Elastomeric seismic-protection isolators

This document specifies minimum requirements and test methods for elastomeric seismic isolators used for buildings and the rubber material used in the manufacture of such isolators. It is applicable to elastomeric seismic isolators used to provide buildings with protection from earthquake damage. The isolators covered consist of alternate elastomeric layers and reinforcing steel plates. They are placed between a superstructure and its substructure to provide both flexibility for decoupling structural systems from ground motion, and damping capability to reduce displacement at the isolation interface and the transmission of energy from the ground into the structure at the isolation frequency.

Appareils d'appuis structuraux en élastomère pour protection sismique

General Information

Status
Published
Publication Date
26-Sep-2018
Current Stage
6060 - International Standard published
Start Date
01-Sep-2018
Completion Date
27-Sep-2018
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ISO 22762-3:2018 - Elastomeric seismic-protection isolators
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INTERNATIONAL ISO
STANDARD 22762-3
Third edition
2018-10
Elastomeric seismic-protection
isolators —
Part 3:
Applications for buildings —
Specifications
Appareils d'appuis structuraux en élastomère pour protection
sismique —
Partie 3: Applications pour bâtiments — Spécifications
Reference number
ISO 22762-3:2018(E)
ISO 2018
---------------------- Page: 1 ----------------------
ISO 22762-3:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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

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Published in Switzerland
ii © ISO 2018 – All rights reserved
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ISO 22762-3:2018(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

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

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

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

4 Symbols .......................................................................................................................................................................................................................... 3

5 Classification ............................................................................................................................................................................................................ 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 Classification by construction .................................................................................................................................................... 7

5.3 Classification by tolerance on shear properties ......................................................................................................... 8

6 Requirement ............................................................................................................................................................................................................. 8

6.1 General ........................................................................................................................................................................................................... 8

6.2 Type tests and routine tests......................................................................................................................................................... 9

6.3 Functional requirements .............................................................................................................................................................10

6.4 Design compressive force and design shear displacement ...........................................................................10

6.5 Performance requirements .......................................................................................................................................................11

6.5.1 General...................................................................................................................................................................................11

6.5.2 Compressive properties ..........................................................................................................................................12

6.5.3 Shear properties ............................................................................................................................................................13

6.5.4 Tensile properties ........................................................................................................................................................13

6.5.5 Dependencies of shear properties .................................................................................................................14

6.5.6 Dependencies of compressive properties ...............................................................................................15

6.5.7 Shear displacement capacity ..............................................................................................................................16

6.5.8 Durability ............................................................................................................................................................................16

6.6 Rubber material requirements ..............................................................................................................................................17

6.6.1 General...................................................................................................................................................................................17

6.6.2 Tensile properties ........................................................................................................................................................17

6.6.3 Properties after ageing in air .............................................................................................................................17

6.6.4 Hardness ..............................................................................................................................................................................18

6.6.5 Ozone resistance ...........................................................................................................................................................19

6.6.6 Other properties ............................................................................................................................................................19

6.7 Dimensional requirements ........................................................................................................................................................19

6.8 Requirements on steel used for flanges and reinforcing plates .................................................................20

6.9 Requirement on lead material for LRB ...........................................................................................................................21

7 Design rules ............................................................................................................................................................................................................21

7.1 General ........................................................................................................................................................................................................21

7.2 Shape factor ............................................................................................................................................................................................21

7.2.1 First shape factor ..........................................................................................................................................................21

7.2.2 Second shape factor ...................................................................................................................................................22

7.3 Compression and shear properties ....................................................................................................................................22

7.3.1 Compressive stiffness ...............................................................................................................................................22

7.3.2 Shear stiffness and equivalent damping ratio .....................................................................................22

7.4 Ultimate properties ..........................................................................................................................................................................23

7.4.1 Stability at zero displacement ...........................................................................................................................23

7.4.2 Stability and failure under large shear displacements ................................................................24

