strength performance of glulam made of obi-sugi laminae with low young’s modulus of bending...
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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
2007 IUFRO All Division 5 Conference, Octorber 29th – November 2nd, 2007, Taipei
About Miyazaki
Miyazaki
Miyazaki Prefectural Wood Utilization Research Center
Japan
Miyazaki Prefectural Wood Utilization Research Center
About the standard of glulam in Japan
The standard of structural glued laminated timber (Glulam) is regulated by JapaneseAgricultural 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.
L200 20.0L180 18.0L160 16.0L140 14.0L125 12.5L110 11.0L100 10.0L90 9.0L80 8.0L70 7.0L60 6.0L50 5.0
Grade by machine rating Young’s modulus of bending( GPa or 103N/mm2 )
The standard of laminae forstructural glulam in JAS
The standard of symmetric-structuredglulam composed of different grade oflaminae in JAS
E170-F495 17.0 14.0 49.5E150-F435 15.0 12.5 43.5E135-F375 13.5 11.5 37.5E120-F330 12.0 10.0 33.0E105-F300 10.5 9.0 30.0E95-F270 9.5 8.0 27.0E85-F255 8.5 7.0 25.5E75-F240 7.5 6.5 24.0E65-F225 6.5 5.5 22.5
Strength grade
Young’s modulus of bending( GPa or 103N/mm2 )
MOR( MPa or N/mm2 )Ave Lower limit
: E ave: E low
Laminae grade (GPa)
Figure.1 The influence of the evaluation method to give it to MOE frequency distribution (Number of samples : 5125)
3 4 5 6 7 8 90
10
20
30
40
Miyazaki Prefectural Wood Utilization Research Center
About 30% of laminae shows Young’s modulus less than
5.0GPa.
These laminae will not meet JAS standards.
The yield of qualifying laminae
for structural glulam cut from obi-sugi log is extremely low
and cost inhibited.
Laminae’s distribution chart
Specimens : Sugi(Japanese cedar) laminae grown in Miyazaki
*MOE was measured with grading machine, and each laminawas classified by minimum MOE value in it
Examine how to effectively utilize of lamina with low
Young’s modulus
Fre
quen
cy(%
)
Miyazaki Prefectural Wood Utilization Research Center
Materials and methods
Miyazaki Prefectural Wood Utilization Research Center
0.3
0.51 3.8
14.0
1/9.4
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
lamina specimen
Diagram of finger-joint (unit:mm)
L70 7.0L60 6.0L50 5.0L40 4.0L30 3.0
Grade by machine rating
Young’s modulusof bending
( GPa or 103N/mm2 )
JASlaminae
Non JASlaminae
Five-grade machine stress graded obi-sugi laminae
Miyazaki Prefectural Wood Utilization Research Center
Glulam specimen
L200 20.0L180 18.0L160 16.0L140 14.0L125 12.5L110 11.0L100 10.0L90 9.0L80 8.0L70 7.0L60 6.0L50 5.0
Grade bymachine rating
Young’s modulusof bending
( GPa or 103N/mm2 )
The standard of laminae forstructural glulam JAS
E65-F225 E65 E55 E55inner laminae inner laminae inner laminae inner laminaegrade is L50 grade is L40 grade is L40 grade is L30
L80 L80 L70 L70L70 L70 L60 L60L60 L60 L50 L50L50 L40 L40 L30L50 L40 L40 L30L50 L40 L40 L30L50 L40 L40 L30L60 L60 L50 L50L70 L70 L60 L60L80 L80 L70 L70
[JAS] [nonJAS]
Figure.2 Set up for symmetric-structured glulam composed of different grade of laminae including those with lower Young's modulus
Miyazaki Prefectural Wood Utilization Research Center
630
210
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
Test method of laminae
Miyazaki Prefectural Wood Utilization Research Center
500 5001,000
180
30
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
Test method of laminae
Miyazaki Prefectural Wood Utilization Research Center
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
5,400
1,200
Test method of glulam
Miyazaki Prefectural Wood Utilization Research Center
