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

ISO 22762-3:2010 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 — Partie 3: Applications pour bâtiments — Spécifications

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Publication Date
20-Oct-2010
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20-Oct-2010
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INTERNATIONAL ISO
STANDARD 22762-3
Second edition
2010-11-01


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 22762-3:2010(E)
©
ISO 2010

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ISO 22762-3:2010(E)
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ii © ISO 2010 – All rights reserved

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ISO 22762-3:2010(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Symbols.4
5 Classification .7
6 Requirements.9
7 Design rules .20
8 Manufacturing tolerances.25
9 Marking and labelling.31
10 Test methods .32
11 Quality assurance.32
Annex A (normative) Tensile stress in reinforcing steel plate.33
Annex B (informative) Determination of ultimate property diagram based on experimental results .35
Annex C (informative) Minimum recommended physical properties of rubber material .38
Annex D (informative) Effect of inner-hole diameter and second shape factor on shear properties .39
Annex E (informative) Determination of compressive properties of elastomeric isolators.42
Annex F (informative) Determination of shear properties of elastomeric isolators.45
Annex G (informative) Method of predicting buckling limit at large deformations.50
Annex H (informative) Design of fixing bolts and flanges.57
Bibliography.60

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ISO 22762-3:2010(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 22762-3 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee
SC 4, Products (other than hoses).
This second edition cancels and replaces the first edition (ISO 22762-3:2005), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 22762-3:2005/Cor.1:2006.
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
iv © ISO 2010 – All rights reserved

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ISO 22762-3:2010(E)
Introduction
ISO 22762 (all parts) consists of 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 this part of ISO 22762 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.

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INTERNATIONAL STANDARD ISO 22762-3:2010(E)

Elastomeric seismic-protection isolators —
Part 3:
Applications for buildings — Specifications
1 Scope
This part of ISO 22762 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 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 630, Structural steels — Plates, wide flats, bars, sections and profiles
ISO 1052, Steels for general engineering purposes
ISO 22762-1:2010, Elastomeric seismic-protection isolators — Part 1: 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
K
v
compressive stiffness for all types of rubber bearings
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ISO 22762-3:2010(E)
3.4
compression-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 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 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
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
EXAMPLE 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,
fabricated using natural rubber
NOTE Any bearing with relatively low damping can be treated as an LNR bearing for the purposes of isolator testing.
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ISO 22762-3:2010(E)
3.15
maximum compressive stress
peak stress acting briefly on elastomeric isolators in compressive direction during an earthquake
3.16
nominal compressive stress
long-term stress acting on elastomeric isolators in compressive direction as 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
test for quality control of the production isolators during and after manufacturing
3.19
second shape factor
〈circular elastomeric isolator〉 ratio of the diameter of the inner rubber to the total thickness of the inner rubber
3.20
second shape factor
〈rectangular or square elastomeric isolator〉 ratio of the effective width of the inner rubber to the total thickness
of the inner rubber
3.21
shear properties of elastomeric isolators
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
3.22
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
3.23
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
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ISO 22762-3:2010(E)
4 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
b
A overlap area between the top and bottom elastomer area of isolator
e
A load-free area of isolator
free
A loaded area of isolator
load
A area of the lead plug for a lead rubber bearing
p
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
0
E apparent Young's modulus of bonded rubber layer
ap
E apparent Young's modulus corrected, if necessary, by allowing for compressibility
c
s
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
0
F tensile force on isolator by uplift
u
G shear modulus
G (γ) equivalent linear shear modulus at shear strain
eq
H height of elastomeric isolator, including mounting flange
H height of elastomeric isolator, excluding mounting flange
n
h equivalent damping ratio
eq
h (γ) equivalent damping ratio as a function of shear strain
eq

