47 results on '"Íñiguez-González, Guillermo"'
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2. Lessons from a Century-Tradition on Ecosystem-Based Disaster Risk Reduction (Eco-DRR) in Mountains: The Case of the Torrential System Los Arañones (Canfranc, Pyrenees)
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Rodríguez, José Luis García, Muñoz, Álvaro Esteban, Garcia-Robredo, Fernando, Sánchez, José Carlos Robredo, Reigosa, Santiago Fábregas, Cerrillo, Guillermo Tardío, Herrero, Miguel Esteban, Martitegui, Francisco Arriaga, Íñiguez-González, Guillermo, Roa, Rocío Hurtado, Cánovas, Juan Antonio Ballesteros, Chen, Sheng-Hong, Series Editor, di Prisco, Marco, Series Editor, Vayas, Ioannis, Series Editor, Kolathayar, Sreevalsa, editor, Pal, Indrajit, editor, Chian, Siau Chen, editor, and Mondal, Arpita, editor
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- 2022
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3. Cross Laminated Timber (CLT) manufactured with European oak recovered from demolition: Structural properties and non-destructive evaluation
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Llana, Daniel F., González-Alegre, Violeta, Portela, María, and Íñiguez-González, Guillermo
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- 2022
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4. In situ assessment of the timber structure of an 18th century building in Madrid, Spain
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Arriaga, Francisco, Osuna-Sequera, Carlos, Esteban, Miguel, Íñiguez-González, Guillermo, and Bobadilla, Ignacio
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- 2021
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5. Lessons from a Century-Tradition on Ecosystem-Based Disaster Risk Reduction (Eco-DRR) in Mountains: The Case of the Torrential System Los Arañones (Canfranc, Pyrenees)
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Rodríguez, José Luis García, primary, Muñoz, Álvaro Esteban, additional, Garcia-Robredo, Fernando, additional, Sánchez, José Carlos Robredo, additional, Reigosa, Santiago Fábregas, additional, Cerrillo, Guillermo Tardío, additional, Herrero, Miguel Esteban, additional, Martitegui, Francisco Arriaga, additional, Íñiguez-González, Guillermo, additional, Roa, Rocío Hurtado, additional, and Cánovas, Juan Antonio Ballesteros, additional
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- 2021
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6. Predicting the mechanical properties of timber from existing structures by the longitudinal vibration method, visual grading and definition of the nominal cross-section.
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Osuna-Sequera, Carlos, Arriaga, Francisco, Llana, Daniel F., and Íñiguez-González, Guillermo
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LONGITUDINAL method ,TIMBER ,BENDING strength ,FREQUENCIES of oscillating systems ,NONDESTRUCTIVE testing ,MODULUS of elasticity - Abstract
The modulus of elasticity (MOE), bending strength (MOR) and density of 45 150 × 200 × 5400 mm
3 Salzmann pine timber pieces from an existing eighteenth century structure were obtained by testing and also estimated by non-destructive testing. Density was estimated by means of the drilling technique and the MOE and MOR by recording the longitudinal natural frequency of vibration. Four methods for defining the dimensions of the nominal cross-section were applied to establish which was most adequate to address the high variability in the cross-sections along the length. MOE and MOR linear regression results showed r2 = 59–68% using dynamic MOE, relative edge knot diameter and slope of grain as independent variables. The nominal cross-section defined as the mean cross-section area along the length proved to be the most effective for estimating mechanical properties, followed by the nominal cross-section defined as the average measurements of the piece taken at the middle part or central third along its length. The longitudinal vibration method enables the acquisition of superior predictive models compared to time-of-flight measurement-based methods. [ABSTRACT FROM AUTHOR]- Published
- 2024
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7. The influence of cross-section variation on bending stiffness assessment in existing timber structures
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Osuna-Sequera, Carlos, Llana, Daniel F., Íñiguez-González, Guillermo, and Arriaga, Francisco
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- 2020
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8. Using acoustic testing to estimate strength and stiffness of wood-polymer composites
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Hillig, Éverton, primary, Bobadilla, Ignacio, additional, Arriaga, Francisco, additional, and Íñiguez-González, Guillermo, additional
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- 2023
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9. Predicting the mechanical properties of timber from existing structures by the longitudinal vibration method, visual grading and definition of the nominal cross-section
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Osuna-Sequera, Carlos, primary, Arriaga, Francisco, additional, Llana, Daniel F., additional, and Íñiguez-González, Guillermo, additional
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- 2023
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10. Mechanical Properties of Wood: A Review
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Arriaga, Francisco, primary, Wang, Xiping, additional, Íñiguez-González, Guillermo, additional, Llana, Daniel F., additional, Esteban, Miguel, additional, and Niemz, Peter, additional
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- 2023
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11. Evaluation of Yield Improvements in Machine vs. Visual Strength Grading for Softwood Species
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Moltini, Gonzalo, primary, Íñiguez-González, Guillermo, additional, Cabrera, Gonzalo, additional, and Baño, Vanesa, additional
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- 2022
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12. Determination of the elastic constants of Scots pine (Pinus sylvestris L.) wood by means of compression tests
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Aira, José R., Arriaga, Francisco, and Íñiguez-González, Guillermo
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- 2014
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13. Design of Timber Buildings for Deconstruction and Reuse — Three methods and five case studies
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Sandin, Ylva, Shotton, Elizabeth, Cramer, Marlene, Sandberg, Karin, Walsh, St John, Östling, Janina, Cristescu, Carmen, González-Alegre, Violeta, Íñiguez-González, Guillermo, Llana, Daniel F, Carlsson, Anders, Uí Chúláin, Caitríona, Jackson, Nicola, García Barbero, Manuel, and Zabala Mejia, Andres
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Electrical Engineering, Electronic Engineering, Information Engineering ,Elektroteknik och elektronik - Abstract
