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MS 758 : 2001
GLUED LAMINATED TIMBER –PERFORMANCE REQUIREMENTS ANDMINIMUM PRODUCTION REQUIREMENTS(FIRST REVISION)
ICS : 79.020
Descriptors : performance requirements, minimum production requirements, adhesive, moisturecontent, finger joints, glued-laminated timber, service class, finishing grade,delamination and block shear
MALAYSIANSTANDARD
© Copyright
DEPARTMENT OF STANDARDS MALAYSIALice
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DEVELOPMENT OF MALAYSIAN STANDARDS
The Department of Standards Malaysia (DSM) is the national standardisation and
accreditation body.
The main function of the Department is to foster and promote standards, standardisation and
accreditation as a means of advancing the national economy, promoting industrial efficiency
and development, benefiting the health and safety of the public, protecting the consumers,
facilitating domestic and international trade and furthering international cooperation in relation
to standards and standardisation.
Malaysian Standards are developed through consensus by committees which comprise of
balanced representation of producers, users, consumers and others with relevant interests,
as may be appropriate to the subject in hand. These standards where appropriate are
adoption of international standards. 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.
The Department of Standards appoints SIRIM Berhad as the agent to develop Malaysian
Standards. The Department also appoints SIRIM Berhad as the agent for distribution and
sale of Malaysian Standards.
For further information on Malaysian Standards, please contact:
Department of Standards Malaysia OR SIRIM BerhadTingkat 21, Wisma MPSA 1, Persiaran Dato' MenteriPersiaran Perbandaran P.O. Box 7035, Section 240675 Shah Alam 40911 Shah AlamSelangor D.E. Selangor D.E.
Tel: 60 3 5519 8033 Tel: 60 3 5544 6000Fax: 60 3 5519 2497 Fax: 60 3 5510 8095
http://www.dsm.gov.my http://www.sirim.my
Email:[email protected]
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MS 758 : 2001
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CONTENTS
Page
Committee representation…………………………………………………………… iii
Foreword……………………………………………………………………………… v
1 Scope………………………………………………………………………………..….. 12 Referenced documents………………………………………………………………… 13 Definitions……………………………………………………………………………..… 14 Symbols……………………………………………………………………………….… 35 General requirements…………………………………………………………………. 56 Manufacturing requirements…………………………………………………………… 97 Quality control……………………………………………………………………..……. 148 Marking……………………………………………………………..………………..….. 18
Tables
1 Type of adhesive for given service conditions…………………………………..…. 52 Qualification and routine test procedures……………………………………….…… 73 Maximum values for the total delamination percentages………………………..…. 74 Minimum wood failure percentages, WFP, relating to the shear strength ƒv……... 85 Tolerance and overlap limits for appearance grade C glulam…………………..… 96 Maximum finished thickness t and maximum cross-sectional area A of the
laminations to be used in structures in different service classes …………….…… 11B1 Climate in the drying duct for the different methods………………………………… 21B2 Number of test cycles to be used in the different test methods………………..….. 22C1 Number of test bars……………………………………………………………….……. 29
Figures
1 Glue lines in cross sections showing the normal position of the glue lines………. 42 Overlap of laminations…………………………………………………………………. 9B1 Test specimen cut from a glulam member…………………………………………... 22C1 Shearing tool with a test bar inserted…………………………………………….….. 26C2 The normal test specimen, a test bar, and the numbering of the individual
glue lines for a test bar cut at the bottom of the cross section……………………. 27C3 A drill core with machined parallel plane surfaces ………………………... 28C4 Test bars to be cut from a full cross-sectional specimen………………………….. 30C5 Suggested identification showing the location of the test bars in the cross
section in a member glued vertically….……………………………………………… 30C6 Additional identification with numbers showing the location of the glulam
member during the cramping…………………………………………………………. 30
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MS 758 : 2001
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CONTENTS (continued)
Page
Appendices
A List of some Malaysian timbers with gluing properties…………………………... 19B Delamination test of glue lines………………………………………………..…….. 21C Shear test of glue lines…………………………………………………………….... 26D Glued laminated timber………………..……………………………………..……… 33E Bibliography..………………………………………………………………………….. 36
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MS 758 : 2001
iii
Committee representation
The Building and Civil Engineering Industry Standards Committee (ISC D) under whose supervision this MalaysianStandard was prepared, comprises representatives from the following organisations:
Association of Consulting Engineers MalaysiaChartered Institute of Building MalaysiaConstruction Industry Development Board MalaysiaDepartment of Standards MalaysiaPertubuhan Akitek MalaysiaJabatan Bekalan Elektrik dan GasJabatan Bomba dan Penyelamat MalaysiaMasters Builders Association MalaysiaMinistry of Housing and Local Government (Housing Department)Ministry of Works (Public Works Department)The Institution of Engineers, MalaysiaUniversiti Teknologi Malaysia
The development of this Malaysian Standard is under the supervision of the following representatives of the CIDBStandards Committee:
Ir. Mohamed bin Mohd Nuruddin General Manager, Technology Development Division.Megat Kamil Azmi bin Megat Rus Kamarani Senior Manager, Standard and Quality UnitPuan Zainora bt. Zainal Manager, Standard and Quality UnitPuan Hanishahani bt. Othman The Secretary of CIDB Standards Committee
The Technical Committee on Structural Use of Timber which developed this Malaysian Standard consists ofrepresentatives from the following organisations:
Dr. Abdul Rashid bin Hj. Ab. Malik Forest Research Institute Malaysia(Chairman)
Puan Hanishahani bt. Othman Construction Industry Development Board Malaysia(Secretary)
Tuan Hj. Mohd Shukari bin Midon Forest Research Institute Malaysia
Encik Zainudin bin Kader Public Works Department
Puan Dang Anom bt. Md. Zin Housing Department
Dr. Badorul Hisham bin Abu Bakar Universiti Sains Malaysia
Prof. Dr. Zainai bin Mohamed /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 Malaysia
Ir. Yap Chin Tian Timber Trade Federation Malaysia
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MS 758 : 2001
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Committee representation (Working Group)
This Malaysian Standard was prepared by the Working Group on Glued Laminated Timber – PerformanceRequirements and Minimum Production Requirements consisting of the following representatives:
Prof. Madya Ir. Dr. Mohd Zamin bin Jumaat (Chairman) Universiti MalayaEncik Chu Yue Pun (Secretary) Forest Research Institute MalaysiaPuan Hanishahani bt. Othman Construction Industry Development Board
MalaysiaDr. Tan Yu Eng Forest Research Institute MalaysiaEncik Suhaimi bin Abu Bakar Universiti Teknologi MalaysiaDr. Paridah bt. Md. Tahir Universiti Putra MalaysiaEncik Ahmad Fahmi bin Hj. Abdul Ghaffar Ministry of Housing and Local
Government(Housing Department)Encik Ahmad Ruslan bin Md. Ridzuan / Universiti Teknologi MaraPuan Zakiah bt. AhmadEncik Haris bin Alpiah Casco AdhesiveDr. Razali bin Abdul Kader Golden Hope Plantations
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MS 758 : 2001
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FOREWORD
This Malaysian Standard was developed by the Working Group on Glued Laminated Timber –Performance Requirements and Minimum Production Requirements, established at theConstruction Industry Development Board Malaysia (CIDB) under the authority of the Buildingand Civil Engineering Industry Standards Committee.