7.4.3 Roll-out properties of isolators with recessed or dowelled connections

(Type III) ..............................................................................................................................................................................24

7.4.4 Tensile properties ........................................................................................................................................................25

7.5 Reinforcing steel plates.................................................................................................................................................................26

7.6 Connections ............................................................................................................................................................................................26

8 Manufacturing tolerances ........................................................................................................................................................................26

© ISO 2018 – All rights reserved iii
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ISO 22762-3:2018(E)

8.1 General ........................................................................................................................................................................................................26

8.2 Measuring instruments ................................................................................................................................................................27

8.3 Plan dimensions ..................................................................................................................................................................................27

8.3.1 Measurement method ..............................................................................................................................................27

8.3.2 Tolerances ...........................................................................................................................................................................28

8.4 Product height ......................................................................................................................................................................................28

8.4.1 Measurement method ..............................................................................................................................................28

8.4.2 Tolerances ...........................................................................................................................................................................29

8.5 Flatness .......................................................................................................................................................................................................29

8.5.1 Measurement method ..............................................................................................................................................29

8.5.2 Tolerances ...........................................................................................................................................................................30

8.6 Horizontal offset .................................................................................................................................................................................30

8.7 Plan dimensions of flanges ........................................................................................................................................................30

8.8 Flange thickness .................................................................................................................................................................................31

8.9 Tolerances on positions of flange bolt holes ..............................................................................................................31

9 Marking and labelling ..................................................................................................................................................................................32

9.1 General ........................................................................................................................................................................................................32

9.2 Information to be provided .......................................................................................................................................................32

9.3 Additional requirements .............................................................................................................................................................32

9.4 Marking and labelling examples ...........................................................................................................................................33

10 Test methods ..........................................................................................................................................................................................................33

11 Quality assurance .............................................................................................................................................................................................33

Annex A (normative) Tensile stress in reinforcing steel plate ...............................................................................................34

Annex B (normative) Determination of ultimate property diagram based on experimental

results ...........................................................................................................................................................................................................................36

Annex C (informative) Minimum recommended physical properties of rubber material ........................39

Annex D (informative) Effect of inner-hole diameter and second shape factor on shear

properties .................................................................................................................................................................................................................40

Annex E (informative) Determination of compressive properties of elastomeric isolators ...................43

Annex F (informative) Determination of shear properties of elastomeric isolators ......................................46

Annex G (informative) Method of predicting buckling limit at large deformations ........................................51

Annex H (informative) Design of fixing bolts and flanges ...........................................................................................................58

Bibliography .............................................................................................................................................................................................................................61

iv © ISO 2018 – All rights reserved
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ISO 22762-3:2018(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 45, Rubber and rubber products,

Subcommittee SC 4, Products (other than hoses).

This third edition cancels and replaces the second edition (ISO 22762-3:2010), which has been

technically revised.
The main changes compared to the previous edition are as follows:
— the definitions of some symbols in Clause 4 have been changed;

— a column stipulating the minimum number of test pieces has been added to Table 4;

— a new subclause (6.9) has been added.
A list of all parts in the ISO 22762 series can be found on the ISO website.

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.
© ISO 2018 – All rights reserved v
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ISO 22762-3:2018(E)
Introduction

ISO 22762 series includes two parts related to specifications for isolators, i.e. ISO 22762-2 for bridges

and ISO 22762-3 for buildings. This is because the isolator requirements for bridges and buildings are

quite different, although the basic concept of the two products is similar. Therefore, ISO 22762-2 and

the relevant clauses in ISO 22762-1 are used when ISO 22762 (all parts) is applied to the design of bridge

isolators whereas ISO 22762-3 and the relevant clauses of ISO 22762-1 are used when it is applied to

building isolators.

