Bending strength and stiffness of structural laminated veneer lumber manufactured from fast-growing argentinean Eucalyptus grandis

The present paper reports the results of an investigation regarding the determination of bending strength and stiffness in specimens of laminated veneer lumber (LVL) manufactured from Argentinean Eucalyptus grandis and tested edgewise according to European standards. For this purpose an empirical research project with one sample containing 44 specimens with nominal sizes of 24.3 mm in width, 100 mm in depth and 2.44m in length was carried out. The characteristic strength value was 74 % and 118 % higher, respectively, than those adopted by Argentinean standards for the best strength class of sawn and glued laminated timber of the same species. It was similar to that reported for LVL of Norway spruce and lower than that published for LVL made from Uruguayan Eucalyptus grandis even though in the latter case the reported value was not obtained according to European standards. The modulus of elasticity mean value was 22 % and 14 % higher, respectively, than those adopted by Argentinean standards for the best strength class of sawn and glued laminated timber of the same species. Modulus of elasticity also exhibited a mean value 22 % and 53 % higher, respectively, than those published for LVL manufactured from Norway spruce and Uruguayan Eucalyptus grandis. A relatively low variation of results was found for both strength (COV = 9 %) and modulus of elasticity (COV = 10 %) and the particularly high stiffness/density relation previously published for sawn timber of this Argentinean deciduous species was confirmed by the results of this study. The coefficient of determination (R2) between density and modulus of elasticity was equal to 0.67 whereas R2 reached 0.37 between modulus of elasticity and strength and 0.19 between density and strength

Densidad y propiedades mecánicas de la madera de Acacia melanoxylon implantada en Argentina

El trabajo se enfocó en la determinación de la densidad normal y las propiedades mecánicas de la madera de Acacia melanoxylon implantada en Argentina, y en analizar la relación entre estas variables. El materialse seleccionó al azar del obtenido del aserrado de 20 árboles provenientes de cuatro sitios del sudeste de la provincia de Buenos Aires. Se determinó la densidad aparente conforme a la norma IRAM 9544 y los ensayos mecánicos se ejecutaron sobre cuerpos de prueba pequeños y libres de defectos según los lineamientos de la norma ASTM D 143. El valor medio de la densidad fue 564 kg.m-3 y la tensión de rotura mostró los siguientes valores medios: 89,9 N.mm-2 en flexión; 49,5 N.mm-2 en compresión paralela a las fibras; 11,7 N.mm-2 en compresión perpendicular y 11,6 N.mm-2 en corte paralelo. La durezapromedio alcanzó 45,3 N.mm-2 y el módulo de elasticidad en flexión exhibió un valor medio de 10926N.mm-2. Los resultados de las propiedades mecánicas son los esperados para una madera de densidadmedia y pueden considerarse adecuados para el uso de la especie en la industria de la construcción y del mueble. Los modelos de regresión entre la densidad y las propiedades mecánicas exhibieron valoresdel coeficiente de determinación (R2) comprendidos entre 0,70 y 0,87. El modelo de regresión entre el módulo de elasticidad y la resistencia en flexión mostró un valor de R2 igual a 0,72.The aim of this paper was to determine the density (at 12 % m. c.) and the mechanical properties of sawn wood of Argentinean Acacia melanoxylon, and to study the relationship between these properties.Test samples were randomly selected from the material obtained by sawing 20 trees harvested in four different plantations grown in the southeast of Buenos Aires province. Density was determined accordingto IRAM 9544 and mechanical tests were carried out by following the procedures of ASTM D 143. The mean value obtained for density reached 564 kg.m-3. Strength exhibited the following mean values:89,9 N.mm-2 in bending, 49,5 N.mm-2 in compression parallel to the grain, 11,7 N.mm-2 in compression perpendicular and 11.6 N.mm-2 in shear parallel. The average hardness reached 45,3 N.mm-2 and the modulus of elasticity in bending exhibited a mean value of 10926 N.mm-2. These results are congruent with those expected for a medium-density wood and they can be considered suitable for uses related to the construction and furniture industries. Coefficients of determination (R2) ranging from 0,73 to 0,87were found between density and mechanical properties. R2 reached 0,72 between modulus of elasticity and bending strength