CIDB is the Standards-Writing Organisation (SWO) appointed by SIRIM Berhad to developstandards for the construction industry.
This standard is based on BS EN 386 : 1995, “Glued Laminated Timber – PerformanceRequirements and Minimum Production Requirements”, and AZ/NZS 1328.1: 1998, “GluedLaminated Structural Timber – Part 1: Performance Requirements and Minimum ProductionRequirements”, as well as BS EN 391: 1995, “Glued Laminated Timber – Delamination Testof Glue Lines”, and BS EN 392: 1995, “Glued Laminated Timber – Shear Test of Glue Lines”,which had been amended where necessary to comply with the Malaysian requirements.
Glued laminated timber is obtained by bonding together a number of laminations having theirgrain essentially parallel. In this way a member with a rectangular solid cross-section can beproduced.
The purpose of the requirements in this standard is to obtain reliable and durable bonding, sothat the bonds in the glued laminated timber will maintain their integrity throughout theintended life of the structure. The requirements will need to be supplemented to take intoconsideration special production conditions, materials or functional requirements. Therequirements apply to structural members of service classes 1 and 2. For timber structures ofservice class 3, special precautions shall be taken, for example weather resistant adhesivesshall be used. The requirements for these are given in BS EN 301 : 1992, “Adhesives,Phenolic and Aminoplastic, for Load-bearing Timber Structures: Classification andPerformance Requirements”.
This standard supersedes MS 758 : 1981, ‘Specification for glued laminated timber structuralmembers’.
Compliance with a Malaysian Standard does not of itself confer immunity from legalobligations.
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MS 758 : 2001
1
GLUED LAMINATED TIMBER – PERFORMANCE REQUIREMENTS ANDMINIMUM PRODUCTION REQUIREMENTS
(FIRST REVISION)
1. Scope
This standard specifies requirements for the components of glued laminated timber membersand minimum requirements for the production of such members for structural use.
The standard is applicable to products with a maximum finished lamination thickness of notmore than 40 mm.
2. Referenced documents
The following referenced documents contain provisions which, through reference in this text,constitute provisions of this Malaysian Standard. For dated references, where there aresubsequent amendments to, or revisions of, any of these publications do not apply. Howeverparties to agreements based on this Malaysian Standard are encouraged to investigate thepossibility of applying the most recent editions of the referenced documents. For undatedreferences, the latest edition of the publication referred to applies.
BS 5756 : 1997 Specification for tropical hardwoods graded for structural use
BS EN 385 : 1995 Finger jointed structural timber – Performance requirements andminimum production requirements
MS 544 : Part 1 Code of practice for structural use of timber : Part 1 : General
AS/NZ 4063 : 1992 Timber - Stress-graded - In-grade strength and stiffness evaluation
3. Definitions
For the purpose of this standard, the following definitions apply :
3.1 Closed assembly
A collection of laminations spread with glue and assembled in a member prior to theapplication of pressure.
3.2 Conditioning time
The minimum time which must elapse after the cramping time before heavy machining orexposure to service conditions. During this time the glue line strength continues to increase.
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MS 758 : 2001
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3.3 Cramping time
The time during which the adhesive is required to remain under the action of pressure. Duringthis time the adhesive reaches a high percentage of its ultimate strength.
3.4 Cramping pressure
The force applied to the contact faces of glued laminations divided by the area of the gluedsurface over which the force is deemed to act (usually expressed in N/mm2).
3.5 Curing temperature
The temperature needed (at the centre of all the glue lines) to develop the required bondstrength.
3.6 Glue spread
The amount of adhesive used (usually measured in g/m2). In single spreading this amount isapplied to one surface; in double spreading it is divided between the two surfaces to bejoined.
3.7 Hardener
A part of some adhesives used to promote setting. It may be supplied in either liquid orpowder form, or may be incorporated in the adhesive by the manufacturer. It is an essentialpart of the adhesive, the properties of which depend on using the components as directed.
3.8 Horizontal laminated beam
A beam having the laminations parallel to the neutral plane (see Figure 1a).
3.9 Jigs
Formers to which laminations are cramped at the time of manufacture to give the member itsfinished shape.
3.10 Laminating
The process of bonding laminations with an adhesive to form a solid unit.
3.11 Lamination
A layer of wood in a laminated member. The lamination may be formed from several boards,end or side jointed or both so as to extend to the full width and length of the member.
3.12 Pot life (working life)
The time between the mixing of the constituent parts of an adhesive and it reaching the stagewhere it is no longer usable.
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3.13 Service class 1
Service class 1 is characterised by a condition whereby most timber will attain an averagemoisture content of not exceeding 12 %. Typical example is an air-conditioned environmentwith temperature of 24 o C and a relative humidity of not more than 60 % most of the time.
3.14 Service class 2
Service class 2 is characterised by a condition whereby most timber will attain an averagemoisture content higher than that of Service class 1, but not exceeding 20 %. This isachieved in a sheltered environment with temperature of 30 oC and a relative humidity of notmore than 90 % most of the time.
3.15 Service class 3
Service class 3 is characterised by a condition whereby most timber will attain an averagemoisture content higher than that of Service class 2. Typical example is an external, fullyexposed condition including marine environment.
3.16 Shelf life (storage life)
The period over which the constituent parts of an adhesive remain usable. This would usuallybe specified by the expiry date of adhesive.
3.17 Synthetic resin adhesive
An adhesive substantially composed of a synthetic resin or resins, e.g. phenolic oraminoplastic resins, including any hardener or modifier which may have been added by themanufacturer or which may be required to be added before use, according to themanufacturer’s instructions.
3.18 Vertically laminated beam
A beam having laminations at right angles to the neutral plane (see Figure 1b).
4. Symbols
A area, in square millimetres;
a width of machined flat face of drill core, in millimetres;
b width of cross section, in millimetres;
d diameter, in millimetres;
Fu ultimate load, in newtons;
ƒm bending strength of a single end joint, in newtons per square millimetre;
ƒm, k characteristic bending strength of the end joints in the lamination, in newtons persquare millimetre;
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ƒm,r,k required characteristic bending strength of the end joints, in newtons per squaremillimetre;
ƒm,15,k characteristic bending strength of 15 tested end joints, in newtons per squaremillimetre;
ƒv shear strength, in newtons per square millimetre;
h depth of cross section, in millimetres;
k modification factor;
l length of test specimen, in millimetres;
l max, delam maximum delamination length of one glue line in the test specimen, inmillimetres;
l glue line length of one glue line, normally the width b shown in Figure B1;
l tot, delam delamination length of all glue lines in the test specimen, in millimetres;
l tot, glue line entire length of glue lines on the two end-grain surfaces of each test specimen, inmillimetres;
m mean value ( the variable is given in parenthesis );
r radius of curvature, in millimetres; and
t lamination thickness, in millimetres.
Figure 1 a) Horizontal glulam Figure 1 b) Vertical glulam
Figure 1. Glue lines in cross sections showing the normal position ofthe glue lines
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5. General requirements
The strength grading of the timber and the bonding operations shall result in reliable anddurable bonds.
These general requirements shall be considered satisfied if both the requirements in thisclause and the minimum production requirements in Clause 6 are fulfilled.
5.1 Timber
The timber shall be strength graded in conformity with BS 5756.
5.2 Adhesives
The adhesive shall be capable of producing strong and durable joints so that the integrity ofthe bond is maintained throughout the intended lifetime of the structure.
Acceptable strength and durability can be achieved by the use of a polycondensationadhesive of the phenolic or aminoplastic type as defined in EN 301. The adhesive shall meetthe requirements for adhesive Type I or II as in Table 1.
Table 1. Type of adhesive for given service conditions
Service Description Timber e.m.c* Temperature AdhesiveClass Type Example
1 Interior ≤ 12 % < 50 °C II Melamine-ureaResorcinol
2 Exterior but ≤ 18 % < 50 °C II Phenol-resorcinolprotected untreated Polyphenolic
timber (tannins)≤ 20 % multi- Any I Resorcinolsalts treated Phenol-resorcinol
timber Polyphenolic
3 Exterior Any Any I (tannins)
*Equilibrium moisture content
NOTE. The adhesive should be chosen considering the climatic conditions in service, the timber species, thepreservative used (if any) and the production methods.
An assurance should be sought from the manufacturer that a particular formulation is suitablefor the service conditions and for the length of life envisaged for the structure.
5.3 Completed glulam
5.3.1 Verification of design properties
The manufacturer shall prove that the finished glulam has the required design properties.Verification shall be provided through:
a) (initial) qualification tests; andb) quality control tests.
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5.3.2 Design properties
Members shall have the design properties as claimed by the manufacturer, or as required bythe designer.
The design properties shall be the characteristic values for bending strength, modulus ofelasticity, compression strength, shear strength and tension strength.
5.3.3 (Initial) Qualification test
Qualification tests shall be undertaken whenever a new process or process change involving,for example, a new adhesive/ species combination, finger joint profile, lamination thickness orsimilar. Initial qualification tests shall be carried out by the following method:
Strength determination of completed glulam
The characteristic strength of a glulam member in bending, compression, tension and shearand characteristic modulus of elasticity in bending, shall be determined by undertaking testson completed 300 mm deep glulam members in accordance with AS/NZS 4063 or equivalent.
5.4 End joints in laminations
The characteristic bending strength ƒm, k obtained from flatwise bending tests of the end jointsshall meet the following requirement:
ƒm,k ≥ ƒm,r,k
where,
ƒm,r,k is the required characteristic bending strengt h.
The flatwise bending tests shall be performed in conformity with EN 385.
The characteristic bending strength shall be determined from the Log - Normal probabilitydistribution function.
5.5 Glue line integrity
5.5.1 General
The requirements for glue line integrity shall be based on testing of the glue line in a fullcross-sectional specimen, which shall be cut from the manufactured glulam member. Thespecimens shall be representative of the production. The test requirements are summarisedin Table 2.
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Table 2. Qualification and routine test procedures
Service Class 1 Class 2 Class 3
Qualification Type I Type II Type I Type II Type ITest1) adhesive adhesive adhesive Adhesive adhesive
only
Delamination Delamination Delamination Delamination Delaminationtest method A, test method C, test method A, test method C, test method A,Appendix B Appendix B Appendix B Appendix B Appendix B
Routine Type I and Type II Type I and Type II Type ITest2) Adhesives adhesives Adhesive
only
Delamination test method C, Delamination test method C, DelaminationAppendix B Appendix B test method Aor or or method B,Block shear test, Appendix C Block shear test, Appendix C Appendix B
NOTES :
1. For each species, adhesive, treatment or process combination, a minimum of 5 full cross-sections shall be tested and shall meet the requirements of 5.5.2 or 5.5.3.2. For each shift in which gluing is carried out, one full cross-sectional specimen shall be tested for each press load or every 10 m3 of production.
5.5.2 Acceptance criteria for delamination tests
Depending on the method and number of cycles the total delamination percentage of eachcross-sectional specimen shall be less than the values given in Table 3.
Table 3. Maximum values for the total delamination percentages
Method Applicable toadhesive type
Maximum total delamination percentage after cycle no. :
1 2 3
A Type I - 5 10B Type I 4 8 -C Type II 10 - -
For all delamination methods the maximum delamination percentage (for a single glue line)shall be less than or equal to 40 %.
5.5.3 Acceptance criteria for glue line shear test
Each test result from the block shear tests of each cross-sectional specimen shall comply withthe following requirements with regard to the shear strength and the wood failure percentage.
The shear strength of each glue line shall be at least 6.0 N/mm2. For lighter density timbers,a shear strength of 4.0 N/mm2 shall be regarded as acceptable if the wood failure percentageis 100.
The average wood failure percentage over a cross-sectional specimen and any individualvalue shall exceed the minimum wood failure percentages stated in Table 4.
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Table 4. Minimum wood failure percentages, WFP, relating to the shear strength ƒƒ v
(For values in between, linear interpolation shall be used)
Average Individual values
Shear strength ƒv in N/mm2 6 8 ≥11 from 4to < 6
6 ≥10
Minimum wood failure percentage,% *
90 72 45 100 74 20
* For average values the minimum wood failure percentage is: 144 - (9ƒv). For the individual values the minimumwood failure percentage for the shear strength ƒv ≥ 6.0N/mm2 is: 153.3 - (13.3ƒv).
5.6 Finishing
5.6.1 Appearance grades
The appearance grades relate to the aesthetic appearance of the visible surfaces of the gluedlaminated members. This classification bears no relationship to structural performance of themember.
5.6.2 Appearance grade A
This grade is intended for use in applications where appearance of the member is importantand clear or painted finishes are used. All surface voids are filled or repaired. Unless it isspecified otherwise, the surfaces shall be sanded to a minimum of 60 grit finish.
The following voids shall be repaired with inserts and not filled:
a) holes (circular in general appearance) with a diameter in excess of 30 mm.;b) holes (elongated in general appearance) with dimensions exceeding 40 mm x 20 mm;
andc) edge checks (elongated) from 40 mm to 100 mm, exceeding 3 mm wide.
NOTE. Fillers used should be non-shrinking and capable of accepting the finish specified for the members.
5.6.3 Appearance grade B
This grade is intended for use in painted applications where surface appearance is importantbut a machine planed finish is acceptable. Each member shall present a machined face onfour sides: there shall be not less than one cutter mark to 5 mm. Occasional skips in thesurface are permissible and minor blemishes, voids and manufacturing want shall beacceptable. The outer-most laminations shall be free of loose knots and voids.
5.6.4 Appearance grade C
This grade is intended for use in applications where appearance is not important. Allblemishes and voids are acceptable. Where the member is not machined after lay-up, theallowable tolerances for overlap of laminations shall be as detailed in Figure 2 and Table 5.
