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Proposal of visual grading rules for Uruguayan loblolly and slash pine timber Laura Moya, Andrea Cardoso , Leandro Domenech, Hugo O´Neill, Vanesa Baño Project: “Technical Documents for standardization of timber structures and buildings”

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Page 1: Proposal of visual grading rules for Uruguayan loblolly ... 2016... · Uruguayan loblolly/slash pine lumber and the ... for coniferous lumber. Flow chart of the analysis process in

Proposal of visual grading rules for Uruguayan loblolly

and slash pine timberLaura Moya, Andrea Cardoso, Leandro Domenech, Hugo O´Neill,

Vanesa Baño

Project: “Technical Documents for standardization of timber structures and buildings”

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Introduction:• Uruguay has a large supply of pine timber, with high percentages of

juvenile wood. The annual average offer of pine timber, between 2010 and 2030, will be about 3 millions of m3 (Dieste, 2012)

2016 SWST International Convention 2

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Introduction:• Uruguay has a large supply of pine timber, with high percentages of

juvenile wood. The annual average offer of pine timber, between 2010 and 2030, will be about 3 millions of m3 (Dieste, 2012)

2016 SWST International Convention 3

MGAP, 2012

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Introduction:• Uruguay has a large supply of pine timber, with high percentages of

juvenile wood. The annual average offer of pine timber, between 2010 and 2030, will be about 3 millions of m3 (Dieste, 2012)

2016 SWST International Convention 4

MGAP, 2012

98% P. taeda and P. elliottii

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Introduction:• Uruguay has a large supply of pine timber, with high percentages of

juvenile wood. The annual average offer of pine timber, between 2010 and 2030, will be about 3 millions of m3 (Dieste, 2012)

2016 SWST International Convention 5

MGAP, 2000MGAP, 2012

98% P. taeda and P. elliottii

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Introduction:• Uruguay has a large supply of pine timber, with high percentages of

juvenile wood. The annual average offer of pine timber, between 2010 and 2030, will be about 3 millions of m3 (Dieste, 2012)

2016 SWST International Convention 6

MGAP, 2000MGAP, 2012

98% P. taeda and P. elliottii

• Currently, in Uruguay there is no available a design specification or building code for wood construction. Was decided to adopt the European standards package.

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Objective:

• The aim of this study was to propose a visual grading rule for Uruguayan loblolly/slash pine lumber and the correspondent limits for the visual parameters, and to assign a strength class in accordance to prEN 338 (2012).

2016 SWST International Convention 7

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Materials:

Sample Provenance Age Nº specimens

1 West 25 yr- old 115

2 Southwest 15 yr -old 146

Total 261

2016 SWST International Convention 8

• A previous database from a timber strength grading project (FMV, 2012) comprised of bending properties and density data was used to characterize pine lumber in accordance to European standards (EN).

MGAP, 2000

• The database with material being representative of currently produced loblolly and slash pine lumber became from two commercial plantations in Uruguay, a 25-year-old west and 15-year- old south-west plantations, and consisted of test results from two samples totaling 261 structural size specimens of 3300 mm-long.

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Materials:

Sample Provenance Age Nº specimens

1 West 25 yr- old 115

2 Southwest 15 yr -old 146

Total 261

2016 SWST International Convention 9

MGAP, 2000

• Database comprised results from

stiffness and strength determined in 4-point bending test density and moisture content values a description of typical visual parameters for each specimen: knots, slope of grain, wane, fissures, pith and warp.

• A previous database from a timber strength grading project (FMV, 2012) comprised of bending properties and density data was used to characterize pine lumber in accordance to European standards (EN).

• The database with material being representative of currently produced loblolly and slash pine lumber became from two commercial plantations in Uruguay, a 25-year-old west and 15-year- old south-west plantations, and consisted of test results from two samples totaling 261 structural size specimens of 3300 mm-long.

