Papers by Francisco Arriaga
Bioresources, Apr 28, 2016
The use of large cross-section timber for structural purposes has increased in Spain, and knowled... more 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 mm 3 , 150 × 250 × 5600 mm 3 , 150 × 250 × 4300 mm 3 , and 200 × 250 × 5000 mm 3 ). 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.
Holzforschung, 2018
Needle penetration resistance (NPR), screw withdrawal resistance (SWR), core drilling (CD) and dr... more Needle penetration resistance (NPR), screw withdrawal resistance (SWR), core drilling (CD) and drilling chips extraction (DCE) are nondestructive and semi-destructive techniques used to estimate density in timber structures. In most of the previous studies, these techniques were tested in clear sawn timber and clear specimens. The goal of the present paper is to study the relationship between density and these techniques by means of five different devices in whole pieces of timber from built-in engineering structures, which are from 12 4.5-m long structural timber joists of Norway spruce from a 19thcentury building in Barcelona (Catalonia, Spain). Although determination coefficients (R2) for density estimation models were lower than those from clear timber, the results obtained confirmed that these four techniques are suitable forin-situdensity estimation of woods in buildings. The best results were obtained by CD (the bigger the bit, the higher the correlation), followed by DCE, an...
Maderas. Ciencia y tecnología, 2015
A group of databases making a total of approximately 9300 sawn timber pieces from Spanish conifer... more A group of databases making a total of approximately 9300 sawn timber pieces from Spanish coniferous species, tested according to European standards and visually graded mainly according Spanish standards were analyzed. The percentiles ratio 20 th /5 th of bending strength, modulus of elasticity and density distribution were obtained for different combinations of species and visual stress grade. The Eurocode 5 proposes this percentile ratio by a coefficient k fi which is used to determine the design values of mechanical properties in fire situation. The percentile ratios obtained were compared with the specified value in Eurocode 5 for solid timber (k fi = 1,25). In lower grades of Spanish coniferous timber, this value was overly conservative. A value of k fi of 1,4 seems to be more adequate for the case of the bending modulus of elasticity and 1,4 to 1,5 for the bending strength. It is noted that, in the case of the upper grades, this value should be of 1,3; close to the Eurocode proposal. Furthermore, in the case of density, the value should be of 1,1; hence lower than suggested in the code.
Forest Products Journal, 2012
Materiales de Construcción, 2010
Holz als Roh- und Werkstoff, 2008
Maderas. Ciencia y tecnología, 2020
Forests, 2020
Canary Island pine (Pinus canariensis C.Sm. ex DC) is a species endemic to the Canary Islands (Sp... more Canary Island pine (Pinus canariensis C.Sm. ex DC) is a species endemic to the Canary Islands (Spain) that was for centuries overexploited for its wood and resin. Due to the state of the pine forest, more than 10,000 hectares were reforested in the middle of the 20th century. Now, under the silvicultural management plan, thinning operations have allowed Canary Island pine wood to be mechanically characterised for the first time using large test pieces. In total, 1529 pieces measuring 2600 × 120 × 35 mm and visually graded according to Spanish standard UNE 56544 (Visual grading of large structural coniferous sawn timber) were assessed, resulting in 872 pieces in grades ME-1 and ME-2 and 657 rejects. After the characteristic values of density (479–453 kg∙m−3), modulus of elasticity (MOE) (14,023–11,276 N∙mm−2) and bending strength (MOR) (26–14 N∙mm−2) were determined for both grades (ME-1 and ME-2), strength class C24 was assigned to grade ME-1, with similar values to Pinus radiata D....
Forests
Wood-based sandwich panels are building products composed of two skins attached to a lightweight ... more Wood-based sandwich panels are building products composed of two skins attached to a lightweight continuous core in which at least one skin is made of wood-based products, contributing to the use of renewable forest goods. Since the connection between the skins and the core is often provided by adhesive bonding, its characteristics affect the mechanical behavior of the sandwich and, therefore, must be thoroughly assessed. Full adhesion is often considered the standard situation, although some batches of the commercial product show incompletely glued surfaces, and scarce data is available with regard to their bonding performance. For this reason, analyses were performed using tensile tests with a load perpendicular to the skins and specific shear tests with a load parallel to the longitudinal direction of the panel. The test samples were obtained from wood-based sandwich panels with extruded polystyrene cores and different skin materials. The tensile tests proved to be suitable only ...
Nondestructive techniques are widely used to assess existing timber structures. The models propos... more Nondestructive techniques are widely used to assess existing timber structures. The models proposed for these methods are usually performed in the laboratory using small clear wood specimens. But in real situations many anomalies, defects and biological damage are found in wood. In these cases the existing models only indicate that the values are outside normality without providing any other information. To solve this problem, a study of non-destructive probing methods for wood was performed, testing the behaviour of four different techniques (penetration resistance, pullout resistance, drill resistance and chip drill extraction) on wood samples with different biological damage, simulating an in-situ test. The wood samples were obtained from existing Spanish timber structures with biotic damage caused by borer insects, termites, brown rot and white rot. The study concludes that all of the methods offer more or less detailed information about the degree of deterioration of wood, but ...