The main differences to be noted between isolators for bridges and isolators for buildings are the

following.

a) Isolators for bridges are mainly rectangular in shape and those for buildings are circular in shape.

b) Isolators for bridges are designed to be used for both rotation and horizontal displacement, while

isolators for buildings are designed for horizontal displacement only.

c) Isolators for bridges are designed to perform on a daily basis to accommodate length changes of

bridges caused by temperature changes as well as during earthquakes, while isolators for buildings

are designed to perform only during earthquakes.

d) Isolators for bridges are designed to withstand dynamic loads caused by vehicles on a daily basis as

well as earthquakes, while isolators for buildings are mainly designed to withstand dynamic loads

caused by earthquakes only.

For structures other than buildings and bridges (e.g. tanks), the structural engineer uses either

ISO 22762-2 or ISO 22762-3, depending on the requirements of the structure.
vi © ISO 2018 – All rights reserved
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INTERNATIONAL STANDARD ISO 22762-3:2018(E)
Elastomeric seismic-protection isolators —
Part 3:
Applications for buildings — Specifications
1 Scope

This document specifies minimum requirements and test methods for elastomeric seismic isolators

used for buildings and the rubber material used in the manufacture of such isolators.

It is applicable to elastomeric seismic isolators used to provide buildings with protection from

earthquake damage. The isolators covered consist of alternate elastomeric layers and reinforcing steel

plates. They are placed between a superstructure and its substructure to provide both flexibility for

decoupling structural systems from ground motion, and damping capability to reduce displacement

at the isolation interface and the transmission of energy from the ground into the structure at the

isolation frequency.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 630 (all parts), Structural steels

ISO 22762-1:2018, Elastomeric seismic-protection isolators — Part 1: Test methods

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:

— ISO Online browsing platform: available at http: //www .iso .org/obp/
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
breaking

rupture of elastomeric isolator (3.8) due to compression- (or tension-) shear loading

3.2
buckling

state when elastomeric isolators (3.8) lose their stability under compression-shear loading

3.3
compressive properties of elastomeric isolator
compressive stiffness for all types of rubber bearings
© ISO 2018 – All rights reserved 1
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ISO 22762-3:2018(E)
3.4
cover rubber

rubber wrapped around the outside of inner rubber and reinforcing steel plates before or after curing of

elastomeric isolators for the purposes of protecting the inner rubber from deterioration due to oxygen,

ozone and other natural elements and protecting the reinforcing plates from corrosion

3.5
design compressive stress

long-term compressive force on the elastomeric isolator (3.8) imposed by the structure

3.6
effective loaded area

area sustaining vertical load in elastomeric isolator (3.8), which corresponds to the area of reinforcing

steel plates
3.7
effective width

the smaller of the two side lengths of inner rubber to which direction

shear displacement is not restricted
3.8
elastomeric isolator

rubber bearing, for seismic isolation of buildings, bridges and other structures, which consists of multi-

layered vulcanized rubber sheets and reinforcing steel plates

EXAMPLE High-damping rubber bearings, linear natural rubber bearings and lead rubber bearings.

3.9
first shape factor

ratio of effectively loaded area to free deformation area of one inner rubber layer between steel plates

3.10
high-damping rubber bearing
HDR

elastomeric isolator with relatively high damping properties obtained by special compounding of the

rubber and the use of additives
3.11
inner rubber

rubber between multi-layered steel plates inside an elastomeric isolator elastomeric isolator (3.8)

3.12
lead rubber bearing
LRB

elastomeric isolator (3.8) whose inner rubber (3.11) with a lead plug or lead plugs press fitted into a hole

or holes of the isolator body to achieve damping properties
3.13
linear natural rubber bearing
LNR

elastomeric isolator (3.8) with linear shear force-deflection characteristics and relatively low damping

properties, fabricated using natural rubber

Note 1 to entry: Any bearing with relatively low damping can be treated as an LNR bearing for the purposes of

isolator testing.
3.14
maximum compressive stress

peak stress acting briefly on elastomeric isolators (3.8) in compressive direction during an earthquake