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Materials:

Sample Provenance Age Nº specimens

1 West 25 yr- old 115

2 Southwest 15 yr -old 146

Total 261

2016 SWST International Convention 10

MGAP, 2000

• Testing and initial analyses were performed following ASTM procedures (ASTM D 198, ASTM D 2395, ASTM D2915)

• Database comprised results from

stiffness and strength determined in 4-point bending test density and moisture content values a description of typical visual parameters for each specimen: knots, slope of grain, wane, fissures, pith and warp.

• A previous database from a timber strength grading project (FMV, 2012) comprised of bending properties and density data was used to characterize pine lumber in accordance to European standards (EN).

• The database with material being representative of currently produced loblolly and slash pine lumber became from two commercial plantations in Uruguay, a 25-year-old west and 15-year- old south-west plantations, and consisted of test results from two samples totaling 261 structural size specimens of 3300 mm-long.

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Materials:

Sample Provenance Age Nº specimens

1 West 25 yr- old 115

2 Southwest 15 yr -old 146

Total 261

2016 SWST International Convention 11

MGAP, 2000

• Testing and initial analyses were performed following ASTM procedures (ASTM D 198, ASTM D 2395, ASTM D2915)

• Database comprised results from

stiffness and strength determined in 4-point bending test density and moisture content values a description of typical visual parameters for each specimen: knots, slope of grain, wane, fissures, pith and warp.

• A previous database from a timber strength grading project (FMV, 2012) comprised of bending properties and density data was used to characterize pine lumber in accordance to European standards (EN).

• The database with material being representative of currently produced loblolly and slash pine lumber became from two commercial plantations in Uruguay, a 25-year-old west and 15-year- old south-west plantations, and consisted of test results from two samples totaling 261 structural size specimens of 3300 mm-long.

Data were reviewed in accordance with European guidelines.

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Materials:

Sample Provenance Age Nº specimens

1 West 25 yr- old 115

2 Southwest 15 yr -old 146

Total 261

2016 SWST International Convention 12

MGAP, 2000

• Testing and initial analyses were performed following ASTM procedures (ASTM D 198, ASTM D 2395, ASTM D2915)

• Database comprised results from

Global modulus of elasticity was adjusted in accordance to EN 408 (2011).

Mean modulus of elasticity, characteristic bending strength and characteristic density values were determined in accordance to EN 384 (2010).

stiffness and strength determined in 4-point bending test density and moisture content values a description of typical visual parameters for each specimen: knots, slope of grain, wane, fissures, pith and warp.

• A previous database from a timber strength grading project (FMV, 2012) comprised of bending properties and density data was used to characterize pine lumber in accordance to European standards (EN).

• The database with material being representative of currently produced loblolly and slash pine lumber became from two commercial plantations in Uruguay, a 25-year-old west and 15-year- old south-west plantations, and consisted of test results from two samples totaling 261 structural size specimens of 3300 mm-long.

Data were reviewed in accordance with European guidelines.

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Methodology for visual parameter analysis1) Preliminary analysis involved selection of the most influential parameters on mean stiffness, characteristic strength and characteristic density, with the aim to establish allowable limits for each parameter;

2016 SWST International Convention 13

Flow chart of the analysis process in Matlab

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Methodology for visual parameter analysis1) Preliminary analysis involved selection of the most influential parameters on mean stiffness, characteristic strength and characteristic density, with the aim to establish allowable limits for each parameter;

2) A first script (a function in Matlab environment) was written to compute mean stiffness, characteristic strength and characteristic density, with test data and allowable limits defined in 1);

2016 SWST International Convention 14

Flow chart of the analysis process in Matlab

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Methodology for visual parameter analysis1) Preliminary analysis involved selection of the most influential parameters on mean stiffness, characteristic strength and characteristic density, with the aim to establish allowable limits for each parameter;

2) A first script (a function in Matlab environment) was written to compute mean stiffness, characteristic strength and characteristic density, with test data and allowable limits defined in 1);

