ISO 12122-4:2017

INTERNATIONAL ISO
STANDARD 12122-4
First edition
2017-01
Timber structures — Determination
of characteristic values —
Part 4:
Engineered wood products
Structures en bois — Détermination des valeurs caractéristiques —
Partie 4: Produits bois reconstitués
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Reference population . 2
6 Sampling . 2
6.1 Sampling method . 2
6.2 Sample size . 2
7 Sample conditioning . 2
8 Test data . 3
8.1 Test method . 3
8.2 Test data compatible with product description . 3
8.3 Failure modes . 3
9 Evaluation of characteristic values for structural properties . 3
9.1 Structural properties . 3
9.2 Characteristic values of material properties . 3
9.2.1 Characteristic modulus of elasticity and shear modulus . 3
9.2.2 Characteristic bearing strength . 4
9.2.3 Other characteristic values for strength based on the 5th percentile test value . 4
9.3 Characteristic values of component properties. 4
9.3.1 Characteristic stiffness . 4
9.3.2 Characteristic bearing strength . 4
9.3.3 Other characteristic capacities for strength based on the 5th percentile
test value . 4
10 Report . 4
Annex A (informative) Commentary . 5
Annex B (informative) Analytical models for determining characteristic properties of
engineered wood products .10
Bibliography .11
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 on 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 the following URL: www . i so .org/ iso/ foreword .html.
The committee responsible for this document is ISO/TC 165, Timber structures.
A list of all the parts in the ISO 12122 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

Introduction
This document sets out a framework for establishing characteristic values from test results on a sample
drawn from a clearly defined reference population of engineered wood products. The characteristic
value is an estimate of the property of the reference population with a consistent level of confidence
prescribed in the standard.
This document is intended to be used in conjunction with ISO 12122-1.
This document permits the evaluation of characteristic values on testing on commercial engineered
wood products.
In some cases, characteristic values determined in accordance with this document may be modified to
become a design value.
The document has the following annexes:
— Annex A presents a commentary on this document;
— Annex B presents information on methods for calculating characteristic values from component
properties.
INTERNATIONAL STANDARD ISO 12122-4:2017(E)
Timber structures — Determination of characteristic
values —
Part 4:
Engineered wood products
1 Scope
This document gives methods of determination of characteristic values for a defined population of
engineered wood products calculated from test values.
This document presents methods for the determination of
a) characteristic value of material properties, where the determined property is multiplied by a
geometric parameter to give a component capacity or component stiffness, or
b) characteristic value of component properties directly, where the determined property is a
component capacity or component stiffness.
This document presents methods for determination of
a) characteristic value of mean-based properties, and
b) characteristic value of 5th percentile-based properties.
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 12122-1:2014, Timber structures — Determination of characteristic values — Part 1: Basic
requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12122-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
engineered wood product
item manufactured from wood, namely plywood, oriented strand board, I beams, laminated veneer
lumber or structural insulated panel walls
Note 1 to entry: These products that are defined in ISO 12465, ISO 16894, ISO 22389-1, ISO 22390 and ISO 22452.
4 Symbols
Symbols defined in the relevant ISO product or test standard shall be used. Other symbols are defined
in ISO 12122-1.
5 Reference population
In addition to the requirements for definition of the reference population in ISO 12122-1, the following
attributes of engineered wood products may be described:
a) sources of raw material;
b) seasoning method (if seasoned);
c) grading or production method for components of the engineered wood product where it is made of
previously graded components (including lamellae);
d) specification of adhesives, method of application and method of curing adhesives;
e) quality control measures;
f) secondary processing, such as preservative treatment, fire retardant treatment, profiling, etc.;
g) variations in the configuration of the product (if any).
6 Sampling
6.1 Sampling method
The sampling method shall comply with the performance objective of sampling defined in ISO 12122-1.
Representation of each of the variants in the sample shall approximate the representation of the same
variants in the reference population.
See Clause 10 and ISO 12122-1 for reporting requirements on the sampling method. The report should
indicate a response to each of the identified attributes of the reference population listed in compliance
with Clause 5 or otherwise important to the description of the reference population.
6.2 Sample size
The sample size shall comply with requirements of ISO 12122-1 and shall take into account the
coefficient of variation (V) expected for the sawn timber in the reference population.
NOTE 1 See notes under the relevant clause in ISO 12122-1.
Engineered wood products’ properties generally have lower population coefficients of variation (V) in
structural properties and should therefore have a smaller sample size.
NOTE 2 ISO 12122-1 gives some guidance on selecting sample size.
7 Sample conditioning
The sample storage and testing environment shall reflect conditioning in accordance with the definition
of the reference population as indicated in ISO 12122-1.
2 © ISO 2017 – All rights reserved

8 Test data
8.1 Test method
The test data shall be obtained from
a) tests in accordance with the ISO test standard relevant to the product, or
b) a standard test method appropriate for the reference population, provided equivalency factors
with the relevant ISO test standard can be established.
NOTE See notes under the relevant clause in ISO 12122-1.
Test methods involve many variables that will affect results including loading configuration and rates,
specimen positioning and measurement methods. The level of precision of these variables should be
appropriate to the objectives of the testing and the adjustments required in 8.2.
8.2 Test data compatible with product description
Where the characteristic value is applicable to a standard size or moisture content, adjustments to
the test data may be required. Any adjustment shall be in accordance with ISO 12122-1 and shall be
detailed in the report.
NOTE These adjustments include those required to pool data from different test programs as outlined in
ISO 12122-1.
8.3 Failure modes
The failure modes obtained in the tests shall be recorded.
The data shall only be included in the analysis if it comes from a test in which the failure mode
appropriate to the property was obtained.
NOTE The same test method may produce different failure modes on different products. The characteristic
value may be underestimated by tests that produce failure modes that are different to the ones that the test
method was intended to produce.
9 Evaluation of characteristic values for structural properties
9.1 Structural properties
For engineered wood products, either material properties or component properties shall be evaluated.
NOTE 1 Annex A gives guidance on the type of property that is appropriate for some common engineered
wood products.
NOTE 2 Where component properties are reported, they are in general specific to a given size of product.
Different sized products will have different component properties.
Determination of the characteristic values for structural properties shall be in accordance with
ISO 12122-1 unless specifically specified in the reference product standard.
9.2 Characteristic values of material properties
9.2.1 Characteristic modulus of elasticity and shear modulus
The characteristic modulus of elasticity and shear modulus shall be the mean value, taken as the
average of the test values evaluated in accordance with ISO 12122-1.
9.2.2 Characteristic bearing strength
The characteristic values for bearing strength, both parallel and perpendicular to grain, shall be the
mean property obtained from results of tests.
9.2.3 Other characteristic values for strength based on the 5th percentile test value
The 75 % lower single-sided confidence limit of the test 5th percentile value shall be evaluated. Suitable
methods for evaluating the 5th percentile value of the test data and estimating the 75 % lower single-
sided confidence limit are presented in ISO 12122-1.
9.3 Characteristic values of component properties
9.3.1 Characteristic stiffness
The characteristic stiffnes
...