The impact of TIMBER CODES AND STANDARDS on construction and design

1. The impact ofTIMBER CODES AND STANDARDSon construction and design Hans Jørgen Larsen Danish Building Research Institute

2. Founded in 1959 • Revitalised in 1973 by John Sunley, BRE • …to work for unification of national timber design codes and standards related to timber International Council for Research and Innovation in Building and Construction W18 - Timber Structures

3. Reliability • Limit state design • Load sharing • Creep buckling • Fracture mechanics

4. CIB-timber design code

5. EU – EuropeanUnionTo remove barriers to trade • The building sector probably the worst

6. EU – European UnionTo remove barriers to trade • The building sector by far the worst • The most effective way: Harmonise building laws, regulations and codes • First step – from1983: The EUROCODES with supporting standards (CEN from 1990)

7. IMPOSSIBLE Harmonise building laws, regulations and codes

8. No productivity increase Prices up – quality down Protected, guild-based Building sector productivity

9. Remove barriers to trade in building products (1988)CONSTRUCTION PRODUCTS DIRECTIVE • Should have been effective end 1992 • Has not yet become operational

10. The Member States shall ensure that construction products are fit for their intended use, which means that the buildings in which they are used will satisfy essential safety requirements provided they are properly designed, built and maintained.

11. The Member States shallensure that construction productsare fit for their intended use, which means that the buildings in which they are used will satisfy essential safety requirements provided they are properly designed, built and maintained.

12. The Member States shallensure that construction productsare fit for their intended use, which means that the buildings in which they are used will satisfy essential safety requirements provided they are properly designed, built and maintained.

13. Member States shall presume that products are fit for their intended use if they comply with a harmonised standard or have a European Technical Approval

14. HARMONISED STANDARD • Ordered by EU (mandate) • produced by CEN

15. Quality Assurance/Production Control System

16. Quality Assurance/Production Control System

17. SYSTEM 2+ • initial determination of the properties • initial inspection of the production facilities • initial approval of the internal production control system • supervision of the internal production control system

18. CEN Committees • TC 38 – Durability of wood and related materials • TC 112 – Wood-based panels • TC 124 – Timber structures • TC 175 – Timber-based products • TC 193 – Adhesives

19. CEN Committees • TC 38 – Durability of wood and related materials • TC 112 – Wood-based panels • TC 124 – Timber structures • TC 175 – Timber-based products • TC 193 – Adhesives

20. CEN Committees • TC 38 – Durability of wood and related materials • TC 112 – Wood-based panels • TC 124 – Timber structures • TC 175 – Timber-based products • TC 193 – Adhesives

21. CEN Committees • TC 38 – Durability of wood and related materials • TC 112 – Wood-based panels • TC 124 – Timber structures • TC 175 – Timber-based products • TC 193 – Adhesives

22. CEN Committees • TC 38 – Durability of wood and related materials • TC 112 – Wood-based panels • TC 124 – Timber structures • TC 175 – Timber-based products • TC 193 – Adhesives

23. CEN Committees • TC 38 – Durability of wood and related materials • TC 112 – Wood-based panels • TC 124 – Timber structures • TC 175 – Timber-based products • TC 193 – Adhesives

24. STANDARDS ON STRUCTURAL TIMBER • Standard for visual grading • Standard for sizes

25. STANDARDS ON STRUCTURAL TIMBER • Standard giving minimum requirements concerning visual grading standards • Standard for sizes

26. STANDARDS ON STRUCTURAL TIMBER • Standard giving minimum requirements concerning visual grading standards • Standard for tolerances on sizes • Standard defining strength classes • Standard on the assignment to strength classes

27. Strength Classes

28. ONE COMPULSORY STANDARD Strength-graded structural timber with rectangular cross section • Part 1: general requirements • Part 2: machine grading – initial type testing • Part 3: machine grading – factory production control

29. VISUALLY graded timber • Graded to a standard that meets the CEN minimum requirements • Tolerances in accordance with the CEN standard • Properties determined by testing or use the strength class system • Each piece marked • Production control system (third party control)

30. VISUALLY graded timber • Graded to a standard that meets the CEN minimum requirements • Tolerances in accordance with the CEN standard • Properties determined by testing or use the strength class system • Each piece marked • Production control system (third party control)

31. VISUALLY graded timber • Graded to a standard that meets the CEN minimum requirements • Tolerances in accordance with the CEN standard • Properties determined by testing or use the strength class system • Each piece marked • Production control system (third party control)

32. VISUALLY graded timber • Graded to a standard that meets the CEN minimum requirements • Tolerances in accordance with the CEN standard • Properties determined by testing or use the strength class system • Each piece marked • Production control system (third party control)

33. VISUALLY graded timber • Graded to a standard that meets the CEN minimum requirements • Tolerances in accordance with the CEN standard • Properties determined by testing oruse the strength class system • Each piece marked • Production control system (third party control)

34. VISUALLY graded timber • Graded to a standard that meets the CEN minimum requirements • Tolerances in accordance with the CEN standard • Properties determined by testing or use the strength class system • Each piece marked • Production control system (third party control)

35. VISUALLY graded timber • Graded to a standard that meets the CEN minimum requirements • Tolerances in accordance with the CEN standard • Properties determined by testing or use the strength class system • Each piece marked • Production control system (third party control)

36. Production Control Per grading shift • timber source and species • tolerances and grading accuracy • moisture content • marking Annually • personnel • moisture meter

37. INVOLVEMENT OF THIRD PARTY • will be costly • dramatic changes in the trade in many countries

40. Eurocode 5

41. Many good reasons for not using prestandards: • Costly to change practice • Liability • No design aids/textbooks • More complicated

42. Example: Stiffness of floors

43. Eurocodes will replace national design codes by 2007 - 2008?

44. Impact of Eurocodes/Eurocode 5? • Direct: small • Indirect: very big • Frame for the product standards • Model for all modern design codes

45. EUROCODE 5 Focus for (European) timber research

46. CIB W18 – Timber Structures

47. FUTURE RESEARCH THEMES • Actions • Bracing • Columns/instability of beams • Durability • Grading • Load sharing/system effects • Reliability

48. There is still a lot to do BOB and we are looking forward to your contributions