Detail of GB 50005-2003(2005)

Introduction of GB 50005-2003(2005)

Announcement of Ministry of Construction of the People's Republic of China No. 375 ___________________________________________________________________________ Announcement on Issuing Local Revision for National Standard "Code for Design of Timber Structures" of Ministry of Construction The local revision provisions of "Code for Design of Timber Structures" GB 50005-2003 has been approved, and will be implement ed from March 1, 2006.Thereinto, Article 3.1.11 is compulsory provision and must be enforced strictly. The revised original provisions for this time shall be abolished simultaneously. Ministry of Construction of the People's Republic of China November 11, 2005 3.1.1 Timber for loadbearing structures includes log, sawn lumber(i.e, square timber, plank and dimension lumber) and glued lumber. Timber such as log, square lumber and plank is classified in three grades for sawn and round timber structures; three grades for glued lumber members; The dimension lumbers used for light wood frame construction are divided into visually-graded dimension lumber and machine-graded dimension lumber; and seven grades for the materials of visually-graded dimension lumber, eight grades for the strength of machine-graded dimension lumber. 3.1.11 When the visually-graded dimension lumber is used for a light wood frame construction design, timber grades shall be chosen properly on the basis of the main purpose of members as required in Table 3.1.11. Table 3.1.11 Material grades of visually-graded dimension lumber No. Main Purposes Grades 1 Members of high strength and rigidity, and of good appearance Ⅰc 2 Ⅱc 3 Members of high strength and rigidity, and of ordinary appearance Ⅲc 4 Members of high strength and rigidity, and of no requirements on appearance Ⅳc 5 Studs Ⅴc 6 Members except for the above-mentioned purposes Ⅵc 7 Ⅶc 4.2.5 The name of species used in this code and the main characteristics of commonly-used species are in Appendix G. Filed grading of main imported timber and the characteristics are set up in Appendix H. The design values of machine-graded dimension lumber and decided design values and species of the visually-graded dimension lumber are presented in Appendix J. Appendix J Design Index of Import Dimension Lumber Strength J．1 Conversions of Design Values of Strength for Visually-graded Imported Dimension Lumber J.1.1 See Table J.1.1-1 and Table J.1.1-2 for the strength design value and modulus of elasticity of reduced partial visually-graded import dimension lumber, but shall be multiplied by the size adjustment coefficient in Table J.1.1-3. Table J.1-1 Strength Design Value and Modulus of Elasticity of Visually-graded Import Dimension Lumber in North America Design Value(N/mm2) Name Grade Max. sectional dimension （mm） Bending resistance fm Compression resistance parallel to grain fc Tension resistance parallel to grain ft Shear resistance parallel to grain fv Compression perp. To grain fc,90 Modulus of elasticity E Douglas Fir- Larch(South) Ⅰc Ⅱc Ⅲc Ⅳc、Ⅴc 285 16 11 9.7 5.6 18 16 15 8.3 11 7.2 6.2 3.5 1.9 1.9 1.9 1.9 7.3 7.3 7.3 7.3 13000 12000 11000 10000 Ⅵc Ⅶc 90 11 6.2 18 15 7.0 4.0 1.9 1.9 7.3 7.3 10000 10000 Douglas Fir- Larch(North) Ⅰc Ⅱc Ⅲc Ⅳc、Ⅴc 285 15 9.1 9.1 9.1 20 15 15 8.8 8.8 5.4 5.4 3.2 1.9 1.9 1.9 1.9 7.3 7.3 7.3 7.3 13000 11000 11000 10000 Ⅵc Ⅶc 90 10 5.6 19 16 6.2 3.5 1.9 1.9 7.3 7.3 10000 10000 Hem-Fir (South.) Ⅰc Ⅱc Ⅲc Ⅳc、Ⅴc 285 15 11 9.1 5.4 16 15 14 7.8 9.9 6.7 5.6 3.2 1.6 1.6 1.6 1.6 4.7 4.7 4.7 4.7 11000 10000 9000 8000 Ⅵc Ⅶc 90 11 5.9 17 14 6.4 3.5 1.6 1.6 4.7 4.7 9000 8000 Hem-Fir(North) Ⅰc Ⅱc Ⅲc Ⅳc、Ⅴc 285 14 11 11 6.2 18 16 16 9.1 8.3 6.2 6.2 3.5 1.6 1.6 1.6 1.6 4.7 4.7 4.7 4.7 12000 11000 11000 10000 Ⅵc Ⅶc 90 12 7.0 19 16 7.0 3.8 1.6 1.6 4.7 4.7 10000 10000 Southern pine Ⅰc Ⅱc Ⅲc Ⅳc、Ⅴc 285 20 13 11 6.2 19 17 16 8.8 11 7.2 5.9 3.5 1.9 1.9 1.9 1.9 6.6 6.6 6.6 6.6 12000 12000 11000 10000 Ⅵc Ⅶc 90 12 6.7 19 16 6.7 3.8 1.9 1.9 6.6 6.6 10000 9000 Spruce-Pine-Fir Ⅰc Ⅱc Ⅲc Ⅳc、Ⅴc 285 13 9.4 9.4 5.4 15 12 12 7.0 7.5 4.8 4.8 2.7 1.4 1.4 1.4 1.4 4.9 4.9 4.9 4.9 10300 9700 9700 8300 Ⅵc Ⅶc 90 11 5.9 15 12 5.4 2.9 1.4 1.4 4.9 4.9 9000 8300 Other species in North America Ⅰc Ⅱc Ⅲc Ⅳc、Ⅴc 285 9.7 6.4 6.4 3.8 11 9.1 9.1 5.4 4.3 2.9 2.9 1.6 1.2 1.2 1.2 1.2 3.9 3.9 3.9 3.9 7600 6900 6900 6200 Ⅵc Ⅶc 90 7.5 4.3 11 9.4 3.2 1.9 1.2 1.2 3.9 3.9 6900 6200 Table J．