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MALAYSIAN STANDARD
MS 544 : PART 2 : 2001
CODE OF PRACTICE FOR STRUCTURAL USE OF TIMBER : PART 2 : PERMISSIBLE STRESS DESIGN OF SOLID TIMBER (FIRST REVISION)
ICS : 91.080.20 Descriptors :
permissible stress design, solid timber, timber grades, strength group, flexural member, compression member, tension member, built-up beam, spaced column
© Copyright DEPARTMENT OF STANDARDS MALAYSIA
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adoption of international standards.
These standards where appropriate are
Approval of a standard as a Malaysian Standard is
governed by the Standards of Malaysia Act 1996 (Act 549).
Malaysian Standards are
reviewed periodically. The use of Malaysian Standards is voluntary except in so far as they are made mandatory by regulatory authorities by means of regulations, local by-laws or any other similar ways.
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OR
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MS 544 : PART 2 : 2001 CONTENTS Page Committee representation............................................................................……………… iv
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Foreword……...............................................................................................……………… vi
1
Scope……………………………………………………………………………………. 1
2
Referenced documents………………………………………………………………..
1
3
Timber specification……………………………………………………………………
2
4
Species………………………………………………………………………………….
2
5
Dimensions and geometrical properties……………………………………………..
2
6
Grades…………………………………………………………………………………..
3
7
Grade stresses for individual species and strength group ………………………..
3
8
Permissible stresses…………………………………………………………………..
19
9
Duration of loading…………………………………………………………………….
19
10
Load-sharing systems…………………………………………………………………
20
11
Flexural members……………………………………………………………………..
21
12
Compression members……………………………………………………………….
26
13
Tension members……………………………………………………………………..
34
1
Wet grade stresses of timber (N/mm2) moisture content > 19 %……………….
5
2
Dry grade stresses of timber (N/mm2) moisture content ≤ 19 %………………..
11
3
Strength groups of timber……………………………………………………………
17
Tables
i
MS 544 : PART 2 : 2001
CONTENTS (continued) Page
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4
Wet and dry grade stresses for various strength groups of timber (stresses and moduli expressed in N/mm2)……………………………………….
18
5
Modification factor K1 for duration of loading……………………………………….
20
6
Modification factor K3 for bearing stress…………………………………………….
22
7
Maximum depth to breadth ratios (solid and laminated members)………………
24
8
Modification factor K7 used to modify the minimum modulus of elasticity for trimmer joints and lintels………………………………………………………………
26
9
Effective length of compression members…………………………………………
27
10
Modification factor K8 for compression members………………………………….
29
11
Modification factor K9 for the effective length of spaced columns……………….
33
Al
Names, densities and specific gravity of some structural timbers……………..
35
Bl
Common commercial timber sizes…………………………………………………..
41
B2
Permissible deviations on surfaced timber sizes at 19 % moisture content…….
42
B3a
Geometrical properties of sawn timber at wet condition…………………………… 43
B3b
Geometrical properties of sawn timber at 19 % moisture content……………….
45
B4
Geometrical properties of dressed sawn timber at 19 % moisture content…….
47
C1
Maximum size of shakes and checks………………………………………………..
50
C2
Maximum slope of grain……………………………………………………………….
50
C3
Maximum amount of wane……………………………………………………………. 51
C4
Maximum amount of pin, shot and borer holes……………………………………..
Tables
ii
52
MS 544 : PART 2 : 2001
CONTENTS (continued) Page
C5
Maximum amount of curvature……………………………………………………….
53
C6
Permissible deviations in curvature………………………………………………….
54
C7
Maximum width of permissible sound knots………………………………………..
55
C8
Maximum width of permissible unsound knots…………………………….……….
55
1
Position of end bearing……………………………………………………………….
21
2
Notched beams……………………………………………………………………….
23
3
Axes in spaced columns……………………………………………………………..
32
Cl
Extent of wane………………………………………………………………………..
51
C2
Extent of sapwood……………………………………………………………………
53
C3
Swivel-handed scriber for the determination of slope of grain in wood………….
56
C4
Use of scriber………………………………………………………………………….
56
C5
Measurement of slope grain…………………………………………………………
57
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Figures
Appendices A
Grading of Malaysian structural timbers……………………………….……………
35
B
Sizes and geometrical properties of Malaysian structural timbers………………
41
C
Grading of Malaysian structural timbers…………………………………………….
49
D
Modification factor for compression members…………………………………….
58
E
Bibliography………………………………….………………………………………..
59
iii
MS 544 : PART 2 : 2001
Committee representation The Building and Civil Engineering Industry Standards Committee (ISC D) under whose supervision this Malaysian Standard was developed, comprises representatives from the following Government Ministries, Trade, Commerce and Manufacturing Associations, and Scientific and Professional Bodies:
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Association of Consulting Engineers Malaysia Construction Industry Development Board Malaysia Department of Standards Malaysia Department of Occupational Safety and Health Jabatan Bomba dan Penyelamat Pertubuhan Akitek Malaysia Master Builders Association Malaysia Ministry of Housing and Local Government (Housing Department) Ministry of Works (Public Works Department) The Institution of Engineers, Malaysia Universiti Teknologi Malaysia
The development of this Malaysian Standard is under the supervision of the following representatives of the CIDB Standard Committee : Ir. Mohamed bin Mohd Nuruddin Megat Kamil Azmi bin Megat Rus Kamarani Puan Zainora bt Zainal Puan Hanishahani Othman
General Manager Technology Development Division Senior Manager Standard and Quality Unit Manager Standard and Quality Unit The Secretary of CIDB Standard Committee
The Technical Committee on Structural Use of Timber which developed this Malaysian Standard consists of the following representatives: Dr. Abdul Rashid bin Hj. Ab. Malik(Chairman)
Forest Research Institute Malaysia
Puan Hanishahani Othman (Secretary)
Construction Industry Development Board Malaysia
Tuan Hj. Mohd Shukari bin Midon
Forest Research Institute Malaysia
Encik Hilmi bin Md. Tahir
Jabatan Kerja Raya Malaysia
Encik Chow Wah/ Puan Dang Anom Md. Zin
Jabatan Perumahan Negara
Prof. Madya Dr. Sabaruddin bin Mohd
Universiti Sains Malaysia
Prof. Dr. Zainai bin Mohamed/ Prof. Madya Dr. Abd. Latif bin Saleh
Universiti Teknologi Malaysia
Prof. Madya Ir. Dr. Mohd Zamin bin Jumaat
Universiti Malaya
Dr. Mohd Ariff bin Jamaludin
Universiti Putra Malaysia
Encik Nor Zamri bin Mat Amin
Malaysian Timber Industry Board
Ir. Yap Chin Tian
Timber Trade Federation Malaysia
Tuan Hj. Wahab bin Abdul Razak
General Lumber Fabricators and Builders Bhd
Dr. Peter Kho C.Seng
Sarawak Timber Association
Encik Lall Singh Gill
Malaysian Wood Moulding and Joint Council
Encik Mohamad Omar b Mohamad Khaidzir
Forest Research Institute Malaysia
iv
MS 544 : PART 2 : 2001
Committee representation (continued)
The Working Group on Solid Timber which developed this Malaysian Standard consists of the following
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representatives: Tuan Hj. Mohd Shukari bin Midon (Chairman)
Forest Research Institute Malaysia
Puan Hanishahani Othman (Secretary)
Construction Industry Development Board Malaysia
Encik Hilmi bin Md. Tahir
Jabatan Kerja Raya
Dr. Mohd Ariff bin Jamaludin
Universiti Putra Malaysia
Prof. Madya Ir. Dr. Mohd Zamin bin Jumaat
Universiti Malaya
Encik Mohd Nor Zamri bin Mat Amin
Malaysian Timber Industry Board
Dr. Peter Kho C.Seng
Sarawak Timber Association
Ir. Yap Chin Tian
Timber Trade Federation Malaysia
Encik Nicolas Roulant
General Lumber Fabricators and Builders Bhd.
v
MS 544 : PART 2 : 2001 FOREWORD This Malaysian Standard was developed by the Technical Committee on Structural Use of Timber established at the Construction Industry Development Board Malaysia (CIDB) under the authority of the Building and Civil Engineering Industry Standards Committee. CIDB is the Standards-Writing Organisation (SWO) appointed by SIRIM Berhad to develop standards for the construction industry. This standard is referred to BS 5268 : Part 2 : 1996, ‘Code of practice for permissible stress design, materials and workmanship’.
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MS 544 consists of the following parts and sections, under the general title, ‘Code of practice for structural use of timber’ : Part 1 :
General
Part 2 :
Permissible stress design of solid timber
Part 3 :
Permissible stress design of glued laminated timber
Part 4 :
Timber panel products: Section 1 : Structural plywood Section 2 : Marine plywood Section 3 : Cement bonded particleboard Section 4 : Oriented strand board
Part 5 :
Timber joints
Part 6 :
Workmanship, inspection and maintenance
Part 7 :
Testing
Part 8 :
Design, fabrication and installation of prefabricated timber for roof trusses
Part 9 :
Fire resistance of timber structures Section 1 : Method of calculating fire resistance of timber members
Part 10 :
Preservative treatment of structural timbers
Part 11 :
Recommendation for the calculation basis for span tables Section 1 : Domestic floor joists Section 2 : Ceiling joists Section 3 : Ceiling binders Section 4 : Domestic rafters
Part 12 :
Laminated veneer lumber for structural application.
This Malaysian Standard supersedes MS 544 : 1978, ‘Code of practice for the structural use of timbers’. Compliance with a Malaysian Standard does not of itself confer immunity from legal obligations.
vi
MS 544 : PART 2 : 2001
CODE OF PRACTICE FOR STRUCTURAL USE OF TIMBER : PART 2 : PERMISSIBLE STRESS DESIGN OF SOLID TIMBER (FIRST REVISION)
1.
