Simplified design for mechanical connections between precast concrete structural elements in buildings

This document refers to connections in precast frame systems, either for single-storey or multi-storey buildings. The connections for all orders of joints are considered. Large wall panel and three-dimensional cell systems are not considered. According to the position in the overall construction and of the consequent different structural functions, the seven following orders of joints are considered: a) mutual joints between floor or roof elements (floor-to-floor) that, in the seismic behaviour of the structural system, concern the diaphragm action of the floor; b) joints between floor or roof elements and supporting beams (floor-to-beam) that give the peripheral constraints to the floor diaphragm in its seismic behaviour; c) joints between beam and column (beam-to-column) that ensure in any direction the required degree of restraint in the frame system; d) joints between column segments (column-to-column) used for multi-storey buildings usually for dual wall braced systems; e) joints between column and foundation (column-to-foundation), able to ensure in any plane a fixed full support of the column; f) fastenings of cladding panels to the structure (panel-to-structure) that ensure the stability of the panels under the high forces or the large drifts expected under seismic action; g) joints between adjacent cladding panels (panel-to-panel) possibly used to increase the stiffness of the peripheral wall system and provide an additional source of energy dissipation. Simple bearings working by gravity load friction are not considered. Sliding and elastic deformable supporting devices neither, being all these types of connections not suitable for the transmission of seismic actions. The document provides formulae for the strength design of a large number of joint typologies.

Conception simplifiée pour les assemblages mécaniques entre éléments structurels en béton préfabriqué dans les bâtiments

General Information

Status
Published
Publication Date
10-Oct-2019
Current Stage
6060 - International Standard published
Start Date
11-Oct-2019
Completion Date
11-Oct-2019
Ref Project

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Error! Reference source not found.
ISO/TC 71/SC 5
Date: 2018‐01‐12
Deleted: /FDIS
ISO 20987:2019(E)
ISO/TC 71/SC 5/WG 4
Secretariat: ICONTEC
Simplified design for mechanical connections between precast
concrete structural elements in buildings
Document type: Error! Reference source not found.
Document subtype: Error! Reference source not found.
Document stage: Error! Reference source not found.
Document language: Error! Reference source not found.

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COPYRIGHT PROTECTED DOCUMENT

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or

utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,

or posting on the internet or an intranet, without prior written permission. Permission can be

requested from either ISO at the address below or ISO’s member body in the country of the

requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH‐1214 Vernier, Geneva, Switzerland
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
copyright@iso.org
www.iso.org
Error! Reference source not found.
---------------------- Page: 2 ----------------------
Error! Reference source not found.
Contents Page

Foreword ........................................................................................................................................................................... 6

Introduction ..................................................................................................................................................................... 7

1 Scope .................................................................................................................................................................... 1

2 Normative references .................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................... 1

4 Properties ........................................................................................................................................................... 3

5 Classification ..................................................................................................................................................... 4

5.1 General ................................................................................................................................................................ 4

5.2 Strength ............................................................................................................................................................... 4

5.3 Ductility ............................................................................................................................................................... 4

5.3.1 Ductile connections ......................................................................................................................................... 5

5.4 Dissipation ......................................................................................................................................................... 5

5.5 Deformation ...................................................................................................................................................... 5

6 Floor-to-floor connections ........................................................................................................................... 6

6.1 Cast-in-situ topping ......................................................................................................................................... 6

6.1.1 General ................................................................................................................................................................ 6

6.1.2 Strength ............................................................................................................................................................... 6

6.1.3 Other properties .............................................................................................................................................. 6

6.2 Cast-in-situ joints ............................................................................................................................................. 7

6.2.1 General ................................................................................................................................................................ 7

6.2.2 Strength ............................................................................................................................................................... 7

6.2.3 Other properties .............................................................................................................................................. 7

6.3 Welded steel connectors ............................................................................................................................... 7

6.3.1 General ................................................................................................................................................................ 7

