strength performance of glulam made of obi-sugi laminae with low young’s modulus of bending...

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


Japan


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


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(%

)


Materials and methods


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


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


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


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


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


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


Result


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


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


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


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


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


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


Conclusion


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.


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

strength performance of glulam made of obi-sugi laminae with low young’s modulus of bending...

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