2.Tensile test [Strength test of structural lumber] Specimens dimension : Width:105mm, Thickness:300mm, Length:2,000mm Number of specimens : Each type 12, Total 36
500 5002,000
720
120
3.Compression test [Strength test of structural lumber] Specimens dimention : Width :120mm, Thickness :300mm, Length :720mm Number of specimens : Each type 8, Total 24
Test method of glulam
Miyazaki Prefectural Wood Utilization Research Center
Result
Miyazaki Prefectural Wood Utilization Research Center
JAS Ave
JAS
MO
R(N
/mm
2 )
Laminae grade
Figure.3 MOR of sugi laminae for each grade
:Average (Max/Min)
:
(Number of specimens : each grade 130, total 650)
L30 L40 L50 L60 L700
20
40
60
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
5th%ile
Lower limit
5th% ile: Lower 5% exclusion limits of the distribution assumed to be normal
Com
pres
sion
str
engt
h (N
/mm
2 )
Laminae grade
Figure.4 Compression strength of sugi laminae for each grade
:Average (Max/Min)
:
(Number of specimens : Each grade 50, Total 250)
L30 L40 L50 L60 L70
Standard strength of structuralsoftwood lumber in JAS
0
20
40
60
Miyazaki Prefectural Wood Utilization Research Center
Results of compression test for laminae
The compression strength of L30 and L40 laminae were over the standard strength of L50 laminae in JAS5th%ile
Ten
sile
str
engt
h (N
/mm
2 )
Laminae grade
Figure.5 Tensile strength of sugi laminae for each grade
:Average (Max/Min)
:
(Number of specimens : Each grade 50, Total 250)
JAS Ave
JAS Lower limit
L30 L40 L50 L60 L700
10
20
30
40
50
Miyazaki Prefectural Wood Utilization Research Center
Results of tensile test for laminae
The tensile strength of L30 and L40 laminae were over the standard strength of L50 laminae in JAS5th%ile
Miyazaki Prefectural Wood Utilization Research Center
Results of bending test for glulam
5th%ile
The MOR of all glulam types were equal or over the standard strength of E65-F225 glulam in JAS
MO
R(N
/mm
2 )
Types of glulam
Figure.6 MOR of sugi glulam for each type
:Average (Max/Min)
:
(Number of specimens : Each type 8, Total 24)
Strength standard of E65-F225 glulam in JAS
E65(L40) E55(L40) E55(L30)0
10
20
30
40
50
Miyazaki Prefectural Wood Utilization Research Center
Results of compression test for glulam
5th%ile
The compression strength of all glulam types were over the standard strength of E65-F225 in Building Standard Law
Failure in the glulam began with a knot and a finger-joint
Com
pres
sion
str
engt
h (N
/mm
2 )
Types of glulam
Figure.7 Compression strength of sugi glulam for each type
:Average (Max/Min)
:
(Number of specimen : Each type 8, Total 24)
Standard strength of E65-F225 glulamin Building Standard Law
E65(L40) E55(L40) E55(L30)0
10
20
30
40
50
Miyazaki Prefectural Wood Utilization Research Center
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.
Ten
sile
str
engt
h(N
/mm
2 )
Types of glulam
Figure.8 Tensile strength of sugi glulam for each type
:Average (Max/Min)
:
(Number of specimen : Each type 12, Total 36)
Standard strength of E65-F225 glulamin Building Standard Law
E65(L40) E55(L40) E55(L30)0
10
20
30
Miyazaki Prefectural Wood Utilization Research Center
Conclusion
Miyazaki Prefectural Wood Utilization Research Center
Strength Performance of Glulam made of Obi-sugi laminae with low Young’s Modulus of Bending
Strength performance of laminae
Strength performance of glulamAs 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.
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.
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
Strength Performance of Glulam made of Obi-sugi Laminaewith low Young’s Modulus of Bending
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