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1、BRITISH STANDARD BS EN 12511:2002 Wood poles for overhead lines Determination of characteristic values The European Standard EN 12511:2001 has the status of a British Standard ICS 79.080; 29.240.99 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Licensed Copy: sheffieldun shef
2、fieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 12511:2002 This British Standard, having been prepared under the direction of the Sector Policy and Strategy Committee for Building and Civil Engineering, was published under the authority of the Standards Policy and S
3、trategy Committee on 26 February 2002 BSI 26 February 2002 ISBN 0 580 39183 3 National foreword This British Standard is the official English language version of EN 12511:2001. The UK participation in its preparation was entrusted by Technical Committee B/518, Structural timber, to Subcommittee B/51
4、8/5, Wood poles for power and telecommunications, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this d
5、ocument may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users o
6、f British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals for c
7、hange, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 10, an inside back cover and a back cover. The BSI copyright
8、date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12511
9、 December 2001 ICS 29.240.20; 79.080 English version Wood poles for overhead lines - Determination of characteristic values Poteaux en bois pour lignes ariennes - Dtermination des valeurs caractristiques Holzmaste fr Freileitungen - Bestimmung von charakteristischen Werten This European Standard was
10、 approved by CEN on 21 October 2001. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such na
11、tional standards may be obtained on application to the Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and no
12、tified to the Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland a
13、nd United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2001 CENAll rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1251
14、1:2001 E Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12511:2001 (E) 2 Contents page Foreword3 Introduction.4 1Scope5 2Normative references5 3Terms and definitions .5 4Symbols and abbreviations6 5Requirements for determination of chara
15、cteristic values.6 5.1General6 5.2Sampling .7 6Testing7 6.1General7 6.2Bending strength.7 6.3Modulus of elasticity7 6.4Test report.8 Bibliography10 Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12511:2001 (E) 3 Foreword This European St
16、andard has been prepared by Technical Committee CEN/TC 124 “Structural timber“, the secretariat of which is held by DS. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2002, and conflicting n
17、ational standards shall be withdrawn at the latest by June 2002. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Gree
18、ce, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12511:2001 (E) 4 Introduction This standard is one of five standard
19、s covering requirements for visual or machine grading, test methods, determination of characteristic values, methods of specifying durability and sizes. This standard has been drafted on the assumption that the design requirements for transmission and telecommunication poles will be left to the end-
20、buyer and are not covered by Eurocode 5, which is for the design of buildings and civil engineering structures. This standard is for initially determining the characteristic values for a given population of poles, and additionally when there is a reason to suspect that the characteristic values for
21、a population have changed. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12511:2001 (E) 5 1 Scope This European Standard specifies the methods for determining characteristic values for bending strength and modulus of elasticity, of any
22、population of wood poles. It is not intended for routine quality control. This standard covers only single poles under cantilever or compression loading. For example, this standard does not cover poles used as beams. The provision of poles for use in any overhead line or cable infrastructure shall t
23、ake into account a range of factors not covered by this standard which will necessitate the specification by the end user of complementary and synonymous attributes to those defined in this standard. This refers to requirements for a number of factors including safety, overhead plant, handling, fitt
24、ings, installation machinery and working practices including climbing. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text, and the publications are li
25、sted hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). EN
26、12479, Wood poles for overhead lines - Sizes - Methods of measurement and permissible deviations. prEN 12509, Wood poles for overhead lines - Test methods - Determination of elasticity, bending strength, density and moisture. EN 12510, Wood poles for overhead lines - Strength grading criteria. 3 Ter
27、ms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1 characteristic value value that corresponds to the 5 % fractile of the statistical distribution of strength or the mean value of modulus of elasticity 3.2 fibre saturation point (fsp) state
28、of a piece of timber when the cell walls are saturated with moisture but no moisture exists in the cell cavities 3.3 pole long round timber for use in a free standing application 3.4 population a group of poles defined by having the same parameters of species, source and grade 3.5 sample number of t
29、est poles from one population Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12511:2001 (E) 6 3.6 standard size poles poles of a size 9 m to 10 m long and 180 mm to 220 mm diameter at 1,5 m from the butt end, used for the determination o
