1、 ISO 2015 Timber structures Structural classification for sawn timber Structures en bois Classification structurelle pour bois scis INTERNATIONAL STANDARD ISO 16598 First edition 2015-09-01 Reference number ISO 16598:2015(E) ISO 16598:2015(E)ii ISO 2015 All rights reserved COPYRIGHT PROTECTED DOCUME
2、NT ISO 2015, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written p
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4、(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 Terms and definitions . 1 4 Timber population and structural property data 2 5 Primary properties 2 5.1 Framework . 2 5.2 Bending or tension property evaluation . 3 5.2.1 General 3 5.2.2 Exception 3 5.3 Density evaluation . 3 5.4 C
5、lass boundaries 3 6 Derived properties . 3 6.1 Framework . 3 6.2 Evaluation 3 6.2.1 General 3 6.2.2 Exception 3 7 Allocation to a class . 4 7.1 Framework . 4 7.1.1 General 4 7.1.2 Normalization of characteristic values . 4 7.2 Grading systems . 4 7.2.1 General 4 7.2.2 Exception 4 7.3 Design values 5
6、 8 Reporting 5 Annex A (normative) Timber population and structural property data 6 Annex B (informative) Structural class example table 9 Annex C (informative) Commentary 13 Bibliography .19 ISO 2015 All rights reserved iii Contents Page ISO 16598:2015(E) Foreword ISO (the International Organizatio
7、n 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
8、 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 p
9、rocedures 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 edit
10、orial 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 rig
11、hts 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 ex
12、planation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this d
13、ocument is ISO/TC 165, Timber structures.iv ISO 2015 All rights reserved ISO 16598:2015(E) Introduction The production of many different combinations of species and grades complicates timber specification and structural design. Structural classification groups together species and grades of similar
14、properties, to make them interchangeable for structural purposes. The development of this International Standard is intended to benefit industry, consumers, governments and distributors, by balancing the principles of simplicity, product utility and structural reliability. One of the key reasons for
15、 developing this International Standard is to provide a framework for understanding and working on compatibility between approaches used in different regions, through standardization of the basic elements of structural classes, including underlying assumptions and the general method for setting up c
16、lasses. An example table is presented in Annex B for illustration purposes. This International Standard provides a model or template that may be modified before adoption and it does not present final design values and adjustment factors. The scope includes evaluation of structural properties; it doe
17、s not cover suitability with regard to durability, fire resistance and other timber properties. ISO 2015 All rights reserved v Timber structures Structural classification for sawn timber 1 Scope This International Standard provides a basic international framework for establishing structural classes
18、for sawn timber. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (in
19、cluding any amendments) applies. ISO 12122-1, Timber structures Determination of characteristic values Part 1: Basic requirements ISO 12122-2, Timber structures Determination of characteristic values Part 2: Sawn timber 3 Terms and definitions For the purpose of this document, the following terms an
20、d definitions apply. 3.1 characteristic value standard estimate of a structural property of a timber population (3.11) corresponding to a fractile, tolerance limit or mean of sample test data after being adjusted to accepted reference conditions 3.2 derived property structural property for which cha
21、racteristic values are determined by correlation with one or more primary properties, and not typically used in deciding how to classify a population 3.3 design value numerical quantity assigned to a timber population for use in structural design, calculated from the characteristic value and modifie
22、d to suit provisions in the appropriate building code and standards Note 1 to entry: Design values are not used directly in structural classes. 3.4 full-size specimen timber test piece that is similar in size and characteristics to typical structural timbers and is prepared and tested in a way simil
23、ar to use in construction Note 1 to entry: See also small clear specimen (3.7). 3.5 normalization adjustment of data, beyond basic data breakdown and moisture and size corrections, to be on a compatible basis with other data for evaluation in the same structural class system 3.6 primary property str
24、uctural property that is used to set criteria for allocating a timber population to a structural class system, based on the characteristic value for that property INTERNATIONAL ST ANDARD ISO 16598:2015(E) ISO 2015 All rights reserved 1 ISO 16598:2015(E) 3.7 small clear specimen timber test piece tha
25、t is much smaller than typical structural timbers and normally prepared to be free of visible defects Note 1 to entry: See also full-size specimen (3.4). 3.8 species combination two or more species or multiple data sets of the same species from different growth or production regions, combined into a
26、 single marketing group on the basis of similar properties and property relationships, or other applicable criteria 3.9 grade solid sawn timber population produced with standardized rules that maintain well-defined limits on strength-controlling characteristics or properties 3.10 structural classifi
27、cation system for assigning shared structural properties to timber populations of similar capacities, for the purpose of structural design and specification 3.11 timber population solid sawn timber product of a grade and species or species combination intended for use in structural applications 4 Ti
28、mber population and structural property data This International Standard is based on the timber population and structural property data estimates conforming to those identified in ISO 12122-1 and ISO 12122-2. NOTE See Annex A for additional information. 5 Primary properties 5.1 Framework Primary pro
