ISO 12578:2008
(Main)Timber structures — Glued laminated timber — Component performance and production requirements
Timber structures — Glued laminated timber — Component performance and production requirements
ISO 12578:2008 specifies requirements for the components of glued laminated timber members and minimum requirements for the production of such members for structural use. ISO 12578:2008 is applicable to products with a finished lamination thickness of not more than 50 mm. Although most glued laminated timber is made from coniferous species, ISO 12578:2008 also applies to broad-leaf species if the tests specified in ISO 12578:2008 show that a satisfactory glue bond can be achieved. The basic requirements apply to structural members of all service classes; however, special precautions are necessary for service class 3, for example, the use of weather-resistant adhesives. ISO 12578:2008 does not apply to the determination of strength and stiffness characteristics.
Structures en bois — Bois lamellé-collé — Performance des composants et exigences de production
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 12578
First edition
2008-09-01
Timber structures — Glued laminated
timber — Component performance and
production requirements
Structures en bois — Bois lamellé-collé — Performance des
composants et exigences de production
Reference number
ISO 12578:2008(E)
©
ISO 2008
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ISO 12578:2008(E)
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ISO 12578:2008(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Symbols .3
5 Component requirements .4
5.1 General.4
5.2 Timber .4
5.3 Adhesives .4
5.4 End joints in laminations .4
5.5 Glue-line integrity and strength .5
6 Manufacturing requirements .6
6.1 General.6
6.2 Adhesives .6
6.3 Timber .6
7 Quality control — Factory production internal quality control.6
7.1 General.6
7.2 End joints.6
7.3 Glue-line integrity .7
7.4 Gluing record .7
8 Quality system .7
Annex A (informative) Personnel, facilities, manufacture and species.8
Bibliography .13
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ISO 12578:2008(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 12578 was prepared by Technical Committee ISO/TC 165, Timber structures.
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ISO 12578:2008(E)
Introduction
Glued laminated timber is obtained by bonding together a number of laminations with their grain essentially
parallel. In this way, a member with a rectangular solid cross-section can be produced. Other non-rectangular
shapes can also be produced.
The purpose of the requirements in this International Standard is to provide minimum production
requirements, which, when coupled with applicable structural performance requirements, assure the in-service
performance of the glued, laminated timber. It can be necessary to supplement the requirements to take into
consideration special conditions, materials or functional requirements.
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INTERNATIONAL STANDARD ISO 12578:2008(E)
Timber structures — Glued laminated timber — Component
performance and production requirements
1 Scope
This International Standard specifies requirements for the components of glued laminated timber members
and minimum requirements for the production of such members for structural use.
This International Standard is applicable to products with a finished lamination thickness of not more than
50 mm.
Although most glued laminated timber is made from coniferous species, this International Standard also
applies to broad-leaf species if the tests specified in this International Standard show that a satisfactory glue
bond can be achieved.
The basic requirements apply to structural members of all service classes; however, special precautions are
necessary for service class 3, for example, the use of weather-resistant adhesives (see 5.3).
This International Standard does not apply to the determination of strength and stiffness characteristics (see
EN 1194).
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 8375, Timber structures — Glued laminated timber — Test methods for determination of physical and
mechanical properties
ISO 9709, Structural timber — Visual strength grading — Basic principles
ISO 10983:1999, Timber structures — Solid timber finger-jointing — Production requirements
ISO 12579:2007, Timber structures — Glued laminated timber — Method of test for shear strength of glue
lines
ISO 12580:2007, Timber structures — Glued laminated timber — Method of test for glue-line delamination
ISO 13912, Structural timber — Machine strength grading — Basic principals
EN 301, Adhesives, phenolic and aminoplastic, for load-bearing timber structures — Classification and
performance requirements
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ISO 12578:2008(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 301, ISO 12579, ISO 12580 and the
following apply.
3.1
adhesive types
adhesive types I and II are adhesives according to the respective durability classes in accordance with
EN 301
3.2
glued laminated timber
glulam
structural member formed by bonding together timber laminations with their grain running essentially parallel
to the beam's longitudinal axis
3.3
horizontal glulam
glued laminated timber with the wide faces of the laminations perpendicular to the direction of the larger cross-
sectional dimension
See Figure 1 a).
3.4
vertical glulam
glued laminated timber with the wide faces of the laminations perpendicular to the direction of the smaller
cross-sectional dimension
See Figure 1 b).
3.5
service class
group designation characterized by the moisture content of the members corresponding to the temperature
and relative humidity of the surrounding air
3.5.1
service class 1
group designation characterized by a moisture content in the materials corresponding to a temperature of
20 °C and the relative humidity of the surrounding air exceeding 65 % for a few weeks per year
NOTE In service class 1, the average equilibrium moisture content of most softwoods does not exceed 12 %.