Bending strength and stiffness of poles of argentinean Eucalyptus grandis

The present paper reports the results of an investigation regarding the determination of bending strength and stiffness in full-size poles of Argentinean Eucalyptus grandis. The importance of accura-tely knowing the mechanical properties of this material has increased with the increasing demand of utility poles of this species and with the use of modern procedures aimed at achieving a reliable and economical structural design. For this purpose an empirical research project with two samples contai-ning new, green, untreated poles was carried out according to the procedures adopted by both the Ame-rican standard ASTM D 1036 (2005) and the Argentinean standard IRAM 9529 (2004) for cantilever bending tests. Sample 1 enclosed 14 year-old poles with nominal length of 12 m and Sample 2 enclosed 11 year-old poles with nominal length of 8 m. The results found for the average circumference taper were similar to the values adopted by the American standard ANSI 05.1 (2002) and knot dimensions as well as knot ratio compared well with those permitted by this standard. The mean value found for maximum fi bre stress at ground line reached 62.9 N/mm2 for Sample 1 and 56.3 N/mm2 for Sample 2. These strength results are relatively high in comparison with values reported for seasoned sawn timber of the same species and they compare well with those published by the American standard ANSI 05.1c (2004) for poles of different species. Both samples showed a coeffi cient of variation of 13 % for streng-th at ground line which is relatively low in comparison with those adopted by the American standard and may be considered an advantage of this material for structural purposes. The mean value found for modulus of elasticity reached 10935 N/mm2 for Sample 1 and 9546 N/mm2 for Sample 2, with a coeffi cient of variation of 14 % for both cases. Results also revealed signifi cant differences between mechanical properties values corresponding to the two samples containing poles with different sizes and age. The correlation coeffi cient between knot ratio and strength showed the insignifi cant values of 0.09 and 0.02 for Sample 1 and 2 respectively, and the corresponding results between modulus of elasticity and strength were 0.52 and 0.37.En el presente trabajo se presentan los resultados de una investigación orientada a determinar la resistencia y la rigidez de postes de Eucalyptus grandis de Argentina. La importancia de conocer con precisión las propiedades mecánicas de este material cobró mayor relevancia con la creciente demanda de postes de esta especie y con la adopción de modernos procedimientos de cálculo orientados a lograr un diseño estructural confi able y económico. Con este fi n se llevó a cabo un proyecto empírico que abarcó dos muestras de postes en tamaño estructural, nuevos y sin tratamientos, los cuales se ensayaron en estado verde conforme a los procedimientos establecidos en la norma estadounidense ASTM D 1036 (2005) y en la Argentina IRAM 9529 (2004) para pruebas en voladizo. La muestra 1 incluyó postes con 12 m de longitud nominal y una edad de 14 años, y la muestra 2 estuvo compuesta por postes con 8 m de longitud nominal y una edad de 11 años. Los valores promedio encontrados para la conicidad fueron similares a los adoptados por la norma ANSI 05.1 (2002) y tanto el tamaño de los nudos como la nudosidad compararon bien con los valores permitidos por esta norma. El valor medio de la tensión de rotura en la línea de empotramiento fue de 62,9 N/mm2 para la Muestra 1 y de 56,3 N/mm2 para la Muestra 2. Estos resultados son relativamente altos en comparación con los publicados para madera aserrada de la misma especie ensayada en estado seco y son comparables a los adoptados por la norma ANSI 05.1c (2004) para postes de diferentes especies. Ambas muestras exhibieron un coefi ciente de variación de 13 % para la resistencia en la línea de empotramiento, valor que es relativamente bajo en comparación con los adoptados por la norma estadounidense y puede ser considerado una ventaja del material para uso estructural. El valor medio del módulo de elasticidad alcanzó 10935 N/mm2 para la muestra 1 y 9546 N/mm2 para la muestra 2, con un coefi ciente de variación de 14 % en ambos casos. Los resultados también pusieron de manifi esto diferencias signifi cativas entre los valores de las pro-piedades mecánicas de ambas muestras, integradas por postes de diferentes edades y dimensiones. El coefi ciente de correlación entre la nudosidad y la resistencia alcanzó los insignifi cantes valores de 0,09 para la muestra 1 y de 0,02 para la muestra 2, mientras que los valores correspondientes entre el módulo de elasticidad y la resistencia fueron 0,52 y 0,37

