AS 1720.1-1988

1 - AS 1720.1-1988 SAA TIMBER STRUCTURES CODE - DESIGN METHODS
4 - PREFACE
5 - CONTENTS
7 - SECTION 1. SCOPE AND GENERAL
7 - 1.1 SCOPE.
7 - 1.2 REFERENCED DOCUMENTS.
7 - 1.3 NEW MATERIALS AND METHODS.
7 - 1.4 TIMBER QUALITY.
7 - 1.5 GENERAL DESIGN CONSIDERATIONS.
7 - 1.5.1 Loads.
7 - 1.5.1.1 General.
7 - 1.5.1.2 Load duration.
8 - 1.5.2 Design methods.
8 - 1.5.2.1 General.
8 - 1.5.2.2 Stress analysis.
8 - 1.5.2.3 Experimentally based design.
8 - 1.5.3 Other design considerations.
8 - 1.5.3.1 Stability.
8 - 1.5.3.2 Buckling restraints.
8 - 1.5.3.3 Erection and other extraneous forces.
8 - 1.5.3.4 Secondary stresses.
8 - 1.5.3.5 Shrinkage.
8 - 1.5.3.6 Deformations.
8 - 1.5.3.7 Timber dimensions for engineering calculations.
8 - 1.5.3.8 Timber in natural pole form.
8 - 1.5.3.9 Biological deterioration.
8 - 1.6 DESIGN AND SUPERVISION.
8 - 1.6.1 Design.
8 - 1.6.2 Supervision.
9 - 1.7 WORKMANSHIP AND MAINTENANCE.
9 - 1.7.1 General.
9 - 1.7.2 Moisture content.
9 - 1.7.3 Corrosion.
9 - 1.7.4 Maintenance.
9 - 1.8 DEFINITIONS.
9 - 1.8.1 Administrative definitions.
9 - 1.8.2 Technical definitions.
9 - 1.9 NOTATION.
9 - 1.10 UNITS.
10 - SECTION 2. BASIC PROPERTIES OF STRUCTURAL TIMBER
10 - 2.1 GENERAL.
10 - 2.2 STRUCTURAL CLASSIFICATIONS.
10 - 2.3 BASIC WORKING STRESSES AND MODULUS OF ELASTICITY.
10 - 2.3.1 Basic working stresses parallel to grain, and shear stresses in beams.
10 - 2.3.2 Basic working stress in compression perpendicular to the grain and shear stress at joint details.
10 - 2.3.3 Basic working stress in compression at an angle to the grain.
10 - 2.3.4 Modulus of elasticity and rigidity.
10 - 2.3.5 Basic working stresses in tension (softwoods only).
10 - 2.4 DESIGN.
10 - 2.4.1 Permissible stresses.
10 - 2.4.2 Deflections.
10 - 2.5 MODIFICATION FACTORS.
10 - 2.5.1 Duration of load.
10 - 2.5.1.1 Effect on strength.
16 - 2.5.1.2 Effect on stiffness.
17 - 2.5.2 Moisture condition.
18 - 2.5.3 Temperature.
18 - 2.5.4 Length and position of bearing.
18 - 2.5.5 Load sharing.
18 - 2.5.6 Size factor for flexural and tension members.
19 - 2.5.7 Stability factor.
19 - 2.5.8 Material and application factor.
20 - SECTION 3. DESIGN OF BASIC STRUCTURAL MEMBERS
20 - 3.1 GENERAL.
20 - 3.2 BEAM DESIGN.
20 - 3.2.1 Maximum stresses.
20 - 3.2.2 Effective span.
20 - 3.2.3 Slenderness coefficient for lateral buckling.
21 - 3.2.4 Stability factor.
21 - 3.2.5 Allowable nominal bending stress.
21 - 3.2.6 Strength of notched beams.
21 - 3.2.7 Concentrated loads and partial area loads on grid systems.
23 - 3.3 COLUMN DESIGN.
23 - 3.3.1 Maximum stresses.
23 - 3.3.2 Slenderness coefficients for lateral buckling.
23 - 3.3.3 Stability factor.
23 - 3.3.4 Allowable nominal axial stress.
24 - 3.3.5 Strength of notched columns.
24 - 3.3.6 Spaced columns.
24 - 3.4 TENSION MEMBER DESIGN.
24 - 3.4.1 Axial stress in tension members.
24 - 3.4.2 Slenderness coefficient.
24 - 3.4.3 Notched tension members.
24 - 3.5 COMBINED BENDING AND AXIAL STRESSES.
24 - 3.5.1 Combined bending and compression.
24 - 3.5.2 Combined bending and tension.
25 - SECTION 4. CONNECTIONS
25 - 4.1 GENERAL.
25 - 4.1.1 Scope of section.
25 - 4.1.2 Joint groups.
25 - 4.1.3 Timber grade.
25 - 4.1.4 Tendency to split.
25 - 4.1.5 Eccentric joints.
25 - 4.2 NAILED JOINTS.
25 - 4.2.1 Lateral loads.