There is a need for a shift towards circular economy in the construction sector and design philosophies as Design for Deconstruction and Reuse (DfDR) and Design for Adaptability (DfA) are being developed as means to design out waste and enhance resource efficiency. However, applying these philosophies is not yet common practice. The amount of DfDR/A timber buildings described in literature is limited. This study aims at increasing and spreading knowledge on DfDR/A for timber buildings. It has four goals: 1) To suggest methods to apply DfDR/A. 2) To suggest new design solutions. 3) To collect experiences on connections in relation to DfDR. 4) To suggest how guidelines for deconstruction and reuse can be formulated. The study presents three methods that all proved valuable in applying DfDR/A: one discussion-based method to improve an already existing timber building design, one indicator system to assess the DfDR/A potential of building designs, and one matrix to guide design decisions. We used the first method to conduct five case studies in four European countries. The studied designs were judged to be well or relatively well adapted for deconstruction and reuse already today. The fact that the studied buildings are all offsite manufactured and of modular composition benefits the deconstruction process, partly because construction and deconstruction are similar processes so that the knowledge and infrastructure that companies have can be directly transferred to enable deconstruction and reuse. Where large modules can be recovered, the time and energy needed for deconstruction as well as the risk for damage will be reduced. Disadvantages to deconstruction and reuse identified were typically linked to the complexity of building modules and that individual components are not independent. This was reflected as irreversible or hidden connections, inaccessible services, interconnected layers of the structural modules and many different component sizes. One of the case study buildings, designed with mass timber panels, excelled in the simplicity and reduction of number of steps required for maximum material recovery. New designs suggested included making fasteners more accessible to deconstruction, avoiding letting sensitive materials as plastic foils and particle boards pass continuously over joints between elements, and (for cases where standard units are not already used) standardizing elements. One case suggested using solid wood components instead of engineered wood products to achieve durability. The study showed that simple changes in design can lead to an augmented reuse potential. Some of the new design solutions generated will be taken into production by the participating manufacturers. Insights on connections included recognizing the fact that the use of reversible screwed connections is not sufficient to ensure deconstructability and that although nailed or glued connections severely complicate reuse of components, they might be accepted within elements in case reuse on element level is the target. Guidelines for deconstruction and reuse were developed in all case studies. Taken as a group of studies, there are advantageous additions proposed to earlier guidance documents. Despite being based on the same source, the different plans suggested varied substantially. There was a noteworthy difference between manufacturers’ in-house plans to those proposed by architects, engineers, or researchers, which speaks to the uncertainty regarding the appropriate structure and format.
- Published
- 2022
14. Short-term performance of the HSB® shear plate-type connector for timber–concrete composite beams
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Fernandez-Cabo, Jose L., Arriaga, Francisco, Majano-Majano, Almudena, and Iñiguez-González, Guillermo
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- 2012
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15. Recovered wood as raw material for structural timber products. Characteristics, situation and study cases: Ireland and Spain
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Llana, Daniel F., Íñiguez-González, Guillermo, de Arana-Fernández, Marina, Uí Chúláin, Caitríona, Harte, Annette M., LeVan-Green, S, Ministerio de Ciencia, Innovación y Universidades, Spain, Department of Agriculture, Food and the Marine, Ireland, and Horizon 2020
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Circular economy ,timber recycling ,wood waste management ,reclaimed timber ,classification system ,construction and demolition waste - Abstract
The circular economy is an efficient system to reuse materials reducing the amount of waste generated. In order to implement it in the timber sector, the InFutUReWood (Innovative Design for the Future Use and Reuse of Wood (Building) Components) is a European project studying the possibilities for reuse and recycling of timber from demolition for structural applications. Nowadays in Ireland and Spain, most of the wood waste is reduced to chips. In Ireland, chips are mainly used for energy production, pallet blocks, and composting, while in Spain are used for energy production and particleboard manufacture. Possible structural applications depend on the amount, dimensions, and condition of recovered timber. Most of the recovered timber in Ireland has medium size cross-sections, while in Spain it is mainly large cross-section. Cross laminated timber (CLT) is a good option for reuse and experimental tests are ongoing in Ireland on CLT manufactured from old timber trusses. However, for large cross-sections, direct reuse for rehabilitation works will be a more efficient use of the material. ProjectInFutUReWood is funded in Spain by the Ministerio de Ciencia, Innovación y Universidades (MICIU). Project reference PCI2019-103544. Diseño innovador para el futuro – uso y reutilización de componentes de edificación de madera. Project InFutUReWood is funded in Ireland by the Department of Agriculture, Food and the Marine under the DAFM research funding program. Project reference 18CENForestValue1. Project InFutUReWood is supported under the umbrella of ERA-NET Cofund Forest Value by Vinnova – Sweden´s Innovation Agency, Formas– Swedish Research Council for Sustainable Development, Swedish Energy Agency, the Forestry Commissioners for the UK, the Department of Agriculture, Food and the Marine for Ireland, the Ministry of the Environment for Finland, the Federal Ministry of Food and Agriculture through the Agency for Renewable Resources for Germany, the Ministry of Science, Innovation and Universities for Spain, the Ministry of Education, Science and Sport for Slovenia. Forest Value has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement N° 773324. The authors would like to thank Mr. Paul Hogan from Hegarty Demolition (InFutUReWood Irish industrial partner), and demolition and waste management companies from Ireland and Spain for kindly supplying information. non-peer-reviewed
- Published
- 2020
16. Recovered timber in Europe: sources, classification, existing and potential reuse and recycling
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Harte, Annette M., Uí Chúláin, Caitríona, Nasiri, Bahareh, Hughes, Mark, Llana, Daniel F., Íñiguez-González, Guillermo, de Arana-Fernández, Marina, Shotton, Elizabeth, Walsh, St. John, Ridley-Ellis, Daniel, Cramer, Marlene, Risse, Michael, Ivanica, Raphaela, Cristescu, Carmen, Sandberg, Karin, Sandin, Ylva, Turk, Goran, Plos, Mitja, Šuligoj, Tamara, and Hogan, Paul
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recovered timber ,recycling ,wood waste classification ,circular construction ,reuse - Abstract
