BS EN 338 pdf free download
BS EN 338 pdf free download. Structural timber — Strength classes.
1 Scope This standard establishes a system of strength classes for general use in structural codes. It gives characteristic strength and stiffness properties and density values for each class and the rules for the allocation of timber populations (i.e. combinations of species, source and grade) to the classes. This standard applies to all softwood and hardwood timber for structural use. 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 listed 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 384, Structural timber – Determination of characteristic values of mechanical properties and density. prEN 1 4081 -1 , Timber structures – Strength graded structural timber with rectangular cross-section – Part 1: General requirements . prEN 1 4081 -2, Timber structures – Strength graded structural timber with rectangular cross-section – Part 2: Machine Grading – Additional requirements for initial type testing . prEN 1 4081 -3, Timber structures – Strength graded structural timber with rectangular cross-section – Part 3: Machine Grading – Additional requirements for factory production control 3 Terms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1 population material for which the characteristic values are relevant NOTE The population is defined by parameters such as species or species grouping, source and strength grade. 5 Classification of structural timber This standard provides for a number of strength classes, each designated by a number indicating the value of bending strength in newtons per square millimetre. The characteristic values of strength, stiffness and density for the strength classes are given in Table 1 . 6 Allocation of a timber population to a strength class 6.1 Grading 6.1.1 Visually graded timber Visually graded timber shall be to a grading standard that meets the requirements of prEN 1 4081 -1 . NOTE EN 1 91 2 lists a number of visual grades and species that are allocated to the strength classes of this standard. 6.1.2 Machine graded timber Machine graded timber shall meet the requirements of prEN 1 4081 -2 and prEN 1 4081 -3. 6.2 Classification 6.2.1 Characteristic values The characteristic values of bending strength, modulus of elasticity in bending (mean) and density for the timber population concerned shall be determined in accordance with EN 384 (see annex A). 6.2.2 Allocation to a strength class A timber population may be assigned to a strength class if its characteristic values of bending strength and density equal or exceed the values for that strength class given in Table 1 , and its characteristic mean modulus of elasticity in bending equals or exceeds 95% of the value for that strength class given in Table 1 . NOTE Provided information is available, a grading machine may be set to grade directly to the strength class strength and stiffness values. Timber graded in this way should be referred to by the strength class number and marked according to prEN 1 4081 -1 , prEN 1 4081 -2 and prEN 1 4081 -3.BS EN 338 pdf download.
