ISO 24322:2024

Timber structures — Methods of test for evaluation of long-term performance — Part 1: Wood-based products in bending

This document gives methods of determination of duration of load and creep factors under bending actions at ambient temperatures for a defined population of structural timber products such as solid timber, LVL, OSB, plywood, particleboard, I-beams calculated from test values. It presents methods for a) determining the duration of load and creep factors for new timber products, b) establishing whether a previously defined set of duration of load and creep factors can be applied to a tested product, and c) an optional method for establishment of sensitivity of duration of load and creep factors to changes in environmental conditions. NOTE 1 This document is intended to apply to wood-based products for which a duration of load factor or a creep factor is used in design. NOTE 2 The effect of elevated temperature on the duration of load factor and creep factor that is derived using these methods for use with timber products can need additional consideration.

Structures en bois — Méthodes d'essai pour l'évaluation du comportement à long terme — Partie 1: Produits à base de bois en flexion

General Information

• Status: Published
• Publication Date: 03-Jan-2024
• ICS: 91.080.20 - Timber structures
• Technical Committee: ISO/TC 165 - Timber structures
• Drafting Committee: ISO/TC 165/WG 10 - Characteristic values and design specifications
• Current Stage: 6060 - International Standard published
• Start Date: 04-Jan-2024
• Due Date: 09-Sep-2023
• Completion Date: 04-Jan-2024

Standards Content (Sample)

International
Standard
ISO 24322
First edition
Timber structures — Methods of
2024-01
test for evaluation of long-term
performance — Part 1: Wood-based
products in bending
Structures en bois — Méthodes d'essai pour l'évaluation du
comportement à long terme — Partie 1: Produits à base de bois
en flexion
Reference number
© ISO 2024
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Published in Switzerland
ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols (and abbreviated terms) . 2
5 Reference population . 3
6 Sampling . 4
6.1 Sampling method .4
6.2 Matched groups within a sample .4
6.3 Sample size .4
7 Sample conditioning prior to testing . 5
8 Bending tests . 5
8.1 Test method .5
8.1.1 General .5
8.1.2 Load location on specimens .5
8.1.3 Load configuration .5
8.1.4 Deformation measurements .6
8.1.5 Reporting failure results .6
8.2 Short-term tests . . .6
8.2.1 Loading rate .6
8.2.2 Reporting .6
8.2.3 Reference loads .7
8.3 Long-term tests .7
8.3.1 Loading levels.7
8.3.2 Initial loading rate .7
8.3.3 Deformation measurements .7
9 Evaluating new duration of load and creep factors . 7
9.1 General .7
9.2 Sampling .8
9.2.1 Service class .8
9.2.2 Sample size .8
9.3 Specimen conditioning .8
9.4 Tests .8
9.4.1 General considerations for short-term tests .8
9.4.2 General considerations for the long-term tests .9
9.4.3 Long-term duration of load tests .9
9.4.4 Long-term creep tests .9
9.5 Evaluation of test results.10
9.5.1 Duration of load factor .10
9.5.2 Creep factor.11
10 Confirmation of duration of load and creep factors .12
10.1 General . 12
10.2 Sampling . 12
10.3 Tests required . 13
10.3.1 Short-term bending tests . 13
10.3.2 Long-duration bending tests . 13
10.4 Acceptance criteria .14
10.4.1 Adequate strength .14
10.4.2 Decreasing creep rate .14
10.4.3 Fractional deflection, D . 15
f
iii
10.5 Retest option . 15
10.6 Acceptance criteria for retest at lower stress level . 15
10.6.1 Average fractional deflection .16
10.6.2 Average creep-recovery .16
10.6.3 Average residual strength and stiffness .16
10.7 Interpretation of retests .16
11 Test report .16
Annex A (informative) Sampling for tests on duration of load and creep .18
Annex B (informative) Testing for sensitivity of duration of load and creep factors to
environment . 19
Bibliography .20

iv
Foreword
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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 document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.or
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