1．1-2 Strength Design Value and Modulus of Elasticity of Visually-graded Import Dimension Lumber in Europe Design Value(N/mm2) Name Grade Max. sectional dimension （mm） Bending resistance fm Compression resistance parallel to grain fc Tension resistance parallel to grain ft Shear resistance parallel to grain fv Compression perp. To grain fc,90 Modulus of elasticity E European Scots Pine European Larch European spruce Ⅰc Ⅱc Ⅲc Ⅳc、Ⅴc 285 17 14 9.3 8.1 18 17 14 13 8.2 6.4 4.6 3.7 2.2 1.8 1.3 1.2 6.4 6.0 5.3 4.8 12000 11000 8000 7000 Ⅵc Ⅶc 90 14 12 16 15 6.9 5.5 1.3 1.2 5.3 4.8 8000 7000 European Douglas fir-larch Ⅰc、 Ⅱc Ⅲc Ⅳc、Ⅴc 285 12 7.9 6.9 16 13 12 5.1 3.6 2.9 1.6 1.2 1.1 5.5 4.8 4.4 11000 8000 7000 Table J.1.1-3 Size modification factors Grades Sectional height (mm) Bending resistance Compression resistance parallel to grain fc Tension resistance parallel to grain ft Others Sectional width (mm) 40 and 65 90 Ⅰc、 Ⅱc、 Ⅲc、 Ⅳc、Ⅴc ≤90 1.5 1.5 1.15 1.5 1.0 115 1.4 1.4 1.1 1.4 1.0 140 1.3 1.3 1.1 1.3 1.0 185 1.2 1.2 1.05 1.2 1.0 235 1.1 1.2 1.0 1.1 1.0 285 1.0 1.1 1.0 1.0 1.0 Ⅵc、 Ⅶc ≤90 1.0 1.0 1.0 1.0 1.0 J.1.2 See Table J.1.2 for the corresponding relation of visually-graded dimension lumber code in North American and visually-graded dimension lumber code in this code. Table J．1．2 Equivalency of the grading marks of dimension lumber in the North America & in this code Grades of dimension lumber in this code Grades of dimension lumber in North America Ⅰc Select structural Ⅱc No.1 Ⅲc No.2 Ⅳc No.3 Ⅴc Stud Ⅵc Construction Ⅶc Standard J.2 Strength design index of machine-graded dimension lumber J.2.1 See Table J.2.1 for strength design value and modulus of elasticity of machine-graded dimension lumber. Table J.2.1 Strength Design Value and Modulus of Elasticity of Machine-graded Dimension Lumber (N/mm2) Strength Grades of strength M10 M14 M18 M22 M26 M30 M35 M40 Bending resistance fm 8.20 12 15 18 21 25 29 33 Tension resistance parallel to grain ft 5.0 7.0 9.0 11 13 15 17 20 Compression resistance parallel to grain fc 14 15 16 18 19 21 22 24 Shear resistance parallel to grain fv 1.1 1.3 1.6 1.9 2.2 2.4 2.8 3.1 Compression perp. To grain fc,90 4.8 5.0 5.1 5.3 5.4 5.6 5.8 6.0 Modulus of elasticity E 8000 8800 9600 10000 11000 12000 13000 14000 J.2.2 See Table J.2.2 for corresponding relation of machine-graded dimension lumber grade of partial countries and graded dimension lumber grade of this code. Table J.2.2 Corresponding Relation Table of Machine-graded Strength Grade Grades adopted in this code M10 M14 M18 M22 M26 M30 M35 M40 Grades adopted in North America 1200f- 1.2E 1450f- 1.3E 1650f- 1.5E 1800f- 1.6E 2100f- 1.8E 2400f- 2.0E 2850f- 2.3E Grades adopted in New Zealand MSG6 MSG8 MSG10 MSG12 MSG15 Grades adopted in Europe C14 C18 C22 C27 C30 C35 C40 Notes: 1 For North American machine-graded dimension lumber, the strength design value of cross-grain bearing and along-grain shear resistant shall be the strength design value of corresponding visually-graded dimension lumber in Table J.1.1-1 of "Code for Design of Timber Structures" GB 50005-2003. 2 For the characteristic strength values through certification and examination and having general full size test during production process, the strength design value may be determined by of test characteristic strength value (not relation related to strength) according to relevant procedures. J.3 Combined action coefficient of dimension lumber J.3.1 When the joist quantity of dimension lumber is larger than 3 roots and having reliable connection with floor plate, roof board or other members, the design value of bending strength fm may be multiplied by 1.15 times of combined action coefficient during joist bending bearing capacity design.

Contents of GB 50005-2003(2005)