Scope
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This Part gives recommendations for the structural use of the Malaysian hardwood and softwood timber species in load bearing members. It includes recommendations on quality, grade stresses and modification factors applicable to these timber when used as simple members, or as parts of built-up components, or as parts of structures incorporating other materials. It does not, and it is not intended to deal comprehensively with all aspects of timber construction. In particular it does not cover well tried and traditional methods of timber construction which have been employed successfully over a long period of time.
2.
Referenced documents
The following referenced documents contain provision which, through reference in this text, constitute provisions of this Malaysian Standard. For dated references, where they are subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this Malaysian Standard are encouraged to investigate the possibility of applying the most recent editions of the referenced documents. For undated references, the latest edition of the publication referred to apply. MS 544 : Part 1
Code of practice for structural use of timber : Part 1 : General.
MS 544 : Part 3 Code of practice for structural use of timber : Part 3 : Permissible stress design of glued laminated timber. MS 544 : Part 5
Code of practice for structural use of timber: Part 5 : Timber joints.
BS 6399 : Part 1 : 1984 imposed loads.
Loading for buildings: Part 1 : Code of practice for dead and
BS 6399 : Part 2 : 1995
Loading for buildings : Part 2 : Code of practice for wind loads.
BS 6399 : Part 3 : 1988 loads.
Loading for buildings : Part 3 : Code of practice for imposed roof
CP3 : Chapter V : Part 2 : 1972
Wind loads.
MS 837 : 1985
Method for determination of moisture content of timber.
MS 360 : 1991 preservative.
Specification for treatment of timber with copper/chrome/arsenic
1
MS 544 : PART 2 : 2001
3.
Timber specification
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Specifiers should consider and, where necessary, specify requirements under each of the following headings. All relevant standards should be referenced. a) b) c) d) e) f)
Strength group, grade and species. Sizes and surface condition. Service class or moisture content. Durability (see MS 837 : 1985). Preservation and preservatives of timber. Special requirements. These may include more restrictive grade, requirements for distortion, wane and marking and preservation treatment (see Appendix C).
4.
Species
Many factors are involved in the choice of species but from the purely structural view, it is the grade stresses which are of prime importance. These differ for each species and grade. To provide an alternative method of specification for the designer and specifiers and greater flexibility of supply, MS 544 : Part 2 gives a series of strength groups which for design use can be considered as being independent of species. The list of species under each strength groups is given in Table 3. For some applications it may be necessary to specify particular species from within a strength group to take into account of particular characteristics, e.g. natural durability, amenability to preservatives (see MS 360), glues and fasteners. Stress values for individual species and grades are given in Tables 1 and 2.
5.
Dimensions and geometrical properties
It is essential to include the required actual dimensions of members in specifications, designs, and drawings. The common commercial timber sizes are given in Table B1 and their geometrical properties given in Tables B3 and B4 of Appendix B. Specification should also provide limits and permissible deviations for dimensions as given in Table B2 of Appendix B. For timber specified in accordance with Appendix B, the design should be based on its minimum size. No modifications need to be made to the geometrical properties which change size with moisture content.
2
MS 544 : PART 2 : 2001
6.
Grades
All timbers used for structural work should be stress graded. The stresses given in MS 544 : Part 2 apply only to timber graded in accordance with Appendix C.
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It should be noted that Appendix C is prepared based on the grading limit of Part III : Section J of the Malaysian Grading Rules for Sawn Hardwood Timber .
7.
Grade stresses for individual species and strength group
7.1
General
Grade stresses for wet and dry conditions are given in Tables 1 and 2 for individual hardwood and softwood species and Table 4 for each strength groups and grades. As it is difficult and expensive to artificially dry timber more than 75 mm thick, the wet stresses and moduli should normally be used for solid timber members more than 75 mm thick, unless they are specially dried. Design may be based either on the grade stresses for the strength group or on those for the individual species and grades. 7.2
Clear wood stresses in timber
The clear wood stresses applicable to some structural timber are given in Tables 1 and 2. These are governed by the general characteristics of the particular species, free from all visible defects and are related to the strength of the timber in wet and dry conditions respectively. In the derivation of clear wood stresses, the following factors have been considered: a)
moisture content;
b)
variability; and
c)
factors of safety (which includes duration of loading, size and shape of member, accidental overloading, errors in design assumptions, etc.)
7.3
Grade stresses in sawn timber
Grade stresses are related to clear wood stresses of the individual species (see 7.2) and governed by the effect of visible gross features such as knots, sloping grain etc. (see Appendix C). The reduction in strength due to a defect is expressed in terms of the strength ratio which may be defined as the ratio of the strength of a piece of timber with a defect to the strength of the same piece without a defect. Strength ratios used in reducing the clear wood stresses to the grade stresses are related to the particular grade and are also governed by the defects which influence the particular strength property. It should be noted that the intrinsic material cost rises with the grade, whilst general availability is reduced. At the design stage, reference should be made to commercial sources for information on the availability of particular species, grades quantities and dimensions. 3
MS 544 : PART 2 : 2001
The stresses of different grades of timber are given in Tables 1 and 2. 7.4