30、f characteristic values 4 Symbols and abbreviations Emodulus of elasticity, in newtons per square millimetre Emeanmean value of modulus of elasticity parallel to grain fmbending strength, in newtons per square millimetre fm,kcharacteristic value of bending strength, in newtons per square millimetre
31、fm,05sample fifth percentile of bending strength, in newtons per square millimetre kstatistical factor mmean value (the variable is given in parentheses) m(E)sample mean values of modulus of elasticity, in newtons per square millimetre m(fm)sample mean value of bending strength, in newtons per squar
32、e millimetre m(fm,05)mean of fm,05 values nnumber of test poles in a sample sstandard deviation (the variable is given in parentheses) s(E)sample standard deviation of modulus of elasticity, in newtons per square millimetre s(fm)sample standard deviation of bending strength, in newtons per square mi
33、llimetre 5 Requirements for determination of characteristic values 5.1 General Characteristic values for poles shall be determined for moisture content levels equivalent to the fibre saturation point (fsp) for each species. Poles for testing shall be conditioned to the fibre saturation point or grea
34、ter. However, tests can be carried out at other levels of moisture content if sufficient data exist to adjust the results to the fibre saturation point. NOTE Results from tests on poles with moisture contents higher than the fibre saturation point will be similar and are acceptable. Characteristic v
35、alues for poles shall be determined after any mechanical processing prior to treatment (e.g. incising). Poles to be tested for characteristic values shall be tested in their final condition prior to preservation. Durable poles, used without preservative treatment, shall be tested in their ready to u
36、se condition. The characteristic values shall be determined for poles of a stated population (species, source and grade) and of the standard size. If it is evident from tests that mechanical properties vary with pole size, then mechanical properties for sizes of pole other than standard size may be
37、determined by applying factors, supported by test evidence, to the characteristic values. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12511:2001 (E) 7 Sampling, testing and the calculation of characteristic values shall be repeated fo
38、r each population if there is evidence to suggest that the characteristic values for the population are incorrect. 5.2 Sampling Several samples of poles shall be selected from the population to represent the range of strength reducing characteristics permitted by the grade and variations within the
39、growth region. The number of samples shall depend upon the size of the growth region and any known or suspected differences in the mechanical properties of poles obtained from different areas of that growth region. In particular the pole taper shall be representative of the range used in service. Fo
40、r the purposes of determining characteristic values all poles in a sample shall be of the same size in accordance with EN 12479 and of the same species and grade in accordance with EN 12510. The number of poles in each sample shall not be less than 40. 6 Testing 6.1 General Testing shall be carried
41、out on standard size poles in accordance with prEN 12509 with the ground line at 1,5 m from the butt end. The characteristic values of bending strength and modulus of elasticity are calculated from the test results using a statistical factor “k” found from Figure 1. This factor takes into account th
42、e size of the smallest sample, the number of samples and the nominal area of the forest from which the samples have been selected. 6.2 Bending strength For each sample a 5-percentile value fm,05 shall be obtained from the equation : fm,05 = m(fm) - 1,65 s(fm) where m(fm) is the mean value of the tes
43、t results, and s(fm) is the standard deviation of the test results The characteristic value fm,k is then found from : fm,k = k m(fm,05) where m(fm,05) is the mean, weighted according to sample size of the fm,05 values for each sample. If m(fm,05) is greater than the lowest sample value of fm,05 time
44、s 1,2 then either the population shall be redefined to eliminate the lowest value, or m(fm,05) shall be given the value of 1,2 times the lowest value of fm,05. The value of k is found from Figure 1. 6.3 Modulus of elasticity The sample mean value of modulus of elasticity m(E) shall be calculated fro
45、m the equation: n E Em ? ? i )( Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12511:2001 (E) 8 where Ei is the value of modulus of elasticity in the range l to n (in N/mm). The characteristic value Emean shall be calculated from the equ
46、ation: ? ? ? j jj mean )( n nEm E where nj is the number of specimens in sample j; m(E)j is the mean value of modulus of elasticity for sample j (in N/mm). 6.4 Test report A written test report giving details of the population, sampling, testing, analytical procedure and calculations shall be prepar
47、ed for consideration for inclusion of each population. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12511:2001 (E) 9 Key AValue of k BLarge forest CSmall forest DSize of smallest sample ENumber of samples Figure 1 - The effect of the n
48、umber of poles and samples on k Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 12511:2001 (E) 10 Bibliography EN 8442, Round and sawn timber - Terminology - Part 2: General terms relating to round timber. EN 8444, Round and sawn timber -
49、 Terminology - Part 4: Terms relating to moisture content. Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI blank Licensed Copy: sheffieldun sheffieldun, na, Sat Oct 28 07:16:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 12511:2002 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter.