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.