3) A second script (order-processing file) was developed in order to evaluate different allowable limit combinations and to return, for each combination, values of mean stiffness, characteristic strength, and characteristic density, plus the number of rejected specimens;

2016 SWST International Convention 15

Flow chart of the analysis process in Matlab

Page 16: Proposal of visual grading rules for Uruguayan loblolly ... 2016... · Uruguayan loblolly/slash pine lumber and the ... for coniferous lumber. Flow chart of the analysis process in

Methodology for visual parameter analysis1) Preliminary analysis involved selection of the most influential parameters on mean stiffness, characteristic strength and characteristic density, with the aim to establish allowable limits for each parameter;

2) A first script (a function in Matlab environment) was written to compute mean stiffness, characteristic strength and characteristic density, with test data and allowable limits defined in 1);

3) A second script (order-processing file) was developed in order to evaluate different allowable limit combinations and to return, for each combination, values of mean stiffness, characteristic strength, and characteristic density, plus the number of rejected specimens;

4) Selection of the limit combination that returned the less amount of rejected specimens, on a minimum basis of C14 strength class.

2016 SWST International Convention 16

The limits were then compared with those established on the Spanish standard UNE 56544 (2011) and Argentinean IRAM 9662-1 (2005) and IRAM 9662-3 (2005) for coniferous lumber.

Flow chart of the analysis process in Matlab

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Results:

Parameter Visual grade EC7

Face knots diameter (d ) d 2/5 h

Edge knots diameter (d) d 2/5 b

Pith Allowed

Slope of grain 1:6

Maximum width of annual ring -

Fissures/ Seasoning Checks 1,0 m ó (1/4)l

Fissures/ Seasoning Splits 1,5 m ó (1/2)l

Wane 1/5 l

Resin pockets 2 h

Reaction: compression wood -

Biological damage:

- Blue stain

- Fungi decay

- Insect´s galleries

Allowed

Not allowed

Holes diameter < 2 mm

Warp:

- Bow

- Crook

- Twist

- Cup

12 mm

9 mm

1,5 mm (per 25 mm of h)

-

Proposal of visual grading rules for Uruguayan loblolly and slash pine

l bh

One visual grade

2016 SWST International Convention 17

1 Dry condition (MC = 14 -18%)2 Referred to mean cross section of 49 x 147 mmIRAM 9662-1 (2005) /IRAM 9662-3 (2005)

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Results:

Sample Provenance Section (mm) Age (yr-old) Grade EC7 Rejected % rejected

1 West 49x146 25 58 57 49,6

2 Southern-west 49x148 15 42 104 71,2

Total 100 161 61,7

Number of pieces classify and the percentage of rejected by location and section.

2016 SWST International Convention 18

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Results:

Sample Provenance Section (mm) Age (yr-old) Grade EC7 Rejected % rejected

1 West 49x146 25 58 57 49,6

2 Southern-west 49x148 15 42 104 71,2

Total 100 161 61,7

Number of pieces classify, rejected and the percentage of rejected by location and section.

2016 SWST International Convention 19

0

10

20

30

40

50

60

70

80

10 20 30 40 50 60 70 80 90 100

Frec

uen

cy

Edge knot (%)

0

5

10

15

20

25

30

35

40

10 20 30 40 50 60 70 80 90 100

Frec

uen

cy

Edge knot(%)

The main reasons for the rejection of pieces were knot size (edge knot) and warp (crook).

MGAP, 2000

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Results:

Sample Provenance Section (mm) Age (yr-old) Grade EC7 Rejected % rejected

1 West 49x146 25 58 57 49,6

2 Southern-west 49x148 15 42 104 71,2

Total 100 161 61,7

Number of pieces classify, rejected and the percentage of rejected by location and section.

2016 SWST International Convention 20

The main reasons for the rejection of pieces were knot size (edge knot) and warp (crook).

