The present paper reports on the results of an investigation regarding the determination of the embedding strength of sawn timber of Argentinean Eucalyptus grandis with dowel-type fasteners. The importance of accurately knowing this property has increased with the increasing demand for this material for structural purposes. An empirical research project with 294 specimens prepared for testing under the embedding action of rigid fasteners (nail, bolt and dowel) was carried out according to the procedures prescribed in EN 383 (2007). The results showed no significant influence of pre-drilling on the embedding strength for nailed joints, which is not in line with the European experience and the corresponding criterion adopted by the Eurocode 5 (2005). The characteristic values of the embedding strength estimated based on the timber density and by applying the corresponding equation from the Eurocode 5 (2005) for bolted joints were 45% and 176% greater than those obtained in this project for the specimens loaded parallel and perpendicular to the grain, respectively, and similar percentages were found for dowelled joints (45% and 126%). These results showed that the reliability of structural design may be strongly affected if the embedding strength of this timber species is estimated by following the procedures adopted by the Eurocode 5 (2005) for dowel-type connections. Lochleibungsfestigkeit von Vollholz ausEucalyptus grandis aus Argentinien. Analyse nach europäischen Normen Zusammenfassung Dieser Beitrag fasst die Ergebnisse einer Studie zusammen, in der die Lochleibungsfestigkeit von Vollholz aus Eucalyptus grandis aus Argentinien untersucht wurde. Das empirische Versuchsprogramm umfasste 294 Prüfkörper, die mittels steifen Verbindungsmitteln (Nagel, Bolzen und Stabdübel) nach EN 383 (2007) beansprucht wurden. Im Gegensatz zu der europäischen Erfahrung und dem entsprechenden Kriterium des Eurocodes 5 (2005) zeigten die Ergebnisse keinen deutlichen Einfluss der Vorbohrung auf die Lochleibungsfestigkeit von Nagelverbindungen. Die Abschätzung der charakteristischen Lochleibungsfestigkeit in Abhängigkeit der Rohdichte nach Eurocode 5 (2005) ergab Werte die 45 % und 176 % höher sind als die Ergebnisse dieser Untersuchung bei Beanspruchung in Richtung parallel bzw. rechwinklig zur Faser. Ähnliche Abweichungen wurden für die Stabdübelverbindungen gefunden. Diese Ergebnisse zeigten, dass die Zuverlässigkeit der Berechnung von Holzbauwerken stark vermindert werden kann, wenn die charakteristische Lochleibungsfestigkeit dieses Holzes nach dem Kriterium des Eurocodes 5 (2005) abgeschätzt wird.

The present paper reports the results of an investigation regarding the determination of characteristic strength and stiffness values in glued laminated beams of fast-growth Argentinean Eucalyptus grandis according to the criteria established in European standards. An empirical research project with 100 beams in structural sizes and 191 fingerjointed laminations was carried out. Test results allow to analyse the mechanical property values of this glued laminated timber in comparison with those adopted by the strength class system established in the European standard EN 1194(1999, and they reveal a very high ratio of modulus of elasticity to density. Test results were also compared with values obtained by means of the equations provided by EN 1194EN (1999. The effectiveness of the criteria established in this European standard for determining mechanical properties in beams of this deciduous species is analysed through the discussion of test results and those obtained from calculations based on lamination properties.

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 (R 2 ) between density and modulus of elasticity was equal to 0.67 whereas R 2 reached 0.37 between modulus of elasticity and strength and 0.19 between density and strength.

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 1036ASTM D (2005 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. Keywords: poles, Eucalyptus grandis, strength and stiffness RESUMENEn 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) Maderas. Ciencia y tecnología 11(1): [71][72][73][74][75][76][77][78][79][80][81][82][83][84] 2009 72 Universidad del Bío -Bío 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/mm 2 para la Muestra 1 y de 56,3 N/mm 2 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 mater...