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Figure 2. Overlap of laminations
Table 5. Tolerance and overlap limits for appearance grade C glulam
Dimensions in millimetres
Height or width Tolerance for Maximum overlap for
height or width appearance Grade C
members
(h or b) < 100 ± 2 4
100 ≤ (h or b) < 300 ± 3 5
300 ≤ (h or b) ± 6 6
6. Manufacturing requirements
6.1 Production conditions
6.1.1 General
The staff shall have the necessary skill for the production of glulam and the grading of thetimber.
6.1.2 Premises
6.1.2.1 The premises shall be suitable for all phases of the production, taking intoconsideration the requirements given in this standard.
Special consideration shall be given to:
a) size of the members to be produced;b) air temperature; andc) relative humidity of the air.
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6.1.2.2 At the time of assembly and during the cure of the adhesive, the timber shall be at atemperature not less than that specified by the adhesive manufacturer.
6.1.2.3 Drying and storage facilities of sufficient capacity shall be available to enable therequired moisture content and temperature of the timber to be achieved.
6.1.2.4 Where pre-dried timber is used, storage facilities shall be available to maintain therequired moisture content of the timber.
6.1.2.5 Unless resin and hardener are pumped directly from storage tanks and mixedautomatically during application, there shall be a separate room for the preparation of theadhesive (mixing of resin and hardener). There shall also be a suitable resin and hardenerstorage facilities and an area with access to adhesive cleaning equipment.
The resin and hardener storage shall be arranged so that the “first in first out” principle ismaintained.
6.1.3 Equipment
Equipment shall be available:
a) to monitor continuously the temperature and relative humidity of the air(thermohygrograph) in storage, production and curing areas;
b) to measure the moisture content of the timber and for checking (calibrating) moisturemeters;
c) for machine and/or visual grading when these operations are carried out by theproducer;
d) to make end joints in the laminations with sufficient and reliable strength;e) to measure lamination thickness;f) to provide surfaces fulfilling the requirements of the thickness tolerances and surface
quality (usually a lamination planer; see 6.4.1.5 and 6.4.1.6);g) for weighing and mixing resin and hardener in the required proportions;h) for the uniform application of the required quantity of adhesive;i) to obtain the required glue line pressure, temperature and relative humidity of the air
during curing of the adhesive;j) to test the strength of end joints in the laminations; andk) to test the integrity of the glue lines.
6.2 Timber
6.2.1 Species
Only species or a mixture of species proven to be suitable by the qualification tests given in5.3.3 shall be used. Appendix A lists the timbers that have been tested and found to possesssatisfactory gluing properties.
6.2.2 Moisture content
It is preferable that the moisture content of the laminations at the time of gluing for non-preservative treated timber or preservative treated timber shall be as stated below, unlessexperimentation has established adequate bond qualities with moisture contents outsidethese limits.
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Non treated timber. At assembly, the moisture content in every lamination shall be in therange of 8 % to 15 %. The range of moisture content of the laminations in a glulam membershall be not greater than 4 %.
Treated timber. At assembly the moisture content in every lamination shall be in the range of11 % to 18 %. The range of moisture content of the laminations in a glulam member shall benot greater than 4 %.
6.2.3 Thickness and cross-sectional area
The finished thickness and cross-sectional area of any lamination shall not exceed the valuesgiven in Table 6.
Table 6. Maximum finished thickness t and maximum cross-sectional area A of thelaminations to be used in structures in different service classes
Service class 1 Service class 2 Service class 3
tmm
Amm2
tmm
Amm2
tmm
Amm2
40 7 500 40 7 500 35 6000
NOTE. It is recommended that grooves are cut into the laminations as described in 6.4.1.2 when the cross-sectional area exceeds 7500 mm2.
For curved members the maximum thickness is also governed by the radius of curvature rand the characteristic bending strength of the end joints. The finished thickness t shallcomply with :
where,
fm,k is expressed in newtons per square millimetre.
6.3 Adhesive
The adhesive shall comply with 5.2.
6.4 Manufacture
6.4.1 Laminations
6.4.1.1 The individual laminations shall be end jointed to the final length before planing.
6.4.1.2 Grooving of laminations to reduce the effect of cupping is permitted. In eachlamination one groove is permitted in the middle part of the cross section, with a maximumwidth of 4 mm and a maximum depth of one third of the lamination thickness. Grooves inadjacent laminations shall be staggered by at least the thickness of the laminations.
t ≤ r
250 ( 1 +
fm,k
80)
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6.4.1.3 When laminations are jointed by finger joints these shall be produced in conformitywith BS EN 385 or equivalent Malaysian standard.
The moisture content of the individual boards used in glued laminated timber members shallcomply with 6.2.2 of this standard.
NOTE. The more relaxed requirements in 6.2 in BS EN 385 are valid for finger joints in single laminations.
6.4.1.4 Where a lamination for horizontal glulam consists of two boards side by side and theedges are not bonded, the edge-joints in adjacent laminations shall be staggered laterally byat least the lamination thickness. For members used in Service class 1 or 2 the outerlamination on each face shall be edge-bonded. For members to be used in service class 3the outer four laminations on each face shall be edge-bonded.
Laminations in vertical glulam to be used in Service classes 1 and 2 are not required to beedge-bonded, but the edge-joints in adjacent laminations shall be staggered by at least onethird of the board width. In members to be used in Service class 3 the outer laminations shallbe edge-bonded.
6.4.1.5 The laminations shall be planed or similarly finished before bonding. The planing shallbe carried out not more than 24 h before bonding, unless the species and the storageenvironment are such that unacceptable surface changes will not take place. With speciesthat are difficult to bond, e.g. have a high resin content or where the laminations have beentreated with preservative, planing shall be carried out within 6 h of bonding. It is theresponsibility of the glued laminated timber producer to qualify any procedures used and todetermine the permissible delay between machining and gluing.
6.4.1.6 The maximum permitted deviation from the average thickness within a laminationlength of 1 m is 0.2 mm. Where non-gap-filling adhesives are used the limit deviation shallnot exceed 0.1 mm.
The difference in thickness over the cross-sectional width of the lamination shall be less than0.15 % of the width and in no case exceed 0.3 mm.
6.4.2 Bonding
At the time of bonding the surfaces of laminations shall be clean.
The adhesive spread shall be uniform and in sufficient quantity in accordance with therecommendations of the adhesive manufacturer.
NOTE. Usually a minimum spread of 350 g/m2 is required, except for high frequency curing, where the minimum is200 g/m2.
6.4.3 Cramping
The cramping arrangement shall ensure a uniform pressure over the glue line.
The pressure shall be that specified in the adhesive manufacturer’s instructions for theadhesive used but in no case shall it be less than 0.7 N/mm2. The application of pressure ata suitable temperature shall be completed within the closed assembly time, when acontinuous “squeeze out” or “bead” along the edge of each glue line shall be produced. Forcurved members higher cramping pressures shall be applied and in such a way that thelaminations can slide over each other in the lengthwise direction to avoid open glue lines.
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Sufficient pressure shall be maintained during cramping. Tightening-up shall be carried out asnecessary, and in all cases immediately after initial cramping.
6.4.4 Curing and conditioning
The adhesive manufacturer’s instructions shall be followed.
The temperature during curing shall be less than the maximum temperature prescribed by theadhesive manufacturer.
