Michele Brunetti

Argentinean native wood species: Physical and mechanical characterization of some Prosopis species and Acacia aroma (Leguminosae; Mimosoideae).

One of the problems in marketing the wood of Prosopis and Acacia is the lack of standardization of its qualities. The aim of this paper was to obtain a preliminary detection of some properties of the wood of four species of the genus Prosopis and one species from Acacia grown in Argentina. To accomplish this objective, the content of extractives and some physical and mechanical characteristics were analyzed. The density rho(12) of all the species indicates that these woods range from heavy to very heavy (>or=0.69g/cm(3)). The total volumetric shrinkage values are low, less than 10%, for all species. The parallel compression strength and the shear strength for all the species indicate a very resistant wood (>or=46.93MPa and >or=18.35MPa, respectively). Brinell hardness was higher than 5kg/mm(2) in all cases. The species with less content of extractives is P. ruscifolia (approximately 9% of anhydrous mass) whereas A. aroma was the one with the greatest content (approximately 25% of anhydrous mass in the heartwood).

Variability of wood properties in two wild cherry clonal trials

There has been an increase in wild cherry cultivation over recent decades, revealing a need for improvements in planting material to be used for the production of high quality timber. To date, trial tests have been carried out mainly on growth and tree architectural traits, while no investigations have focused on wood properties. The present study investigated the variability of the growth traits and the physical and mechanical properties of wild cherry wood, both within the tree, within and among clones and between sites. The aims of the study are to provide useful information on the genetics of wood traits in valuable hardwoods and to discuss how within-tree variation can affect early selection of genotypes. The results suggest that site was the most important source of variation in growth traits and in the proportion of heartwood, although differences among clones were highly significant. The number of sapwood rings was very homogeneous both between sites and among clones. Concerning the wood traits, most variation was detected within the tree, rather than within or among clones or between sites. Within tree variability seems to be mainly due to heartwood/sapwood presence. However, since there is a high correlation between heartwood and sapwood properties, a quite efficient selection made on the basis of sapwood should provide an efficient means of selecting heartwood traits.

Relationship between local and global modulus of elasticity in bending and its consequence on structural timber grading

The study analyses the relationship between local and global modulus of elasticity and develops and evaluates different models to predict local from global modulus measurements. The mechanical tests were performed on four species commonly used in Italy for structural purposes: fir, Douglas-fir, Corsican pine and chestnut. Two or three cross-sections and two provenances were sampled for each species. A theoretical analysis showed that the local–global modulus relationship was of polynomial form with only one coefficient. The effect of the species on the relationship was significant as well as the cross-section but only for softwoods. The effect of the cross-section was explained by the presence and the size of defects in the mid span. The different models were applied and then compared by means of the optimum grading: only slight differences among models emerged. Although optimum grading was strongly dependent on the sampling and on the grade combination, for softwoods the model for species and section showed very similar results to the grading with the true local modulus; inclusion of the knot values in the model led to only slight improvements. For chestnut all models were found to be comparable.ZusammenfassungDiese Studie untersucht den Zusammenhang zwischen lokalem und globalem E-Modul von Schnittholz und entwickelt und vergleicht verschiedene Modelle, um den lokalen E-Modul aus globalen Messungen zu bestimmen. Die Versuche wurden an vier in Italien häufig als Bauholz verwendeten Holzarten durchgeführt: Tanne, Douglasie, Korsische Schwarzkiefer und Edelkastanie. Je Holzart wurden zwei oder drei Querschnitte aus jeweils zwei Wuchsgebieten beschafft. Eine theoretische Untersuchung zeigte, dass der Zusammenhang zwischen lokalem und globalem E-Modul einer Polynom-Funktion mit nur einem Koeffizienten entspricht. Signifikanten Einfluss auf den Zusammenhang hatte die Holzart und bei Nadelhölzern auch der Querschnitt, was durch das Vorhandensein und die Größe der Äste im mittleren Prüfbereich begründet wurde. Die verschiedenen Modelle wurden angewandt und bezüglich ihrer Auswirkung auf die optimale Sortierung verglichen: Es zeigten sich nur geringe Unterschiede. Obwohl die optimale Sortierung sehr stark von der Probenahme und der Sortierklassen-Kombination abhing, führte das Modell auf Basis von Holzart und Querschnitt bei den Nadelhölzern zu sehr ähnlichen Ergebnissen wie eine Sortierung nach dem gemessenen lokalen E-Modul; die Berücksichtigung der Astwerte führte nur zu geringen Verbesserungen. Für die Edelkastanie waren alle Modelle vergleichbar.

