REVISED MALAYSIAN CODE OF PRACTICE FOR STRUCTURAL USE OF TIMBERAbdul Rashid A.M.1, Mohd Shukari Midon2, Mohd Zamin Jumaat3 & Wan Mahmood Wan Ab. Majid4 1. Senior Director/Chairman Technical Committee on Timber Structures, Forest Research Institute Malaysia (FRIM), Kepong, 52109 Kuala Lumpur, MALAYSIA. 2. Senior Research Officer, Forest Research Institute Malaysia (FRIM), Kepong, 52109 Kuala Lumpur, MALAYSIA. 3. Assoc. Professor, Department of Civil Engineering, Faculty of Engineering, Universiti Malaya, 50603 Kuala Lumpur, MALAYSIA. 4. Professor, Department of Civil Engineering, Universiti Teknologi Mara (UiTM), 40450 Shah Alam, Selangor D.E., MALAYSIA SUMMARY The Malaysian Standard (M.S.) 544:1978, The Code of Practice for Structural Use of Timber is being revised. The revision is being coordinated by the Technical Committee on Timber Structures (TC 4), a committee formed by the Construction Industrial Development Board Malaysia (CIDB). The new M.S. 544 will have 12 Parts and 11 Sections. So far TC 4 has completed 10 Parts and 8 Sections including Parts on fire resistance and design for glued-laminated timber members. The revision of the Standard is in its final stages. The task involves ten Working Groups formed by TC 4 and comprised sixty members. Once completed the Standard contains basic working stresses, design methods and general guidance on structural use of Malaysian timbers including wood-based panel products and glued-laminated timber members. This paper highlights some of the features of the newly published Parts. Keywords: Code, Standard, Timber, Strength grouping, Joints, Glued laminated members, Panel products, Fire resistance 1. INTRODUCTION In the past, design and detailing of timber structures in Malaysia was done according to the Malaysian Standard (M.S.) 544: 1978, Code of Practice for Structural Use of Timber [1]. The Code was purely a carbon copy of the British Codes of Practice for design of timber structures, CP 112: 1967, except for the species used [2]. The code has never been revised since its first circulation. Only in late 1997 was revision for the Standard initiated by the Technical Committee on Timber Structures (TC 4). TC 4 was formed by the Construction Industrial Development Board Malaysia (CIDB), a Standard Writing Organisation on building material appointed by the Standards Industrial Research Institute of Malaysia (SIRIM) Bhd. The revision of the Standard is currently in its final stages. The prodigious task has been undertaken by 10 Working Groups (WG), commissioned by TC 4. The WG comprises 60 members from various government agencies, research institutions and professional 1 The first document was published in 2001. timber joints (Part 5) and fire resistance of timber structures (Part 9). seven Parts are considered new and five are revised documents.bodies. heavy hardwoods (800–1120 kg/m3). designs of glued-laminated timber (Part 3). It is based on permissible stress design (elastic design) rather than limit state design. CIDB and TC 4 have organised several workshops to introduce the newly published Parts of the Standard to professional engineers. Part 1: General (revised) Part 2: Permissible stress design of solid timber (revised) Part 3: Permissible stress design of glued-laminated timber (new) Part 4: Timber panel products (new) Section 1: Structural plywood Section 2: Marine plywood Section 3: Cement-bonded particleboard Section 4: Oriented-strand board (OSB) Part 5: Timber joints (revised) Part 6: Workmanship. namely. medium hardwoods (720-880 kg/m3). contractors and government bodies. DESIGN OF SOLID MEMBERS Part 2 of the Code outlines design procedures to be followed depending on the type of element being designed. Unlike the previous Code of Practice. the new Code will ultimately be published into 12 Parts under the title ‘Code of Practice for Structural Use of Timber’ [3]. This paper highlights some of the features of the newly published Parts. 