Glulam members shall not be loaded until the adhesive has cured completely.
NOTE. It is recommended that this requirement is kept for at least 72 h after the end of cramping for phenolic basedadhesives and 24 h for aminoplastic based adhesives .
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7. Quality Control
7.1 Factory production control (internal control)
7.1.1 General
To ensure that the produced glulam members conform with this standard, the manufacturershall establish and maintain documented internal factory production control.
The documented factory production control shall be efficiently implemented in accordancewith procedures and instructions documented in a work’s quality manual.
The adhesive shall be chosen by the manufacturer in consultation with the adhesive supplierconsidering the climatic conditions in service, any preservative or fire retardant treatment andthe particular production methods. All conditions which affect the performance of the adhesiveshall be documented in the quality manual.
NOTE. It is recommended that the production control system is audited by a third party. Further information is givenin 7.5.
7.1.2 End joints
From each work shift and each production line a representative sample of end joints shall bedrawn and tested in flatwise bending as described in BS EN 385. Only full size end jointsshall be tested.
For each production line and shift the bending strength is acceptable if one of the followingconditions is met:
The bending strength ƒm of each single end joint tested, is larger than or equal to the requiredcharacteristic bending strength of the end joint ƒm,r,k
ƒm ≥ ƒm,r,k
The characteristic bending strength ƒm,15,k of the last 15 end joints tested from the productionline, is larger than or equal to the required characteristic bending strength of the end jointsƒm,r,k
ƒm,15,k ≥ ƒm,r,k
The required characteristic bending strength of the end joints is defined in 5.4.
The characteristic bending strength ƒm,15,k shall be determined as described in 7.1.4 of BS EN385 or equivalent.
7.1.3 Gluing record
7.1.3.1 A gluing record shall be kept containing:
a) date and number of production;b) species;c) timber quality;d) dimensions of the structure;e) moisture content of the timber;
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f) time for start of adhesive application;g) time for start and end of the cramping process;h) cramping pressure;i) resin and hardener;j) adhesive spread (g/m2); andk) calibration of moisture meter.
The gluing record shall be signed by the nominated responsible member of staff.
7.1.3.2 The details of temperature and relative humidity of the air in timber storage, endjointing room, gluing and cramping area shall be recorded.
7.1.4 Glue line integrity
7.1.4.1 The glue lines shall be tested in a full cross-sectional specimen, which is to be cutfrom a cured glulam member produced during each working shift. For each shift in whichgluing is carried out one full cross-sectional specimen shall be taken for every press load orevery 10 m3 of production.
If all tests for a three-month period satisfy the requirements the number of samples may bereduced to not less than half the number prescribed above.
7.1.4.2 The results of the testing for glue line integrity shall be documented as described inAppendix B and Appendix C for delamination and block shear respectively.
7.2 Organisation of factory production control
7.2.1 Responsibility and authority
The responsibility, authority and the interrelation of all personnel who manage, perform andverify work-affecting quality shall be defined, particularly for personnel who need theorganisational freedom and authority to:
a) initiate action to prevent the occurrence of non-conformity of glulam members; andb) identify and record any quality problems with glulam members.
7.2.2 Management representative for factory production control
At every factory unit the manufacturer shall appoint a person who shall have appropriateauthority, knowledge and experience of the production of glulam to be responsible forconducting and supervising factory production control procedures and ensuring that therequirements given in this standard are implemented and maintained.
7.2.3 Management review
The production control system adopted to satisfy the requirements of this standard shall bereviewed at appropriate intervals by the manufacturer’s management to ensure its continuingsuitability and effectiveness. Records of such reviews shall be maintained.
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7.3 Documentation of the quality control system
7.3.1 The manufacturer’s documentation, procedures and instructions shall be relevant tothe production and process control of the glulam, and shall be adequately described in awork’s quality manual, covering:
a) quality aims and organisational structure, responsibilities and powers of management with regard to conformity of the glulam;
b) procedures for specifying and verifying the quality of the timber and the adhesive;c) manufacturing, production control and other techniques, processes and systematic
actions to be used; andd) inspections and tests that will be carried out before, during and after manufacture,
and the frequency with which they are to be carried out.
NOTE. The documentation of the end joint tests, the gluing record and the glue line tests may be recorded and keptseparately.
7.3.2 Responsibility
The manufacturer shall produce structural timber members in such a way that they are strong,durable and suitable for use in one of the Service classes 1, 2 or 3 defined in 3.13, 3.14 and3.15 respectively.
The manufacturer shall identify the Service class that the manufacturer has selected for eachstructural member.
Each and every species-adhesive combination and manufacturing process used for eachstructural member shall be identified in the work’s quality manual. Each and every adhesiveshall be used in accordance with the supplier’s instructions.
The work’s quality manual shall detail the production controls necessary to ensure that therequired strength and durability characteristics are present in the finished product.
The manufacturer shall maintain records of all relevant production controls which shall bekept for at least 10 years. All documentation shall be sufficiently detailed that the rawmaterials and processing are traceable to the production week and year.
7.3.3 Documentation
The documentation of the end joint tests, the gluing record and the glue line tests may berecorded and kept separately.
All documentation shall be kept for at least ten years.
All documentation shall be retained so that the raw materials and production conditions foreach glulam member are traceable, at least to the production week and year.
7.4 Inspection and testing
7.4.1 General
All necessary facilities, equipment and personnel shall be available to carry out the necessaryinspections and tests. This requirement may also be fulfilled, if by means of a contract themanufacturer or his agent involves a subcontractor having the necessary facilities, equipment
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and personnel. The manufacturer shall control, calibrate and maintain inspection, measuringand test equipment, whether owned by the manufacturer, or on hire, to demonstrate theconformity of the glulam members to the specified requirements of this standard. Equipmentshall be used in a manner which ensures that measurement tolerances are known and areconsistent with the required measurement capability.
7.4.2 Action in case of non-conformity
If there is reason to doubt the quality of any production operation or of the raw materials used,the internal quality control shall be increased and intensified.
If serious defects are discovered, the inspection body shall be informed immediately.
7.4.3 Control of non-conforming glulam
If the result of the test or inspection of a glulam member is unsatisfactory, the manufacturershall at once take the necessary steps to rectify the shortcoming. Glulam members which donot comply with the requirements shall be set aside and marked accordingly. When theshortcoming has been rectified, the test or inspection in question shall be repeated withoutdelay, provided that this is technically possible and is necessary as evidence that the defectshave been overcome.
If glulam members have been dispatched before the test results are available, notificationshall be made to customers, if necessary, for the purpose of avoiding any consequentialdamage.
7.5 The inspection body (external control)
NOTE. The purpose of the external control is to supervise the internal control, to check by sampling the quality of theend joints and the glue lines and to get an insight in the production of glulam so that a certificate can be issued ormaintained.
7.5.1 A minimum of two inspections per year shall be carried out. These shall beunannounced unless special conditions necessitate an announcement.
7.5.2 The inspection body shall have access to all storage and production rooms, and themanufacturer shall answer any technical questions. The inspection body shall regard alltechnical information as confidential.