MGAP, 2000

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Fre

cue

ncy

Crook (mm)

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Fre

cue

ncy

Crook (mm)

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Results:

Species Property

Pin

us

ellio

tti/

taed

a

50

x15

0 m

m

Modulus of elasticity (kN/mm2) E0,mean 7,04

5th percentile of bending strength (N/mm2) fm,k 14,63

5th percentile density (kg/m3) k 348

Mechanical properties of visual grade EC7

2016 SWST International Convention 21

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Results:

Species Property

Pin

us

ellio

tti/

taed

a

50

x15

0 m

m

Modulus of elasticity (kN/mm2) E0,mean 7,04

5th percentile of bending strength (N/mm2) fm,k 14,63

5th percentile density (kg/m3) k 348

Mechanical properties of visual grade EC7

2016 SWST International Convention 22

The mechanical properties were calculated using the requirements of EN 408 and EN 384:2010: • Modulus of elasticity and density were adjusted by a moisture content of 12% • The bending strength adjusted by section and corrected in function of the number

and size of samples

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Results:

Species Property

Pin

us

ellio

tti/

taed

a

50

x15

0 m

m

Modulus of elasticity (kN/mm2) E0,mean 7,04

5th percentile of bending strength (N/mm2) fm,k 14,63

5th percentile density (kg/m3) k 348

Mechanical properties of visual grade EC7

2016 SWST International Convention 23

Property Strength class

Modulus of elasticity (kN/mm2) E0,mean 7

C14

5th percentile of bending strength (N/mm2) fm,k 14

5th percentile density (kg/m3) k 290

Minimum strength requirements for coniferous strength classes (prEN 338:2012)

The mechanical properties were calculated using the requirements of EN 408 and EN 384:2010: • Modulus of elasticity and density were adjusted by a moisture content of 12% • The bending strength adjusted by section and corrected in function of the number

and size of samples

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Results:

Species Property

Pin

us

ellio

tti/

taed

a

50

x15

0 m

m

Modulus of elasticity (kN/mm2) E0,mean 7,04

5th percentile of bending strength (N/mm2) fm,k 14,63

5th percentile density (kg/m3) k 348

Mechanical properties of visual grade EC7

2016 SWST International Convention 24

Property Strength class

Modulus of elasticity (kN/mm2) E0,mean 7

C14

5th percentile of bending strength (N/mm2) fm,k 14

5th percentile density (kg/m3) k 290

Minimum strength requirements for coniferous strength classes (prEN 338:2012)

The mechanical properties were calculated using the requirements of EN 408 and EN 384:2010: • Modulus of elasticity and density were adjusted by a moisture content of 12% • The bending strength adjusted by section and corrected in function of the number

and size of samples

Strength class

C14

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Conclusions:

• Knot diameter and warp were the visual parameters with more influence on bending properties.

2016 SWST International Convention 25

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Conclusions:

• Knot diameter and warp were the visual parameters with more influence on bending properties.

• The visual grade of the Uruguayan pine lumber was EC7 associated with the strength class C14 (prEN 338:2012)

2016 SWST International Convention 26

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Conclusions:

• Knot diameter and warp were the visual parameters with more influence on bending properties.

• The visual grade of the Uruguayan pine lumber was EC7 associated with the strength class C14 (prEN 338:2012)

• Modulus of elasticity and characteristic bending strength were the defining properties for class assignment.

2016 SWST International Convention 27

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Conclusions:

• Knot diameter and warp were the visual parameters with more influence on bending properties.

• The visual grade of the Uruguayan pine lumber was EC7 associated with the strength class C14 (prEN 338:2012)

• Modulus of elasticity and characteristic bending strength were the defining properties for class assignment.

• The warp was a decisive parameter to assign a visual grade because the width of the annual ring was not recorded on the database used.

2016 SWST International Convention 28

Commentaries:

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Conclusions:

• Knot diameter and warp were the visual parameters with more influence on bending properties.

• The visual grade of the Uruguayan pine lumber was EC7 associated with the strength class C14 (prEN 338:2012)

• Modulus of elasticity and characteristic bending strength were the defining properties for class assignment.