Strength groups of timbers
Timbers having similar strength and stiffness properties have been grouped together for simplicity in design procedure (see Tables 1 and 4).
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The groups thus formed are necessarily based on the weakest species in the particular group.To overcome possible shortages of certain timber species in different regions of Malaysia it is recommended that designs be based on strength groups, and that designers specify structural timber requirements in terms of strength groups. Where designers wish to take full advantage of the strength of particular species, and where commercial supplies are known to exist, a particular timber species may be specified, and the grade quoted for individual species may be used.
4
Table 1. Wet grade stresses of timber (N/mm2) moisture content > 19 % Timber
5
Bending parallel to grain
Tension parallel to grain 2)
Compression parallel to grain
Compression perpendicular to grain
Shear parallel to grain
1)
Modulus of elasticity for all grades
Sel 22.9
Std 18.1
Com 14.3
Sel 13.8
Std 10.8
Com 8.6
Sel 20.3
Std 16.0
Com 12.7
Basic 4.82
Sel 4.10
Std 3.86
Com 3.61
Sel 1.99
Std 1.55
Com 1.25
Mean 14900
Minimum 9800
13.8
10.9
8.6
8.3
6.5
5.2
12.4
9.8
7.7
1.29
1.10
1.03
0.97
1.61
1.25
1.01
12000
8100
7.7
6.0
4.8
1.03
0.87
0.82
0.77
1.02
0.79
0.63
6200
4200
1
Agoho
2
Alan bunga
3
Ara
6.9
5.4
4.3
3)
4.1
3.2
2.6
4
Babai
12.5
9.8
7.8
3)
7.5
5.9
4.7
3)
10.7
8.4
6.7
1.86
1.58
1.49
1.40
1.68
1.31
1.05
10600
7100
5
Balau
30.3
23.9
18.9
18.2
14.3
11.3
26.8
21.1
16.8
4.59
3.90
3.67
3.44
2.67
2.08
1.67
18400
13500
6
Balau, red
18.1
14.2
11.3
10.9
8.5
6.8
15.3
12.0
9.5
2.38
2.02
1.90
1.78
2.07
1.61
1.30
13700
9800
7
Balek angin bopeng
10.8
8.5
6.7
6.5
5.1
4.0
14.7
11.6
9.2
2.59
2.20
2.07
1.94
2.18
1.70
1.36
13200
10100
8
Batai
8.7
6.8
5.4
5.2
4.1
3.2
6.1
4.8
3.8
0.62
0.53
0.50
0.46
0.91
0.71
0.57
6800
4400
9
Bayur
12.2
9.6
7.6
7.3
5.8
4.6
8.5
6.7
5.3
1.64
1.39
1.31
1.23
1.19
0.92
0.74
7500
5700
2.89
2.25
1.80
15300
12200
10
3)
Bekak 3)
3)
3)
20.8
16.4
13.0
12.5
9.8
7.8
17.2
13.5
10.7
3.20
2.72
2.56
2.40
29.0
22.8
18.1
17.4
13.7
10.9
28.6
22.6
17.9
5.43
4.62
4.34
4.07
2.75
2.14
1.72
18000
12100
11
Belian
12
Berangan
14.3
11.3
8.9
8.5
6.7
5.4
13.8
10.8
8.6
3.03
2.57
2.42
2.27
1.53
1.19
0.96
12000
10300
13
Bintangor
11.7
9.2
7.3
7.0
5.5
4.4
10.6
8.4
6.6
1.52
1.29
1.22
1.14
1.61
1.25
1.01
12100
8300
14
Bitis
30.0
23.6
18.8
18.0
14.2
11.3
32.3
25.5
20.2
5.53
4.70
4.42
4.15
2.54
1.98
1.59
21900
18400
15
Brazil nut
18.1
14.2
11.3
10.8
8.5
6.8
11.7
9.2
7.3
3.01
2.56
2.41
2.26
2.48
1.93
1.55
10100
8900
16
Chengal
31.6
24.9
19.7
19.0
14.9
11.8
30.2
23.8
18.9
5.85
4.97
4.68
4.39
3.13
2.44
1.96
18100
13300
1.47
1.14
0.92
10500
6700
17
Damar Minyak
9.6
7.6
6.0
5.8
4.6
3.6
8.2
6.5
5
5.2
1.08
0.92
0.86
0.81
3)
MS 544 : PART 2 : 2001
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MS 544 : PART 2 : 2001
Timber
6
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Table 1. Wet grade stresses of timber (N/mm2) moisture content > 19 % (continued) Bending parallel to grain
Tension parallel to grain 2)
Compression parallel to grain
Compression 1) perpendicular to grain
Shear parallel to grain
Modulus of elasticity for all grades
Sel
Std
Com
Sel
Std
Com
Basic
Sel
Std
Com
Sel
Std
Com
Mean
Minimum
18
Dedali
14.2
11.2
8.8
8.5
6.7
5.3
12.2
9.6
7.7
2.26
1.92
1.81
1.69
1.53
1.19
0.96
10700
7400
19
Dedaru
28.6
22.5
17.9
17.2
13.5
10.7
23.7
18.7
14.9
3.50
2.97
2.80
2.62
2.67
2.08
1.67
17300
12600
20
Delek
21.5
16.9
13.4
12.9
10.1
8.0
16.2
12.7
10.1
3.95
3.36
3.16
2.96
2.10
1.63
1.31
16900
10500
2.68
2.08
1.67
12500
9500
Sel
Std
Com
3)
21
Derum
15.4
12.1
19.6
9.2
7.3
5.8
14.3
11.3
8.9
2.54
2.16
2.03
1.90
22
Durian
13.1
10.3
8.2
7.9
6.2
4.9
11.4
8.9
7.1
1.41
1.20
1.13
1.06
1.43
1.11
0.89
8600
6600
23
Geronggang
9.5
7.5
5.9
5.7
4.5
3.5
6.6
5.2
4.1
0.94
0.80
0.75
0.70
1.09
0.85
0.68
8000
6300
24
Gerutu
16.3
12.9
10.2
9.8
7.7
6.1
15.6
12.3
9.7
1.69
1.44
1.35
1.27
1.33
1.04
0.83
13200
10000
25
Giam
26.0
20.5
16.3
15.6
12.3
9.8
21.9
17.3
13.7
5.33
4.53
4.26
4.00
3.26
2.54
2.04
14600
8700
1.23
0.96
0.77
7900
5400
1.26
0.98
0.79
9100
6500
1.44
1.12
0.90
9300
6200
3)
26
Jelutong
9.4
7.4
5.9
5.6
4.4
3.5
8.0
6.3
5.0
1.02
0.87
0.82
0.76
27
Jenitri
10.1
7.9
6.2
6.0
4.7
3.8
7.8
6.2
4.9
1.02
0.87
0.82
0.76 3)
28
Jongkong
11.3
8.9
7.0
6.8
5.3
4.2
9.4
7.4
5.9
1.02
0.87
0.82
0.76
29
Kapur
19.2
15.1
12.0
11.5
9.1
7.2
17.2
13.5
10.8
2.70
2.30
2.16
2.03
1.71
1.33
1.07
13200
9500
30
Kasah
10.0
7.9
6.2
6.0
4.7
3.7
9.1
7.2
5.7
1.53
1.30
1.22
1.15
1.71
1.33
1.07
9200
5500
12.6
9.9
7.8
2.40
2.04
1.92
1.80
2.00
1.56
1.25
12400
8300
31
Kasai
14.9
11.7
9.3
32
Kayu Kundur
13.9
11.0
33
Kedondong
13.3
34
Kekatong
26.4
3)
3)
8.9
7.0
5.6
8.7
8.4
6.6
5.2
12.3
9.6
7.7
2.37
2.01
1.90
1.78
1.86
1.44
1.16
12600
7700
10.5
8.3
8.0
6.3
5.0
11.4
8.9
7.1
1.50
1.28
1.20
1.13
1.38
1.07
0.86
11200
8200
20.8
16.5
15.8
12.5
9.9
22.3
17.6
13.9
4.46
3.79
3.57
3.34
2.76
2.15
1.73
17000
11700
6
MS 544 : PART 2 : 2001
MS 544 : PART 2 : 2001
Table 1. Wet grade stresses of timber (N/mm2) moisture content > 19 % (continued)
Timber
Bending parallel to grain Sel
7
Std
Tension parallel to grain 2)
Sel
Std
Com
3)
12.1
9.5
7.5
8.6
6.8
5.4
Com
35
Kelat
20.1
15.8
12.5
36
Keledang
14.4
11.3
9.0
Compression parallel to grain
3)
Compression 1) perpendicular to grain
Sel
Std
Com
Basic
Sel
Std
Com
Sel
Std
Com
Modulus of elasticity for all grades Mean Minimum
19.7
15.5
12.3
2.41
2.05
1.93
1.81
2.17
1.68
1.35
16400
10200
11.4
8.9
7.1
2.00
1.70
1.60
1.50
3)
1.71
1.33
1.07
11600
7000
3)
1.84
1.43
1.15
15500
12900
2.24
1.74
1.40
16600
13100
1.84
1.43
1.15
18800
13900
1.36
1.06
0.85
10200
6400
1.99
1.55
1.24
14400
10200
37
Kembang semangkok
20.9
16.5
13.1
12.5
9.9
7.9
17.8
14.0
11.1
2.38
2.02
1.90
1.78
38
Kempas
20.7
16.3
13.0
12.4
9.8
7.8
22.3
17.6
13.9
3.73
3.17
3.00
2.80 3)
39
Keranji
23.5
18.5
14.7
14.1
11.1
8.8
18.6
14.6
11.6
3.60
3.06
2.88
2.70
40
Keruing
12.3
9.7
7.7
7.4
5.8
4.6
10.2
8.0
6.4
1.97
1.67
1.58
1.48 3)
Shear parallel to grain
41
Keruntum
17.2
13.5
10.7
10.3
8.1
6.4
16.1
12.7
10.0
2.71
2.30
2.17
2.03
42
Ketapang
14.6
11.5
9.1
8.8
6.9
5.5
9.6
7.6
6.0
1.53
1.30
1.22
1.15
1.71
1.33
1.07
9700
8500
43
Kulim
20.2
15.9
12.6
12.1
9.5
7.6
19.1
15.0
11.9
2.55
2.17
2.04
1.91
2.15
1.67
1.35
13300
10200
1.84
1.43
1.15
10400
7200
1.22
0.95
0.76
7300
4200
44
Kungkur
16.7
13.2
10.5
10.0
7.9
6.3
12.8
10.1
8.0
2.00
1.70
1.60
1.50
3)
45
Laran
8.8
6.9
5.5
5.3
4.1
3.3
7.6
6.0
4.7
0.95
0.81
0.76
0.71
3)
46
Machang
11.0
8.7
6.9
6.6
5.2
4.1
9.3
7.3
5.8
2.24
1.90
1.79
1.68
1.71
1.33
1.07
6700