NOTE. The manufacturer may be required to forward, at certain intervals some production information and testresults to the inspection body.
7.5.3 During the inspections the following shall be inspected or checked:
a) raw materials;b) production in accordance with the stated requirements of this standard;c) components of glulam members (end joints, laminations); andd) finished glulam members.
7.5.4 Selection of samples for external testing (end joints and full cross-sectionalspecimens for glue line integrity test) shall normally be done by the inspection body.
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The number of specimens shall be at least 15 for end joints in the laminations and at least sixfull cross-sectional specimens for glue line integrity tests. Such samples shall be taken ateach inspection. If superior test values can be documented both from the previous externaltest taken at the last inspection and from the internal production control then the sampling canbe omitted.
End joints shall be deemed to have superior strength if the characteristic bending strength isessentially larger than the required characteristic bending strength. For finger joints see also7.5.4 of EN 385.
For glue lines a superior block shear test result is equivalent to a shear strength of at least 8.0N/mm2.
For glue lines a superior delamination test result is equivalent to a total delaminationpercentage less than two thirds of the maximum value given in Table 3.
7.5.5 The inspection body shall prepare a report of each inspection.
8. Marking
Glulam shall be marked. The durable mark shall contain:
a) name or identity of the producer;b) strength class or other strength identification;c) adhesive type;d) production week and year;e) certificate number; andf) standard number.
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Appendix A(informative)
List of some Malaysian timbers with gluing properties
No. Timbers Gluing characteristic
1 Bintangor Satisfactory
2 Damar minyak Good
3 Durian Satisfactory
4 Gerutu Good
5 Jelawai Satisfactory
6 Jelutong Satisfactory
7 Kapur Satisfactory
8 Kedondong Good
9 Keledang Satisfactory
10 Kembang semangkok Satisfactory
11 Kempas Satisfactory
12 Keranji Satisfactory
13 Keruing Satisfactory
14 Machang Satisfactory
15 Mempisang Satisfactory
16 Mata-ulat Good
17 Mengkulang Good
18 Meranti bakau Good
19 Meranti (Dark red) Good
20 Meranti (Light red) Good
21 Meranti (White) Good
22 Meranti (Yellow) Good
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23 Merbau Satisfactory
24 Merpauh Good
25 Mersawa Good
26 Minyak berok Satisfactory
27 Penarahan Good
28 Ramin Good
29 Sepetir Good
30 Sesendok Good
31 Simpoh Good
32 Terap Good
33 Terentang Good
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Appendix B(normative)
Delamination test of glue lines
B1. Scope
This Appendix specifies three delamination test methods for continuous quality control of theglue line integrity of glued laminated timber.
B2. Principle
A gradient is introduced in the moisture content of the wood to build up internal stresses. Thiswill result in tensile stresses perpendicular to the glue lines so that inadequate bonding qualitywill result in delamination of the glue lines.
B3. Apparatus
B3.1 Pressure vessel
A pressure vessel designed to withstand safely a pressure of at least 600 kPa (700 kPaabsolute pressure) and a vacuum of at least 85 kPa (15 kPa absolute pressure), andequipped with pumps or similar device capable of giving a pressure of at least 600 kPa (700kPa absolute pressure) and of drawing a vacuum of at least 85 kPa (15 kPa absolutepressure).
B3.2 Drying duct
A drying duct where air is circulating at a velocity of 2 m/s to 3 m/s, and at a temperature anda relative air humidity as given in Table B1.
Table B1. Climate in the drying duct for the different methods
Method Temperature 00 C Relative humidity %
A 60 to 70 < 15
B 65 to 75 8 to 10
C 25 to 30 25 to 35
B3.3 Balance
A balance capable of determining mass to an accuracy of 5 g.
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B4. Preparation of test specimens
The test specimens shall be prepared or selected in such a manner that they arerepresentative of the production run.
Each test specimen shall be taken from a full cross section of the laminated member to betested, prepared by cutting perpendicular to the grain of the wood. It shall be (75± 5) mm inlength (along the grain). The end-grain surfaces of the test specimen shall be cut with asharp saw or tool that produces a smooth surface.
If the width b of the cross section is greater than 300 mm the test specimen may be split intotwo or more test specimens each at least 130 mm wide. If the depth h is greater than 600mm the test specimen(s) may be cut into two or more pieces each with a depth of at least 300mm, see Figure B1.
Figure B1. Test specimen cut from a glulam member
B5. Procedure
B5.1 General
Measure the total length in millimetres of glue lines on the end-grain surfaces of the testspecimens.
Subject the test specimens to the appropriate test cycle described in B5.2, B5.3 or B5.4. Thenumber of cycles shall be as given in Table B2.
Table B2. Number of test cycles to be used in the different test methods
Method Number of initial cycles Number of extra cycles
A 2 1
B 1 1
C 1 0
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An extra test cycle needs only be carried out if the total delamination percentage according toB6.2 is larger than a prescribed maximum value.
At the end of the drying period, measure, in millimetres, the length of open glue lines on end-grain surfaces of the test specimens. Open glue lines at knots shall be ignored and failure inthe wood due to checking or other causes shall not be included as delamination. Isolateddelamination less than 3 mm long and more than 5 mm away from the nearest delaminationshall also be ignored.
NOTES:
1. When the separation is in the wood, even though very close to the glue line, it is termed wood failure orchecking. Magnification is often necessary to determine whether the failure is in the adhesive or in the wood. Afeeler gauge of 0.08 mm to 0.10 mm in thickness is convenient for probing into the joint to determine ifseparation actually exists.
2. Since glue lines at knots and knotty areas in general are not durable under severe exposure, development ofdelamination at knots should be disregarded and not included in the measurements or calculations.
B5.2 Test cycle for method A
Place the test specimens in the pressure vessel and weigh them down. Admit water at atemperature of 10 °C to 20 °C in sufficient quantity so that the pieces are completelysubmerged. Separate the test specimens by stickers, wire screens, or other means in such amanner that all end-grain surfaces are freely exposed to the water. Draw a vacuum of 70 kPato 85 kPa (i.e. an absolute pressure of 15 kPa to 30 kPa at sea level) and hold it for 5 min.Then release the vacuum and apply a pressure of 500 kPa to 600 kPa (600 kPa to 700 kPaabsolute pressure) for 1 h. Whilst the test specimens are still completely immersed, repeatthis vacuum pressure cycle making a two-cycle impregnating period requiring a total of 130min.
Dry the test specimens for a period of between 21 h and 22 h in air at 60 °C to 70 °C and arelative humidity not greater than 15 %, and circulating at a velocity of 2 m/s to 3 m/s. Duringdrying, the test specimens shall be placed at least 50 mm apart with the end-grain surfacesparallel to the stream of air.
B5.3 Test cycle for method B
Weigh and record to the nearest 5 g the weight of each test specimen. Place the testspecimens in the pressure vessel and weigh them down. Admit water, at a temperature of10 °C to 20 °C in such quantity that the specimens are completely submerged. Separate thetest specimens by stickers, wire screens, or other means in such a manner that all end-grainsurfaces are freely exposed to the water. Draw a vacuum of 70 kPa to 85 kPa (i.e. anabsolute pressure of 15 kPa to 30 kPa at sea level) and hold it for 30 min. Release thevacuum and apply a pressure of 500 kPa to 600 kPa (600 kPa to 700 kPa absolute pressure)for 2 h.