6.3.2 Strength ............................................................................................................................................................... 8

6.3.3 Other properties ........................................................................................................................................... 11

6.4 Bolted steel connectors .............................................................................................................................. 11

6.4.1 General ............................................................................................................................................................. 11

6.4.2 Strength ............................................................................................................................................................ 11

6.4.3 Other properties ........................................................................................................................................... 14

7 Floor-to-beam connections ....................................................................................................................... 14

7.1 Cast-in-situ joints .......................................................................................................................................... 14

7.1.1 General ............................................................................................................................................................. 14

7.1.2 Other properties ........................................................................................................................................... 15

7.2 Supports with steel angles ......................................................................................................................... 15

7.2.1 General ............................................................................................................................................................. 15

7.2.2 Strength ............................................................................................................................................................ 17

7.2.3 Ductility ............................................................................................................................................................ 23

7.2.4 Dissipation ...................................................................................................................................................... 23

7.2.5 Deformation ................................................................................................................................................... 23

7.2.6 Cyclic decay ..................................................................................................................................................... 23

7.2.7 Damage ............................................................................................................................................................. 24

7.3 Supports with steel shoes .......................................................................................................................... 24

Error! Reference source not found.
iii
---------------------- Page: 3 ----------------------
Error! Reference source not found.

7.3.1 General ............................................................................................................................................................. 24

7.3.2 Strength ........................................................................................................................................................... 24

7.3.3 Ductility ........................................................................................................................................................... 30

7.3.4 Dissipation ...................................................................................................................................................... 30

7.3.5 Deformation ................................................................................................................................................... 30

7.3.6 Cyclic decay .................................................................................................................................................... 31

7.3.7 Damage ............................................................................................................................................................ 31

7.4 Welded supports .......................................................................................................................................... 31

7.4.1 General ............................................................................................................................................................. 31

7.4.2 Strength ........................................................................................................................................................... 31

7.4.3 Other properties ........................................................................................................................................... 34

7.5 Hybrid connections ..................................................................................................................................... 34

7.5.1 General ............................................................................................................................................................. 34

7.5.2 Strength ........................................................................................................................................................... 34

7.5.3 Other properties ........................................................................................................................................... 37

8 Beam-to-column connections .................................................................................................................. 37

8.1 Cast-in-situ joints ......................................................................................................................................... 38

8.1.1 General ............................................................................................................................................................. 38

8.1.2 Strength ........................................................................................................................................................... 40

8.1.3 Ductility ........................................................................................................................................................... 42

8.1.4 Dissipation ...................................................................................................................................................... 42

8.1.5 Deformation ................................................................................................................................................... 42

8.1.6 Cyclic decay .................................................................................................................................................... 42

8.1.7 Damage ............................................................................................................................................................ 42

8.2 Dowel connections ....................................................................................................................................... 42

8.2.1 General ............................................................................................................................................................. 42

8.2.2 Strength ........................................................................................................................................................... 43

8.2.3 Ductility ........................................................................................................................................................... 49

8.2.4 Dissipation ...................................................................................................................................................... 49

8.2.5 Deformation ................................................................................................................................................... 49

8.2.6 Cyclic decay .................................................................................................................................................... 49

8.2.7 Damage ............................................................................................................................................................ 50

8.3 Mechanical coupler connections ............................................................................................................ 50

8.3.1 General ............................................................................................................................................................. 50

8.3.2 Strength ........................................................................................................................................................... 51

8.3.3 Ductility ........................................................................................................................................................... 52

8.3.4 Dissipation ...................................................................................................................................................... 52

8.3.5 Deformation ................................................................................................................................................... 52

8.3.6 Cyclic decay .................................................................................................................................................... 52

8.3.7 Damage ............................................................................................................................................................ 52

8.4 Hybrid connections ..................................................................................................................................... 53

8.4.1 General ............................................................................................................................................................. 53

8.4.2 Strength ........................................................................................................................................................... 53