The Innovative Design for the Future Use and Reuse of Wooden building components (InFutUReWood) project aims to examine if recovered timber is suited for contemporary timber architecture. To address this aim, a study was undertaken as part of Work Package 3 to identify the current range of timber products obtained from demolition and their current and potential reuse. The study was conducted across all partner countries using a combination of site visits and industry surveys The information compiled shows that the motivation for deconstruction in each country depends mainly on the building location and site value. The type of timber available for recovery was largely contingent on the age of the structures. Building deterioration and rising building standards were common causes for demolition; however, a more significant incentive for urban demolition was market depreciation. In these instances, site clearance makes way for redevelopment, facilitating alternative building use or general urban renewal. An overview of international and national classification systems for timber waste from construction and demolition is presented. Differences were found between partner countries in terms of the potential to reuse recovered timber in loading bearing applications in buildings. Most timber extracted from construction and demolition across the surveyed counties is reduced to woodchip, regardless the size or quality of the extracted material. The main uses of the wood chip are particle board manufacture or bioenergy generation. Exceptions to this are mass timber, such as glulam, and old, large section timber members with high cultural value, which are reused directly. Potential alternative building products recovered timber are presented that will extend the lifespan of the material. non-peer-reviewed
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- 2020
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17. Timber moisture content adjustment factors for nondestructive testing (NDT): acoustic, vibration and probing techniques
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Llana, Daniel F., primary, Íñiguez-González, Guillermo, additional, Esteban, Miguel, additional, Hermoso, Eva, additional, and Arriaga, Francisco, additional
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- 2020
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18. Nondestructive testing used on timber in Spain: A literature review
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Llana, Daniel F., primary, Íñiguez-González, Guillermo, additional, Díez, M. Rafael, additional, and Arriaga, Francisco, additional
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- 2020
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19. In-situ density estimation by four nondestructive techniques on Norway spruce from built-in wood structures
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Llana, Daniel F., primary, Íñiguez-González, Guillermo, additional, Montón, Joaquín, additional, and Arriaga, Francisco, additional
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- 2018
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20. Comparison of various multivariate models to estimate structural properties by means of non-destructive techniques (NDTs) in Pinus sylvestris L. timber
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Villasante, Antonio, primary, Íñiguez-González, Guillermo, additional, and Puigdomenech, Lluis, additional
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- 2018
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21. Análisis y consolidación de la estructura de madera del Real Taller de Aserrío Mecánico de Valsaín, en Segovia.
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Esteban Herrero, Miguel Esteban, Arriaga Martitegui, Francisco, and Íñiguez González, Guillermo
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MECHANICAL behavior of materials ,BUILDINGS ,BIOTIC communities ,NONDESTRUCTIVE testing ,COMMERCIAL product testing - Abstract
Copyright of Montes is the property of Colegio y Asociación de Ingenieros de Montes and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2019
22. Influence of timber moisture content on wave time-of-flight and longitudinal natural frequency in coniferous species for different instruments
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Llana, Daniel F., primary, Íñiguez-González, Guillermo, additional, Martínez, Roberto D., additional, and Arriaga, Francisco, additional
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- 2018
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23. Influence of length and sensor positioning on acoustic time-of-flight (ToF) measurement in structural timber
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Arriaga, Francisco, primary, Llana, Daniel F., additional, Esteban, Miguel, additional, and Íñiguez-González, Guillermo, additional
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- 2017
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24. Madera aserrada de gran escuadría para uso estructural y sus particularidades
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Bobadilla Maldonado, Ignacio, Esteban Herrero, Miguel, Íñiguez González, Guillermo, and Arriaga Martitegui, Francisco
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clasificación visual ,gruesa escuadría ,mechanical properties ,madera estructural ,lcsh:TH1-9745 ,size effect ,propiedades mecánicas ,efecto de tamaño ,lcsh:Architecture ,visual grading ,large cross section ,structural timber ,lcsh:NA1-9428 ,lcsh:Building construction - Abstract
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 sectiontimber 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 specifications is proposed. The output is highly improved in the proposal of standard (rejected percentage of 11 to 17%) whereas the mechanical properties are not modified in practice.A similar procedure was applied to 85 timber pieces from old timber structures of building demolition of Pinus sylvestris L. and 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%.En este artículo se realiza una exposición general del efecto del tamaño en las propiedades mecánicas de la madera y la evolución que han sufrido los procedimientos de ensayo y clasifi caciónpor esta razón. Además se expone un trabajo de investigación específi co sobre madera de gran escuadría. Sobre un total de 395 piezas de madera aserrada de tres especies (Pinus sylvestris L., Pinus nigra subs. salzmanii (Dunal) Franco y Pinus radiata D. Don) con secciones comprendidas entre 150x200 y 200x250 mm, se ha procedido a su clasifi cación de acuerdo con la norma UNE 56544:2003 determinando su rendimiento y propiedades mecánicas. El porcentaje de piezas que son rechazadas es demasiado elevado (38 a 45%) y por tanto se propone una modifi cación de las especifi caciones de la norma. Con la nueva propuesta de norma el rendimiento aumenta en alto grado (rechazo del 11 al 17%) sin que las propiedades mecánicas se vean afectadas significativamente.Por otro lado se ha seguido un procedimiento similar con 85 piezas de madera procedentes de estructuras antiguas en proceso de derribo de Pinus sylvestris L. y Pinus pinaster Ait. La clasifi cación de acuerdo con la norma UNE 56544:2003 da lugar a un 52% de rechazo aplicando estrictamente todos los parámetros de clasifi cación. Este procedimiento resulta poco viable en la prácticaen el caso de estructuras existentes y por tanto, se propone la aplicación de una clasificación basada únicamente en los parámetros del tamaño de los nudos y de la desviación de la fi bra. De esta forma el rendimiento aumenta reduciendo el porcentaje de rechazo al 10%.
