DIN EN 384:2010-08

This European Standard specifies a method for determining characteristic values of mechanical properties and density, for defined populations of timber of visual and/or mechanical strength grades. A method is also given for checking the strength of a timber sample against its designated value. The values determined in accordance with this standard for mechanical properties and density are suitable for assigning grades and species to the strength classes of EN 338. For assigning grades and species to the strength classes in EN 338 only three characteristic values, that is bending strength, mean modulus of elasticity parallel to grain and density, need to be determined. The other properties may be taken from the table in EN 338. EN 1912 gives examples of assignment to strength classes of established national and regional visual grades. In this revised edition, changes have been made to the equations giving the relativities between properties in 6.2.1, and the method of calculating the 5-percentile density. Also, the verification requirements in clause 9 have been rewritten. A total accuracy of characteristic values for any defined population is not achievable. A major aim of the procedures given in this standard is to produce characteristic values that are comparable in terms of the populations they represent. It is also important that the standard permits the use of as much existing test data as possible from various sampling and testing techniques. This standard also contains methods specifying how characteristic values may be determined if a less than ideal amount of structural size test data or only small, defect-free specimen test data are available. In these cases the lower degree of confidence by reduction factors is taken into account. For the determination of the characteristic values this standard covers the sections definition of the population, sampling, testing, calculation and expression of results. This document (EN 384:2010) has been prepared by Technical Committee CEN/TC 124 "Timber structures", the secretariat of which is held by SFS (Finland). The responsible German Committee is Working Committee NA 005-04-01 AA "Holzbau" ("Timber structures") of the Building and Civil Engineering Standards Committee at DIN, the German Institute for Standardization.