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The use of large cross-section timber for structural purposes has increased in Spain, and knowledge of its properties is strategically necessary. The Spanish visual strength-grading standard UNE 56544 (2011) efficiency applied to large cross-section structural timber was analyzed using a sample of 363 specimens of radiata pine (Pinus radiata D. Don.) from the Basque Country and Catalonia, Spain. Different sizes were tested (80 × 120 × 2400 mm³, 150 × 250 × 5600 mm³, 150 × 250 × 4300 mm³, and 200 × 250 × 5000 mm³). Bending strength, modulus of elasticity, and density were obtained, and characteristic values were determined in order to assign strength class according to European standard EN 338 (2010). Knots and twists were the most relevant singularities for visual strength grading. It was concluded that large crosssection Spanish radiata pine timber was suitable for structures, and it was assigned to the C20 strength class. [ABSTRACT FROM AUTHOR]

Both non-destructive and semi-destructive tests can potentially be very efficient methods for the assessment of structural timber density. This paper describes an investigation into the suitability of three techniques: core drilling, probing, and screw withdrawal. It presents the results after testing 150 pieces of large cross-section (80 mm x 120 mm) structural timber of radiata pine (Pinus radiata D. Don.) from a Spanish source. A strong correlation was found between specimen density and core drilling. Meanwhile, there was also a meaningful correlation with the screw withdrawal, and an acceptable correlation with probing. Even though differences were observed in their predictive capacity, none of these procedures should be rejected as a way of estimating density, as each has its own respective advantages and limitations. [ABSTRACT FROM AUTHOR]

Three samples of sawn Radiata pine (Pinus radiata D. Don) timber, consisting of 150 pieces with dimensions of 80 mm x 120 mm x 2400 mm, 80 pieces with dimensions of 150 mm x 200 mm x 4500 mm, and 75 pieces with dimensions of 150 mm x 250 mm x 5600 mm, were visually graded according to the Spanish standard UNE 56544 (2011) to analyze the influence of visual grading requirements on both the grading yield and mechanical properties. The resulting percentages of the rejected pieces stood at 19 and 28% for 150 x 200 mm and 150 x 250 mm cross-section pieces, respectively. That percentage increased to 73% for 80 x 120 mm cross-section pieces. The grading yield and mechanical properties were then analyzed to determine the influence of warp defects. Three different criteria for limiting warp defects were considered, reducing the standard specifications. The modulus of elasticity, bending strength, and density were obtained. The results concluded that loosening specified requisites improves the visual grading output in the smallest cross-section, with no significant reduction in the mechanical properties. A proposal for a less rigorous specification of twist defects in the Spanish visual grading standard has been introduced. [ABSTRACT FROM AUTHOR]