8.4.3 Ductility ........................................................................................................................................................... 56

8.4.4 Dissipation ...................................................................................................................................................... 56

8.4.5 Deformation ................................................................................................................................................... 56

8.4.6 Cyclic decay .................................................................................................................................................... 57

8.4.7 Damage ............................................................................................................................................................ 57

9 Column-to-foundation connections ....................................................................................................... 57

9.1 Pocket foundations ...................................................................................................................................... 57

9.1.1 General ............................................................................................................................................................. 57

9.1.2 Strength ........................................................................................................................................................... 57

Error! Reference source not found.
---------------------- Page: 4 ----------------------
Error! Reference source not found.

9.1.3 Other properties ........................................................................................................................................... 58

9.2 Foundations for columns with protruding bars ................................................................................ 58

9.2.1 General ............................................................................................................................................................. 58

9.2.2 Strength ............................................................................................................................................................ 59

9.2.3 Ductility ............................................................................................................................................................ 61

9.2.4 Dissipation ...................................................................................................................................................... 61

9.2.5 Deformation ................................................................................................................................................... 61

9.2.6 Cyclic decay ..................................................................................................................................................... 61

9.2.7 Damage ............................................................................................................................................................. 61

9.3 Foundations with bolted sockets ............................................................................................................ 62

9.3.1 General ............................................................................................................................................................. 62

9.3.2 Strength ............................................................................................................................................................ 63

9.3.3 Ductility ............................................................................................................................................................ 65

9.3.4 Dissipation ...................................................................................................................................................... 66

9.3.5 Deformation ................................................................................................................................................... 66

9.3.6 Cyclic decay ..................................................................................................................................................... 66

9.3.7 Damage ............................................................................................................................................................. 66

9.4 Foundations with bolted flanges ............................................................................................................. 67

9.4.1 General ............................................................................................................................................................. 67

9.4.2 Strength ............................................................................................................................................................ 68

9.4.3 Other properties ........................................................................................................................................... 68

9.5 Foundations with mechanical couplers ................................................................................................ 68

9.5.1 General ............................................................................................................................................................. 68

9.5.2 Strength ............................................................................................................................................................ 68

9.5.3 Ductility ............................................................................................................................................................ 70

9.5.4 Dissipation ...................................................................................................................................................... 70

9.5.5 Deformation ................................................................................................................................................... 70

9.5.6 Cyclic decay ..................................................................................................................................................... 70

9.5.7 Damage ............................................................................................................................................................. 70

10 Calculation of actions .................................................................................................................................. 70

10.1 General criteria ............................................................................................................................................. 70

10.2 Capacity design .............................................................................................................................................. 70

Error! Reference source not found.
---------------------- Page: 5 ----------------------
Error! Reference source not found.
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national

standards bodies (ISO member bodies). The work of preparing International Standards is normally

carried out through ISO technical committees. Each member body interested in a subject for which a

technical committee has been established has the right to be represented on that committee.

International organizations, governmental and non‐governmental, in liaison with ISO, also take part in

the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all

matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT)

see www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 71, Concrete, reinforced concrete and pre-

stressed concrete, Subcommittee SC 5, Simplified design standard for concrete structures.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
Error! Reference source not found.
---------------------- Page: 6 ----------------------
Error! Reference source not found.
Introduction

This document contains a set of practical provisions for the design of the mechanical connections in

precast elements under seismic actions. Design of the connections is carried out in terms of strength

verifications. Indications are also provided for defining the actions to be used in design.

If national standards provide alternate formulae for the same typology, those can be used instead of the

ones given in this document.
Error! Reference source not found.
vii
---------------------- Page: 7 ----------------------
Error! Reference source not found. Error! Reference source not found.
Simplified design for mechanical connections between precast
concrete structural elements in buildings
1 Scope

This document refers to connections in precast frame systems, either for single‐storey or multi‐storey

buildings. The connections for all orders of joints are considered. Large wall panel and three‐

dimensional cell systems are not considered.