- Published
- 2007
25. Los métodos de vibración como herramienta no destructiva para la estimación de las propiedades resistentes de la madera aserrada estructural
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Íñiguez González, Guillermo, Arriaga Martitegui, Francisco, Esteban Herrero, Miguel, and Argüelles Álvarez, Ramón
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frecuencia longitudinal de vibración ,plg (portable lumber grader) ,Building construction ,resonant frequency ,métodos de vibración ,Architecture ,non-destructive testing ,gross cross-section structural saw timber ,NA1-9428 ,clasifi cación no destructiva ,madera aserrada estructural de gruesa escuadría ,TH1-9745 - Abstract
The non-destructive testing of structural sawn timber using the resonant frequency methods uses the natural frequency of pieces to assess the quality of test samples. This paper describes the theoretical basis of this non-destructive technique and an investigation into the suitability of this tool. The results of grading 120 pieces of gross cross-section (150 x 200 x 4,060 mm and 200 x 250 x 5,060 mm) structural timber of European black pine, (Pinus nigra subsp. salzmannii (Dunal) Franco) are shown. Furthermore, the specimens were tested for bending according to the UNE-EN 408: 2004 standard, to compare the values of strength and stiffness obtained from this test with the results estimated using the non-destructive method. PLG (the Portable Lumber Grader) developed at the Wood NDT Laboratory of the University of Western Hungary, in Sopron, was used to measure the frequency of the longitudinal stress wave. This equipment determines the frequency and the density of the specimens, and uses them, to evaluate the dynamic modulus of elasticity and to estimate the strength. For gross cross-section European black pine pieces, a strong relationship exists between dynamic modulus obtained by longitudinal vibration frequency and the mechanical properties. Acoustic measurements have become widely acceptable, because they are accurate, portable, cheap and easy to apply., La clasificación no destructiva de madera aserrada estructural mediante los métodos de vibración, utiliza la frecuencia natural de la pieza para llegar a definir la calidad del material. Este artículo describe los fundamentos teóricos de esta técnica no destructiva y un trabajo de investigación enfocado a valorar la idoneidad de dicha herramienta. Se muestran los resultados de clasificación de 120 piezas de gruesa escuadría (150 x 200 x 4.060 mm y 200 x 250 x 5.060 mm) de madera aserrada estructural de pino laricio, (Pinus nigra subsp. salzmannii (Dunal) Franco). Adicionalmente, las probetas fueron ensayadas a fl exión conforme a la norma UNE-EN 408: 2004, para comparar los valores de resistencia y rigidez obtenidos mediante este ensayo con los estimados utilizando este método no destructivo. Se utilizó el PLG (Portable Lumber Grader), desarrollado en el Laboratorio de Técnicas No Destructivas para la Madera de la Universidad del Oeste de Hungría, en Sopron, para la determinación de la frecuencia longitudinal de vibración. Este equipo permite medir la frecuencia y la densidad de las piezas, a partir de las cuales calcula el módulo de elasticidad dinámico y estima la resistencia. Para piezas de gruesa escuadría de pino laricio existe un alto grado de correlación entre el módulo de elasticidad dinámico obtenido a partir de la frecuencia longitudinal de vibración, y las propiedades mecánicas. Los métodos acústicos de clasificación han sido ampliamente aceptados porque son precisos, portátiles, baratos y fáciles de aplicar.
