ISO 22762-1:2005

Elastomeric seismic-protection isolators — Part 1: Test methods

ISO 22762 applies to elastomeric seismic isolators used to provide buildings or bridges with protection from earthquake damage. The isolators covered consist of alternate elastomer 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. ISO 22762-1:2005 specifies the test methods for determination of the characteristics of elastomeric seismic isolators and for measurement of the properties of the rubber material used in their manufacture. The specifications cover testing for all properties required in the elastomeric isolators, such as compression and shear properties, the durability of the isolators and the physical properties of the materials used in isolators.

Appareils d'appuis structuraux en élastomère pour protection sismique — Partie 1: Méthodes d'essai

General Information

• Status: Withdrawn
• Publication Date: 21-Jul-2005
• Withdrawal Date: 21-Jul-2005
• ICS: 83.140.99 - Other rubber and plastics products
• Technical Committee: ISO/TC 45/SC 4 - Products (other than hoses)
• Drafting Committee: ISO/TC 45/SC 4/WG 9 - Elastomeric isolators
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 21-Oct-2010

Relations

• Revised: ISO 22762-1:2010 - Elastomeric seismic-protection isolators — Part 1: Test methods
• Effective Date: 12-May-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 22762-1
First edition
2005-07-15


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 22762-1:2005(E)
©
ISO 2005

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ISO 22762-1:2005(E)
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ii © ISO 2005 – All rights reserved

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ISO 22762-1:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 2
4 Symbols and abbreviated terms. 4
5 Rubber material tests . 10
5.1 Test items. 10
5.2 Test conditions and test pieces . 10
5.3 Tensile properties . 10
5.4 Ageing test. 11
5.5 Hardness. 11
5.6 Adhesion. 11
5.7 Compression set . 11
5.8 Dynamic shear properties. 11
5.9 Fracture properties . 14
5.10 Brittleness point. 14
5.11 Ozone resistance . 14
5.12 Low temperature crystallization . 14
6 Isolator tests. 15
6.1 General. 15
6.2 Compression and shear stiffness tests. 15
6.3 Various dependence tests. 26
6.4 Ultimate shear properties. 39
6.5 Tensile testing . 41
6.6 Durability testing. 44
6.7 Reaction force due to low-rate deformation. 51
Annex A (normative) Determination of accelerated ageing conditions equivalent to expected life
at 23 °C . 54
Annex B (normative) Inertia force correction . 57
Annex C (normative) Friction force correction. 59
Annex D (normative) Determination of coefficient of linear thermal expansion . 62
Annex E (informative) Confirmation list . 64
Annex F (informative) Alternative methods of determining shear properties. 66
Annex G (informative) Creep test.68
Annex H (informative) Determination of reaction force due to low-rate deformation . 70
Annex I (informative) Durability investigation of elastomeric isolators used for 10 years in a
bridge . 72
Annex J (informative) Durability investigation of elastomeric isolators used for 7 years in a
building . 74
Bibliography . 78

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ISO 22762-1:2005(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 22762-1 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee
SC 4, Products (other than hoses).
ISO 22762 consists of the following parts, under the general title Elastomeric seismic-protection isolators:
 Part 1: Test methods
 Part 2: Applications for bridges — Specifications
 Part 3: Applications for buildings — Specifications
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ISO 22762-1:2005(E)
Introduction
This International Standard contains two parts related to specifications for isolators — one for bridges and the
other for buildings — since the requirements for isolators for bridges and for buildings are quite different,
although the basic concept of the two products is similar. Therefore, when this International Standard is
applied to the design of bridge isolators, Part 2 and the relevant clauses in Part 1 are used and, when it is
applied to building isolators, Part 3 and the relevant clauses in Part 1 are used.
The main differences to be noted between isolators for bridges and isolators for buildings are as below:
a) Isolators for bridges are mainly rectangular in shape and those for buildings 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 that are neither buildings nor bridges (e.g. tanks), the structural engineer may use either Part 2
or Part 3 of this International Standard, depending on the requirements of the structure.
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INTERNATIONAL STANDARD ISO 22762-1:2005(E)