According to the position in the overall construction and of the consequent different structural

functions, the seven following orders of joints are considered:

a) mutual joints between floor or roof elements (floor‐to‐floor) that, in the seismic behaviour of the

structural system, concern the diaphragm action of the floor;

b) joints between floor or roof elements and supporting beams (floor‐to‐beam) that give the peripheral

constraints to the floor diaphragm in its seismic behaviour;

c) joints between beam and column (beam‐to‐column) that ensure in any direction the required degree

of restraint in the frame system;

d) joints between column segments (column‐to‐column) used for multi‐storey buildings usually for

dual wall braced systems;

e) joints between column and foundation (column‐to‐foundation), able to ensure in any plane a fixed

full support of the column;

f) fastenings of cladding panels to the structure (panel‐to‐structure) that ensure the stability of the

panels under the high forces or the large drifts expected under seismic action;

g) joints between adjacent cladding panels (panel‐to‐panel) possibly used to increase the stiffness of

the peripheral wall system and provide an additional source of energy dissipation.

Simple bearings working by gravity load friction are not considered. Sliding and elastic deformable

supporting devices neither, being all these types of connections not suitable for the transmission of

seismic actions.

The document provides formulae for the strength design of a large number of joint typologies.

2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

Error! Reference source not found.
---------------------- Page: 8 ----------------------
Error! Reference source not found.
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
union
generic linking constraint between two or more members
3.2
connection
local region that includes the union (3.1) between two or more members
3.3
connector
linking device (usually metallic) interposed between the parts to be connected
3.4
node
local region of convergence between different members
3.5
joint
equipped interface between adjacent members
3.6
system

set of linking practices classified on the basis of the execution technology

3.7
typical joint

dry joint (3.5) with mechanical connectors (3.3) generally composed of angles, plates, channel bars,

anchors, fasteners, bolts, dowel bars, etc., including joints completed in‐situ with mortar for filling or

fixing
3.8
emulative joint

wet joint (3.5) with rebar splices and cast‐in‐situ concrete restoring the monolithic continuity typical of

cast‐in‐situ structures and leading usually to “moment‐resisting” unions (3.1)
3.9
strength
maximum value of the force which can be transferred between the parts
3.10
ductility
ultim
...

INTERNATIONAL ISO
STANDARD 20987
First edition
2019-10
Simplified design for mechanical
connections between precast concrete
structural elements in buildings
Conception simplifiée pour les assemblages mécaniques entre
éléments structurels en béton préfabriqué dans les bâtiments
Reference number
ISO 20987:2019(E)
ISO 2019
---------------------- Page: 1 ----------------------
ISO 20987:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 20987:2019(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................vi

Introduction ..............................................................................................................................................................................................................................vii

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Properties ....................................................................................................................................................................................................................3

5 Classification ............................................................................................................................................................................................................4

5.1 General ........................................................................................................................................................................................................... 4

5.2 Strength ......................................................................................................................................................................................................... 4

5.3 Ductility ......................................................................................................................................................................................................... 4

5.3.1 Ductile connections ....................................................................................................................................................... 4

5.4 Dissipation .................................................................................................................................................................................................. 5

5.5 Deformation .............................................................................................................................................................................................. 5

6 Floor-to-floor connections .........................................................................................................................................................................5

6.1 Cast-in-situ topping ............................................................................................................................................................................ 5

6.1.1 General...................................................................................................................................................................................... 5

6.1.2 Strength ................................................................................................................................................................................... 6

6.1.3 Other properties ............................................................................................................................................................... 6

6.2 Cast-in-situ joints .................................................................................................................................................................................. 6

6.2.1 General...................................................................................................................................................................................... 6

6.2.2 Strength ................................................................................................................................................................................... 6

6.2.3 Other properties ............................................................................................................................................................... 7

6.3 Welded steel connectors ................................................................................................................................................................. 7