- Published
- 2007
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26. Estimación de la densidad de la madera aserrada de conífera mediante técnicas no destructivas de arranque de tornillos y penetrómetro y su aplicación en la estimación del módulo de elasticidad
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Palacios Monteagudo, José, Ballarín Montesinos, Daniel, Arriaga Martitegui, Francisco, Íñiguez González, Guillermo, Esteban Herrero, Miguel, and Bobadilla Maldonado, Ignacio
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madera ,destructivos ,arranque de tornillo ,pilodyn density ,penetration depth ,lcsh:Architecture ,non-destructive ,penetrómetro ,screw withdrawal ,lcsh:TH1-9745 ,wood ,lcsh:NA1-9428 ,lcsh:Building construction - Abstract
The results of probing 395 sawn pieces of Radiata pine (Pinus radiata D. Don), Scots pine (Pinus sylvestris L.) and Laricio pine (Pinus nigra Arn. ssp. salzmannii) from Spanish sources are presented. Specimens had a cross section from 150 x 200 mm, 150 x 250 mm, and 200 x 250 mm. The Screw Withdrawal Force Meter (SWFM) developed by the Wood NDT Laboratory of the University of Western Hungary, in Sopron, and the Pilodyn 6J Wood Tester by Proceq, are the items of equipment used to measure screw withdrawal force and penetration depth, respectively. Based on our results, this paper concludes that for structural coniferous timber the density values estimated from probing measurements are reliable. There is a positive correlation between non-destructive parameters and density (a coefficient of determination r2 of 48.5% to 49.9% is obtained). The authors believe that it is possible to use probing with ultrasonic methods as a good combined nondestructive technique to improve the results of visual grading and modulus of elasticity assessment, at least as an additional parameter in structural sawn timber.Se han efectuado medidas indirectas de la densidad de la madera mediante métodos no destructivos, como la penetración de una varilla con penetrómetro o el arranque de tornillos, sobre probetas procedentes de 395 vigas de tamaño estructural de Pinus radiata D. Don (155), Pinus sylvestris L (120), y Pinus nigra Arn (120). El objeto es tratar de establecer una metodología, para la estimación en obra de la densidad, cuando se realizan tareas de mantenimiento, rehabilitación o restauración.Se han obtenido relaciones estadísticamente significativas entre los valores obtenidos en los ensayos no destructivos y la densidad real de las piezas. Se proponen tres modelos para la estimación de la densidad basados en el resultado del ensayo no destructivo de arranque de tornillos con coeficientes de determinación (R2) de 48,5%, 49,5% y 49,9%. Por ultimo, se plantea, si se desconoce la especie, el uso de un modelo común, que permite estimar la densidad con un R2 de 48,6%. Este dato, permite posteriormente la estimación, junto con los sistemas de ultrasonidos, del módulo de elasticidad de las piezas y su clasificación.  
- Published
- 2007
27. Los métodos de vibración como herramienta no destructiva para la estimación de las propiedades resistentes de la madera aserrada estructural
- Author
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Argüelles Álvarez, Ramón, Esteban Herrero, Miguel, Arriaga Martitegui, Francisco, and Íñiguez González, Guillermo
- Subjects
PLG (Portable Lumber Grader) ,clasifi cación no destructiva ,frecuencia longitudinal de vibración ,métodos de vibración ,madera aserrada estructural de gruesa escuadría ,resonant frequency ,non-destructive testing ,lcsh:Architecture ,gross cross-section structural saw timber ,lcsh:TH1-9745 ,lcsh:NA1-9428 ,lcsh:Building construction - Abstract
The non-destructive testing of structural sawn timber using the resonant frequency methods uses the natural frequency of pieces to assess the quality of test samples. This paper describes the theoretical basis of this non-destructive technique and an investigation into the suitability of this tool. The results of grading 120 pieces of gross cross-section (150 x 200 x 4,060 mm and 200 x 250 x 5,060 mm) structural timber of European black pine, (Pinus nigra subsp. salzmannii (Dunal) Franco) are shown. Furthermore, the specimens were tested for bending according to the UNE-EN 408: 2004 standard, to compare the values of strength and stiffness obtained from this test with the results estimated using the non-destructive method. PLG (the Portable Lumber Grader) developed at the Wood NDT Laboratory of the University of Western Hungary, in Sopron, was used to measure the frequency of the longitudinal stress wave. This equipment determines the frequency and the density of the specimens, and uses them, to evaluate the dynamic modulus of elasticity and to estimate the strength. For gross cross-section European black pine pieces, a strong relationship exists between dynamic modulus obtained by longitudinal vibration frequency and the mechanical properties. Acoustic measurements have become widely acceptable, because they are accurate, portable, cheap and easy to apply.La clasificación no destructiva de madera aserrada estructural mediante los métodos de vibración, utiliza la frecuencia natural de la pieza para llegar a definir la calidad del material. Este artículo describe los fundamentos teóricos de esta técnica no destructiva y un trabajo de investigación enfocado a valorar la idoneidad de dicha herramienta. Se muestran los resultados de clasificación de 120 piezas de gruesa escuadría (150 x 200 x 4.060 mm y 200 x 250 x 5.060 mm) de madera aserrada estructural de pino laricio, (Pinus nigra subsp. salzmannii (Dunal) Franco). Adicionalmente, las probetas fueron ensayadas a fl exión conforme a la norma UNE-EN 408: 2004, para comparar los valores de resistencia y rigidez obtenidos mediante este ensayo con los estimados utilizando este método no destructivo. Se utilizó el PLG (Portable Lumber Grader), desarrollado en el Laboratorio de Técnicas No Destructivas para la Madera de la Universidad del Oeste de Hungría, en Sopron, para la determinación de la frecuencia longitudinal de vibración. Este equipo permite medir la frecuencia y la densidad de las piezas, a partir de las cuales calcula el módulo de elasticidad dinámico y estima la resistencia. Para piezas de gruesa escuadría de pino laricio existe un alto grado de correlación entre el módulo de elasticidad dinámico obtenido a partir de la frecuencia longitudinal de vibración, y las propiedades mecánicas. Los métodos acústicos de clasificación han sido ampliamente aceptados porque son precisos, portátiles, baratos y fáciles de aplicar.