27 - 4.2.2 Withdrawal loads.
28 - 4.3 SCREWED JOINTS.
28 - 4.3.1 Lateral loads.
28 - 4.3.2 Withdrawal loads.
29 - 4.4 BOLTED JOINTS.
29 - 4.4.1 General.
29 - 4.4.2 Lateral loads.
38 - 4.4.3 Axial loads.
38 - 4.5 COACH SCREWS.
38 - 4.5.1 General.
38 - 4.5.2 Lateral loads.
38 - 4.5.3 Withdrawal loads.
39 - 4.6 SPLIT-RING CONNECTORS.
39 - 4.6.1 General.
39 - 4.6.2 Basic loads.
39 - 4.6.3 Permissible loads.
39 - 4.6.4 Spacings, edge and end distances.
39 - 4.7 SHEAR PLATE CONNECTORS.
39 - 4.7.1 General.
39 - 4.7.2 Basic loads.
39 - 4.7.3 Permissible loads.
39 - 4.7.4 Spacings, edge and end distances.
42 - SECTION 5. PLYWOOD
42 - 5.1 GENERAL.
42 - 5.2 BASIC WORKING STRESSES AND STIFFNESS.
42 - 5.3 DESIGN.
42 - 5.3.1 Permissible stresses.
42 - 5.3.2 Deflections.
42 - 5.4 MODIFICATION FACTORS.
42 - 5.4.1 Duration of load.
42 - 5.4.2 Moisture condition.
42 - 5.4.3 Temperature.
42 - 5.4.4 Plywood assembly factor.
42 - 5.4.5 Stability factors.
42 - 5.5 JOINTS.
42 - 5.5.1 Nailed and screwed joints.
42 - 5.5.2 Glued joints.
45 - SECTION 6. ROUND TIMBERS
45 - 6.1 GENERAL.
45 - 6.2 BASIC WORKING STRESSES AND STIFFNESS.
45 - 6.3 DESIGN.
45 - 6.3.1 Permissible stresses.
45 - 6.3.2 Deflections.
45 - 6.4 ADDITIONAL MODIFICATION FACTORS.
45 - 6.4.1 Factor for immaturity.
45 - 6.4.2 Shaving factor.
45 - 6.5 DESIGN DETAILS.
45 - 6.5.1 Effective pole cross-section.
45 - 6.5.2 Effective cross-section of untreated timber.
45 - 6.5.3 Moisture content of timbers in ground contact.
45 - 6.5.4 Connectors.
47 - SECTION 7. GLUED-LAMINATED CONSTRUCTION
47 - 7.1 GENERAL.
47 - 7.2 DESIGN.
47 - 7.2.1 Basic and permissible stresses.
47 - 7.2.2 Deflections.
47 - 7.3 MODIFICATION FACTORS.
47 - 7.3.1 Moisture condition.
47 - 7.3.2 Lamination effects.
47 - 7.4 OTHER REQUIREMENTS.
47 - 7.4.1 General.
47 - 7.4.2 End joints in laminations.
48 - 7.4.3 Edge joints in laminations.
48 - 7.4.4 Lamination thickness.
48 - 7.4.5 Combination of grades of timbers.
48 - 7.4.6 Combination of species.
48 - 7.4.7 Curved and tapered members.
49 - APPENDIX A - ACCEPTANCE TESTING OF TIMBER STRUCTURES AND ELEMENTS
49 - A1 GENERAL.
49 - A1.1 Limitations of acceptance testing.
49 - A1.2 Circumstances requiring tests.
49 - A1.3 Testing authority.
49 - A1.4 Information required.
49 - A2 DEFINITIONS.
49 - A2.1 Prototype testing-
49 - A2.2 Proof testing-
50 - A3 METHOD OF TESTING.
50 - A3.1 General.
50 - A3.2 Test load.
50 - A3.3 Eccentricities.
50 - A3.4 Load-deflection curve.
50 - A4 PROOF TESTING.
50 - A4.1 Equivalent test load.
50 - A4.2 Loading.
51 - A4.3 Acceptance for strength.
51 - A4.4 Acceptance of deflection.
51 - A5 PROTOTYPE TESTING.
51 - A5.1 General.
51 - A5.2 Materials.
51 - A5.3 Manufacture.
51 - A5.4 Equivalent test load.
52 - A5.5 Test procedure.
52 - A5.5.1 Preloads.
52 - A5.5.2 Test loading.
52 - A5.6 Acceptance of prototype.
52 - A5.6.1 For strength.
52 - A5.6.2 For deflection.
52 - A5.6.3 Acceptance of production units.
52 - A6 REPORT OF TESTS.
53 - A7 USE OF TESTED STRUCTURES.
54 - APPENDIX B - BASIC DESIGN PROPERTIES OF STRUCTURAL TIMBER
55 - APPENDIX C - DESIGN OF BASIC STRUCTURAL MEMBERS
55 - C1 SCOPE.
55 - C2 THE MATERIAL CONSTANT .
56 - C3 SLENDERNESS COEFFICIENTS FOR BEAMS.
