cleaned and pressure hosed. The concrete should not be cast until the surface dries. 11. See 1.2 and 1.3 for descriptions of how to tie bars and place spacers.

2. STATUTORY LEGISLATION None in place.

89

CD-01.24

BORED PILE

SOLUTION A

SOLUTION B Future cap

Future cap

5cm

5cm

10 cm 10 cm

10 cm 10 cm

Spacer

ELEVATION

ELEVATION

CROSS-SECTION

CROSS-SECTION

90

CD-01.24

NOTES

1. RECOMMENDATIONS 1. Cover r1 is taken to be 7.5 cm. Under certain circumstances, European standard EN 1536 (24) allows smaller values for bored piles. 2.

Transverse reinforcement shall be tied or welded at all intersections with the main reinforcing bars.

3.

The reinforcement should protrude upward from the top of the pile after removal of the concrete above the cutoff level.

4.

At least six cj> 1 longitudinal bars should be used. (Five may exceptionally suffice in small diameter piles.)

5.

cj> 2 2 ~ cj>1 (cj>1 2 16 mm). (See EN 1536 ((24)), which allows smaller diameters.) 4

6.

s :S;20cj>1.

7.

L1 is the cj> 2 bar lap length.

8.

Lb is the cj> 1 bar anchorage length.

9. The standard 15-cm blinding depth may be changed to absorb levelling tolerances at the bottom of the cap. 10. Wheel spacers should be used and attached to the transverse reinforcement with sufficient clearance to turn.

2. STATUTORY LEGISLATION EC2 (5), EN 1536 (24).

91

CD - 01.25

PILE CAP

See@ in CD-01.03

H