5800
47
Malabera
17.4
13.7
10.8
10.4
8.2
6.5
13.7
10.8
8.5
3.26
2.77
2.61
2.44
1.55
1.20
0.97
12800
9800
48
Mata ulat
27.9
22.0
17.4
16.7
13.2
10.4
23.6
18.6
14.8
4.58
3.89
3.66
3.43
2.67
2.08
1.67
16300
14900
49
Medang
13.7
10.8
8.6
8.2
6.5
5.2
11.6
9.1
7.2
1.21
1.03
0.97
0.91
1.50
1.17
0.94
7900
7700
50
Melantai/Kawang
10.6
8.4
6.6
6.4
5.0
4.0
8.7
6.9
5.4
1.20
1.02
0.96
0.90
1.17
0.91
0.73
10800
6200
51
Melunak
12.8
10.1
8.0
7.7
6.1
4.8
13.7
10.8
8.6
1.92
1.63
1.54
1.44
1.49
1.16
0.93
10600
7000
7
MS 544 : PART 2 : 2001
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MS 544 : PART 2 : 2001
Timber
Bending parallel to grain
Tension parallel to grain 2)
Compression parallel to grain
perpendicular to grain
1)
Sel
Std
Com
Sel
Std
Com
Basic
Sel
Std
Com
52
Mempening
16.5
13.0
10.3
9.9
7.8
6.2
14.2
11.2
8.9
3.39
2.88
2.71
2.54
53
Mempisang
13.0
10.2
8.1
7.8
6.1
4.9
10.2
8.1
6.4
1.25
1.06
1.00
54
Mengkulang
15.5
12.2
9.7
9.3
7.3
5.8
11.3
8.9
7.1
2.03
1.72
55
Meransi
21.2
16.7
13.2
12.7
10.0
7.9
17.0
13.3
10.6
3.95
56
Meranti bakau
16.1
12.7
10.0
9.7
7.6
6.0
12.4
9.8
7.7
57
Meranti, dark red
14.1
11.1
8.8
8.5
6.7
5.3
11.4
9.0
58
Meranti, light red
10.8
8.5
6.7
6.5
5.1
4.0
9.6
59
Meranti, white
14.8
11.7
9.2
8.9
7.0
5.5
60
Meranti, yellow
11.7
9.2
7.3
7.0
5.5
4.4
Sel
Std
Com
Modulus of elasticity for all grades
Shear parallel to grain
Compression
Sel
Std
Com
Mean
Minimum
2.24
1.74
1.40
16300
10600
0.94
1.49
1.16
0.93
12100
7300
1.62
1.52
1.86
1.45
1.17
10600
6500
3.36
3.16
2.96
2.53
1.96
1.58
12400
10000
1.83
1.55
1.46
1.37
1.63
1.27
1.02
14700
11000
7.1
1.12
0.95
0.90
0.84
1.50
1.16
0.94
10100
9000
7.6
6.0
1.10
0.93
0.88
0.82
1.05
0.82
0.66
9300
6900
13.4
10.6
8.4
1.28
1.09
1.02
0.96
1.21
0.95
0.76
10800
6100
10.0
7.9
6.2
1.55
1.32
1.24
1.16
1.07
0.83
0.67
10500
7900
15000
10600
3)
3)
61
Merawan
22.9
18.0
14.3
13.7
10.8
8.6
20.3
16.0
12.7
2.72
2.31
2.18
2.04
1.74
1.35
1.09
62
Merbatu
24.2
19.0
15.1
14.5
11.4
9.1
18.8
14.8
11.7
3.50
2.97
2.80
2.623)
2.32
1.80
1.45
18100
12900
63
Merbau
21.1
16.6
13.2
12.7
10.0
7.9
15.7
12.3
9.8
3.23
2.74
2.58
2.42
2.35
1.83
1.47
13900
8600
64
Merpauh
15.7
12.4
9.8
9.4
7.4
5.9
14.4
11.3
9.0
2.35
2.00
1.88
1.76
2.13
1.66
1.33
14200
9600
65
Mersawa
12.6
10.0
7.9
7.6
6.0
4.7
10.2
8.0
6.4
2.26
1.92
1.81
1.69
1.55
1.21
0.97
9200
4900
2.38
1.85
1.49
15700
12500
3)
66
Mertas
24.8
19.5
15.5
14.9
11.7
9.3
20.1
15.9
12.5
3.50
2.97
2.80
2.62
67
Nyalin
18.2
14.4
11.4
10.9
8.6
6.8
15.0
11.8
9.4
3.53
3.00
2.82
2.65
2.66
2.07
1.66
13000
8600
68
Nyatoh
13.7
10.8
8.6
8.2
6.5
5.2
11.8
9.3
7.4
1.99
1.69
1.59
1.49
1.73
1.35
1.08
10600
8200
8
MS 544 : PART 2 : 2001
Table 1. Wet grade stresses of timber (N/mm2) moisture content > 19 % (continued)
8
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MS 544 : PART 2 : 2001
Table 1. Wet grade stresses of timber (N/mm2) moisture content > 19 % (continued) Timber
Bending parallel to grain Sel
Std
Tension parallel to grain 2)
Sel
Std
Com
3)
13.3
10.5
8.3
Com
69
Pauh Kijang
22.2
17.5
13.9
70
Pelajau
8.2
6.5
5.1
4.9
3.9
71
Penaga
29.2
23.0
18.2
17.5
13.8
72 73
Penarahan Penyau
3)
Compression parallel to grain
12.6
9.9
7.9
23.4
18.4
14.6 3)
Shear parallel to grain Sel
Std
Com
Modulus of elasticity for all grades Mean Minimum
2.78
2.16
1.74
17200
11600
0.51
0.91
0.71
0.57
8600
4100
5.01
3.42
2.66
2.14
17000
14300
1.45
1.13
0.90
9400
7600
Compression perpendicular to grain
1)
Sel
Std
Com
Basic
Sel
Std
Com
25.1
19.8
15.7
2.60
2.21
2.08
1.95
3.1
9.3
7.3
5.8
0.68
0.58
0.54
10.9
28.9
22.8
18.1
6.68
5.68
5.34
3)
3)
3)
7.6
5.9
4.7
11.2
8.8
7.0
2.84
2.41
2.27
1.42
14.0
11.0
8.8
25.2
19.8
15.7
6.05
5.14
4.84
4.54
2.21
1.72
1.38
17600
11800
11.8
9.3
7.4
24.8
19.5
15.7
2.73
2.32
2.18
2.05
3.04
2.37
1.90
14800
10000
74
Perah
19.7
15.5
12.3
75
Perupok
17.5
13.8
10.9
10.5
8.3
6.5
13.8
10.8
8.6
2.00
1.70
1.60
1.50
1.54
1.19
0.96
11300
7700
76
Petai
11.0
8.7
6.9
6.6
5.2
4.1
9.1
7.2
5.7
1.35
1.15
1.08
1.01
1.37
1.07
0.86
9600
6700
19.3
15.2
12.0
2.59
2.20
2.07
1.94
2.38
1.85
1.48
15000
10100
1.07
0.83
0.67
6200
3400
2.24
1.74
1.40
13500
11700
1.49
1.16
0.93
14200
11000
9 77
Petaling
19.0
15.0
11.9
78
Pulai
7.2
5.6
79
Punah
19.3
15.2
3)
3)
11.4
9.0
7.1
4.5
4.3
3.4
2.7
5.3
4.2
3.3
0.83
0.70
0.66
0.62
12.1
11.6
9.1
7.3
15.0
11.8
9.4
2.64
2.24
2.11
1.98
3)
3)
3)
80
Ramin
14.2
11.2
8.9
8.5
6.7
5.3
12.4
9.8
7.8
1.87
1.59
1.50
1.40
81
Ranggu
20.8
16.4
13.0
12.5
9.8
7.8
19.4
15.3
12.1
3.34
2.84
2.67
2.50
2.39
1.86
1.49
15300
10700
82
Rengas
18.8
14.8
11.8
11.3
8.9
7.1
12.1
9.5
7.6
2.63
2.23
2.10
1.97
2.48
1.93
1.55
14000
11000
83
Resak
21.1
16.6
13.2
12.7
10.0
7.9
15.0
11.8
9.3
2.92
2.48
2.34
2.19
1.80
1.40
1.12
14400
8500
84
Rubberwood
12.6
9.9
7.9
7.6
5.9
4.7
9.1
7.2
5.7
2.21
1.88
1.77
1.66
2.20
1.71
1.38
8800
6200
85
3)
17.0
13.4
10.6
10.2
8.0
6.4
15.2
12.0
9.5
2.26
1.92
1.81
1.69
1.91
1.49
1.20
10400
7000
Sengkuang
9
MS 544 : PART 2 : 2001
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MS 544 : PART 2 : 2001
Timber
10
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Table 1. Wet grade stresses of timber (N/mm2) moisture content > 19 % (concluded)
Bending parallel to grain
Tension parallel to grain 2)
Compression parallel to grain
Shear parallel to grain
Compression 1) perpendicular to grain
Modulus of elasticity for all grades
Sel
Std
Com
Sel
Std
Com
Basic
Sel
Std
Com
Sel
Std
Com
Mean
Minimum
86
Sepetir
11.0
8.6
6.8
6.6
5.2
4.1
9.4
7.4
5.9
1.92
1.63
1.54
1.44
1.92
1.49
1.20
11700
6800
87
Sesendok
10.8
8.6
6.8
6.5
5.2
4.1
9.1
7.2
5.7
0.99
0.84
0.79
0.74
1.28
1.00
0.80
8500
7100
88
Simpoh
16.5
13.0
10.3
9.9
7.8
6.2
18.2
14.3
11.4
2.87
2.44
2.30
2.15
1.61
1.25
1.01
14300
9400
89
Surian batu
21.0
16.5
13.1
12.6
9.9
7.9
16.7
13.2
10.4
5.06
4.30
4.05
3.79
2.77
2.16
1.73
12400
10800
90
Teak
16.2
12.8
10.1
9.7
7.7
6.1
12.8
10.1
8.0
2.99
2.54
2.39
2.24
2.56
1.99
1.60
9400
6100
1.68
1.30
1.05
12600
6300
Sel
Std
Com
3)
91
Tembusu
14.2
11.2
8.9
8.5
6.7
5.3
14.8
11.7
9.3
3.20
2.72
2.56
2.40
92
Terap
10.2
8.1
6.4
6.1
4.9
3.8
7.9
6.2
5.0
1.37
1.16
1.10
1.03
1.30
1.01
0.81
9900
5400
93
Terentang
6.6
5.2
4.2
4.0
3.1
2.5
5.3
4.2
3.3
0.62
0.53
0.50
0.46
0.99
0.77
0.62
5700
3000
94
Tualang
22.4
17.6
14.0
13.4
10.6
8.4
18.2
14.3
11.4
3.67
3.12
2.94
2.75
2.30
1.79
1.44
16400
10800
1)
When there is no wane at the bearing area, the basic stress figures may be used for all grades.
2)
Sel, Std and Com stand for select structural, standard structural and common building grades respectively as defined in the Malaysian Grading Rules (MGR)(see Appendix C).
3)
Figures are estimated due to data not fully available but can be safely used in design.