2. The designs of curved and tapered members are not within the scope of the Standard. after about four years since the inception of TC 4. 2. light 2 . For promotion. inspection and maintenance (revised) Part 7: Testing (revised) Part 8: Design. Malaysian timbers are generally classified into four categories. fabrication and installation of prefabricated timber for roof trusses (new) Part 9: Fire resistance of timber structures (new) Section 1: Methods of calculating fire resistance of timber members Part 10: Preservative treatment of structural timbers (new) Part 11: Recommendations for the calculation basis for span tables and their calculations (new) Section 1: Domestic floor joists Section 2: Ceiling joists Section 3: Ceiling binders Section 4: Domestic rafters Part 12: Laminated veneer lumbers for structural application (new) Out of the twelve Parts. architects.1 Timber Classification Based on densities. Emphasis will be given to some of the new Parts. namely. timber panel products (Part 4). 5 Teak Tembusu S.2 Strength Grouping For design purposes the species are divided into seven strength groups. For timber requiring treatment. (Source: MS360. red Merbau Kelat Mertas Kembang semangkok Kulim Pauh Kijang Penyau Perah Petaling Ranggu Durian batu Tualang S.G. So far.G.6 S. Table 1. yellow Mersawa Terap Ara Batai Geronggang Laran Pelajau Pulai Sesendok Terentang Notes: 1.hardwoods (400–720 kg/m3) and softwoods [4]. sapwood should be excluded. SG 7 is considered weak and is generally unsuitable for many structural applications.G. they should be amenable to preservative treatment Table 2. The wet and dry grade stresses for strength groups are given Table 2.G. white Nyatoh Penarahan Petai Ramin Rubberwood Sengkuang Sepetir Bayur Damar minyak Durian Jelutong Jenitri Jongkong Kasah Machang Medang Melantai/Kawang Meranti. SG 1 to SG 7.3 A) Naturally Durable Balau Belian Bekak Bitis Mata ulat Delek Chengal Kekatong Keranji Penaga B) Requiring Treatment Dedaru Agoho Kempas Balau. dark red Meranti.4 Giam Malabera Merbau Resak Berangan Dedali Derum Kapur Kasai Keruntum Mempening Meransi Meranti bakau Merawan Merpauh Nyalin Perupok Punah Rengas Simpoh S. The strength data are based on small clear test specimens.G.2 S. preservative treatment is necessary. light red Meranti.G. in the order of decreasing strength (Table1). 1986) 2. 2. Wet and dry grade stresses for various strength groups of Malaysian timber (stresses and moduli expressed in N/mm2) Strength groups Conditi on1) Bending parallel to grain Tension parallel to grain Compression parallel to grain Compression perpendicular to grain 2) Shear parallel to grain Modulus of elasticity for all grades 3 . Strength groups of Malaysian timber S.1 S. For naturally durable timbers. about 100 timber species with densities ranging from 350 kg/m3 to 1100 kg/m3 (measured at 19% moisture content) have been included in the new MS 544: Part 2: 2001: Code of Practice for Structural Use of Timber . If sapwood is included.7 Alan bunga Babai Balek angin bopeng Bintangor Brazil nut Gerutu Kayu kundur Kedondong Keledang Keruing Ketapang Kungkur Melunak Mempisang Mengkulang Meranti.G.Permissible Stress Design of Solid Timber compared with 56 species in the previous Code. 8 7.98 1.1 3.5 9.1 6.90 1.62 3. J1.50 2.43 1.28 3.61 1. However.5 14.0 12.8 7.4 9.7 7.2 5.9 20.9 7.75 0.7 23.05 0.95 1.4 