Dry the test specimens for a period of approximately 10 h to 15 h in air at 65 °C to 75 °C and arelative humidity of 8 % to 10 % and circulating at a velocity of 2 m/s to 3 m/s. During drying,the test specimens shall be placed at least 50 mm apart with the end-grain surfaces parallelto the stream of air.
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The actual time in the drying duct shall be controlled by the mass of the test specimens.Delamination shall be observed and recorded when the mass of the test specimens hasreturned to within 15 % of the original mass.
B5.4 Test cycle for method C
Place the test specimens in the pressure vessel and weigh them down. Admit water at atemperature of 10 °C to 20 °C in sufficient quantity so that the pieces are completelysubmerged. Separate the test specimens by stickers, wire screens, or other means in such amanner that all end-grain surfaces are freely exposed to the water. Draw a vacuum of 70 kPato 85 kPa (i.e. an absolute pressure of 15 kPa to 30 kPa at sea level) and hold it for 30 min.
Then release the vacuum and apply a pressure of 500 kPa to 600 kPa (600 kPa to 700 kPaabsolute pressure) for 2 h. Whilst the test specimens are still completely immersed, repeatthis vacuum pressure cycle giving a two-cycle impregnating period requiring a total of 5 h.
Dry the test specimens for a period of 90 h in air at 25 °C to 30 °C and a relative humidity inthe range of 25 % to 35 %, and circulating at a velocity of 2 m/s to 3 m/s. During drying, thetest specimens shall be placed at least 50 mm apart with the end-grain surfaces parallel tothe stream of air.
B6. Results
B6.1 General
For each test specimen the delamination percentages shall be calculated. If an extra cycle isperformed calculate the results before and after the extra cycle.
B6.2 Total delamination
The total delamination percentage of a test specimen is calculated from the following formula:
B6.3 Maximum delamination
The maximum delamination percentage for a single glue line in a test specimen is calculatedfrom the following formula :
100 xl tot, delam
l tot, glue line
100 xl max, delam
2 lglue line
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B6.4 Test report
The report shall include the following items :
a) date of the test;
b) identification of test specimens and members from which they have been cut. Anyother relevant information, e.g. about preconditioning;
c) species of timber;d) type of adhesive;e) test method;f) delamination percentage and the maximum delamination percentage after the
prescribed number of cycles and any additional cycle that may be necessary;g) any relevant observation made during or after testing; andh) signature of the person responsible for the testing.
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Appendix C(normative)
Shear test of glue lines
C1. Scope
This Appendix specifies a method for measuring the shear strength of the glue line parallel tothe direction of the grain.
C2. Principle
Shear stress is applied to the glue line until failure occurs. The load at failure is recorded andthe wood failure percentage is evaluated.
C3. Apparatus
C3.1 Testing machine
A calibrated testing machine capable of applying a compressive force to the shearing tool,referred to in C3.2. The accuracy of measuring the maximum load shall be within ± 3 %.
C3.2 Shearing tool
A shearing tool as illustrated in Figure C1. The cylindrical bearing shall be self-aligning sothat the test specimen is loaded at the end grain with a stress field uniform in the widthdirection.
Figure C1. Shearing tool with a test bar inserted
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C4. Preparation of test specimens
C4.1 Test specimens
Special care shall be taken in preparing the test specimens to ensure that the loaded surfacesare smooth and parallel to each other and perpendicular to the grain direction.
The test specimens shall be of the form shown in either Figure C2 or C3. That depicted inFigure C2 shows the normal test specimen.
Dimensions : length, l ;width, b : 40 mm – 50 mm;thickness, t: : 40 mm – 50 mm.
NOTE. If the test bar is cut from a position higher in the cross section the numbers of the lines do not start with 1(see C4.3).
Figure C2. The normal test specimen, a test bar, and the numbering of the individualglue lines for a test bar cut at the bottom of the cross section
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Dimensions: length, l : 70 mm to 80 mm;diameter, d : approx. 35 mm;straight edges, a : approx. 23 mm;thickness, t : approx. 26 mm.
Figure C3. A drill core with machined parallel plane surfaces
C4.2 Sampling
Test bars shall be cut from the full cross-sectional specimens as described in this Standard.At least three glue lines in each of the lower, middle and upper part shall be tested. If thereare less than 10 laminations all glue lines shall be tested.
NOTE. It is recommended that the full cross-sectional specimens are taken within areas of the glulam memberwhere sufficient cramping pressure has been established. In practice the specimens are frequently cut from the endof the glulam members where the cramping pressure may be variable and insufficient. If the required shear strengthis obtained from test specimens of this nature, the quality of the glue lines in the member should be deemedadequate.
The shear testing shall include as far as possible the total cross-sectional width of the glulammember. The number of test bars to be taken shall be as given in Table C1.
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Table C1. Number of test bars
Width of full cross section(see Figure C4)
mm
Number of test bars
≤ 100 1
> 100 ≤ 160 2
> 160 3
If two or more members are cramped in one operation, see Figure C6, the test barsnecessary according to the testing quantity quoted above, have to be taken from each of themembers.
For testing glue lines within the glulam member, drill cores shall be sampled.
The drill cores shall be cut out perpendicular to the face of the glulam member in such a waythat the glue line to be tested is situated in the middle of the core.
NOTE. For guidance of the drilling tool it is recommended that an appropriate support is used.
The drill cores shall be machined at two faces perpendicular to the glue line as shown inFigure C3 and divided lengthwise so that the test specimens have a rectangular shearingarea.
C4.3 Marking
Every test bar shall be marked with a durable identification. This shall indicate the location ofthe test bar within the cross section of the glulam member.
NOTES:
1. The relationship between identification and location may be as shown in Figure C5. If the glulam member isglued vertically the front side of the element should be marked with U and the back side with L. The glue lines ofthe glulam member should be numbered beginning with the bottom edge of the member, see Figure C2.
2. If two glulam members are cramped in one operation, the test bars from the lower member should be markedadditionally with 1 and those from the upper member with 2. An example of this marking is shown in Figure C6.
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Figure C4. Test bars to be cut from a full cross-sectional specimen
Figure C5. Suggested identification showing the location of the test bars in the crosssection in a member glued vertically
Figure C6. Additional identification with numbers showing the location of the glulammember during the cramping
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C5. Procedure
The test specimens shall be conditioned to an equilibrium moisture content in the standardclimate 20/65, i.e. temperature (20 ± 2) °C and a relative humidity of (65 ± 5) %. For internalquality control the moisture content of the wood shall be uniform over the test specimen andwithin the range of 8 % to 13 %.
Measure the sizes from which the sheared area is determined to the nearest 0.5 mm.
Place the test specimen in the shearing tool so that it is loaded in the direction of the grain.The glue line shall be positioned so that the distance between this and the sheared planedoes not exceed 1 mm.
The loading shall be undertaken at a constant rate and so that failure occurs after at least 20s.
Estimate the amount of wood failure percentage rounded off to the nearest 5 %.