10
MS 544 : PART 2 : 2001
MS 544 : PART 2 : 2001
Bending parallel to grain
Timber
11
1
Agoho
2
Alan bunga
3)
Tension parallel to grain 2)
Compression parallel to grain
Shear parallel to grain
Compression 1) perpendicular to grain
Modulus of elasticity for all grades
Sel 27.1
Std 21.4
Com 17.0
Sel 16.3
Std 12.8
Com 10.2
Sel 23.3
Std 18.3
Com 14.5
Basic 6.00
Sel 5.10
Std 4.80
Com 4.50
Sel 4.43
Std 3.44
Com 2.77
Mean 16000
Minimum 10400
15.4
12.2
9.6
9.2
7.3
5.8
14.2
11.2
8.9
1.42
1.21
1.14
1.06
1.72
1.34
1.08
12300
8300
9.2
7.2
5.7
1.56
1.32
1.25
1.17
1.08
0.84
0.67
6700
4500
3
Ara
8.4
6.6
5.2
4
Babai
14.7
11.6
5
Balau
33.6
6
Balau, red
7
3)
3)
3)
5.0
4.0
3.1
9.2
8.8
7.0
5.5
13.1
10.3
8.2
2.13
1.81
1.70
1.60
1.89
1.47
1.18
10800
7200
26.5
21.0
20.2
15.9
12.6
28.5
22.5
17.8
4.67
3.97
3.74
3.50
2.94
2.28
1.84
19400
14200
20.2
15.9
12.6
12.1
9.5
7.6
17.8
14.0
11.1
2.82
2.40
2.26
2.11
2.33
1.81
1.46
14500
10400
Balek angin bopeng
15.8
12.5
9.9
9.5
7.5
5.9
19.1
15.0
11.9
3.82
3.25
3.06
2.86
2.81
2.21
1.75
15600
12000
8
Batai
9.7
7.6
6.0
5.8
4.6
3.6
7.0
5.5
4.4
0.77
0.65
0.62
0.58
0.98
0.76
0.61
7300
4800
9
Bayur
13.7
10.8
8.6
8.2
6.5
5.2
10.2
8.1
6.4
1.64
1.39
1.31
1.23
1.19
0.92
0.74
7500
5700
3.26
2.54
2.04
16500
13100
10
Bekak
11
Belian
12
3)
26.8
21.1
16.7
16.1
12.7
10.0
22.2
17.5
13.9
3.61
3.07
2.89
2.71
31.1
24.5
19.5
18.7
14.7
11.7
30.0
23.6
18.7
5.83
4.96
4.66
4.37
2.92
2.27
1.83
18800
12600
Berangan
16.8
13.2
10.5
10.1
7.9
6.3
16.8
13.2
10.5
3.34
2.84
2.67
2.50
1.68
1.31
1.05
12500
10700
13
Bintangor
15.9
12.5
9.9
9.5
7.5
5.9
14.1
11.2
8.8
1.68
1.43
1.34
1.26
2.13
1.66
1.33
14000
9600
14
Bitis
35.9
28.3
22.5
21.5
17.0
13.5
36.0
28.4
22.5
5.60
4.76
4.48
4.20
2.97
2.31
1.86
23000
19300
15
Brazil nut
19.0
14.9
11.9
11.4
8.9
7.1
12.8
10.1
8.0
3.40
2.89
2.72
2.55
2.64
2.06
1.65
10300
9100
16
Chengal
35.8
28.1
22.3
21.5
16.9
13.4
31.9
25.1
19.9
5.85
4.97
4.68
4.39
3.13
2.44
1.96
19000
14000
17
Damar Minyak
13.1
10.3
8.2
7.9
6.2
4.9
11.4
9.0
7.1
1.35
1.15
1.08
1.01
1.47
1.14
0.92
11700
7500
3)
11
MS 544 : PART 2 : 2001
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MS 544 : PART 2 : 2001 Table 2. Dry grade stresses of timber (N/mm2) moisture content ≤ 19 %
Timber
12
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Table 2. Dry grade stresses of timber (N/mm2) moisture content ≤ 19 % (continued) Bending parallel to grain
Tension parallel to grain 2)
Compression parallel to grain
Shear parallel to grain
Compression 1) perpendicular to grain
Modulus of elasticity for all grades
Std 13.9
Com 11.0
Sel 10.6
Std 8.3
Com 6.6
Sel 14.8
Std 11.7
Com 9.3
Basic 2.35
Sel 2.00
Std 1.88
Com 1.76
Sel 1.73
Std 1.34
Com 1.08
Mean Minimum 11000 7600
18
Dedali
Sel 17.6
19
Dedaru
32.3
25.5
20.2
19.4
15.3
12.1
26.7
21.0
16.7
3.82
3.25
3.05
2.86
3.14
2.48
1.96
18000
13100
20
Delek
22.8
17.9
14.2
13.7
10.7
8.5
18.1
14.2
11.3
4.15
3.53
3.32
3.11
2.23
1.73
1.39
17600
10900
3.38
2.63
2.11
14800
11200
3)
21
Derum
18.2
14.4
11.4
10.9
8.6
6.8
17.7
13.9
11.0
4.37
3.71
3.50
3.28
22
Durian
15.6
12.3
9.7
9.4
7.4
5.8
13.1
10.3
8.2
1.46
1.24
1.17
1.10
1.58
1.23
0.99
9200
7000
23
Geronggang
11.0
8.6
6.8
6.6
5.2
4.1
7.8
6.1
4.8
1.13
0.96
0.90
0.85
1.23
0.96
0.77
8100
6400
24
Gerutu
18.0
14.2
11.2
10.8
8.5
6.7
17.9
14.1
11.2
1.84
1.56
1.47
1.38
1.47
1.14
0.92
13600
10300
25
Giam
29.7
23.4
18.6
17.8
14.0
11.2
23.3
18.3
14.6
5.89
5.00
4.71
4.42
3.57
2.78
2.23
16000
9500
26
Jelutong
11.3
8.9
7.1
6.8
5.3
4.3
9.2
7.2
5.8
1.28
1.09
1.02
0.96
1.32
1.02
0.82
8000
5500
27
Jenitri
12.3
9.7
7.7
7.4
5.8
4.6
10.1
7.9
6.3
1.28
1.09
1.02
0.96
1.46
1.15
0.91
10000
7200
0.91
1.48
1.19
10500
7000
3)
28
Jongkong
15.0
11.8
9.4
9.0
7.1
5.6
12.3
9.7
7.7
1.36
1.16
1.09
1.02
29
Kapur
22.0
17.3
13.7
13.2
10.4
8.2
20.4
16.0
12.7
3.00
2.55
2.40
2.25
1.85
1.44
1.16
13700
9800
30
Kasah
11.3
8.9
7.0
6.8
5.3
4.2
9.6
7.6
6.0
1.68
1.43
1.34
1.27
1.76
1.37
1.10
9600
5700
15.6
12.3
9.7
2.90
2.46
2.32
2.17
2.68
2.09
1.68
12800
8600
31
Kasai
17.2
13.5
10.7
32
Kayu Kundur
14.6
11.5
33
Kedondong
15.8
34
Kekatong
33.4
3)
3)
10.3
8.1
6.4
9.1
8.8
6.9
5.5
13.5
10.6
8.5
2.68
2.27
2.15
2.01
1.98
1.53
1.23
13000
7900
12.4
9.8
9.5
7.4
5.9
14.5
11.4
9.1
1.74
1.48
1.39
1.30
1.76
1.37
1.10
11900
8700
26.3
20.8
20.0
15.8
12.5
26.3
20.7
16.4
4.60
3.91
3.68
3.45
3.17
2.47
1.98
18400
12700
12
MS 544 : PART 2 : 2001
MS 544 : PART 2 : 2001
Table 2. Dry grade stresses of timber (N/mm2) Moisture content ≤ 19 % (continued) Timber
Bending parallel to grain
35
Kelat
Sel 23.1
36
Keledang
15.9
37 38
13
Kembang semangkok Kempas
Tension parallel to grain 2)
Compression parallel to grain
Shear parallel to grain
Compression 1) perpendicular to grain
Modulus of elasticity for all grades
Std 18.2
Com 14.4
Sel 13.9
Std 10.9
Com 8.6
Sel 24.3
Std 19.2
Com 15.2
Basic 2.87
Sel 2.44
Std 2.30
Com 2.15
Sel 2.82
Std 2.20
Com 1.76
Mean Minimum 17300 10700
12.5
9.9
9.5
7.5
5.9
12.9
10.1
8.0
2.24
1.90
1.79
1.68
3)
1.79
1.39
1.12
11900
7200
3)
2.07
1.61
1.30
16500
13700
2.53
1.97
1.58
17700
14000
2.43
1.89
1.52
19800
14700
1.99
1.55
1.25
12000
7500
1.99
1.55
1.24
15800
11200
24.1
19.0
15.0
14.5
11.4
9.0
22.2
17.5
13.9
2.73
2.32
2.18
2.05
23.3
18.3
14.6
14.0
11.0
8.8
24.9
19.6
15.6
4.16
3.54
3.33
3.12 3)
39
Keranji
27.4
21.6
17.2
16.4
13.0
10.3
22.9
18.0
14.3
4.13
3.51
3.30
3.10
40
Keruing
17.5
13.8
11.0
10.5
8.3
6.6
15.4
12.1
9.6
2.11
1.79
1.67
1.58 3)
41
Keruntum
20.8
16.4
13.0
12.5
9.8
7.8
19.9
15.7
12.4
3.00
2.55
2.40
2.25
42
Ketapang
17.8
14.0
11.1
10.7
8.4
6.7
13.6
10.7
8.5
1.91
1.62
1.53
1.43
1.95
1.52
1.22
10700
9300
43
Kulim
24.7
19.4
15.4
14.8
11.6
9.2
22.5
17.7
14.1
2.77
2.35
2.22
2.08
44
Kungkur
19.1
15.0
11.9
11.5
9.0
7.1
14.5
11.4
9.0
2.66
2.26
2.13
2.33
1.81
1.46
14300
11000
2.00
3)
2.09
1.62
1.31
10600
7300
3)
1.22
0.95
0.76
7600
4400
45
Laran
9.9
7.8
6.2
5.9
4.7
3.7
9.6
7.6
6.0
1.30
1.10
1.04
0.97
46
Machang
13.9
10.9
8.7
8.3
6.5
5.2
11.8
9.3
7.4
2.74
2.33
2.19
2.06
2.33
1.81
1.46
7300
6300
47
Malabera
20.3
16.0
12.7
12.2
9.6
7.6
16.2
12.7
10.1
3.79
3.22
3.03
2.84
1.94
1.53
1.21
13500
10400
48
Mata ulat
31.2
24.6
19.5
18.7
14.8
11.7
25.9
20.4
16.2
4.93
4.19
3.94
3.70
2.92
2.27
1.82
16800
15300
49
Medang
16.0
12.6
10.0
9.6
7.6
6.0
14.4
11.3
9.0
1.44
1.22
1.15
1.08
1.74
1.35
1.08