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ISO 22762-3:2010(E)
Table 1 (continued)
Symbol Description
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 shear stiffness of lead plug inserted in lead rubber bearing
p
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 rectangular flange
f
M resistance to rotation
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 compressive force
max
P minimum compressive force
min
P tensile force at break of isolator
Tb
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 standard temperature, 23 °C or 27 °C;
0
where specified tolerance is ± 2 °C, T is standard laboratory temperature
0
T total rubber thickness, given by T = n × t
r r r
t thickness of one rubber layer
r
t , t 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
0
U(γ) function giving ratio of characteristic strength to maximum shear force of a loop
V uplift force
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ISO 22762-3:2010(E)
Table 1 (continued)
Symbol Description
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 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
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 design 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 rubber
ε creep strain
cr
ε tensile strain of isolator
T
ε tensile-break strain of isolator
Tb
ε tensile-yield strain of isolator
Ty
ζ ratio of total height of rubber and steel layers to total rubber height
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
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ISO 22762-3:2010(E)
Table 1 (continued)
Symbol Description
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
ρ safety factor for roll-out
R
ρ safety factor for tensile force
T
σ compressive stress in isolator
σ design compressive stress
0
σ tensile stress in bolt
B
σ bending stress in flange
b
σ allowable bending stress in steel
bf
σ critical stress in isolator
cr
σ allowable tensile stress in steel
f
σ maximum compressive stress
max
σ minimum 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 yield stress of steel for flanges and reinforcing steel plates
sy
σ tensile strength of steel for flanges and reinforcing steel plates
su
σ tensile stress
t
σ allowable tensile stress in isolator
te
τ shear stress in bolt
B
τ allowable shear stress in steel
f
φ factor for computation of buckling stability
ξ factor for computation of critical stress

5 Classification
5.1 General
Elastomeric isolators are classified by construction, their ultimate properties and tolerances on their
performance.
5.2 Classification by construction
Elastomeric isolators are classified by construction, as shown in Table 2.
Other methods not listed in Table 2 may be used to fix flanges to the laminated rubber, if the resulting
construction has adequate strength to resist the shear forces and bending moments due to shear deflection.
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ISO 22762-3:2010(E)
Furthermore, such constructions shall be capable of resisting tension if the elastomeric isolator is designed for
uplift.
Table 2 — Classification by construction
Type Construction Illustration
Mounting flanges are bolted to connecting
flanges, which are bonded to the laminated
rubber.
Cover rubber is added before curing of
isolator.

Type I
Mounting flanges are bolted to connecting
flanges, which are bonded to the laminated
rubber.
Cover rubber is added after curing of
isolator.

Mounting flanges are directly bonded to the
Type II
laminated rubber.


Recess connection
Isolators without mounting flanges,
Type III connected to base by either recess rings or
dowell pins.

Dowell connection

5.3 Classification by tolerance on shear properties
Elastomeric isolators are classified by tolerance on shear properties, as shown in Table 3.
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ISO 22762-3:2010(E)
Table 3 — Classification by tolerance of shear properties
Class Individual Global
S-A ± 15 % ± 10 %
S-B ± 25 % ± 20 %