RELATIONSHIP BETWEEN GLOBAL AND LOCAL MODULUS OF ELASTICITY IN BEAMS OF ARGENTINEAN Eucalyptus grandis

The present paper reports the results of an investigation regarding the relationship between the global and the local Modulus of Elasticity in sawn timber of Argentinean Eucalyptus grandis. For this purpose an empirical research project with 50 beams in structural sizes subjected to bending was carried out. The results obtained according to European standards show the values of both types of Modulus of Elasticity and the influence of the more important strength and stiffness reducing growth characteristics on their variation, as well as give evidence of the effectiveness of the criterion established in the American standard ASTM D 198 (1999) for correcting the influence of shear on the global Modulus of Elasticit

RELATIONSHIP BETWEEN GLOBAL AND LOCAL MODULUS OF ELASTICITY IN BEAMS OF ARGENTINEAN Eucalyptus grandis RELACIÓN ENTRE EL MÓDULO DE ELASTICIDAD GLOBAL Y EL LOCAL EN VIGAS DE Eucalyptus grandis DE ARGENTINA

The present paper reports the results of an investigation regarding the relationship between the global and the local Modulus of Elasticity in sawn timber of Argentinean Eucalyptus grandis. For this purpose an empirical research project with 50 beams in structural sizes subjected to bending was carried out. The results obtained according to European standards show the values of both types of Modulus of Elasticity and the influence of the more important strength and stiffness reducing growth characteristics on their variation, as well as give evidence of the effectiveness of the criterion established in the American standard ASTM D 198 (1999) for correcting the influence of shear on the global Modulus of ElasticityEn esta publicación se presentan los resultados de una investigación orientada a estudiar la relación entre el Módulo de Elasticidad global y el local en madera aserrada de Eucalyptus grandis de Argentina. Con este fin, se llevó a cabo un programa experimental con 50 vigas de tamaño estructural sometidas a flexión. Los resultados obtenidos según las normas europeas muestran los valores para ambos Módulos de Elasticidad y la influencia que sobre ellos ejercen las características que más afectan su resistencia y rigidez, así como también dan evidencia de la efectividad del criterio adoptado por la norma ASTM D 198 (1999) para corregir la influencia del esfuerzo de corte sobre el Módulo de Elasticidad globa

Bending strength and stiffness of structural laminated veneer lumber manufactured from fast-growing Argentinean Eucalyptus grandis

The present paper reports the results of an investigation regarding the determination of bending strength and stiffness in specimens of laminated veneer lumber (LVL) manufactured from Argentinean Eucalyptus grandis and tested edgewise according to European standards. For this purpose an empirical research project with one sample containing 44 specimens with nominal sizes of 24.3 mm in width, 100 mm in depth and 2.44m in length was carried out. The characteristic strength value was 74 % and 118 % higher, respectively, than those adopted by Argentinean standards for the best strength class of sawn and glued laminated timber of the same species. It was similar to that reported for LVL of Norway spruce and lower than that published for LVL made from Uruguayan Eucalyptus grandis even though in the latter case the reported value was not obtained according to European standards. The modulus of elasticity mean value was 22 % and 14 % higher, respectively, than those adopted by Argentinean standards for the best strength class of sawn and glued laminated timber of the same species. Modulus of elasticity also exhibited a mean value 22 % and 53 % higher, respectively, than those published for LVL manufactured from Norway spruce and Uruguayan Eucalyptus grandis. A relatively low variation of results was found for both strength (COV = 9 %) and modulus of elasticity (COV = 10 %) and the particularly high stiffness/density relation previously published for sawn timber of this Argentinean deciduous species was confirmed by the results of this study. The coefficient of determination (R²) between density and modulus of elasticity was equal to 0.67 whereas R² reached 0.37 between modulus of elasticity and strength and 0.19 between density and strength

