Elastomeric seismic-protection isolators

This document specifies the test methods for determination of a) the properties of the rubber material used to manufacture the elastomeric seismic isolators, and b) the characteristics of elastomeric seismic isolators. It is applicable to elastomeric seismic isolators used to provide buildings or bridges with protection from earthquake damage. The isolators covered consist of alternate elastomeric layers and reinforcing steel plates which 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
24-Sep-2018
Current Stage
6060 - International Standard published
Start Date
01-Sep-2018
Completion Date
25-Sep-2018
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INTERNATIONAL ISO
STANDARD 22762-1
Third edition
2018-10
Elastomeric seismic-protection
isolators —
Part 1:
Test methods
Appareils d'appuis structuraux en élastomère pour protection
sismique —
Partie 1: Méthodes d'essai
Reference number
ISO 22762-1:2018(E)
ISO 2018
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ISO 22762-1:2018(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 22762-1:2018(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Symbols and cross-section of isolator ............................................................................................................................................ 4

4.1 Symbols ......................................................................................................................................................................................................... 4

4.2 Cross-section of isolator ................................................................................................................................................................. 7

5 Rubber material tests ...................................................................................................................................................................................... 9

5.1 Test items ..................................................................................................................................................................................................... 9

5.2 Test conditions and test pieces ................................................................................................................................................. 9

5.3 Tensile properties ................................................................................................................................................................................. 9

5.4 Ageing test ...............................................................................................................................................................................................10

5.4.1 Ageing properties of inner rubber ................................................................................................................10

5.4.2 Ageing properties of cover rubber ................................................................................................................10

5.5 Hardness ....................................................................................................................................................................................................10

5.6 Adhesion ....................................................................................................................................................................................................10

5.7 Compression set ......... .........................................................................................................................................................................10

5.8 Dynamic shear properties ..........................................................................................................................................................10

5.8.1 General...................................................................................................................................................................................10

5.8.2 Test equipment ...............................................................................................................................................................11

5.8.3 Test pieces ..........................................................................................................................................................................11

5.8.4 Test conditions................................................................................................................................................................12

5.8.5 Test results .........................................................................................................................................................................12

5.9 Fracture properties ..........................................................................................................................................................................13

5.10 Brittleness point .................................................................................................................................................................................13

5.11 Ozone resistance.................................................................................................................................................................................13

5.12 Low-temperature crystallization .........................................................................................................................................13

6 Isolator tests ..........................................................................................................................................................................................................14

6.1 General ........................................................................................................................................................................................................14

6.2 Compression and shear stiffness tests ............................................................................................................................14

6.2.1 Compression properties .........................................................................................................................................14

6.2.2 Compressive-shear test ...........................................................................................................................................21

6.3 Various dependence tests ...........................................................................................................................................................27

6.3.1 Strain dependence of shear properties .....................................................................................................27

6.3.2 Compressive force dependence of shear properties ......................................................................28

6.3.3 Frequency dependence of shear properties..........................................................................................30

6.3.4 Repeated deformation dependence of shear properties ............................................................32

6.3.5 Temperature dependence of shear properties ...................................................................................34

6.3.6 Dependence of compression properties on shear strain ...........................................................36

6.3.7 Dependence of compressive stiffness on compressive stress range ................................37

6.4 Ultimate shear properties ..........................................................................................................................................................39

6.4.1 Principle ...............................................................................................................................................................................39

6.4.2 Test machine .....................................................................................................................................................................39

6.4.3 Test piece .............................................................................................................................................................................39

6.4.4 Test conditions................................................................................................................................................................39

6.4.5 Procedure ............................................................................................................................................................................40

6.4.6 Expression of results .................................................................................................................................................40

6.4.7 Test report ..........................................................................................................................................................................41

6.5 Tensile testing .......................................................................................................................................................................................41

6.5.1 Principle ...............................................................................................................................................................................41

6.5.2 Test machine .....................................................................................................................................................................42

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ISO 22762-1:2018(E)

6.5.3 Test piece .............................................................................................................................................................................42

6.5.4 Test conditions................................................................................................................................................................42

6.5.5 Procedure ............................................................................................................................................................................42

6.5.6 Expression of results .................................................................................................................................................43

6.5.7 Test report ..........................................................................................................................................................................44

6.6 Durability testing ...............................................................................................................................................................................44

6.6.1 Degradation test ............................................................................................................................................................44

6.6.2 Creep test ...................................................................... .......................................................................................................46

6.6.3 Fatigue test .........................................................................................................................................................................50

6.7 Reaction force due to low-rate deformation ..............................................................................................................52

6.7.1 Principle ...............................................................................................................................................................................52

6.7.2 Test machine .....................................................................................................................................................................52

6.7.3 Test piece .............................................................................................................................................................................53

6.7.4 Test conditions................................................................................................................................................................53

6.7.5 Procedure ............................................................................................................................................................................53

6.7.6 Expression of result ....................................................................................................................................................54

6.7.7 Test report ..........................................................................................................................................................................54

Annex A (normative) Determination of accelerated ageing conditions equivalent to

expected life at standard laboratory temperature (23 °C or 27 °C) .............................................................55

Annex B (normative) Inertia force correction .........................................................................................................................................59

Annex C (normative) Friction force correction ......................................................................................................................................61

Annex D (normative) Determination of coefficient linear thermal expansion .....................................................64

Annex E (informative) Alternative methods of determining shear properties .....................................................66

Annex F (informative) Creep test...........................................................................................................................................................................68

Annex G (informative) Determination of reaction force due to low-rate deformation .................................70

Annex H (informative) Durability investigation of elastomeric isolators used for 10 years in

a bridge ........................................................................................................................................................................................................................73

Annex I (informative) Durability investigation of elastomeric isolators used for seven years

in a building ............................................................................................................................................................................................................75

Bibliography .............................................................................................................................................................................................................................79

iv © ISO 2018 – All rights reserved
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ISO 22762-1:2018(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 22762-1:2010), 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;

— the number of test pieces and the thickness of the metal plates have been added in 5.8.3;

— alleviation of the restriction on the upper value of the ageing temperature in 6.6.1.4.