8000
7800
50
Melantai/Kawang
11.8
9.3
7.4
7.1
5.6
4.4
10.6
8.3
6.6
1.35
1.15
1.08
1.01
1.25
0.97
0.78
10900
6300
51
Melunak
14.7
11.6
9.2
8.8
7.0
5.5
15.7
12.3
9.8
2.15
1.83
1.72
1.61
1.87
1.46
1.17
11500
7600
13
MS 544 : PART 2 : 2001
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MS 544 : PART 2 : 2001
Timber
Bending parallel to grain
Tension parallel to grain 2)
Compression parallel to grain
Compression 1) Perpendicular to grain
Shear parallel to grain
Modulus of elasticity for all grades
Std 17.3
Com 13.7
Sel 13.1
Std 10.3
Com 8.2
Sel 18.6
Std 14.6
Com 11.6
Basic 3.68
Sel 3.13
Std 2.94
Com 2.76
Sel 2.53
Std 1.97
Com Mean 1.58 17500
Minimum 11300
52
Mempening
Sel 21.9
53
Mempisang
16.1
12.7
10.1
9.7
7.6
6.1
14.6
11.5
9.1
1.95
1.66
1.56
1.46
1.68
1.31
1.05 13100
7900
54
Mengkulang
17.8
14.0
11.1
10.7
8.4
6.7
13.4
10.6
8.4
2.47
2.10
1.98
1.85
2.20
1.71
1.37 10900
6700
55
Meransi
24.2
19.0
15.1
14.5
11.4
9.1
19.5
15.4
12.2
4.68
3.98
3.74
3.51
2.53
1.96
1.58 12800
10300
56
Meranti bakau
18.2
14.3
11.4
10.9
8.6
6.8
14.1
11.1
8.8
2.06
1.75
1.65
1.54
1.80
1.40
1.13 15000
11200
57
Meranti, dark red
18.2
14.3
11.4
10.9
8.6
6.8
13.9
11.0
8.7
1.53
1.30
1.22
1.15
1.89
1.47
1.18 11200
10000
58
Meranti, light red
13.3
10.4
8.3
8.0
6.2
5.0
11.4
8.9
7.1
1.23
1.04
0.98
0.92
1.11
0.86
0.69
9800
7200
59
Meranti, white
17.1
13.5
10.7
10.3
8.1
6.4
15.7
12.3
9.8
1.62
1.38
1.30
1.21
1.55
1.20
0.97 11200
6300
60
Meranti, yellow
13.2
10.4
8.2
7.9
6.2
4.9
12.4
9.8
7.7
1.73
1.47
1.38
1.30
1.25
0.97
0.78 10800
8100
61
Merawan
25.1
19.8
15.7
15.1
11.9
9.4
23.0
18.1
14.4
2.95
2.51
2.36
2.21
1.91
1.48
1.19 15500
11000
62
Merbatu
29.0
22.8
18.1
17.4
13.7
10.9
23.8
18.8
14.9
4.07
3.46
3.25
3.05
2.51
1.95
1.57 19400
13800
63
Merbau
24.6
19.4
15.4
14.8
11.6
9.2
17.9
14.1
11.2
4.00
3.40
3.20
3.00
2.57
2.00
1.61 14800
9100
64
Merpauh
19.2
15.1
12.0
11.5
9.1
7.2
17.4
13.7
10.9
3.22
2.74
2.58
2.41
2.62
2.04
1.64 15400
10400
65
Mersawa
14.7
11.6
9.2
8.8
7.0
5.5
11.5
9.1
7.2
2.42
2.06
1.94
1.81
1.72
1.34
1.08
9700
5200
66
Mertas
28.5
22.4
17.8
17.1
13.4
10.7
23.4
18.5
14.7
3.82
3.25
3.05
2.863)
2.53
1.97
1.58 17300
13800
67
Nyalin
22.5
17.7
14.1
13.5
10.6
8.5
19.6
15.5
12.3
4.44
3.77
3.55
3.33
3.17
2.46
1.98 14300
9500
68
Nyatoh
16.2
12.3
10.1
9.7
7.7
6.1
14.5
11.4
9.0
2.08
1.77
1.66
1.56
1.99
1.55
1.25 11300
8700
14
MS 544 : PART 2 : 2001
Table 2. Dry grade stresses of timber (N/mm2) moisture content ≤ 19 % (continued)
14
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MS 544 : PART 2 : 2001
Table 2. Dry grade stresses of timber (N/mm2) moisture content ≤ 19 % (continued) Bending parallel to grain
Timber
15
Tension parallel to grain 2)
Compression parallel to grain
Shear parallel to grain
Compression 1) perpendicular to grain
Modulus of elasticity for all grades
Std 19.7
Com 3) 15.60
Sel 15.0
Std 11.8
Com 3) 9.4
Sel 27.7
Std 21.8
Com 17.3
Basic 4.80
Sel 4.08
Std 3.84
Com 3) 3.6
Sel 3.35
Std 2.60
Com 2.09
Mean Minimum 18000 12100
69
Pauh kijang
Sel 25.0
70
Pelajau
9.1
7.2
5.7
5.5
4.3
3.4
10.3
8.1
6.4
0.77
0.65
0.62
0.58
0.98
0.76
0.61
8800
4200
71
Penaga
35.3
27.8
22.1
21.2
16.7
13.3
33.9
26.8
21.2
8.55
7.27
6.84
6.41
4.17
3.24
2.61
18800
15800
72
Penarahan
14.3
11.3
8.9
8.6
6.8
5.3
13.0
10.2
8.1
4.30
3.65
3.44
3.22
1.60
1.25
1.00
9600
77003)
26.9
21.2
16.8
16.1
12.7
10.1
27.0
21.3
16.9
6.74
5.73
5.39
5.05
2.80
2.18
1.75
18600
12500
3)
73
Penyau
74
Perah
21.8
17.2
13.6
13.1
10.3
8.2
27.0
21.3
16.9
2.99
2.54
2.39
2.24
3.31
2.58
2.07
15200
10300
75
Perupok
20.6
16.2
12.9
12.4
9.7
7.7
17.9
14.1
11.2
2.80
2.38
2.24
2.10
1.58
1.23
0.99
12200
8300
76
Petai
12.1
9.5
7.5
7.3
5.7
4.5
11.0
8.6
6.8
1.55
1.32
1.24
1.16
1.37
1.07
0.86
10200
7100
22.4
17.6
14.0
2.61
2.22
2.09
1.96
2.38
1.85
1.48
15400
10400
1.10
0.86
0.69
6900
3800
2.44
1.90
1.52
15400
13300
1.73
1.35
1.08
15700
12100
77
Petaling
21.2
16.6
13.2
12.7
10.0
7.9
3)
3)
3)
78
Pulai
9.0
7.0
5.6
5.4
4.2
3.4
7.7
6.0
4.8
1.02
0.87
0.82
0.76
79
Punah
25.4
20.0
15.8
15.2
12.0
9.5
21.5
16.9
13.4
3.58
3.04
2.86
2.68 3)
80
Ramin
19.8
15.5
12.3
11.9
9.3
7.4
17.0
13.4
10.6
2.15
1.83
1.72
1.61
81
Ranggu
25.2
19.8
15.7
15.1
11.9
9.4
22.9
18.0
14.3
3.65
3.10
2.92
2.74
2.47
1.92
1.54
16600
11600
82
Rengas
23.1
18.2
14.4
13.9
10.2
8.6
15.2
12.0
9.5
3.32
2.82
2.65
2.49
2.83
2.20
1.77
14600
11500
83
Resak
23.4
18.4
14.6
14.0
11.0
8.8
17.0
13.4
10.6
3.27
2.78
2.62
2.45
1.99
1.55
1.25
14600
8600
84
Rubberwood
13.9
11.0
8.7
8.3
6.6
5.2
10.8
8.5
6.7
2.68
2.28
2.14
2.01
2.57
2.00
1.61
9100
6400
19.8
15.6
12.4
11.9
9.4
7.4
18.3
14.4
11.4
2.59
2.20
2.07
1.94
2.36
1.84
1.48
12000
8100
85
Sengkuang
3)
15
MS 544 : PART 2 : 2001
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MS 544 : PART 2 : 2001
Timber
Bending parallel to grain
Tension parallel to grain 2)
Compression parallel to grain
Shear parallel to grain
Compression 1) Perpendicular to grain
Modulus of elasticity for all grades
Sel 7.9
Std 6.2
Com 4.9
Sel 11.2
Std 8.8
Com 7.0
Basic 2.42
Sel 2.06
Std 1.94
Com 1.81
Sel 2.38
Std 1.85
Com 1.48
Mean Minimum 13000 7600
7.6
7.3
5.8
4.6
10.9
8.5
6.8
1.11
0.94
0.89
0.83
1.37
1.06
0.85
8600
7200
14.2
11.3
10.9
8.5
6.8
20.8
16.4
13.0
3.14
2.67
2.51
2.35
1.70
1.33
1.06
14400
9500
23.8
18.7
14.8
14.3
11.2
8.9
21.6
17.0
13.5
6.13
5.20
4.90
4.60
3.70
2.91
2.31
14300
11900
17.9
14.1
11.2
10.7
8.5
6.7
14.9
11.7
9.3
3.12
2.65
2.50
2.34
2.56
1.99
1.60
10300
6300
1.68
1.30
1.05
13600
6800
86
Sepetir
Sel 13.2
Std 10.3
Com 8.2
87
Sesendok
12.2
9.6
88
Simpoh
18.1
89
Surian batu
90
Teak
3)
91
Tembusu
17.3
13.6
10.8
10.4
8.2
6.5
16.5
13.0
10.3
3.75
3.19
3.00
2.81
92
Terap
11.4
8.9
7.1
6.8
5.3
4.3
8.8
6.9
5.5
1.68
1.43
1.34
1.26
1.76
1.37
1.10
10100
5500
93
Terentang
8.2
6.5
5.1
4.9
3.9
3.1
6.9
5.4
4.3
0.95
0.80
0.76
0.71
1.20
0.93
0.75
6600
3400
94
Tualang
25.7
20.2
16.1
15.4
12.1
9.7
20.4
16.1
12.8
4.00
3.40
3.20
3.00
3.08
2.40
1.93
17500
11500
1)
When there is no wane at the bearing area, the basic stress figures may be used for all grades.
2)
Sel, Std and Com stand for select structural, standard structural and common building grades respectively as defined in the Malaysian Grading Rules (MGR)(see Appendix C).
3)
Figures are estimated due to data not fully available but can be safely used in design.