From every tested test bar with at least five remaining glue lines a part shall be marked withthe order number, element number, gluing date and position of the test specimen according toC4.3, and stored for a period as agreed with the certification body.
C6. Results
C6.1 Calculation of shear stress
Determine the equivalent shear strength ƒv with two significant digits from the followingequation:
ƒv = k
where,
A is the sheared area (for a test bar A = bt, and for a drill core A = l t);
k is a modification factor,
k = 0.78 + 0.0044 t; and
t is the thickness, in millimetres.
NOTE. The factor k modifies the shear strength for test specimens where the thickness in the grain direction of thesheared area is less than 50 mm.
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C6.2 Test report
The test report shall include the following items:
a) date of the test;b) identification of test specimens and members from which they have been cut. Any
other relevant information, e.g. about preconditioning;c) species of timber;d) moisture content;e) type of adhesive;f) sizes of the test specimen;g) ultimate load and shear strength;h) any relevant observation made during or after testing; andi) signature of the person responsible for the testing.
NOTE. The information mentioned in items f) to i) is not required to be registered and filed directly, if other data arefiled from which the information may be derived.
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Appendix D(informative)
Glued laminated timber
NOTE. The clauses below list the terms and recommendations for the manufacture, marketing and installation ofglued laminated members.
D1. Typical stock glulam members
Straight, horizontally laminated, glulam members are available from commercial suppliers inthe country. A typical specification for such stock glulam members is as follows:
- timber: Mengkulang;- finished lamination thickness: 35 mm or 40 mm;- moisture content at manufacture: 8 % to 15 %;- end joints in laminations: finger joints;- adhesive (including end joints): type I of BS EN 301; and- manufactured surface finish: planed surfaces.
Such components are referred to as stock glulam members. The strength class according toMS 544: Part 3 will normally be marked on the member. They may, if required by thespecifier, be given a sanded finish or treated with preservatives, or surface coatings.
D2. Storage and protection of finished members
Finished members should be stored so that they are maintained in an environment not moresevere than that for which they were designed. They should be protected from the effects ofadverse weather and damage or deformation by incorrect methods of handling, stacking,storage, delivery and erection. Temporary covering during delivery or short term storage toprotect from the effects of adverse weather conditions is recommended.
D3. Surface fissuring
The natural propensity of timber to shrink when dried can lead to the development of surfacefissures. Glulam will normally be manufactured at around 12 % moisture content and few enduses result in significantly drier conditions. In practice, however, extremely dry conditions dooccasionally occur. Glulam can also take up moisture during the building process. Botheffects can lead to some degree of fissures developing during the initial period of occupancy.
The following guidelines should be used in the assessment and measuring of fissures:
a) if the depth of the fissure on the edge of a laminate is less than or equal to 25 % ofthe breadth of the member the length of the fissure should not exceed eight times thebreadth of the member; and
b) if the depth of the defect on the edge of a laminate is greater than 25 % and less than33 % of the breadth of the member, the fissures should be permitted only if theyoccur at the ends of the member and their length should not exceed four times thebreadth of the member.
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The fissures should be measured in accordance with the following:
a) if a transverse longitudinal plane cuts through two or more fissures on opposite faces,then the size of the defect is the sum of the individual sizes; and
b) the depth of a fissure should be verified by means of a feeler gauge not exceeding0.3 mm thick.
D4. Preservative and flame retardant treatment
D4.1 General
Glulam members intended for use in Service class 1, and in the majority of cases Serviceclass 2, see 3.13 and 3.14, do not normally require treatment to protect them from wooddestroying fungi. Timber is not normally at risk from decay if it is kept dry, that is at a moisturecontent below about 20 %. Preservation is a valuable tool, but avoiding risk of high moisturecontent is always preferable to dependence on a defensive measure. For Service class 3,see 3.15, the specifier should consult with the glulam manufacturer and adhesive supplier.
Specifiers may sometimes require members to be treated with insecticides or flame retardant,irrespective of the service or hazard classes in which they will be used. Both the treatment ofindividual laminations before bonding and the treatment of finished members can presentserious practical problems, summarized below. It is essential that these are carefullyconsidered in cases where preservative and/or flame retardant treatments are applied.
Treatment against decay, or the application of flame retardant and insecticides, either beforeor after the individual lamination have been bonded, can affect the performance andappearance of the finished member and may also interfere with satisfactory application anddurability of surface coatings (such as stains or varnishes).
D4.2 Treatment of laminations before gluing
Treatment of laminations before bonding can result in excessive increases in moisturecontent (if water-borne preservatives are used) and high surface concentrations of chemicalswhich will impair bond strength and durability. The laminations should be planed not morethan 24 h before bonding and, in some circumstances, a significant proportion of chemicalswill be removed by this planing. When re-drying laminations to the appropriate moisturecontent for bonding it is essential that machining is carried out after such re-drying.
D4.3 Treatment of finished members
Treatment of finished members by vacuum/pressure processes may be impracticable due totheir shape and/or size. Members which have been treated with water-borne preservativeswill need to be re-dried to the moisture content appropriate to the service class in which thefinished member is to be used. Re-drying may result in distortion, checking or splitting,impaired appearance due to colour changes (possibly uneven) and raising of the grain.
D4.4 Hazardous substances
Those responsible for the application of preservatives should ensure that the necessarytraining and full hazard assessments required by any relevant existing regulations aredeveloped and complied with.
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D5. Stress grading
Individual laminations will be visually graded in accordance with BS 5756, or machine gradedin accordance with appropriate standards.
Due regard should also be paid to relevant references in MS 544 : Part 1.
Additionally, they should meet the following recommendations:
a) Wane. There should be no wane for any grade.b) Resin. Pieces containing large resin pockets, which would affect bonding, should not
be permitted for any grade.c) Distortion. Any piece which is bowed, sprung, twisted or cupped to an excessive
extent, having regard to the method of laminating, should be rejected.d) Wormholes. There should be no wood wasp holes, but pinholes and wormholes may
be permitted in a small number of pieces, provided there is no active infestation of thewood.
D6. Sapstain
This is not a structural defect and may be acceptable without limitation from a strengthviewpoint.
D7. Abnormal defects
Any piece which contains defects such as compression wood, insect damage, fungal decay(but not sapstain), mechanical damage, combinations of knots and/or other characteristics,which may cause a decrease in strength properties of an amount which threatens theserviceability of the finished component should be excluded.
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Appendix E(Informative)
Bibliography
The following are informative references.
MS 544 Malaysian Standard Code of Practice for Structural Use of TimberPart 3 Glued laminated timberPart 10 Preservative treatment
BS EN 355 : 1992 Hazard classes of wood and wood-based products againstbiological attack
BS EN 355-1 : 1992 Classification of hazard classes
BS EN 518 : 1995 Structural timber – Grading – Requirements for visual strengthgrading standards
BS EN 519 : 1995 Structural timber – Grading – Requirements for machine strengthgraded timber and grading machines
DD ENV 1995 Eurocode 5: Design of timber structures
DD ENV 1995-1-1 : 1994 General rules for building (together with United Kingdom NationalApplication Document)
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