29、perties shall be established on a standardized basis to ensure compatibility between different sets of test data from accepted sampling and testing programs. Primary characteristic properties include the following: bending strength: the modulus of rupture at the 5th percentile, with specified level
30、of confidence; bending stiffness: the modulus of elasticity at the mean and 5th percentile levels; density: the density at the mean and 5th percentile levels. NOTE 1 Strength properties are typically estimated as tolerance limits at the 5th percentile level with confidence specified at 75 %. Stiffne
31、ss and density properties are typically estimated as either means or percentiles without a confidence statement, or as tolerance limits with confidence specified at 75 %. NOTE 2 An alternative approach is to use axial (tension) strength instead of bending strength as a primary property. Some represe
32、ntative testing standards for primary properties are identified in the Bibliography.2 ISO 2015 All rights reserved ISO 16598:2015(E) 5.2 Bending or tension property evaluation 5.2.1 General Primary bending property data or, where applicable, tension property data shall be evaluated as characteristic
33、 values determined on the basis of standardized full-size specimen testing, except as permitted in 5.2.2. 5.2.2 Exception Where it is necessary to evaluate bending or tension property data on a basis other than full-size testing, the data shall be supported by but not combined or interchanged with f
34、ull-size testing results. NOTE Although full-size timber testing is preferred, small clear specimen testing is used in cases where full-size bending or tension testing is not feasible or practical, with modification factors to partially calibrate the data in accordance with characteristic value stan
35、dards, and subject to a review of consistency in the level of safety between small clear and full-size testing approaches (see Annex C). 5.3 Density evaluation Density property data shall be evaluated as characteristic values determined on the basis of standardized small clear wood specimen testing.
36、 NOTE ISO 13910 provides a standardized approach to evaluating density properties. 5.4 Class boundaries Class boundaries for primary bending or tension strength properties shall be set at intervals of no less than 2 MPa. 6 Derived properties 6.1 Framework Derived properties shall be established on t
37、he basis of standardized relationships to one or more of the primary properties provided that it can be demonstrated that these relationships are generally applicable to the timber population. Derived strength and stiffness properties for structural classes shall include properties other than the pr
38、imary strength and stiffness properties and shall be expressed on the same basis as primary properties (See NOTES to 5.1). 6.2 Evaluation 6.2.1 General Derived properties shall be assigned as characteristic values determined on the basis of standardized relationships identified in 6.1 or, where furt
39、her evidence of compliance is required, evaluated in accordance with the alternative method in 6.2.2. 6.2.2 Exception Where derived properties are to be evaluated or corroborated by testing, they shall be evaluated on a standardized basis to ensure compatibility between different sets of test data f
40、rom accepted sampling and test programs. Bending or tension property data used to evaluate derived properties shall be ISO 2015 All rights reserved 3 ISO 16598:2015(E) determined as characteristic values on the basis of standardized full-size specimen testing, except as permitted in 5.2.2. NOTE Ongo
41、ing monitoring or quality control testing is sometimes used to demonstrate suitability for cases involving new or modified products or grading systems. 7 Allocation to a class 7.1 Framework 7.1.1 General A timber population shall be qualified to be allocated to a class if the characteristic values f
42、or the primary properties equal or exceed the tabulated class values. In addition, where derived properties are to be evaluated or corroborated by testing, the population shall be qualified to be allocated to a class only if its characteristic values for such properties also equal or exceed the tabu
43、lated class values, except as provided in 7.1.2. 7.1.2 Normalization of characteristic values Prior to allocation to a class, characteristic values for data sets derived following standard methods for sampling the timber population and evaluating the primary properties shall be permitted to be norma
44、lized to account for documented differences in property estimation as well as the dispersion in data sets around the characteristic value. NOTE 1 This requirement is based on the assumption that a uniform approach will be applied to structural property modification for each or all structural classes
45、 to achieve a desired level of safety. Timber from grading systems or processes that are very different can require the use of normalization factors to calibrate characteristic values (see Annex C) to ensure that products allocated to a class demonstrate a consistent level of structural performance
46、in end use. NOTE 2 A different basis for sampling and deriving characteristic values (such as the use of small clear specimens versus samples of full-size commercial production) will yield different levels of dispersion in the data set as well as characteristic values. These differences require the
47、development of different data set adjustments; for example, see Annex C for a comparison between the small clear and full-size specimen approach. 7.2 Grading systems 7.2.1 General Structural classes shall be permitted to include timber populations from different grading systems provided that these p
48、opulations fit within the established framework of structural property relationships. NOTE An example of a structural classification framework appears in Annex B. 7.2.2 Exception Where timber populations from different grading systems have significantly different structural property relationships or
49、 levels of variability, they shall be allocated either under separate classification systems, or in accordance with rules addressing these differences through appropriate adjustments to properties or grading processes.4 ISO 2015 All rights reserved ISO 16598:2015(E) 7.3 Design values This International Standard is based on the assumption that any structural property modifications made to establish design values in building codes and design standards will be consistent with the data and assumptions used to allocate populations to struc