11.3 6.5 6.44 3.15 2. J2.84 1.99 1.86 1.3 Eccentric Joints The Code also gives guidelines for the eccentric joints which state that the combined effects of primary and secondary stresses due to the resulting bending and shear stress shall be checked.37 1.90 2.0 18.8 5.11 0.1 12.67 3.6 26.9 12. in decreasing order of strength as in the previous Code.8 21.8 10.8 4. standard structural and common building grades respectively as defined in the Malaysian Grading Rules (MGR) 3. a total of 90 species are listed compared with 53 species in the previous Code.3 4.96 1.78 1.8 6. for Dry 19% When there is no wane at the bearing area.5 22.5 13.76 0. Numerous changes and addition have been made in the revised edition of the Code.54 0.5 21.96 1.5 11. J4 and J5.3 6.66 1.5 5.84 1.8 13.2 23.6 5.97 2.9 7.6 12.2 15.65 0.2 8.5 3. J3.55 1.91 0.0 23.62 0.2 10.4 5.86 0.14 1.06 1.9 8.54 1.59 4.07 1.5 14.1 9.8 18.3 13.82 2.1 Additional Species to the Joint Groups Timber species are classified into five joint groups.57 1. 3.50 0.3 12.7 16.25 2.3 3.76 1. 3.6 8.Sel SG1 SG2 SG3 SG4 SG5 SG6 SG7 1) 2) 3) Std Com3) Sel Std Com Sel Std Com Basic Sel 4. 3.37 1.0 11.9 12.09 1.2 6.3 4.21 Std Com Sel Std Com Mean 17000 18800 15700 16800 13300 14300 10700 11000 8800 9100 6700 7300 5700 6600 Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry 29.1 16.8 7.1 9.82 0.30 1.1 4.1 11.7 4.02 2.2 8.2 5.2 Plywood to Timber Joint Part 5 also provides the basic working loads for plywood to timber joints that was not covered in the previous Code.05 2.02 0.98 0.2 15.96 0.58 2.4 Coach Screws 4 .5 3.95 1.3 5.21 0.3 2.65 Moisture content for Wet > 19%.2 5.62 0.0 4.9 5.8 5. Structural or marine plywood are recommended for the application.3 6.6 6.50 3.61 Minimu m 13300 14000 11700 12600 9800 10300 7400 7600 6100 6300 4900 5200 3000 3400 0. The determination of basic load is based on the standard nail penetration.59 2.46 0.71 0.8 16.6 7.46 1.74 1.5 6.74 3.5 17.5 4.80 2.51 1.90 3.61 1.76 0.97 3.1 8.2 11.38 2.5 6.8 11.02 1.8 14.8 14.4 18. the basic stress figures may be used for all grades Sel.53 1.24 1.8 28.69 0.07 0. 3.0 10.9 12.1 14.9 8.2 11.8 8.6 18.2 8.06 0.84 2.23 0.3 3.7 15.2 33.9 5.8 14.09 1.5 17.12 1.1 10.3 14.57 0.6 8.6 9.1 26.87 0.82 1.1 9.7 5.5 10.4 7.22 1.86 1.40 2.7 6.6 14.42 1.0 20.9 7.1 17.5 7.94 2.83 2.1 4.3 18.0 5.9 4.5 3.0 9.95 0.77 0.4 8.19 0. DESIGN OF TIMBER JOINTS Part 5 of the Code outlines recommendations for the design of joints in solid timber intended for use with various types of mechanical fasteners.2 6.3 20. Std and Com stand for select structural.58 1.28 1.1 11.53 0.67 3. glued-laminated structure is not a common construction material used in Malaysia. However. Part 3 of the Code follows closely Part 2 of BS 5268. namely.0 Meranti. some conditions have to be met when coach screws are used laterally in dry timber. a new component of the Code. This Part provides guidance on structural use of timber-based panels. deals with the guidelines on the designs of structural components made of glued laminated members. Light Red C22 Meranti.0 24. Yellow C24 Meranti. Recommendations on quality. 4. namely. Dark Red D35 Mengkulang D40 Merbau D50 Keruing Kapur D60 60. Glued-laminated members should be manufactured in accordance with BS EN 386.0 DESIGN OF STRUCTURAL USE OF TIMBER PANELS Unlike the previous Code. Table 3.0 NOTE: Additional species/grades could be incorporated in accordance with BS EN 338 5. However. the new Code includes a new part. concerted efforts have been made by FRIM and other relevant government agencies and universities to promote the use of this product for future applications.0 35.The uses and designs of coach screws are