6.3.1 General...................................................................................................................................................................................... 7

6.3.2 Strength ................................................................................................................................................................................... 7

6.3.3 Other properties ............................................................................................................................................................10

6.4 Bolted steel connectors ................................................................................................................................................................10

6.4.1 General...................................................................................................................................................................................10

6.4.2 Strength ................................................................................................................................................................................10

6.4.3 Other properties ............................................................................................................................................................13

7 Floor-to-beam connections ....................................................................................................................................................................14

7.1 Cast-in-situ joints ...............................................................................................................................................................................14

7.1.1 General...................................................................................................................................................................................14

7.1.2 Other properties ............................................................................................................................................................14

7.2 Supports with steel angles .........................................................................................................................................................14

7.2.1 General...................................................................................................................................................................................14

7.2.2 Strength ................................................................................................................................................................................16

7.2.3 Ductility ................................................................................................................................................................................22

7.2.4 Dissipation .........................................................................................................................................................................22

7.2.5 Deformation ......................................................................................................................................................................23

7.2.6 Cyclic decay .................. .................................................... ..................................................................................................23

7.2.7 Damage ..................................................................................................................................................................................23

7.3 Supports with steel shoes ...........................................................................................................................................................23

7.3.1 General...................................................................................................................................................................................23

7.3.2 Strength ................................................................................................................................................................................23

7.3.3 Ductility ................................................................................................................................................................................30

7.3.4 Dissipation .........................................................................................................................................................................30

7.3.5 Deformation ......................................................................................................................................................................30

7.3.6 Cyclic decay .................. .................................................... ..................................................................................................30

7.3.7 Damage ..................................................................................................................................................................................30

7.4 Welded supports.................................................................................................................................................................................30

7.4.1 General...................................................................................................................................................................................30

© ISO 2019 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 20987:2019(E)

7.4.2 Strength ................................................................................................................................................................................31

7.4.3 Other properties ............................................................................................................................................................33

7.5 Hybrid connections ..........................................................................................................................................................................34

7.5.1 General...................................................................................................................................................................................34

7.5.2 Strength ................................................................................................................................................................................34

7.5.3 Other properties ............................................................................................................................................................37

8 Beam-to-column connections ..............................................................................................................................................................37

8.1 Cast-in-situ joints ...............................................................................................................................................................................38

8.1.1 General...................................................................................................................................................................................38

8.1.2 Strength ................................................................................................................................................................................39

8.1.3 Ductility ................................................................................................................................................................................41

8.1.4 Dissipation .........................................................................................................................................................................42

8.1.5 Deformation ......................................................................................................................................................................42

8.1.6 Cyclic decay .................. .................................................... ..................................................................................................42

8.1.7 Damage ..................................................................................................................................................................................42

8.2 Dowel connections............................................................................................................................................................................42

8.2.1 General...................................................................................................................................................................................42

8.2.2 Strength ................................................................................................................................................................................43

8.2.3 Ductility ................................................................................................................................................................................49

8.2.4 Dissipation .........................................................................................................................................................................49

8.2.5 Deformation ......................................................................................................................................................................49

8.2.6 Cyclic decay .................. .................................................... ..................................................................................................49

8.2.7 Damage ..................................................................................................................................................................................50

8.3 Mechanical coupler connections ..........................................................................................................................................50

8.3.1 General...................................................................................................................................................................................50

8.3.2 Strength ................................................................................................................................................................................51

8.3.3 Ductility ................................................................................................................................................................................52

8.3.4 Dissipation .........................................................................................................................................................................52

8.3.5 Deformation ......................................................................................................................................................................52

8.3.6 Cyclic decay .................. .................................................... ..................................................................................................52

8.3.7 Damage ..................................................................................................................................................................................52

8.4 Hybrid connections ..........................................................................................................................................................................53

8.4.1 General...................................................................................................................................................................................53

8.4.2 Strength ................................................................................................................................................................................53