- Published
- 2007
28. Estado actual de la investigación sobre madera estructural en España
- Author
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Esteban Herrero, Miguel, Argüelles Álvarez, Ramón, Arriaga Martitegui, Francisco, Íñiguez González, Guillermo, and Bobadilla Maldonado, Ignacio
- Subjects
Building construction ,research ,timber ,structures ,NA1-9428 ,lcsh:TH1-9745 ,madera ,investigación ,construcción ,building ,Architecture ,estructuras ,lcsh:Architecture ,TH1-9745 ,lcsh:NA1-9428 ,lcsh:Building construction - Abstract
This article intends to show the current state of the research about structural timber in Spain. An ample compilation of information from people and institutions has been carried out. Information received has been so extensive that a hard work of synthesis has been necesary in order to offer a general and objective vision of the subject.In a few years a new legislative and normative frame has been implanted in Spain, defi ned by the Law of Arrangement of the Construction, the Construction Technical Code and the European Construction Products Directive. In this frame some challenges for the sector arise from the construction and the timber. It is the fi rst time that structural timber is framed within a norm of forced fulfillment, which it supposes not only a challenge but the putting in value of all its potential like structural material.In this frame research necessities have been increased, as well as development and innovation, and it is demostrated by several research iniciatives started in our country, with a clear vocation to respond to the necessities arisen in the sector and to satisfy the raised requirements of security in the norm. In this work, using the compiled information, the research lines on structural timber at the moment in Spain are summarized, as well as their presence in means of national or international diffusion or their direct applications in the industry., Este artículo pretende dibujar un panorama sobre el estado actual de la investigación en torno a la madera estructural desarrollada actualmente en España. Se ha realizado una amplia recopilación de información entre personas e instituciones. La información recibida ha sido tan extensa que ha sido necesaria una difícil labor de síntesis para ofrecer una visión general y objetiva.En poco tiempo ha sido implantado en España un nuevo marco legislativo y normativo defi nido por la Ley de Ordenación de la Edifi cación, el Código Técnico de la Edificación y la Directiva Europea de Productos de la Construcción. En este marco surgen algunos retos para el sector de la construcción a los que la madera no resulta ajena. La madera estructural se enmarca por primera vez en una normativa de obligado cumplimiento, lo que supone no sólo un reto sino la puesta en valor de todo su potencial como material estructural.En este marco se han disparado las necesidades de investigación, desarrollo e innovación, y así lo demuestran las muchas líneas de investigación abiertas en nuestro país, con una clara vocación de responder a las necesidades surgidas en el sector y de satisfacer los requisitos de seguridad planteados en la normativa. En este artículo, con la información recopilada se resumen las líneas de investigación sobre madera estructural que se están desarrollando actualmente en España, así como su presencia en medios de difusión nacional o internacional o sus aplicaciones directas en la industria.
- Published
- 2007
- Full Text
- View/download PDF
29. Comparison of various multivariate models to estimate structural properties by means of non-destructive techniques (NDTs) in Pinus sylvestris L. timber.
- Author
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Villasante, Antonio, Íñiguez-González, Guillermo, and Puigdomenech, Lluis
- Subjects
- *
SCOTS pine , *STRESS waves , *FREQUENCIES of oscillating systems , *FLEXURAL strength , *MODULUS of elasticity - Abstract
The predictability of modulus of elasticity (MOE), modulus of rupture (MOR) and density of 120 samples of Scots pine (Pinus sylvestris L.) were investigated using various non-destructive variables (such as time of flight of stress wave, natural frequency of longitudinal vibration, penetration depth, pullout resistance, visual grading and concentrated knot diameter ratio), and based on multivariate algorithms, applying WEKA as machine learning software. The algorithms used were: multivariate linear regression (MLR), Gaussian, Lazy, artificial neural network (ANN), Rules and decision Tree. The models were quantified based on the root-mean-square error (RMSE) and the coefficient of determination (R2). To avoid model overfitting, the modeling was built and the results validated via the so-called 10-fold cross-validation. MLR with the "greedy method" for variable selection based on the Akaike information metric (MLRak) significantly reduced the RMSE of MOR and MOE compared to univariate linear regressions (ULR). However, this reduction was not significant for density prediction. The predictability of MLRak was not improved by any other of the tested algorithms. Specifically, non-linear models, such as multilayer perceptron, did not contribute any significant improvements over linear models. Finally, MLRak models were simplified by discarding the variables that produce the lowest RMSE increment. The resulted models could be even further simplified without significant RMSE increment. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
30. Visual Grading and Structural Properties Assessment of Large Cross-Section Pinus radiata D. Don Timber
- Author
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Hermoso Prieto, Eva, primary, Mateo, Raquel, additional, Íñiguez-González, Guillermo, additional, Montón, Joaquín, additional, and Arriaga, Francisco, additional
- Published
- 2016
- Full Text
- View/download PDF
31. Reference conditions and modification factors for the standardization of nondestructive variables used in the evaluation of existing timber structures
- Author
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Íñiguez-González, Guillermo, primary, Arriaga, Francisco, additional, Esteban, Miguel, additional, and Llana, Daniel F., additional
- Published
- 2015
- Full Text
- View/download PDF
32. Experimental and numerical investigation of effect of sawn timber dimensions in ultrasonic velocity measurements of Spanish softwoods (NDT 2013)
- Author
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Llana, Daniel F., Martin, Sergio Jose Sanabria, Íñiguez-González, Guillermo, Arriaga, Francisco, and Niemz, Peter
- Published
- 2013
- Full Text
- View/download PDF
33. La madera en las estructuras y el incendio de la catedral de Notre Dame (París).
- Author
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Esteban Herrero, Miguel, Arriaga Martitegui, Francisco, and Íñiguez González, Guillermo
- Subjects
WOOD ,NOTRE Dame Cathedral fire, 2019 ,CHURCH building fires ,FIRE prevention ,PUBLIC safety - Abstract
The article reports on the role of wood in the structure fire that broke out beneath the roof of Notre-Dame Cathedral in Paris, France, on April 15, 2019. The fire in the cathedral has caused many news, interviews and technical assessments which are very diverse in nature. In the majority, wood is presented as the protagonist of the fire.