• The warp was a decisive parameter to assign a visual grade because the width of the annual ring was not recorded on the database used.

• The percentages of rejected boards will probably decrease if more samples (or larger sample size) were considered in the analysis;

2016 SWST International Convention 29

Commentaries:

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Conclusions:

• Knot diameter and warp were the visual parameters with more influence on bending properties.

• The visual grade of the Uruguayan pine lumber was EC7 associated with the strength class C14 (prEN 338:2012)

• Modulus of elasticity and characteristic bending strength were the defining properties for class assignment.

• The warp was a decisive parameter to assign a visual grade because the width of the annual ring was not recorded on the database used.

• The percentages of rejected boards will probably decrease if more samples (or larger sample size) were considered in the analysis;

• Inclusion of annual ring width measurement in the visual grading rules would probably improve the criteria.

2016 SWST International Convention 30

Commentaries:

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Thank you for your attention Andrea Cardoso

[email protected]

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Acknowledgment:

2016 SWST International Convention 32

• The authors would like to thank the National Direction of Industry, Uruguay, for the funding of the project “Technical Documents for standardization of timber structures and buildings”

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Standards references:

2016 SWST International Convention 33

• ASTM D198-09:2011. Standard test methods of static tests of lumber in structural sizes

• ASTM D2395-07: 2011. Standard test methods for specific gravity of wood and wood based-materials

• ASTM D2915-10: 2011. Standard practice for sampling and data-analysis for structural wood and wood-based panels

• IRAM 9662-1:2005. Madera laminada encolada estructural. Clasificación visual de las tablas por resistencia. Parte 1: Tablas de pino Paraná (Araucaria angustifolia)

• IRAM 9662-3:2005. Madera laminada encolada estructural. Clasificación visual de las tablas por resistencia. Parte 3: Tablas de pino taeda y elliotti (Pinus taeda y elliottii)

• NCh 1198:2006. Madera – Construcciones en madera – Cálculo

• NCh 1207:2005. Pino radiata – Clasificación visual para uso estructural – Especificaciones de los grados de calidad.

• UNE EN 338:2010. Madera estructural. Clases resistentes

• PrEN 338:2012. Structural timber. Strength classes

• UNE EN 384:2010. Madera estructural. Determinación de los valores característicos de las propiedades mecánicas y la densidad

• PrEN 384:2014. Structural timber. Determination of characteristic values of mechanical properties and density

• UNE EN 408:2011+A1:2012. Estructuras de madera. Madera aserrada y madera laminada encolada para uso estructural. Determinación de algunas propiedades físicas y mecánicas.

• UNE EN 1912:2012/AC2013. Madera estructural. Clases resistentes. Asignación de calidades visuales y especies

• prEN 1912:2015. Structural timber. Strength classes. Assignment of visual grades and species

• UNE 56544 (2011). Clasificación visual de la madera aserrada para uso estructural. Madera de coníferas. AENOR, Madrid.

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Materials:

Sample Provenance Age Nº specimens

1 West 25 yr- old 115

2 Southwest 15 yr -old 146

Total 261

• Database comprised results from stiffness and strength determined in 4-point

bending test, density and moisture content values.

• A series of considerations had to be done to adapt the data base to the European

standards

Considerations in regards to Previous standard Currently standard Principal adaptation

Visual grading NCh 1207 UNE 56544 (2011) Projection of knot area versus face knot diameter and edge knot diameter

Testing methods ASTM D198-09ASTM D2395-07

EN 408 Deformation registered

Property determination and strength class assignment

ASTM D2915-10 EN 384, EN 338

Determination of the elasticity modulus.

2016 SWST International Convention 34

• Database from a previous project (FMV-2009-1-2772)

• Representative of currently produced loblolly and slash pine lumber, became from 2 commercial plantation in Uruguay.

• Consisted of test results from 2 samples with structural size specimens (49 x 147 x 3300 mm)

MGAP, 2000