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 22762-1:2018(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 for buildings

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

and the relevant clauses in this document are used when ISO 22762 (all parts) is applied to the design

of bridge isolators, whereas ISO 22762-3 and the relevant clauses of this document 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 22762-1:2018(E)
Elastomeric seismic-protection isolators —
Part 1:
Test methods
1 Scope
This document specifies the test methods for determination of

a) the properties of the rubber material used to manufacture the elastomeric seismic isolators, and

b) the characteristics of elastomeric seismic isolators.

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

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

steel plates which 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 37, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties

ISO 48, Rubber, vulcanized or thermoplastic — Determination of hardness (hardness between 10 IRHD and

100 IRHD)

ISO 188, Rubber, vulcanized or thermoplastic — Accelerated ageing and heat resistance tests

ISO 812, Rubber, vulcanized or thermoplastic — Determination of low-temperature brittleness

ISO 813, Rubber, vulcanized or thermoplastic — Determination of adhesion to a rigid substrate — 90

degree peel method

ISO 815-1, Rubber, vulcanized or thermoplastic — Determination of compression set — Part 1: At ambient

or elevated temperatures

ISO 815-2, Rubber, vulcanized or thermoplastic — Determination of compression set — Part 2: At low

temperatures

ISO 1431-1, Rubber, vulcanized or thermoplastic — Resistance to ozone cracking — Part 1: Static and

dynamic strain testing

ISO 1827, Rubber, vulcanized or thermoplastic — Determination of shear modulus and adhesion to rigid

plates — Quadruple-shear methods

ISO 3387, Rubber — Determination of crystallization effects by hardness measurements

ISO 4664-1, Rubber, vulcanized or thermoplastic — Determination of dynamic properties — Part 1: General

guidance
© ISO 2018 – All rights reserved 1
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ISO 22762-1:2018(E)

ISO 7500-1:2018, Metallic materials — Calibration and verification of static uniaxial testing machines —

Part 1: Tension/compression testing machines — Calibration and verification of the force-measuring system

ISO 7619-2, Rubber, vulcanized or thermoplastic — Determination of indentation hardness — Part 2: IRHD

pocket meter method

ISO 22762-2, Elastomeric seismic-protection isolators — Part 2: Applications for bridges — Specifications

ISO 22762-3, Elastomeric seismic-protection isolators — Part 3: Applications for buildings — Specifications

ISO 23529, Rubber — General procedures for preparing and conditioning test pieces for physical 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 (3.9) due to compression- (or tension-) shear loading

3.2
buckling

state when elastomeric isolators (3.9) lose their stability under compression-shear loading

3.3
compressive stiffness
compressive stiffness for all types of rubber bearings
3.4
compression-shear testing machine

machine used to test elastomeric isolators (3.9), which has the capability of shear loading under constant

compressive load
3.5
cover rubber

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

of elastomeric isolators (3.9) 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

3.6
design compressive stress

long-term compressive force on the elastomeric isolator (3.9) imposed by the structure

3.7
effective loaded area

area sustaining vertical load in elastomeric isolators (3.9), which corresponds to the area of reinforcing

steel plates
3.8
effective width

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

shear displacement is not restricted
2 © ISO 2018 – All rights reserved
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ISO 22762-1:2018(E)
3.9
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.

3.10
first shape factor

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

3.11
high-damping rubber bearing
HDR

elastomeric isolator (3.9) with relatively high damping properties obtained by special compounding of

the rubber and the use of additives
3.12
inner rubber
rubber between multi-layered steel plates inside an elastomeric isolator (3.9)
3.13
lead rubber bearing
LRB

elastomeric isolator (3.9) whose inner rubber (3.12) with a lead plug or lead plugs press fitted into a hole

or holes of the isolator body to achieve damping properties
3.14
linear natural rubber bearing
LNR

elastomeric isolator (3.9) 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.
3.15
maximum compressive stress

peak stress acting briefly on elastomeric isolators (3.9) in compressive direction during an earthquake

3.16
nominal compressive stress

long-term stress acting on elastomeric isolators (3.9) in compressive direction as recommended by the

manufacturer for the isolator, including the safety margin
3.17
post-yield stiffness
shear stiffness of LRB
3.18
roll-out

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

3.19
routine test

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

3.20
second shape factor

ratio of the diameter of the inner rubber to the total thickness of the

inner rubber
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ISO 22762-1:2018(E)
3.21
second shape factor

ratio of the effective width of the inner rubber to the total

thickness of the inner rubber
3.22
shear properties
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
3.23
shear stiffness
shear stiffness of LNR and HDR
3.24
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 (3.9)
3.25
property

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

4 Symbols and cross-section of isolator
4.1 Symbols
For the purposes of this document, the symbols given in Table 1 apply.
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
4 © ISO 2018 – All rights reserved
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ISO 22762-1:2018(E)
Table 1 (continued)
Symbol Description
d diame
...

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