56 - C3.1 General.
56 - C3.2 End-supported beams.
56 - C3.2.1 General.
57 - C3.2.2 Beams with intermediate buckling restraints.
58 - C3.3 Beams with no intermediate buckling restraints.
58 - C3.4 Continuously restrained beams.
58 - C4 SLENDERNESS COEFFICIENTS FOR COLUMNS.
58 - C4.1 End supported columns.
58 - C4.2 Continuously restrained columns.
61 - C5 BEAM-COLUMN BENT ABOUT BOTH AXES.
61 - C6 SPACED COLUMNS.
61 - C6.1 Definitions.
61 - C6.2 Special requirements for spaced columns.
61 - C6.2.1 Size of connecting pieces.
61 - C6.2.2 Bolted connections.
61 - C6.2.3 Glued connections.
61 - C6.2.4 Spacing of intermediate packing pieces and batten plates.
61 - C6.2.5 Distance between shafts.
61 - C6.2.6 Battened columns.
61 - C6.3 Shear between components.
61 - C6.3.1 The design shear force.
62 - C6.3.2 Force effects on packing pieces.
63 - C6.3.3 Force effects on batten plates.
63 - C6.4 Permissible loads.
63 - C6.4.1 Slenderness coefficients.
63 - C6.4.1.1 Slenderness coefficients of individual shafts.
63 - C6.4.1.2 Slenderness coefficient of composite cross-sections.
63 - C6.4.2 Design procedure.
63 - C7 BUCKLING RESTRAINTS.
63 - C7.1 Definitions.
64 - C7.2 Notation.
64 - C7.3 Columns.
65 - C7.4 Beam with lateral restraints.
65 - C7.5 Beam with torsional restraints.
65 - C8 CONCENTRATED LOADS AND PARTIAL AREA LOADS ON GRID SYSTEMS.
65 - C8.1 General.
65 - C8.2 Concentrated load.
67 - C8.3 Partial area load.
67 - C9 NOTCHED BEAMS.
68 - C10 NOTCHED COLUMNS.
68 - C11 NOTCHED TENSION MEMBERS.
69 - APPENDIX D - JOINTS IN TIMBER STRUCTURES
69 - D1 CONNECTORS FOR PLYWOOD.
69 - D1.1 General.
69 - D1.2 Strength of joints with plywood.
70 - D2 DEFORMATION OF JOINTS.
70 - D2.1 General.
70 - D2.2 Displacement of nailed and screwed joints in solid timber.
70 - D2.3 Displacement of solid timber joints fabricated with bolts, split-ring connectors and shear plates connectors.
72 - D3 EQUATIONS AND TABLES FOR BASIC WORKING LOADS FOR BOLTS.
72 - D3.1 Load
72 - D3.2 Load
73 - APPENDIX E - BUCKLING STRENGTH OF PLYWOOD DIAPHRAGMS
73 - E1 SCOPE.
73 - E2 BUCKLING STRENGTH FOR DIAPHRAGMS LOADED IN-PLANE.
73 - E2.1 General.
73 - E2.2 Diaphragms with lateral edges supported and subjected to uniformly loaded edge forces.
75 - E2.3 Diaphragms with lateral edges free and subjected to uniformly loaded edge forces.
75 - E2.4 Diaphragms subjected to concentrated edge forces.
76 - E2.5 Stiffeners for beam webs.
78 - APPENDIX F - CONNECTIONS FOR ROUND TIMBERS
79 - APPENDIX G - GLUED-LAMINATED CONSTRUCTION - SPECIAL CONDITIONS
79 - G1 SPECIAL LAMINATION FACTOR.
79 - G2 DESIGN STRENGTH OF BUTT JOINTS.
79 - G2.1 General.
79 - G2.2 Tension members and horizontally laminated beams.
80 - G2.3 Vertically laminated beams.
80 - G2.4 Columns.
80 - G2.5 Conditions of use.
81 - APPENDIX H - REFERENCED AND RELATED DOCUMENTS
82 - APPENDIX I - NOTATION AND FACTORS
87 - INDEX

Sets out the methods to be used in the design or appraisal of structural elts out the methods to be used in the design or appraisal of structuralements comprised of timber or wood products, and of structures comprised substantially of timber. It provides design data for sawn timber, glued-laminated timber, timber in pole form, plywood, and various types of fastenings. In addition, it provides methods of test for components or assemblies of unconventional design which are not readily amenable to detailed analysis.

This Standard sets out the design methods for the structural use of timber which are based on the principles of structural mechanics and on data established by research. The Standard is intended for use in the design or appraisal of structural elements comprised of timber or wood products and of structures comprised substantially of timber. To this end, the Standard provides design data for sawn timber, laminated timber, timber in pole form, plywood and various types of fastenings. In addition, it provides methods of test for components or assemblies of unconventional design which may not be readily amenable to detailed analysis. For ease of use, the simpler design situations are covered in the main body of the text. Related appendices, which form an integral part of the Standard, give acceptable procedures for detailed design situations.

Under Revision See DR 94276