Elastomeric seismic-protection isolators —
Part 1:
Test methods
1 Scope
ISO 22762 applies to elastomeric seismic isolators used to provide buildings or bridges with protection from
earthquake damage. The isolators covered consist of alternate rubber 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.
This part of ISO 22762 specifies the test methods for determination of the characteristics of elastomeric
seismic isolators and for measurement of the properties of the rubber material used in their manufacture.
The specifications cover testing for all properties required in the elastomeric isolators, such as compression
and shear properties, the durability of the isolators and the physical properties of the materials used in
isolators.
Annex E may be used to review those requirements needing confirmation prior to the test programme.
2 Normative references
The following referenced documents are indispensable for the application 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 — Determination of low-temperature brittleness
ISO 813, Rubber, vulcanized or thermoplastic — Determination of adhesion to a rigid substrate — 90° peel
method
ISO 815, Rubber, vulcanized or thermoplastic — Determination of compression set at ambient, elevated or
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 modulus in shear or adhesion to rigid
plates — Quadruple shear method
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ISO 22762-1:2005(E)
ISO 3387, Rubber — Determination of crystallization effects by hardness measurements
ISO 4664-1, Rubber, vulcanized or thermoplastic — Determination of dynamic properties — Part 1: General
considerations
ISO 7500-1:2004, Metallic materials — Verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Verification and calibration of the force-measuring system
ISO 7619-2, Rubber, vulcanized or thermoplastic — Determination of indentation hardness — Part 2: IRHD
pocket meter method
ISO 11346:2004, Rubber, vulcanized or thermoplastic — Estimation of life-time and maximum temperature of
use
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.
3.1
breaking
rupture of elastomeric isolator due to compression (or tension)-shear loading
3.2
buckling
state when elastomeric isolators lose their stability under compression-shear loading
3.3
compressive properties of elastomeric isolator
compressive stiffness (K ) for all types of rubber bearings
v
3.4
compressive-shear testing machine
machine used to test elastomeric isolators, 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 for the purpose of protecting the inner rubber from deterioration due to oxygen, ultraviolet
rays and other natural elements and protecting the reinforcing plates from corrosion
3.6
design compressive stress
long term compressive force on the elastomeric isolator imposed by the structure
3.7
effective loaded area
area sustaining vertical load in elastomeric isolators, which corresponds to the area of reinforcing steel plates
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ISO 22762-1:2005(E)
3.8
effective width
〈rectangular elastomeric isolator〉 the smaller of the two side lengths of inner rubber to which direction shear
displacement is not restricted
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
NOTE Types of such isolators include high-damping rubber bearings, linear natural rubber bearings and lead rubber
bearings.
3.10
first shape factor
ratio of effectively loaded area to free deformation area of one inner rubber layer between steel plates
3.11
high-damping rubber bearing
HDR
elastomeric isolator with relatively high damping properties obtained by special compounding of the rubber
and the use of additives
3.12
inner rubber
rubber between multi-layered steel plates inside an elastomeric isolator
3.13
lead rubber bearing
LRB
elastomeric isolator whose inner rubber 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 with linear shear force-deflection characteristics and relatively low damping properties and
fabricated using natural rubber
NOTE Any bearing with relatively low damping may be treated as an LNR bearing for the purposes of isolator testing.
3.15
maximum compressive stress
maximum compressive stress acting briefly on elastomeric isolators during an earthquake
3.16
nominal compressive stress
long-term compressive stress recommended by the manufacturer for the isolator, including the safety margin
3.17
roll-out
instability of an isolator with either dowelled or recessed connection under shear displacement
3.18
routine test
a test for quality control of the production isolators during and after manufacturing
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ISO 22762-1:2005(E)
3.19
second shape factor
〈circular elastomeric isolator〉 ratio of the diameter of the inner rubber to the total thickness of the inner rubber
〈rectangular or square elastomeric isolator〉 ratio of the effective width of the inner rubber to the total thickness
of the inner rubber
3.20
shear properties of elastomeric isolators
a comprehensive term that covers characteristics determined from isolator tests:
 shear stiffness (K ) for LNR;
h
 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
structural engineer
engineer who is in charge of designing of structure for base-isolated bridges or buildings and is responsible for
specifying the requirements for elastomeric isolators
3.22
type test
test for verification either of material properties and isolator performances during development of the product
or that project design parameters are achieved
3.23
ultimate properties
properties at either buckling, breaking, or roll-out of an isolator under compression-shear loading
3.24
ultimate property diagram
UPD
diagram giving the interaction curve of compressive stress and buckling strain or breaking strain of an
elastomeric isolator
4 Symbols and abbreviated terms
For the purposes of all three parts of ISO 22762, the symbols given in Table 1 apply.
Table 1 — Symbols and definitions
Symbol Definition
A effective plan area; plan area of elastomeric isolator excluding cover rubber portion
A
effective area of bolt
b
A overlap area between the top and bottom elastomer area of isolator sheared under non-seismic
e
displacement
A
load-free area of isolator
free
A
loaded area of isolator
load
A
p area of the lead plug for a lead rubber bearing
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ISO 22762-1:2005(E)
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
e