2 © ISO 2018 – All rights reserved
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ISO 22762-3:2018(E)
3.15
nominal compressive stress

long-term stress acting on elastomeric isolators (3.8) in compressive direction as recommended by the

manufacturer for the isolator, including the safety margin
3.16
roll-out

instability of an isolator with either dowelled or recessed connection under shear displacement

3.17
routine test

test for quality control of the production isolators during and after manufacturing

3.18
second shape factor

ratio of the diameter of the inner rubber (3.11) to the total thickness of

the inner rubber
3.19
second shape factor

ratio of the effective width of the inner rubber (3.11) to

the total thickness of the inner rubber
3.20
shear properties of elastomeric isolators
comprehensive term that covers characteristics determined from isolator tests:
— shear stiffness, K , for LNR;
— shear stiffness, K , and equivalent damping ratio, h , for HDR and LRB;
h eq
— post-yield stiffness, K , and characteristic strength, Q , for LRB
d d
3.21
standard value

value of isolator property defined by manufacturer based on the results of type test

3.22
structural engineer

engineer who is in charge of designing the structure for base-isolated bridges or buildings and is

responsible for specifying the requirements for elastomeric isolators (3.8)
3.23
type test

test for verification either of material properties and isolator performances during development of the

product or that project design parameters are achieved
3.24
ultimate properties

properties at either buckling, breaking, or roll-out of an isolator under compression-shear loading

3.25
ultimate property diagram
UPD

diagram giving the interaction curve of compressive stress and buckling strain or breaking strain of an

elastomeric isolator
4 Symbols
For the purposes of this document, the symbols given in Table 1 apply.
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ISO 22762-3:2018(E)
Table 1 — Symbols and descriptions
Symbol Description

A effective plan area; plan area of elastomeric isolator, excluding cover rubber portion

A effective area of bolt
A overlap area between the top and bottom elastomer area of isolator
A load-free area of isolator
free
A loaded area of isolator
load
A area of the lead plug for a lead rubber bearing

a side length of square elastomeric isolator, excluding cover rubber thickness, or length in longitudinal

direction of rectangular isolator, excluding cover rubber thickness

a length of the shorter side of the rectangular isolator, including cover rubber thickness

a′ length in longitudinal direction of the rectangular isolator, including cover rubber thickness

B effective width for bending of flange

b length in transverse direction of the rectangular isolator, excluding cover rubber thickness

b′ length in transverse direction of the rectangular isolator, including cover rubber thickness

c distance from centre of bolt hole to effective flange section
D′ outer diameter of circular isolator, including cover rubber
D diameter of flange
d inner diameter of reinforcing steel plate
d diameter of bolt hole
d outer diameter of reinforcing steel plate
E apparent Young's modulus of bonded rubber layer

E apparent Young's modulus corrected, if necessary, by allowing for compressibility

E apparent Young’s modulus corrected for bulk compressibility depending on its shape factor (S )

c 1
E bulk modulus of rubber
E Young's modulus of rubber
F tensile force on isolator by uplift
G shear modulus
G (γ) equivalent linear shear modulus at shear strain
H height of elastomeric isolator, including mounting flange
H height of elastomeric isolator, excluding mounting flange
h equivalent damping ratio
h (γ) equivalent damping ratio as a function of shear strain

K post-yield stiffness (tangential stiffness after yielding of lead plug) of lead rubber bearing

K shear stiffness
K initial shear stiffness
K shear stiffness of lead plug inserted in lead rubber bearing
K shear stiffness of lead rubber bearing before inserting lead plug
K tangential shear stiffness
K compressive stiffness
L length of one side of a rectangular flange
M resistance to rotation
M moment acting on bolt
M moment acting on isolator
n number of rubber layers
n number of fixing bolts
4 © ISO 2018 – All rights reserved
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