BS EN 338:2003 pdf 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. 4 Symbols and abbreviations E 0,mean mean characteristic value of modulus of elasticity parallel to grain (in N/mm 2 ) E 0,05 5-percentile characteristic value of modulus of elasticity parallel to grain (in N/mm 2 ) E 90,mean mean characteristic value of modulus of elasticity perpendicular to grain (in N/mm 2 ) f c,0,k characteristic value of compressive strength parallel to grain (in N/mm 2 ) f c,90,k characteristic value of compressive strength perpendicular to grain (in N/mm 2 ) f m,k characteristic value of bending strength (in N/mm 2 ) f t,0,k characteristic value of tensile strength parallel to grain (in N/mm 2 ) f t,90,k characteristic value of tensile strength perpendicular to grain (in N/mm 2 ) f v,k characteristic value of shear strength (in N/mm 2 ) G mean mean characteristic value of shear modulus (in N/mm 2 ) ? k characteristic value of density (in kg/m 3 ) ? mean mean value of density (in kg/m 3 ) 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 .BS EN 338 pdf download.