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
f
d
inner diameter of reinforcing steel plate
i
d
diameter of bolt hole
k
d
outer diameter of reinforcing steel plate
o
E
ap apparent Young’s modulus of bonded rubber layer
E
apparent Young’s modulus corrected, if necessary, by allowing for compressibility
c
s
apparent Young’s modulus corrected for bulk compressibility depending on its shape factor (S )
E
1
c

E
bulk modulus of rubber
∞
E
Young’s modulus of rubber
0
F
tensile force on isolator by uplift
u
G
shear modulus
G γ equivalent linear shear modulus at shear strain γ
( )
eq
H height of elastomeric isolator including mounting flange
H
height of elastomeric isolator excluding mounting flange
n
h
eq equivalent damping ratio
h γ
( )
equivalent damping ratio as a function of shear strain
eq
K
post-yield stiffness (tangential stiffness after yielding of lead plug) of lead rubber bearing
d
K
shear stiffness
h
K
initial shear stiffness
i

K
p shear stiffness of lead plug inserted in lead rubber bearing
K
shear stiffness of lead rubber bearing before inserting lead plug
r
K
tangential shear stiffness
t

K
compressive stiffness
v
L
length of one side of a square flange
f
M resistance to rotation
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ISO 22762-1:2005(E)
M
moment acting on bolt
f
M
moment acting on isolator
r
n
number of rubber layers
n
number of fixing bolts
b
P compressive force
P
design compressive force
0

P
maximum design compressive force
max
P
minimum design compressive force
min
Q
shear force
Q
shear force at break
b
Q
shear force at buckling
buk
Q
characteristic strength
d
S
first shape factor
1
S
second shape factor
2
T temperature
T total rubber thickness, given by T = nt×
r r r
t
thickness of one rubber layer
r
tt,
thickness of rubber layer laminated on each side of plate
r1 r2
t
thickness of one reinforcing steel plate
s
t
thickness of outside cover rubber
o
U γ
( ) function giving ratio of characteristic strength to maximum shear force of a loop

V
uplift force
v
loading velocity
W
energy dissipated per cycle
d
X shear displacement
X
design shear displacement
0

X
shear displacement at break
b
X
shear displacement at buckling
buk
X
shear displacement due to quasi-static shear movement
s

X
maximum design shear displacement
max
X
shear displacement due to dynamic shear movement
d
Y compressive displacement
Z section modulus of flange
α
coefficient of linear thermal expansion

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ISO 22762-1:2005(E)
γ
shear strain
γ
design shear strain
0
γ
upper limit of the total of design strains on elastomeric isolators
a
γ
shear strain at break
b
γ
local shear strain due to compressive force
c
γ
shear strain due to dynamic shear movement
d

γ
maximum shear strain during earthquake
max
γ
local shear strain due to rotation
r
γ
shear strain due to quasi-static shear movement
s
γ
ultimate shear strain
u
δ
horizontal offset of isolator
H
δ
difference in isolator height measured between two points at opposite extremes of the isolator
V
ε
compressive strain of isolator
ε
creep strain
cr

ε
tensile strain of isolator
T
ε
tensile-break strain of isolator
Tb
ε
Ty tensile-yield strain of isolator
ζ
ratio of total rubber height to total height of rubber and steel layers
θ
rotation angle of isolator about the diameter of a circular bearing or about an axis through a
rectangular bearing
θ
rotation angle of isolator in the longitudinal direction (a)
a
θ
rotation angle of isolator in the transverse direction (b)
b
λ
correction factor for calculation of stress in reinforcing steel plates
η
correction factor for calculation of critical stress
κ correction factor for apparent Young’s modulus according to hardness
Σγ
total local shear strain
σ
compressive stress in isolator
σ
design compressive stress
0
σ
tensile stress in bolt
B
σ
bending stress in flange
b
σ
b allowable bending stress in steel
f
σ
critical stress in isolator
cr
σ
allowable tensile stress in steel
f
σ
maximum design compressive stress
max
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ISO 22762-1:2005(E)
σ
minimum design compressive stress
min
σ
for building: nominal long term compressive stress recommended by manufacturer
nom
σ
tensile stress in reinforcing steel plate
s
σ
allowable tensile stress in steel plate
sa