Strength Properties of Chestnut Structural Timber with Wane

Grading of timber for structural purposes allows material with similar physical and mechanical properties to be grouped together. The groups are defined by specific strength values and indicate the basic working stresses and stiffnesses to be used for structural design purposes. In particular, visual strength grading bases the assignment of each timber element to a grade on the characteristics that are visually measurable (i.e. knots, slope of grain, annual ring width). Very similar principles are implemented for the in situ assessment of timber structures, as recommended for example by the Italian standard UNI 11119, that specifies the procedures for the diagnosis of timber members. Currently, however, European standards and most of the national standards on strength grading refer to timber elements with rectangular cross section, while in existing buildings, members with irregular cross section are extremely common. Thus, 10 different provenances (5 from Italy and 5 from France) of chestnut timber were sampled. More than 600 structural elements with wane were visually examined in laboratory and all the characteristics were collected. Bending tests were then performed on each timber element until failure, and bending strength, as well as modulus of elasticity and density, were determined. Here, the limitations for the main strength-reducing characteristics and the characteristic values (fifth percentile for bending strength and density and the mean value for modulus of elasticity) of chestnut timber with wane are presented.

Understanding Spanish Timber Jack Arch Floors: Examples of Assessment and Conservation Issues

Jack arch floors are structures made of timber joists, with round or squared section, and segmental vaults either made of flat tiles or poured plaster conglomerate. They are especially diffused along the Mediterranean coast of Spain and can be considered as a main feature of the historical and vernacular architecture of the area. In order to assess and grade these structures several Spanish standards have been considered; however, even if the information contained is useful the Italian standard for the on-site diagnosis UNI 11119 of 2004 has been preferred. The method described in this standard leads the assessment through the grading of each and every timber element and the assignation of bearing properties that are essential for the consolidation project. This article will expose three examples of jack arch floors of the Valencian Community graded using the Italian standard and the conservation issues that arise from the results.

A Peculiar Spanish Timber Floor, the "Revoltón": A Diagnostic Example at the "Palacio del Marqués de Benicarló"

The paper deals with the application of the Italian method for assessing on-site and diagnosing timber elements to a distinctive Spanish type of horizontal structure called “revoltón” i.e. jack arch floor. As in Spain does not exist a specific regulation for the on-site diagnosis of timber elements, this analysis was performed according to the Italian standard UNI 11119. Due to the peculiar features of the jack arch floor some modifications were applied to the method.During spring 2012 the authors had the opportunity to carry out a pilot project by making a diagnostic analysis on a whole three stories building. The building, “Palacio del Marqués de Benicarló”, located in Spain in the town of Benicarló, between Barcelona and Valencia, was erected during the second half of the XVIII century. It maintains the original internal distribution and structure, and it is characterized by precious ceramic decorations on walls and floors. All the horizontal structures studied inside the palace were jack arch floor except the roof structure that was also made of timber.The results of the project described in the paper clarify the specific problems of the horizontal structures and the roof surveyed during the fieldwork. These results are accompanied by several plans that represent the information recovered on-site and lead to a complete assessment of the structures. The plans include the grading based on wood defects, the local moisture content of wood, the superficial and inner decay due to insects and rot and the deformation of the joists. In this way it was possible to locate the areas of the palace where more problems were concentrated, and better understand the causes and origin of the damages.