BENDING STRENGTH AND STIFFNESS OF POLES OF ARGENTINEAN Eucalyptus grandis

The present paper reports the results of an investigation regarding the determination of bending strength and stiffness in full-size poles of Argentinean Eucalyptus grandis. The importance of accurately knowing the mechanical properties of this material has increased with the increasing demand of utility poles of this species and with the use of modern procedures aimed at achieving a reliable and economical structural design. For this purpose an empirical research project with two samples containing new, green, untreated poles was carried out according to the procedures adopted by both the American standard ASTM D 1036 (2005) and the Argentinean standard IRAM 9529 (2004) for cantilever bending tests. Sample 1 enclosed 14 year-old poles with nominal length of 12 m and Sample 2 enclosed 11 year-old poles with nominal length of 8 m. The results found for the average circumference taper were similar to the values adopted by the American standard ANSI 05.1 (2002) and knot dimensions as well as knot ratio compared well with those permitted by this standard. The mean value found for maximum fibre stress at ground line reached 62.9 N/mm² for Sample 1 and 56.3 N/mm² for Sample 2. These strength results are relatively high in comparison with values reported for seasoned sawn timber of the same species and they compare well with those published by the American standard ANSI 05.1c (2004) for poles of different species. Both samples showed a coefficient of variation of 13 % for strength at ground line which is relatively low in comparison with those adopted by the American standard and may be considered an advantage of this material for structural purposes. The mean value found for modulus of elasticity reached 10935 N/mm² for Sample 1 and 9546 N/mm² for Sample 2, with a coefficient of variation of 14 % for both cases. Results also revealed significant differences between mechanical properties values corresponding to the two samples containing poles with different sizes and age. The correlation coefficient between knot ratio and strength showed the insignificant values of 0.09 and 0.02 for Sample 1 and 2 respectively, and the corresponding results between modulus of elasticity and strength were 0.52 and 0.37

Densidad y propiedades mecánicas de la madera de Acacia melanoxylon implantada en Argentina

El trabajo se enfocó en la determinación de la densidad normal y las propiedades mecánicas de la madera de Acacia melanoxylon implantada en Argentina, y en analizar la relación entre estas variables. El materialse seleccionó al azar del obtenido del aserrado de 20 árboles provenientes de cuatro sitios del sudeste de la provincia de Buenos Aires. Se determinó la densidad aparente conforme a la norma IRAM 9544 y los ensayos mecánicos se ejecutaron sobre cuerpos de prueba pequeños y libres de defectos según los lineamientos de la norma ASTM D 143. El valor medio de la densidad fue 564 kg.m-3 y la tensión de rotura mostró los siguientes valores medios: 89,9 N.mm-2 en flexión; 49,5 N.mm-2 en compresión paralela a las fibras; 11,7 N.mm-2 en compresión perpendicular y 11,6 N.mm-2 en corte paralelo. La durezapromedio alcanzó 45,3 N.mm-2 y el módulo de elasticidad en flexión exhibió un valor medio de 10926N.mm-2. Los resultados de las propiedades mecánicas son los esperados para una madera de densidadmedia y pueden considerarse adecuados para el uso de la especie en la industria de la construcción y del mueble. Los modelos de regresión entre la densidad y las propiedades mecánicas exhibieron valoresdel coeficiente de determinación (R2) comprendidos entre 0,70 y 0,87. El modelo de regresión entre el módulo de elasticidad y la resistencia en flexión mostró un valor de R2 igual a 0,72.The aim of this paper was to determine the density (at 12 % m. c.) and the mechanical properties of sawn wood of Argentinean Acacia melanoxylon, and to study the relationship between these properties.Test samples were randomly selected from the material obtained by sawing 20 trees harvested in four different plantations grown in the southeast of Buenos Aires province. Density was determined accordingto IRAM 9544 and mechanical tests were carried out by following the procedures of ASTM D 143. The mean value obtained for density reached 564 kg.m-3. Strength exhibited the following mean values:89,9 N.mm-2 in bending, 49,5 N.mm-2 in compression parallel to the grain, 11,7 N.mm-2 in compression perpendicular and 11.6 N.mm-2 in shear parallel. The average hardness reached 45,3 N.mm-2 and the modulus of elasticity in bending exhibited a mean value of 10926 N.mm-2. These results are congruent with those expected for a medium-density wood and they can be considered suitable for uses related to the construction and furniture industries. Coefficients of determination (R2) ranging from 0,73 to 0,87were found between density and mechanical properties. R2 reached 0,72 between modulus of elasticity and bending strength