3.5.2
service class 2
group designation characterized by a moisture content in the materials corresponding to a temperature of
20 °C and the relative humidity of the surrounding air exceeding 85 % for a few weeks per year
NOTE In service class 2, the average equilibrium moisture content of most softwoods exceeds 12 % but is less than
20 %.
3.5.3
service class 3
group designation characterized by climatic conditions leading to moisture contents higher than service
class 2, such as when a member is fully exposed to the weather
NOTE In service class 3, the average equilibrium moisture content of most softwoods exceeds 20 %.
3.6
maximum delamination percentage
maximum delamination length of one glue line in the test piece, measured on both end-grain surfaces of the
test specimen multiplied by 100 and divided by the total length of glue lines on the two end-grain surfaces of
each test piece for a single glue line in a test piece
Modified from ISO 12580:2007, 8.3.
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ISO 12578:2008(E)
3.7
total delamination percentage
delamination length of all glue lines on the two end-grain surfaces in the test piece multiplied by 100 and
divided by two times the length of one glue line
Modified from ISO 12580:2007, 8.2.
3.8
wood failure percentage
percentage of the wood-failure area in relation to the total sheared area
ISO 12579:2007, 3.6
3.9
lamination
piece or pieces of timber not more than 50 mm thick with or without end joints that form(s) part of a glulam
member
a) Horizontal glulam b) Vertical glulam
Figure 1 — Glue lines in cross-sections showing the normal position of the glue lines
4 Symbols
A area, expressed in square millimetres
f strength of a single end joint, expressed in megapascals
x
f characteristic strength of the end joints (5th percentile at 75 % confidence), expressed in
x,k
megapascals
f required characteristic strength of the end joints, expressed in megapascals
x,dc,k
f characteristic strength of 15 tested end joints, expressed in megapascals
x,15,k
f shear strength, expressed in megapascals
v
r radius of curvature, expressed in millimetres
t finished thickness, expressed in millimetres
fin
t lamination thickness, expressed in millimetres
lam
x subscript indicating bending or tension
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ISO 12578:2008(E)
5 Component requirements
5.1 General
The grading of the timber shall result in reliable strength and stiffness properties in the laminations. The
bonding operations shall result in reliable and durable bonds in end joints and between laminations.
5.2 Timber
The timber shall be graded in accordance with either ISO 9709 or ISO 13912. The strength and stiffness
properties of the glued laminated timber shall be established in accordance with ISO 8375.
5.3 Adhesives
The adhesive shall enable joints of such strength and durability to be produced such that the integrity of the
bond is maintained throughout the intended lifetime of the structure.
The adhesive shall be chosen considering the conditions in service, including climate, moisture conditions,
exposure to elevated temperatures, the timber species, the preservative used (if any) and the production
methods.
Adhesives of type I, as classified in accordance with EN 301, may be employed for structural members used
in all service classes.
For structures in service classes 1 or 2, an adhesive of type II, as classified in accordance with EN 301, may
be used, provided the temperature of the member in the structure is always below 50 °C.
Special precautions shall be taken for service class 3, for which weather-resistant adhesives shall be used.
For structures in service class 3, the required strength and durability can be achieved by a phenolic- or
aminoplastic-type poly-condensation adhesive classified as type 1 in accordance with EN 301.
For adhesives of types other than those covered by EN 301, a bond with an equivalent durability and strength
shall be achieved. Structural-wood-adhesive standards, such as ASTM D2559 and CSA 0112.9, have
provisions defining these strength and durability requirements.
5.4 End joints in laminations
The characteristic strength, f , (5th percentile at the 75 % confidence level) obtained from flat-wise bending
x,k
or tension tests of the end joints shall meet the requirement of Equation (1):
ffW (1)
x,k x,dc,k
where f is the required characteristic strength of the end joint in flat-wise bending or tension to achieve
x,dc,k
the end-use beam performance, which shall be determined in accordance with a documented process in
accordance with the applicable standard.
The tests shall be carried out as follows.
a) Bending tests shall be carried out in accordance with ISO 10983:1999, 7.1.4.2.
b) Tension tests shall be carried out in accordance with ISO 10983:1999, 7.1.4.3.
If the distribution is not known, the characteristic strength, f , shall be determined from the log-normal
x,k
probability distribution function in accordance with ISO 10983.
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ISO 12578:2008(E)
5.5 Glue-line integrity and strength
5.5.1 The glue-line integrity shall be based on testing the glue line in a full cross-sectional specimen cut
from the manufactured glulam member. The specimens shall be representative of the manufactured product
and of any pre-gluing chemical treatment of the laminations. For all service classes, bond strength shall be
determined using block-shear tests in accordance with ISO 12579. Delamination tests shall be performed
based on the service class as specified in 5.5.2.
5.5.2 For structures of service class 3, delamination tests shall be made in accordance with methods A, B
or D plus E of ISO 12580:2007.
For structures of service class 2, delamination tests shall be performed according to methods A, B, C or
D plus E of ISO 12580:2007.
For structures of service class 1, de
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