1. TEMTIS seminar Horsens 2008 Eurocode 5: Compression perpendicular to the Grain H J Larsen Denmark A J M Leijten TU-Eindhoven – The Netherlands T A C M van der Put TU-Delft – The Netherlands

2. TEMTIS seminar Horsens 2008 Acknowledsments Based on paper for CIB-W18 2008 by H J Larsen, Denmark A J M Leijten, TU-Eindhoven – The Netherlands T A C M van der Put, TU-Delft – The Netherlands

3. TEMTIS seminar Horsens 2008 Problem Introduction of a ”scientific” test method and definition for compression perpendicular to grain has halved the characteristic strength

4. TEMTIS seminar Horsens 2008 Problem Introduction of a ”scientific” test method and definition for compression perpendicular to grain has halved the characteristic strength Many traditional structures and details e. g. in timber frame houses will no longer be acceptable

5. TEMTIS seminar Horsens 2008

6. Standard Test Methods 51x51x152mm 152 51 ASTM – D143 Australian (technological ) test 45 European (scientifical) test EN 408 Poussa et all. Proc.:CIB-W18-2007: paper 40-2-2 Compressive strength =

7. TEMTIS seminar Horsens 2008 Standard Test Methods Compressive stress

8. TEMTIS seminar Horsens 2008 Definition Compressive strength European test EN 408 Compressive strength 1% off-set 1 %

9. TEMTIS seminar Horsens 2008 Comparison of test results Ref: Poussa et al. Helsinki CIB-W18 paper 40-2-2

10. TEMTIS seminar Horsens 2008 Proposal Thelandersson & Mårtensson and others Regard exceedance of scientific compression strength as violation of a serviceability state (and not an ultimate limit state)

11. TEMTIS seminar Horsens 2008 Limit states Ultimate limit states Serviceability limit states

12. TEMTIS seminar Horsens 2008 Ultimate limit states Failure of whole structure or part of it Precise internationally agreed definitions On the whole agreed safety level

13. TEMTIS seminar Horsens 2008 Topping-up day

14. TEMTIS seminar Horsens 2008 Next day - failure

15. TEMTIS seminar Horsens 2008 Failure (at least in lower story)

16. TEMTIS seminar Horsens 2008 Failure (at least in lower story)

17. TEMTIS seminar Horsens 2008 Deformations preceding failure

18. TEMTIS seminar Horsens 2008 Serviceability limit states Unacceptable behaviour at normal use

19. TEMTIS seminar Horsens 2008 Serviceability limit states Unacceptable behaviour at normal use, e. g. visually unacceptable

20. TEMTIS seminar Horsens 2008 Serviceability limit states Unacceptable behaviour at normal use, e. g. visually unacceptable

21. TEMTIS seminar Horsens 2008 Serviceability limit states Unacceptable behaviour at normal use, e. g. visually or functionally unacceptable deformations

22. TEMTIS seminar Horsens 2008 Serviceability limit states In most cases: No precise requirements Criteria fixed by designer in agreement with client National tradition and taste

23. TEMTIS seminar Horsens 2008 Serviceability limit states Formally it is not required to perform a serviceability verification as long as it is possible to perform the ultimate state verification

24. TEMTIS seminar Horsens 2008 Serviceability, compression perp. It is difficult, to put it mildly, to understand why exceeding a marginal deformation in a block compression test should be taken as the governing criteria for structures where much larger deformations are normally acceptable and loaded in a completely different way.

25. TEMTIS seminar Horsens 2008 Serviceability, compression perp. It is difficult, to put it mildly, to understand why exceeding a marginal deformation in a block compression test should be taken as the governing criteria for structures where much larger deformations are normally acceptable and loaded in a completely different way. Especially when the use of the Serviceability limit state is accepted only half heartedly and without a proper definition and understanding

26. TEMTIS seminar Horsens 2008 Eurocode design equation EN1995-1-1 Impirical model Hilmer Riberholt Incomplete, discontinous, strange jumps

27. TEMTIS seminar Horsens 2008 New design equation EN1995-1-1:2005/A1 Blass and Görlacher based on Borg Madsen (2000 ) l + 60mm l ef =

28. TEMTIS seminar Horsens 2008 Alternative Model Based on Van der Put (1986) Slip-line theory

29. TEMTIS seminar Horsens 2008 Alternative Model Slope 1:1 for 1% off-set Slope 1:1,5 for 10% deformation

30. TEMTIS seminar Horsens 2008 Alternative Model Based on Van der Put (1986) Slip-line theory (Schoenmakers)

31. TEMTIS seminar Horsens 2008 Model comparison A B C D E F Test results reported by many authors Test A: n = 418 Tests B to F: 1% n= 582 (52 samples) 10% n= 125 (23 samples) -Solid wood -Glued laminated wood Load cases reported

32. TEMTIS seminar Horsens 2008 Comparison 1 % off-set

33. TEMTIS seminar Horsens 2008 Model comparison

34. TEMTIS seminar Horsens 2008 Comparison

35. TEMTIS seminar Horsens 2008 Comparisons ln(model/test)=ln(R) ideally: ln(R)=0  R=1 n = 582Van der PutEC 5 Mean- 0,04- 0,36 Standard deviation 0,170,20

36. TEMTIS seminar Horsens 2008 Model evaluation

37. TEMTIS seminar Horsens 2008 Model evaluation

38. TEMTIS seminar Horsens 2008 Conclusion Compression perpendicular to grain The evaluation of both models show that Van der Put model is far more accurate in predicting accurately the bearing strength perpendicular to the grain than the model currently in Eurocode 5/A1.

39. TEMTIS seminar Horsens 2008 Proposal for EC5 adoption Compression perpendicular to grain Deformation limit 1% Deformation limit 10% for h < 4 b

40. TEMTIS seminar Horsens 2008 Proposal for EC5 adoption Compression perpendicular to grain Deformation limit 1% Deformation limit 10% for h < 4 b

41. TEMTIS seminar Horsens 2008 Restriction Formally verified only for continously supported beams

42. TEMTIS seminar Horsens 2008 Restriction Formally verified only for continously supported beams Not too difficult to extend to concentrated supports

43. TEMTIS seminar Horsens 2008 Future Formally verified only for continously supported beams Not too difficult to extend to concentrated supports No tests for unsupported loads

44. TEMTIS seminar Horsens 2008 Future Tests needed for unsupported loads !