Influencia de las dimensiones de la sección transversal sobre la resistencia a flexión en madera aserrada de "Populus deltoides" cultivado en Argentina

The present paper reports the results of an investigation regarding the study of size effects on bending strength in sawn timber of Argentinean Populus deltoides ‘Australian 129/60’ and ‘Stoneville 67’. An empirical research project with 5 samples containing a total of 820 specimens in usual structural sizes was carried out according to European standards. Results showed that strength decreases when depth increases but no clear influence of either the timber quality or the specimen thickness on size effects was found. The analysis evidenced that the European criterion -adopted by Argentinean standards- is suitable for considering the influence of depth on bending strength in the investigated species.En el artículo se analiza el efecto de las dimensiones de la sección transversal sobre la resistencia a flexión en piezas de madera aserrada de Populus deltoides ‘Australiano 129/60’ y ‘Stoneville 67’, cultivados en el delta del río Paraná, Argentina. El programa experimental se llevó a cabo según las normas europeas sobre un total de 820 cuerpos de prueba separados en 5 muestras exhibiendo las dimensiones estructurales usuales. Los resultados mostraron que el aumento de la altura de la sección fue acompañado de una tendencia decreciente de la tensión de rotura en flexión, pero no permiten afirmar que esa relación está vinculada a la calidad de la madera. Se confirmó que puede despreciarse una correlación entre la resistencia y el ancho de la sección. El análisis puso en evidencia que la relación entre la altura de la sección y la resistencia del material investigado está adecuadamente expresada por el criterio europeo, el cual fue adoptado por la normativa de Argentina

Variación radial y axial del hinchamiento, del factor anisotrópico y de la densidad, en el Eucalyptus grandis de Argentina.

The present paper reports the results of an investigation regarding the variation in swelling, coefficient of anisotropy and density, as a function of the distance from the pith and the height, in trees of Argentinean Eucalyptus grandis. For this purpose an empirical research project with samples randomly selected was designed and carried out. According to the results and for practical purposes, it may be assumed that swelling and the coefficient of anisotropy decrease with height and increase with the distance from the pith. Wood of the outer part of the tree stem exhibits more problems related to dimensional changes than wood of the inner part of the tree stem, even though it presents higher density and, consequently, higher quality for many purposes.En este trabajo se presentan los resultados de una investigación orientada a estudiar la variación de los hinchamientos tangencial y radial, así como del coeficiente de anisotropía y la densidad anhidra, en función de la altura y la distancia a la médula de árboles de Eucalyptus grandis cultivados en la Mesopotamia de Argentina. Con este propósito se diseñó y llevó a cabo una investigación empírica con muestras seleccionadas al azar. Los resultados muestran que, para propósitos prácticos, puede asumirse que el hinchamiento y el coeficiente de anisotropía tienen una tendencia decreciente al aumentar la altura, y creciente al aumentar la distancia a la médula. La madera de la periferia exhibe un comportamiento más desfavorable desde el punto de vista de los movimientos dimensionales que la del interior del tronco, si bien presenta mayor densidad y consecuentemente mejor calidad para numerosos empleos