- Published
- 2019
34. Vibration method for grading of large cross-section coniferous timber species
- Author
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Arriaga, Francisco, primary, Íñiguez-González, Guillermo, additional, Esteban, Miguel, additional, and Divos, Ferenc, additional
- Published
- 2012
- Full Text
- View/download PDF
35. Density estimation by screw withdrawal resistance and probing in structural sawn coniferous timber, and modulus of elasticity assessment
- Author
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Bobadilla Maldonado, Ignacio, primary, Esteban Herrero, Miguel, additional, Íñiguez González, Guillermo, additional, Arriaga Martitegui, Francisco, additional, Ballarín Montesinos, Daniel, additional, and Palacios Monteagudo, José, additional
- Published
- 2007
- Full Text
- View/download PDF
36. Vibration methods as non-destructive tool for structural properties assessment of sawn timber
- Author
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Íñiguez González, Guillermo, primary, Arriaga Martitegui, Francisco, additional, Esteban Herrero, Miguel, additional, and Argüelles Álvarez, Ramón, additional
- Published
- 2007
- Full Text
- View/download PDF
37. Large cross section sawn timber for structural use and its singularities
- Author
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Arriaga Martitegui, Francisco, primary, Íñiguez González, Guillermo, additional, Esteban Herrero, Miguel, additional, and Bobadilla Maldonado, Ignacio, additional
- Published
- 2007
- Full Text
- View/download PDF
38. Current state of research on structural timber in Spain
- Author
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Esteban Herrero, Miguel, primary, Argüelles Álvarez, Ramón, additional, Arriaga Martitegui, Francisco, additional, Íñiguez González, Guillermo, additional, and Bobadilla Maldonado, Ignacio, additional
- Published
- 2007
- Full Text
- View/download PDF
39. In-Situ Assessment of Structural Timber Density Using Non-Destructive and Semi-Destructive Testing.
- Author
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Íñiguez-González, Guillermo, Montón, Joaquín, Arriaga, Francisco, and Segués, Edgar
- Subjects
- *
TIMBER , *PINUS radiata , *CORE drilling , *DENSITY , *SCREWS - Abstract
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]
- Published
- 2015
- Full Text
- View/download PDF
40. Warp Requirements and Yield Efficiency in the Visual Grading of Sawn Radiata Pine Timber.
- Author
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Montón, Joaquín, Arriaga, Francisco, Íñiguez-González, Guillermo, and Segués, Edgar
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PINUS radiata ,TIMBER ,PLANT species ,ELASTICITY ,DENSITY - Abstract
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]
- Published
- 2015
41. Remarkable ancient timber bridges up to the 1850's. Part I: general review.
- Author
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ÍÑIGUEZ-GONZÁLEZ, Guillermo, FERNÁNDEZ-CABO, José L., FERNÁNDEZ-CABO, Miguel C., ARRIAGA-MARTITEGUI, Francisco, and MAJANO-MAJANO, M. Almudena
- Subjects
BESSEMER process ,BRIDGE design & construction ,WOODEN bridge design & construction ,TIMBER - Abstract
In 1850, the Bessemer converters were able to produce mass-production inexpensive steel. This technical advance was the key point that leaded to a suddenly extended use of steel in the bridge engineering field. Consequently, timber was pushed into the backstage as a structural material during many decades. In the other hand, timber has been fortunately recovered, especially from 1970's, as engineering material. This paper presents the part I of a first stage work concerning to the study of remarkable ancient timber bridges from 1650 to 1850. Part I consists of a general review. The comparison with the current state of art proves that the technical heritage is worth analyzing as a lesson for the present. Selected case studies would be used to explain the historical timber bridge breakthroughs in part II [1]. The geographical areas analysed were restrained to Europe and USA due to the limitations to the access to first-hand sources. Nowadays works following these principles are many (see e.g. [2]), but James's work [3] still continues being a basic guide for authors. [ABSTRACT FROM AUTHOR]