6 Requirements
6.1 General
Elastomeric isolators for buildings and the materials used in manufacture shall meet the requirements
specified in this clause. For test items (see Table 4) that have no specific required values, the manufacturer
shall define the values and inform the purchaser prior to production.
The standard temperature for determining the properties of elastomeric isolators is 23 °C or 27 °C in
accordance with prevailing International Standards. However, it is advisable to establish a range of working
temperatures taking into consideration actual environmental temperatures and possible changes in
temperatures at the work site where the elastomeric isolators are installed.
Table 4 — Test pieces for type testing
Properties Test item Test piece
Compressive properties Compressive stiffness Full-scale only
Shear stiffness
Equivalent damping ratio
Shear properties Full-scale only
Post-yield stiffness (for LRB)
Characteristic strength (for LRB)
Tensile fracture strength
Tensile properties Scale B
Tensile yield strength
Shear strain dependency Full-scale only
Compressive stress dependency Full-scale only
Dependency of shear properties Frequency dependency Scale A, STD, SBS
Repeated loading dependency Scale B
Temperature dependency Scale A, STD, SBS
Shear strain dependency
Dependency of compressive
Scale B
properties
Compressive stress dependency
Ultimate properties Shear displacement capacity Scale B
Ageing Scale A, STD, SBS
Durability
Creep Scale A
Scale A: Scaling such that, for a circular bearing, diameter W 150 mm, for a rectangular bearing, side length W 100 mm
and, for both types, rubber layer thickness W 1,5 mm and thickness of reinforcing steel plates W 0,5 mm.
Scale B: Scaling such that, for a circular bearing, diameter W 500 mm, for a rectangular bearing, side length W 500 mm
and, for both types, rubber layer thickness W 1,5 mm and thickness of reinforcing steel plates W 0,5 mm. Minimum scale
factor 0,5.
STD = standard test piece (see Tables 10 and 11 of ISO 22762-1:2010).
SBS = shear-block test piece specified in ISO 22762-1:2010, 5.8.3. With LRB, SBS shall only be used for ageing tests.
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ISO 22762-3:2010(E)
Some of these properties may be determined using one of the standard test pieces detailed in Tables 10 and
11 in ISO 22762-1:2010. The standard test pieces are used for non-specific product tests, such as testing in
the development of new materials and products.
6.2 Type tests and routine tests
6.2.1 Testing to be carried out on elastomeric isolators is classified into “type tests” and “routine tests”.
6.2.2 Type tests shall be conducted either to ensure that project design parameters have been achieved (in
which case the test results shall be submitted to the structural engineer for review prior to production) or to
verify isolator performance and material properties during development of the product. The test piece for each
type test shall be full-scale or one of the options specified in Table 4. The test piece shall not have been
subjected to any previous test programme. The tests shall be performed on test pieces not subjected to any
scragging, unless the production isolators are to be supplied after scragging. In that case, the test pieces shall
be subjected to the same scragging procedure as the production isolators.
6.2.3 Previous type test results may be substituted, provided the following conditions are met.
a) Isolators are fabricated in a similar manner and from the same compound and adhesive.
b) All corresponding external and internal dimensions are within 10 % of each other. Flange plates are
excluded.
c) First and second shape factors are equal to or larger than those in previous tests.
d) The test conditions, such as maximum and minimum vertical load applied in the ultimate property test
(see 6.5.7), are more severe.
Routine tests are carried out during production for quality control. Sampling is allowed for routine testing for
projects with agreement between structural engineer and manufacturer. Sampling shall be conducted
randomly and cover not less than 20 % of the production of any isolator design. For a given project, tests shall
cover not less than four test pieces for each size and not less than 20 test pieces in total.
If isolators are supplied after scragging, the routine test shall be performed on scragged isolators.
6.3 Functional requirements
Elastomeric isolators for buildings are designed and manufactured to have the performance characteristics
required so that they deform in all directions with the proper stiffness (with damping, if required) during an
earthquake.
In the application of elastomeric isolators, attention shall be paid to the following points.
a) The isolators shall be installed horizontally between the structure and foundation.
b) Once installed, the isolators shall not be subjected to a constant shear force.
c) When isolators are to be installed under relatively flexible columns, the rotation at the top of the isolator
caused by bending deformation shall be carefully considered.
d) Exposed steel surfaces, such as the surfaces of mounting flanges, shall be properly painted or galvanized
to prevent rusting.
e) Proper maintenance shall be carried out on installed isolators to prevent any abnormalities such as
distortion, cracks or rust occurring.
f) Fire protection of the isolators may be required.
g) The seismic gap shall be maintained at all times.
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ISO 22762-3:2010(E)
6.4 Design compressive force and design shear displacement
6.4.1 The design stress and strain of an isolator are defined by the following relationships with the design
force and the displacement.
PP P
0max min
σσ==,,σ=
0max min
A AA
XX
0max
γγ==,
0max
TT
rr
6.4.2 The design compressive forces, P , and maximum and minimum compressive forces, respectively
0
P and P , and the design shear displacements X and the maximum shear displacement X for an
max min 0 max
isolator shall be provided by the structural engineer. If the P , P , P , X and X are not known at the
0 max min 0 max
time of type testing, the design stress and design strain to be used for testing can be determined as follows.
σ==σσ,2σ
0 nom max nom
where
σ , σ , γ and γ are determined by the manufacturer.
nom min 0 max
6.5 Performance requirements
6.5.1 General
The isolators shall be tested and the results recorded using the specified test methods. They shall satisfy all of
the requirements listed below. The design value for each isolator shall be specified prior to the tests. The test
items are summarized in Table 5, which indicates those type tests that are optional, where a material test
piece may substitute an isolator, and the tests to be
...

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