Maderas. Ciencia y tecnología, 2015
Detailed morphological and dimensional analysis of the detritus deposited in the galleries of woo... more Detailed morphological and dimensional analysis of the detritus deposited in the galleries of woodboring insects was performed for some of the most common xylophagous insect larvae in timber construction in Spain. The samples studied belong to six species of four common families of borers: Cerambycidae, Anobiidae, Curculionidae and Lyctidae. The samples were provided by Spanish and German companies and laboratories. The detritus was assessed for size, shape, and colour and, for different species, was found to show morphological and dimensional differences, enabling better and faster identification of these destructive agents. Frass shape and colour assessment together with statistical dimensional data of the six species are presented. A predictive function based on length and width variables of the detritus is proposed, using multivariate discriminant analysis methodology. This function has been proven to be more than 78% effective in tests of the model.
Informes de la Construcción, 2007
Informes de la Construcción, 2007
La clasifi cación no destructiva de madera aserrada estructural mediante los métodos de vibración... more La clasifi cación no destructiva de madera aserrada estructural mediante los métodos de vibración, utiliza la frecuencia natural de la pieza para llegar a defi nir la calidad del material.
Informes de la Construcción, 2007
Materiales de Construcción, 2010
Congresos Carga Final, Jun 1, 2009
Informes de la Construcción, 2007
The size effect on mechanical properties of timber is described including the recent evolution of... more The size effect on mechanical properties of timber is described including the recent evolution of testing procedures and stress grading. Further, a specifi c research work on large cross section timber is explained. A total of 395 pieces of sawn timber from three species (Pinus sylvestris L., Pinus nigra subs. salzmanii (Dunal) Franco and Pinus radiata D. Don) with cross section between 150x200 y 200x250 mm, have been visually graded according to UNE 56544 standard obtaining its output and mechanical properties. The percentage of rejected pieces is too high (38 to 45%) and therefore, a modifi cation of standard specifi cations is proposed. The output is highly improved in the proposal of standard (rejected percentage of 11 to 17%) whereas the mechanical properties are not modifi ed in practice. A similar procedure was applied to 85 timber pieces from old timber structures of building demolition of Pinus sylvestris L. y Pinus pinaster Ait. The percentage of rejected pieces is 52% in a visual grading according to the application of all grading parameters of the standard UNE 56544:2003. This procedure is not practical for existing structures and therefore, it is proposed the application of grading considering only the parameters of knots size and slope of grain. In that way the output is improved reducing the rejected percentage to 10%. Madera aserrada de gran escuadría para uso estructural y sus particularidades Large cross section sawn timber for structural use and its singularities
espanolEsta publicacion tiene un caracter eminentemente practico, ya que esta fundamentada en el ... more espanolEsta publicacion tiene un caracter eminentemente practico, ya que esta fundamentada en el proceso tecnologico que fue necesario desarrollar durante la redaccion de un proyecto singular de arquitectura con madera, como es el Portcullis House en Londres. En el planteamiento de la estructura, propuesta con madera de frondosas, se solvento la ausencia de documentacion tecnica mediante la realizacion de un programa de ensayos encargado al Building Research Establishement (BRE) con el objeto de determinar las clases resistentes de las calidades defi nidas conforme a las reglas de clasifi cacion visual de la norma britanica BS 5756. Gracias a este esfuerzo el proyecto de la estructura pudo optimizarse mas desde el punto de vista de la ingenieria. A la vez, el resultado del trabajo de caracterizacion ha quedado a disposicion de otros proyectistas. Las cuatro especies de madera cuyas propiedades mecanicas se recogen en esta publicacion (roble blanco, roble rojo, fresno y tulipie) son ...
El objetivo de este estudio ha sido comparar el metodo de regresion tradicional frente al diseno ... more El objetivo de este estudio ha sido comparar el metodo de regresion tradicional frente al diseno de una red neuronal artificial del tipo perceptron multicapa para obtener el MOEestatico de la madera de Pinus radiata D. Don. a partir del MOEdinamico obtenido por tecnica de ultrasonidos en el primer caso y a partir de la velocidad de propagacion de la onda de ultrasonidos en el segundo.
Depósito Legal: M-2.972-2004 ISBN: 84-87381-28-6 Imprime: Artes Gráficas Palermo, SL Avda. de la ... more Depósito Legal: M-2.972-2004 ISBN: 84-87381-28-6 Imprime: Artes Gráficas Palermo, SL Avda. de la Técnica 7. Pol. Ind. Santa Ana 28529 Rivas (Madrid) Autores: Fernando Peraza Sánchez Dr. Ingeniero de Montes Directortécnico de AITIM Francisco Arriaga Martitegui Dr. ...
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Papers by Francisco Arriaga