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MS 544 : PART 2 : 2001
Table 2. Dry grade stresses of timber (N/mm2) moisture content ≤ 19 % (concluded)
16
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MS 544 : PART 2 : 2001
Table 3. Strength groups of timber S.G. 1 S.G.2 A) Naturally Durable Balau Belian Bitis Mata ulat Chengal Kekatong Penaga B) Requiring Treatment Dedaru Kempas Merbatu Mertas
17
S.G. 3
S.G. 4
S.G. 5
Bekak Delek Keranji
Giam Malabera Merbau Resak
Teak Tembusu
Agoho Balau, red Kelat Kembang semangkok Kulim Pauh kijang Penyau Perah Petaling Ranggu Durian batu Tualang
Berangan Dedali Derum Kapur Kasai Keruntum Mempening Meransi Meranti bakau Merawan Merpauh Nyalin Perupok Punah Rengas Simpoh
Alan bunga Babai Balek angin bopeng Bintangor Brazil nut Gerutu Kayu kundur Kedondong Keledang Keruing Ketapang Kungkur Melunak Mempisang Mengkulang Meranti, dark red Meranti, white Nyatoh Penarahan Petai Ramin Rubberwood Sengkuang Sepetir
S.G. 6
Bayur Damar Minyak Durian Jelutong Jenitri Jongkong Kasah Machang Medang Melantai/Kawang Meranti, light red Meranti, yellow Mersawa Terap
S.G. 7
Ara Batai Geronggang Laran Pelajau Pulai Sesendok Terentang
NOTES: 1. For naturally durable timbers, sapwood should be excluded. If sapwood is included, preservative treatment is necessary.(Source: MS360, 1986) 2. For timber requiring treatment, they should be amenable to preservative treatment.
17
MS 544 : PART 2 : 2001
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MS 544 : PART 2 : 2001
Strength groups
18
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Table 4. Wet and dry grade stresses for various strength groups of timber (Stresses and moduli expressed in N/mm2)
1) 2) 3)
Condition
1)
Bending parallel to grain Sel
Std
Com
Sel
Std
Com
Sel
Std
Com
Basic
Sel
Std
Com
Sel
Std
Com
Modulus of elasticity for all grades Mean Minimum
Tension parallel to grain 3)
Compression parallel to grain
Compression 2) perpendicular to grain
Shear parallel to grain
SG 1
Wet Dry
29.2 33.6
23.0 26.5
18.2 21.0
17.5 20.2
13.8 15.9
10.9 12.6
26.8 28.5
21.1 22.5
16.8 17.8
4.59 4.67
3.90 3.97
3.67 3.74
3.44 3.50
2.54 2.94
1.98 2.28
1.59 1.84
17000 18800
13300 14000
SG 2
Wet Dry
20.7 23.3
16.3 18.3
13.0 14.6
12.4 14.0
9.8 11.0
7.8 8.8
18.8 23.4
14.8 18.5
11.7 14.7
3.50 3.82
2.97 3.25
2.80 3.05
2.62 2.86
2.24 2.51
1.74 1.95
1.40 1.57
15700 16800
11700 12600
SG 3
Wet Dry
18.1 20.2
14.2 15.9
11.3 12.6
10.9 12.1
8.5 9.5
6.8 7.6
15.3 17.8
12.0 14.1
9.5 11.1
2.38 2.61
2.02 2.22
1.90 2.09
1.78 1.96
1.84 2.07
1.43 1.61
1.15 1.30
13300 14300
9800 10300
SG 4
Wet Dry
14.2 16.8
11.2 13.2
8.8 10.5
8.5 10.1
6.7 7.9
5.3 6.3
12.1 14.1
9.5 11.1
7.6 8.8
1.83 2.06
1.55 1.75
1.46 1.65
1.37 1.54
1.53 1.58
1.19 1.23
0.96 0.99
10700 11000
7400 7600
SG 5
Wet Dry
11.0 12.1
8.6 9.5
6.8 7.5
6.6 7.3
5.2 5.7
4.1 4.5
9.1 10.8
7.2 8.5
5.7 6.7
1.12 1.42
0.95 1.21
0.90 1.14
0.84 1.06
1.21 1.37
0.95 1.07
0.76 0.86
8800 9100
6100 6300
SG 6
Wet Dry
9.4 11.3
7.4 8.9
5.9 7.1
5.6 6.8
4.4 5.3
3.5 4.3
7.9 8.8
6.2 6.9
5.0 5.5
1.02 1.28
0.87 1.09
0.82 1.02
0.76 0.96
1.05 1.11
0.82 0.86
0.66 0.69
6700 7300
4900 5200
SG 7
Wet Dry
6.6 8.2
5.2 6.5
4.2 5.1
4.0 4.9
3.1 3.9
2.5 3.1
5.3 6.9
4.2 5.4
3.3 4.3
0.62 0.77
0.53 0.65
0.50 0.62
0.46 0.58
0.91 0.98
0.71 0.76
0.57 0.61
5700 6600
3000 3400
Moisture content for Wet > 19 %, for dry ≤ 19 %. When there is no wane at the bearing area, the basic stress figures may be used for all grades. Sel, Std and Com stand for select structural, standard structural and common building grades respectively as defined in the Malaysian Grading Rules (MGR)(see Appendix C).
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MS 544 : PART 2 : 2001
MS 544 : PART 2 : 2001
MS 544 : PART 2 : 2001 8.
Permissible stresses
8.1
General
Permissible stresses in timber are governed by the particular conditions of service and loading. 8.2
Load inclined to grain
Where the direction of the load is inclined to the grain by an angle α, the permissible compression stress for the inclined surface is given by the equation:
σc,adm, α = σc,adm,ll − (σc,adm,ll
_
σc,adm,⊥)sin α
where σc,adm,ll and σc,adm,⊥ are the grade compression stresses parallel and perpendicular to the grain respectively, modified as appropriate, for moisture content and / or duration of load (see Clause 9).
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8.3
Additional properties
In the absence of specific test data, values which are one-third of those for shear parallel to the grain (see Tables 1, 2 and 4) should be use for tension perpendicular to the grain, torsional shear and rolling shear. For modulus of elasticity perpendicular to grain, a value of one-twentieth (i.e. 0.05) of permissible modulus of elasticity (see Tables 1, 2 and 4) should be used. For shear modulus, a value of one-sixteenth (i.e. 0.0625) of permissible modulus of elasticity (see Tables 1, 2 and 4) should be used.
9.
Duration of loading
The stresses given in Tables 1, 2 and 4 apply to long term loading. Table 5 gives the modification factor K1 by which these should be multiplied for various duration of loading. When advantage is taken of this clause to use a modification factor K1, greater than unity, the design should be checked to ensure that the permissible stresses are not exceeded for any other condition of loading that might be relevant. This modification factor is applicable to all strength properties but is not applicable to moduli of elasticity or to shear moduli. For domestic floors, the possible concentrated loading condition given in BS 6399: Part 1 (i.e. 1.4 kN) may be superimposed on the dead load and both treated as of medium term duration.
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MS 544 : PART 2 : 2001
Table 5. Modification factor K1 for duration of loading Duration of loading
Value of K1
Long term (e.g. dead + permanent imposed )
1)
1.00
Medium term (dead + temporary imposed)
1.25
2)
Short term (e.g. dead + imposed + wind )
1.50 3)
Very short term (e.g. dead + imposed + wind )
1.75
NOTES: 1)
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2)
3)
For uniformly distributed imposed floor loads K1 = 1 except for type 2 and type 3 buildings (see Table 5 of BS 6399 : Part 1:1984 (UBBL: 1997) where, for corridors, hallways, landings and stairways only, K1 may be assumed to be 1.5. For wind , short term category applies to class C (15 s gust) as defined in CP3: Chapter V: Part 2 or, where the largest diagonal dimension of the loaded area a, as defined in BS 6399: Part 2, exceeds 50 m. For wind, very short term category applies to class A and B ( 3 s or 5 s gust) as defined in CP3: Chapter V : Part 2 or, where the largest diagonal dimension of the loaded area a, as defined in BS 6399 : Part 2, does not exceed 50 m.
10.
Load-sharing systems
In a load-sharing system which consists of four or more members such as rafters, joists, trusses or wall studs, spaced a maximum of 610 mm centre to centre, and which has adequate provision for the lateral distribution of loads by means of purlins, binders, boarding, battens, etc., the following permissible stresses and moduli of elasticity appropriate to the strength class or species and grade should apply. a)
The appropriate grade stresses should be multiplied by the load sharing modification factor K2 which has a value of 1.1.
b)
The mean modulus of elasticity should be used to calculate deflections and displacements under both dead and imposed load unless the imposed load is for an area intended for mechanical plant and equipment, or for storage, or for floors subject to vibrations, e.g. gymnasia and ballrooms, in which case the minimum modulus of elasticity should be used.
Special provisions for built-up beams, trimmer joists and lintels, and laminated beams, are given in 11.10, 11.11 and MS 544 : Part 3 respectively. The provisions of this clause do not extend to the calculation of modification factor K8 given in Table 10 and Appendix D for load-sharing columns.
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MS 544 : PART 2 : 2001
11.
Flexural members
11.1
General
Permissible stresses for timber flexural members are governed by the particular conditions of service and loading as given in Clauses 9 and 10 and by the additional factors given in this clause. They should be taken as the product of the grade stress given in Clause 7 and the appropriate modification factors. 11.2
Length and position of bearing
The grade stresses for compression perpendicular to the grain apply to bearings of any length at the ends of a member, and bearings 150 mm or more in length at any position.
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For bearings less than 150 mm long located 75 mm or more from the end of a member, as shown in Figure 1 the grade stress should be multiplied by the modification factor K3 given in Table 6. NOTES: 1. At any bearing on the side grain of timber, the permissible stress in compression perpendicular to the grain is dependent on the length and position of the bearing. 2. No allowance need be made for the difference in intensity of the bearing stress due to rotation of a beam at the supports.
75 mm or more
Bearing less than 150 mm
Figure 1. Position of end bearing
21
MS 544 : PART 2 : 2001
Table 6. Modification factor K3 for bearing stress Length of bearing
1)
10
15
25
40
50
75
100
(mm)
more
Value of K3
1)
1.74
1.67
1.53
1.33
1.20
1.14
1.10
1.00
Interpolation is permitted
11.3
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150 or
Effective span
The span of flexural members should be taken as the distance between the centres of bearings. Where members extend over bearings which are longer than is necessary, the spans may be measured between the centres of bearings of a length which could be adequate according to MS 544 : Part 2. Where advantage is taken of this clause, due attention should be paid to the eccentricity of the load on the supporting structure.