also highlighted in the new Code. C22. The tropical hardwoods strength classes and their corresponding characteristic bending strengths for glued laminated timber design Standard Name Strength Class Characteristic bending strength ( N/mm2) 22. Part 4. marine plywood.0 50. There are seven strength classes. D40. cement-bonded particleboard and oriented-strand board in load bearing members. except with the inclusion of two additional local species [5]. By and large. The basic calculation is similar to the designs of bolted joints. or as parts of built-up components. DESIGN OF GLUED-LAMINATED TIMBER Currently. on the design of structural use of timber-panel products. grade stresses and modification factors are included for these materials when used as simple members. Part 3. D60 and D70 in increasing order of strength. C24. structural plywood. Table 3 shows the tropical hardwoods strength classes and the corresponding characteristic bending strengths for glued-laminated timber design.0 40. or as parts of structures in 5 . D50. D35. Glued-laminated strength classifications for structural tropical hardwoods are based on strength classes graded in accordance with BS 5756.0 Kempas Balau D70 70. 1996. London. The method of calculation is based on the notional charring rates of 0. CONCLUSION The Technical Committee on Timber Structures (TC 4) formed by the Construction Industrial Development Board Malaysia (CIDB) has almost completed a prodigious task on the revision of the old MS 544. Materials and Workmanship. Wong. K. Forest Research Institute Malaysia. So far ten Parts have been published as the new Code of Practice for structural use of Malaysian timber. Anon. M. Code of Practice for the Structural Use of Timbers. 210 pp. 2001.incorporating other materials. 1997. 8. Code of Practice for Permissible Stress Design. M. British Standard Institution. FIRE RESISTANCE OF TIMBER STRUCTURES Part 9. MS 544:Parts 1 – 12: 2001. Malayan Forest Records No. P. Anon. 6. Forest Research Institute Malaysia. The same charring rates are applied to members laminated with approved heat resistant adhesive. The rates were based on BS 5268: Part ? and confirmed by a study done on the charring rates of twelve Malaysian structural timber species [6]. 2002. Mohd Shukari Midon and Abdul Rashid.. Timber Design Handbook. 7. 1967. Malayan Forest Record No. 1978. ACKNOWLEDGEMENTS The authors would like to express their deepest appreciation to the Construction Industrial Development Board Malaysia (CIDB) for the continued support rendered to the Technical Committee on Timber Structures (TC 4). Anon. [1] [2] [3] [4] [5] [6] REFERENCES Anon. a new scope of the Standard. 42. BS 5268: Part 2: 1996. S. A. compressed cement-bonded plywood (CBP) as well as medium and heavy duty oriented-strand board (OSB). Part 9 also includes a section on the fire protection of metal fasteners and components.7 mm/min for strength groups SG 1 to SG 3 and SG 4 to SG 5 respectively. British Standard Institution.. 288 pp. The Standard applies only to Malaysian basic structural grade (MBSG) plywood. 544: 1978.S.M. Chu. 6 .. British Code of Practice. Standard Industrial Research Institute Malaysia (SIRIM). Ho. A Dictionary of Malaysian Timbers.rated marine plywood. The Structural Use of Timber. London. T. 30. MBSG.5 mm/min and 0. CP 112: 1967. The authors are also grateful to members of the TC 4 and the Working Groups for their valuable contributions. Code of Practice for the Structural Use of Timbers. Y. Department of Standards Malaysia. outlines a method for evaluating the duration of fire resistance of an exposed load bearing of solid or a glued-laminated timber. 9.