Strength Performance of Glulam made of Obi-sugi Laminae with low Young’s Modulus of Bending

1. 2007 IUFRO All Division 5 Conference, Octorber 29th – November 2nd, 2007, Taipei Strength Performance of Glulam made of Obi-sugi Laminae with low Young’s Modulus of Bending Miyazaki Prefectural Wood Utilization Research Center Akihiro Matsumoto, Hideki Morita, Yoshiyasu Fujimoto Atsushi Shiiba, Yutaka Iimura Miyazaki Prefectural Wood Utilization Research Center

2. About Miyazaki Japan Miyazaki Miyazaki Prefectural Wood Utilization Research Center

3. About the standard of glulam in Japan The standard of structural glued laminated timber (Glulam) is regulated by Japanese Agricultural Standard (JAS) in Japan. What’s the JAS? The JAS is based on “The Law Concerning Standardization and Proper Labeling of Agricultural and Forestry Products”. The JAS standardize to regulate the quality of products, such as Agricultural, forestry, livestock and marine products including manufactured or processed products. The standard of laminae for structural glulam in JAS The standard of symmetric-structured glulam composed of different grade of laminae in JAS Young’s modulus of bending （GPa or 103N/mm2 ） Grade by machine rating Young’s modulus of bending （GPa or 103N/mm2 ） MOR （MPa or N/mm2） Strength grade Ave Lower limit Miyazaki Prefectural Wood Utilization Research Center

4. Laminae’s distribution chart Specimens : Sugi(Japanese cedar) laminae grown in Miyazaki About 30% of laminae shows Young’s modulus less than 5.0GPa. These laminae will not meet JAS standards. Frequency(%) The yield of qualifying laminae for structural glulamcut from obi-sugi log is extremely low and cost inhibited. Examine how to effectively utilize of lamina with low Young’s modulus *MOE was measured with grading machine, and each lamina was classified by minimum MOE value in it Miyazaki Prefectural Wood Utilization Research Center

5. Materials and methods Miyazaki Prefectural Wood Utilization Research Center

6. lamina specimen Five-grade machine stress graded obi-sugi laminae Young’s modulus of bending （GPa or 103N/mm2 ） Grade by machine rating JAS laminae Non JAS laminae Profile of the finger-joint Length ： 14mm Width ： 3.8mm Top Width ： 0.51mm Bottom Width ： 0.3mm Angle ： 1/9.4 Adhesive ： Water-base poly-isocyanate resin adhesive Press pressure ： 10MPa Diagram of finger-joint (unit:mm) Miyazaki Prefectural Wood Utilization Research Center

7. Glulam specimen The standard of laminae for structural glulam JAS Young’s modulus of bending （GPa or 103N/mm2 ） Grade by machine rating Miyazaki Prefectural Wood Utilization Research Center

8. Test method of laminae 1.Bending test [Bending test C in JAS] Specimens dimension ： Width:120mm, Thickness:30mm, Length:800mm Test method ： 4 points bending test Distance between loading points : 210mm、 Distance between fulcra : 630mm Loading speed ：5mm/min Number of specimens : Each grade 130, Total 650 Miyazaki Prefectural Wood Utilization Research Center

9. Test method of laminae 2.Tensile test [Tensile strength test in JAS] Specimens dimension : Width:120mm, Thickness:30mm, Length:2,000 Number of specimens : Each grade 50, Total 250 3.Compression test [Strength test of structural lumber] Specimens dimension : Width:120mm, Thickness:30mm, Length:180mm Number of specimens : Each grade 50, Total 250 Miyazaki Prefectural Wood Utilization Research Center

10. Test method of glulam 1.Bending test [Bending test A in JAS] Specimens dimension : Width :120mm, Thickness :300mm, Length :6,000mm Test method : 4 points bending test Distance between loading points :1,200mm Distance between fulcra:5,400mm Number of specimens : Each type 8, Total 24 Miyazaki Prefectural Wood Utilization Research Center

11. Test method of glulam 2.Tensile test [Strengthtest of structural lumber] Specimens dimension : Width:105mm, Thickness:300mm, Length:2,000mm Number of specimens : Each type 12, Total 36 3.Compression test [Strengthtest of structural lumber] Specimens dimention : Width :120mm, Thickness :300mm, Length :720mm Number of specimens : Each type 8, Total 24 Miyazaki Prefectural Wood Utilization Research Center

12. Result Miyazaki Prefectural Wood Utilization Research Center

13. 5th% ile: Lower 5% exclusion limits of the distribution assumed to be normal Results of bending test for laminae The bending strength of L30 and L40 laminae were equal or over the standard strength of L50 laminae in JAS Lower limit 5th%ile Miyazaki Prefectural Wood Utilization Research Center

14. Results of compression test for laminae The compression strength of L30 and L40 laminae were over the standard strength of L50 laminae in JAS 5th%ile Miyazaki Prefectural Wood Utilization Research Center

15. Results of tensile test for laminae The tensile strength of L30 and L40 laminae were over the standard strength of L50 laminae in JAS 5th%ile Miyazaki Prefectural Wood Utilization Research Center

16. Results of bending test for glulam The MOR of all glulam types were equal or over the standard strength of E65-F225 glulam in JAS 5th%ile Miyazaki Prefectural Wood Utilization Research Center

17. Results of compression test for glulam The compression strength of all glulam types were over the standard strength of E65-F225 in Building Standard Law 5th%ile Failure in the glulam began with a knot and a finger-joint Miyazaki Prefectural Wood Utilization Research Center

18. Results of tensile test for glulam Some of the specimens were slightly lower in tensile strength than that of E65-F225. 5th%ile Most of the specimens broke close to where they were chucked. Miyazaki Prefectural Wood Utilization Research Center

19. Conclusion Miyazaki Prefectural Wood Utilization Research Center

20. Strength Performance of Glulam made of Obi-sugi laminae with low Young’s Modulus of Bending Strength performance of laminae The strength performances of laminae with lower Young’s modulus such as L30 and L40 were nearly equal to that of sugi wood with Young’s modulus of 5.0 kN/mm2. Strength performance of glulam As for the glulam made with composition of these lower Young’s modulus laminae, such as E65(using L40 laminae for inner layer), E55(L40 for inner layer) and E55(L30 for inner layer), the glulam performed well in bending and compression tests. Some specimens showed slightly lower tensile strength than that of E65-F225. It seems to be necessary to examine the strength performance of glulam made of laminae classified by average MOE value in it. Miyazaki Prefectural Wood Utilization Research Center

21. Strength Performance of Glulam made of Obi-sugi Laminae with low Young’s Modulus of Bending Miyazaki Prefectural Wood Utilization Research Center