11.4
Shear at notched ends
Square cornered notches at the ends of a flexural member cause a stress concentration, which should be allowed for as follows. The shear strength should be calculated by using the effective depth, he (see Figure 2) and a permissible stress equal to the grade stresses multiplied by the factor K4 where, a)
for a notch on the top edge (see Figure 2(a)) h (he- a) + a h e K4 =
h e2
K4 = 1.0 b)
for a ≤ h e
for a > h e
for a notch on the underside (see Figure 2 (b)), he K4 = ⎯⎯
h where, h
is the total depth of the beam (mm);
a
is as shown in Figure 2 (mm).
22
MS 544 : PART 2 : 2001
The effective depth, he should be not less than 0.6 h. a
h he
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a)
Beam with notch on the top edge
he
h
b)
Beam with notch on the underside.
Figure 2. Notched beams
11.5
Form factor
Grade bending stresses apply to solid timber members of rectangular cross section. For other shapes of cross section, the grade bending stresses should be multiplied by the modification factor K5 where, K5
= 1.18 for solid circular sections; and
K5
= 1.41 for solid square sections loaded on a diagonal.
11.6
Depth factor
The grade bending stresses given in Tables 1, 2 and 4, apply to material having a depth, h, up to 300 mm. For depths of beams greater than 300 mm, the grade bending stresses should be multiplied by the depth modification factor K6 where: ( h2 + 92300) K6 = 0.81 ⎯⎯⎯⎯⎯⎯ for solid and glued laminated beams. (h2 + 56800) 23
MS 544 : PART 2 : 2001
11.7
Deflection and stiffness
The dimensions of flexural member should be such as to restrict deflection within limits appropriate to the type of structure, having regard to the possibility of damage to surfacing materials, ceilings, partitions and finishing, and to the functional needs as well as aesthetic requirements. For glued laminated members in addition to the deflection due to bending, the shear deflection may be significant and should be taken into account. For most general purposes, this recommendation may be assumed to be satisfied if the deflection of member when fully loaded does not exceed 0.003 of the span. For domestic floor joists, the deflection under full load should not exceed 0.003 times the span or 14 mm, whichever is the lesser.
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NOTE. 14 mm deflection limitation is to avoid undue vibration under moving or impact loading.
Subject to consideration being given to the effect of excessive deformation, members may be precambered to account for the deflection under full dead or permanent load, and in this case the deflection under live or intermittent load should not exceed 0.003 of the span. The deflection of solid timber members acting alone should be calculated using the minimum modulus of elasticity for the strength group or species and grade. The deflections of load-sharing systems, built-up beams, trimmer joists and lintels should be calculated using the provisions of Clauses 10, 11.10 and 11.11 respectively. 11.8
Lateral support
The depth to breadth ratio of solid and laminated beams of rectangular section should be checked to ensure that there is no risk of buckling under design load. Alternatively, the recommendations of Table 7 should be followed.
Table 7. Maximum depth to breadth ratios (solid and laminated members) Degree of lateral support
Maximum depth to breadth ratio
No lateral support
2
Ends held in position
3
Ends held in position and member held in line as by purlins or tie rods at centres not more
4
than 30 times breadth of the member Ends held in position and compression edge held in line, as by direct connection of
5
sheathing, deck or joists Ends held in position and compression edge held in line, as by direct connection of
6
sheathing, deck or joists, together with adequate bridging or blocking spaced at intervals not exceeding 6 times the depth. Ends held in position and both edges held firmly in line
7
24
MS 544 : PART 2 : 2001
11.9
Notched beams
In calculating the strength of notched or drilled beams, allowance should be made for the notches or holes, the effective depth being taken as the minimum depth of the net section.
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The effect of notches and holes need not be calculated in simply supported floor and roof-joist not more than 250 mm deep where: a)
notches not exceeding 0.125 of the depth of a joist are located between 0.07 and 0.25 of the span from the support; and
b)
holes drilled at the neutral axis with diameter not exceeding 0.25 of the depth of a joist and not less than three diameters (centre to centre) apart are located between 0.25 and 0.4 of the span from the support.
11.10
Built - up beams
Built-up beams should be checked to ensure that there is no risk of buckling under design load. In built-up members with thin webs, web stiffeners should be provided to ensure the strength and stability of the member at all points of concentrated load, or elsewhere as may be necessary. The lateral stability should be determined by calculation, or by consideration of the compression flange as a column which tends to deflect sideways between points of lateral support, or in accordance with one of the following: a)
if the ratio of the second moments of area of the cross section about the neutral axis to the second moment of area about the axis perpendicular to the neutral axis does not exceed 5 to 1, no lateral support is required;
b)
if the ratio of the second moments of area is between 5 to 1 and 10 to 1, the ends of the beam should be held in position at the bottom flange at the supports;
c)
if the ratio of the second moments of area is between 10 to 1 and 20 to 1, the beam should be held in line at the ends;
d)
if the ratio of the second moments of area is between 20 to 1 and 30 to 1, one edge should be held in line;
e)
if the ratio of the second moments of area is between 30 to 1 and 40 to 1, the beam should be restrained by bridging or other bracing at intervals of not more than 2.4 m; and
f)
if the ratio of the second moments of area is greater than 40 to 1, the compression flanges should be fully restrained.
The modification factors K17, K18 and K19 given in Table 7 of MS 544 : Part 3 may be used for the flanges of glued built-up beams such as box and I-beams. The number of pieces of timber in each flange should be taken as the number of laminations, irrespective of their orientation, to determine the value of the stress modification factor K17, K18, and K19 for that flange.
25
MS 544 : PART 2 : 2001
The total number of pieces of timber in both flanges should be taken as the number of laminations to determine the value of K18 that is to be applied to the minimum modulus of elasticity for deflection calculations. In addition to the deflection of a built-up beam due to bending, the shear deflection may be significant and should be taken into account. 11.11
Trimmer joists and lintels
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For trimmer joists and lintels comprising two or more pieces connected together in parallel and acting together to support the loads, the grade stresses in bending and shear parallel to the grain, and in compression perpendicular to the grain should be multiplied by the load-sharing stress modification factor K2, which has a value of 1.1. The minimum modulus of elasticity modified by the factor K7 given in Table 8 should be used for the calculation of deflection.
Table 8. Modification factor K7 used to modify the minimum modulus of elasticity for trimmer joists and lintels Number of pieces
Values of K7
1
1.00
2
1.06
3
1.08
4 or more
12.
Compression members
12.1
General
1.10
The limitations on bow in most stress grading rules are inadequate for the selection of material for columns. Particular attention should therefore be paid to the straightness of columns, e.g. by limiting bow to approximately 1/300 of the length. Permissible stresses for timber members subjected to compression in the direction of the grain are governed by the particular conditions of loading given in Clauses 9 and 10 and by the additional factors given in this clause. 12.2
Size factors
The grade compression stresses given in Tables 2, 3 and 4 apply to all solid timber members graded in accordance with Section J of the Malaysian Grading Rules.
26
MS 544 : PART 2 : 2001
12.3
Effective length
The effective length of a compression member should be derived from either: a)
Table 9 for the particular end conditions; or
b)
the deflected form of the compression member as affected by any restraint and/or fixing moment(s), the effective length being the distance between adjacent points of zero bending between which the member is in single curvature.
Table 9. Effective length of compression members Effective length End conditions
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Actual length Restrained at both ends in position and in direction
0.7
Restrained at both ends in position and one end in direction
0.85
Restrained at both ends in position but not in direction
1.0
Restrained at one end in position and in direction and at the
1.5
L
other end in direction but not in position Restrained at one end in position and in direction and free at
2.0
the other end
12.4
Slenderness ratio
The slenderness ratio of compression members should be calculated as the effective length, Le divided by the radius of gyration, i. The slenderness ratio should not exceed 180 for: a)
any compression member carrying dead and imposed loads other than loads resulting from wind; and
b)
any compression member, however loaded, which by its deformation will adversely affect the stress in another member carrying dead and imposed loads other than wind.
The slenderness ratio should not exceed 250 for: a)
any member normally subject to tension or combined tension and bending arising from dead and imposed loads, but subject to a reversal of axial stress solely from the effect of wind; and
b)
any compression member carrying self weight and wind loads only (e.g. wind bracing).
27
MS 544 : PART 2 : 2001
12.5
Members subject to axial compression (without bending)
For compression members with slenderness ratios of less than 5, without undue eccentricity of loading, the permissible stress should be taken as the grade compression parallel to the grain stress modified as appropriate for duration of load and load sharing (Clauses 9 and 10).
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For compression members with slenderness ratios equal to or greater than 5, the permissible stress should be calculated as the product of the grade compression parallel to the grain stress, modified as appropriate for size, moisture content, duration of load and load sharing, and the modification factor K8 given in Table 10 or calculated using the equation in Appendix D. The value of modulus of elasticity used to enter Table 10 or the equation in Appendix D for both compression members acting alone and compression members in load-sharing systems should be the minimum modulus of elasticity. For members comprising two or more pieces connected together in parallel and acting together to support the loads, the minimum modulus of elasticity should be modified by K7 ( see Table 8 ) or K18 (see Table 7 of MS 544: Part 3). For horizontally laminated members, the modified mean modulus of elasticity should be used (see Clauses 4 and 8 of MS 544 : Part 3). The compression parallel to the grain stress σc used to enter Table 10 or the equation in Appendix D should be the grade stress modified only for duration of loading, and size where applicable. When checking that the permissible stresses of a compression member are not exceeded, consideration should be given to all relevant loading conditions, since in the expression E/σc,ll , used to enter Table 10 or the equation in Appendix D, the modulus of elasticity is constant for all load duration, whereas the compression stress should be modified for duration of loading (Clause 9).
28
Table 10. Modification factor K8 for compression members Value of K8 Values of slenderness ratio λ (= Le/i ) E/σc,ll