σ
sy yield stress of steel for flanges and reinforcing steel plates
σ
tensile strength of steel for flanges and reinforcing steel plates
su
σ
tensile stress
t
σ
allowable tensile stress in isolator
te

σ
yi yield stress in steel plate
τ
shear stress in bolt
B
τ
allowable shear stress in steel
f
φ
factor for computation of buckling stability
ψ
factor for computation of buckling check
ξ
factor for computation of critical stress

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ISO 22762-1:2005(E)

a) Circular type b) Rectangular type
(lhs of drawings shows LNR and HDR, rhs shows LRB) (lhs of drawings shows LNR and HDR, rhs shows LRB)

Key
1 cover rubber cured with insulator
2 cover rubber added after isolator cured
3 lead plug
Figure 1 — Cross-section of isolator
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ISO 22762-1:2005(E)
5 Rubber material tests
5.1 Test items
In order to assure the required quality of elastomeric isolators, it is necessary to specify the physical
properties of the rubber materials and the adhesion between the rubber and the steel plates. The basic
properties of rubber materials related to performance of elastomeric isolators are shown as test items in
Table 2.
Table 2 — Test items of rubber materials
Properties Test items Related standard(s)
Tensile properties Tensile strength ISO 37
Elongation at break
100 % modulus
Ageing properties Tensile strength ISO 188
Elongation at break ISO 37

100 % modulus
Hardness Hardness ISO 48
ISO 7619-2
Adhesion 90° peel strength between metal and rubber ISO 813
Classification of fracture mode
Compression set Compression set ISO 815
Shear properties Shear modulus ISO 4664-1
Equivalent damping ratio
Temperature dependence of shear modulus and
equivalent damping ratio
Repeated deformation dependence of shear modulus
and equivalent damping ratio
Fracture strength ISO 1827
Fracture strain
Brittleness point Brittleness temperature ISO 812
Inspection of deterioration
Ozone resistance ISO 1431-1 (static strain
(ozone cracking test on test)
vulcanized rubber)
Low temperature Hardness ISO 3387
crystallization

5.2 Test conditions and test pieces
The temperature and humidity in the laboratory, the preparation of test pieces, and methods for measuring
thickness and width, etc., shall be in accordance with ISO 23529.
Moulded test pieces shall be used. They shall be cured to have properties as similar as practicable to the
rubber in the bulk of the isolator.
5.3 Tensile properties
The tensile test should preferably be carried out by the method specified in ISO 37. However, the test piece
specified in Table 3 can be used.
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ISO 22762-1:2005(E)
Table 3 — Test piece dimensions
Dimensions in millimetres
Width of parallel-sided Length of parallel-sided Thickness of parallel- Distance between
section section sided section marked lines
5 ± 0,1 20 2,0 ± 0,2 20

5.4 Ageing test
5.4.1 Ageing properties of inner rubber
5.4.1.1 Anaerobic ageing
A set of ageing tests shall be performed on the inner rubber under anaerobic conditions as described in
Annex A. The properties monitored shall be either 100 % shear modulus and shear failure strain or the tensile
properties — 100 % modulus, tensile strength and elongation at break. From the results of these tests, the
activation energy is obtained based on the method specified in Annex A. Ageing conditions equivalent to the
expected lifetime (60 years or the period specified by the structural engineer) at 23 °C shall be determined
from this activation energy, and an ageing test shall then be performed for the properties monitored under
conditions equivalent to the expected lifetime.
5.4.1.2 Air ageing
An ageing test shall be performed on the inner rubber in accordance with the method specified in ISO 188,
monitoring the tensile strength and elongation at break. The test time and temperature shall be as specified in
ISO 22762-2 or ISO 22762-3.
5.4.2 Ageing properties of cover rubber
An ageing test shall be performed on the cover rubber in accordance with the method specified in ISO 188,
monitoring the tensile strength and elongation at break. The test time and temperature shall be as specified in
ISO 22762-2 or ISO 22762-3.
5.5 Hardness
Hardness shall be me
...