8.4.3 Ductility ................................................................................................................................................................................56

8.4.4 Dissipation .........................................................................................................................................................................56

8.4.5 Deformation ......................................................................................................................................................................57

8.4.6 Cyclic decay .................. .................................................... ..................................................................................................57

8.4.7 Damage ..................................................................................................................................................................................57

9 Column-to-foundation connections ...............................................................................................................................................57

9.1 Pocket foundations ...........................................................................................................................................................................57

9.1.1 General...................................................................................................................................................................................57

9.1.2 Strength ................................................................................................................................................................................57

9.1.3 Other properties ............................................................................................................................................................58

9.2 Foundations for columns with protruding bars ......................................................................................................58

9.2.1 General...................................................................................................................................................................................58

9.2.2 Strength ................................................................................................................................................................................59

9.2.3 Ductility ................................................................................................................................................................................61

9.2.4 Dissipation .........................................................................................................................................................................61

9.2.5 Deformation ......................................................................................................................................................................61

9.2.6 Cyclic decay .................. .................................................... ..................................................................................................61

9.2.7 Damage ..................................................................................................................................................................................61

9.3 Foundations with bolted sockets .........................................................................................................................................62

9.3.1 General...................................................................................................................................................................................62

9.3.2 Strength ................................................................................................................................................................................63

9.3.3 Ductility ................................................................................................................................................................................65

9.3.4 Dissipation .........................................................................................................................................................................66

iv © ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 20987:2019(E)

9.3.5 Deformation ......................................................................................................................................................................66

9.3.6 Cyclic decay .................. .................................................... ..................................................................................................66

9.3.7 Damage ..................................................................................................................................................................................66

9.4 Foundations with bolted flanges ..........................................................................................................................................67

9.4.1 General...................................................................................................................................................................................67

9.4.2 Strength ................................................................................................................................................................................67

9.4.3 Other properties ............................................................................................................................................................68

9.5 Foundations with mechanical couplers ..........................................................................................................................68

9.5.1 General...................................................................................................................................................................................68

9.5.2 Strength ................................................................................................................................................................................68

9.5.3 Ductility ................................................................................................................................................................................69

9.5.4 Dissipation .........................................................................................................................................................................70

9.5.5 Deformation ......................................................................................................................................................................70

9.5.6 Cyclic decay .................. .................................................... ..................................................................................................70

9.5.7 Damage ..................................................................................................................................................................................70

10 Calculation of actions....................................................................................................................................................................................70

10.1 General criteria ....................................................................................................................................................................................70

10.2 Capacity design ....................................................................................................................................................................................70

© ISO 2019 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 20987:2019(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso

.org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 71, Concrete, reinforced concrete and pre-

stressed concrete, Subcommittee SC 5, Simplified design standard for concrete structures.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/members .html.
vi © ISO 2019 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 20987:2019(E)
Introduction

This document contains a set of practical provisions for the design of the mechanical connections in

precast elements under seismic actions. Design of the connections is carried out in terms of strength

verifications. Indications are also provided for defining the actions to be used in design.

If national standards provide alternate formulae for the same typology, those can be used instead of the

ones given in this document.
© ISO 2019 – All rights reserved vii
---------------------- Page: 7 ----------------------
INTERNATIONAL STANDARD ISO 20987:2019(E)
Simplified design for mechanical connections between
precast concrete structural elements in buildings
1 Scope

This document refers to connections in precast frame systems, either for single-storey or multi-

storey buildings. The connections for all orders of joints are considered. Large wall panel and three-

dimensional cell systems are not considered.

According to the position in the overall construction and of the consequent different structural

functions, the seven following orders of joints are considered:

a) mutual joints between floor or roof elements (floor-to-floor) that, in the seismic behaviour of the

structural system, concern the diaphragm action of the floor;

b) joints between floor or roof elements and supporting beams (floor-to-beam) that give the peripheral

...

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