- Published
- 2010
42. Remarkable ancient timber bridges up to the 1850's. Part II: case studies and breakthroughs.
- Author
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FERNÁNDEZ-CABO, Miguel C., FERNÁNDEZ-CABO, José L., ÍÑIGUEZ-GONZÁLEZ, Guillermo, MAJANO-MAJANO, M. Almudena, and ARRIAGA-MARTITEGUI, Francisco
- Subjects
WOODEN bridge design & construction ,STRUCTURAL analysis (Engineering) ,STRUCTURAL engineering - Abstract
As showed in the first part of this work [1], the technical heritage prior to the 1850's presents an important number of remarkable timber bridges, especially in the last hundred years of that period. This paper presents, in a deeper detail, some of these masterpieces. The study is limited to Europe and USA due to the lack of first-hand sources. The examples were selected trying to thread the history of breakthroughs in timber bridge engineering up to the 1850's. They will show that the past is still a lesson for the present. The authors assume, in agreement with others [2], that a case study should be developed according to the following three key features: the structural type, the material and the connection system. The case study has been complemented with an explanation around the corresponding temporal context, which has the advantage of facilitating a global and deeper understanding. This is a first stage work, trying to follow the one by James [3];and claiming, as other current works [4] do, for an effort to study this cultural and technical heritage. [ABSTRACT FROM AUTHOR]
- Published
- 2010
43. Visual grading and structural properties assessment of large cross - section Pinus radiata D. Don timber
- Author
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Montón Lecumberri, Joaquín, Arriaga Martitegui, Francisco, Íñiguez-González, Guillermo, Hermoso Prieto, Eva, Mateo Campos, Raquel, Universitat Politècnica de Catalunya. Departament de Construccions Arquitectòniques II, and Universitat Politècnica de Catalunya. GICITED - Grup Interdiciplinari de Ciència i Tecnologia en l'Edificació
- Subjects
Pinus radiata ,Characterization ,Enginyeria dels materials::Assaig de materials::Assaigs mecànics [Àrees temàtiques de la UPC] ,Density ,Timber ,Modulus of elasticity ,Singularities ,Fusta d'obra ,Bending strength - Abstract
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 cross-section Spanish radiata pine timber was suitable for structures, and it was assigned to the C20 strength class.
44. Clasificación visual estructural de la madera de pino radiata procedente de Cataluña
- Author
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Montón Lecumberri, Joaquín|||0000-0002-3781-4783, Arriaga Martitegui, Francisco, Avellaneda Diaz-Grande, Jaime|||0000-0003-4016-4897, Íñiguez-González, Guillermo, Farràs, Jordi, Plensa, Rubén, Universitat Politècnica de Catalunya. Departament de Construccions Arquitectòniques II, Universitat Politècnica de Catalunya. Departament de Construccions Arquitectòniques I, Universitat Politècnica de Catalunya. GICITED - Grup Interdiciplinari de Ciència i Tecnologia en l'Edificació, and Universitat Politècnica de Catalunya. LiTA - Laboratori d'Innovació i Tecnologia en l'Arquitectura
- Subjects
Materiales ,Rendimiento ,Propiedades mecánicas ,Timber ,Mechanical properties ,Ingeniería Civil y de la Construcción ,Clasificación visual ,Visual grading ,Edificació::Materials de construcció::Fusta [Àrees temàtiques de la UPC] ,Grading outcome ,Radiata pine ,Twist ,Alabeo ,Fusta d'obra ,Pino radiata - Abstract
Se han clasificado visualmente, según la norma española UNE 56544; 150 piezas de madera aserrada de pino radiata procedentes de Cataluña (España) con una sección de 80x150 mm y una longitud de 2.500 mm. Esta norma establece dos calidades visuales (ME-1 y ME-2) para piezas con grueso menor o igual que 70 mm y una única calidad visual (MEG) para gruesos mayores de 70 mm. Con el fin de conocer el efecto frontera entre la pequeña y la gran escuadría se clasificaron las piezas según ambas categorías. Se determinó la tensión de rotura en flexión, el módulo de elasticidad en flexión y la densidad de cada pieza mediante el ensayo de acuerdo con la norma UNE-EN 408 siguiendo los ajustes definidos en la norma UNE-EN 384. Un 53 % de las piezas se clasificaron como MEG con una resistencia característica a flexión de 28 N/mm2 y un valor medio del módulo de elasticidad de 9.900 N/mm2. Por otra, un 42 % de las piezas se clasificaron como ME-2 y sólo un 3 % como ME-1; en este caso las propiedades mecánicas de la calidad ME-2 no se alejan mucho de las de la calidad MEG. El elevado porcentaje de piezas rechazadas (47 % frente a la MEG) se debe principalmente al defecto de alabeo responsable de un 39 % de rechazo. Si no se considera el alabeo en la clasificación el porcentaje de rechazo desciende al 17 % y las propiedades mecánicas de la calidad MEG presentan un valor característico de resistencia a flexión de 21 N/mm2 y un módulo de elasticidad de 9.100 N/mm2. A sample of 150 pieces of radiata pine sawn timber with 180x120 mm in cross-section and 2.500 mm in length sourcing from Catalonia (Spain) were visually graded according to Spanish standard UNE 56544. This standard establish two visual grades (ME-1 and ME-2) for timber pieces with thickness equal or less than 70 mm, and one grade (MEG) for thickness bigger than 70 mm. In order to know the border effect between small and larger cross-section the pieces were graded in both categories. The modulus of rupture, modulus of elasticity and density were obtained by test according to EN 408 standard and the adjustments of EN 384. A 53 % of pieces were classified as MEG with a characteristic bending strength of 28 N/mm2 and a mean value of MOE of 9.900 N/mm2. On the other hand, a 42 % of pieces were classified as ME-2 and only a 3 % as ME-1; in this case the mechanical properties of ME-2 are not far from MEG properties. The high percentage of rejected pieces (47 % vs MEG) is mainly due to the twist defect with a 39 % of rejected pieces. If twist is not considered in the grading process the reject percentage decreases to 17 % and the mechanical properties of MEG grade present a characteristic value of bending strength of 21 N/mm2 and a MOE of 9.100 N/mm2.
45. Estudio sobre el estado de conservación de la cubierta del Martinete de Navafría
- Author
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González Sanz, Mariano, Esteban Herrero, Miguel, and Íñiguez González, Guillermo
- Subjects
Ingeniería Civil y de la Construcción ,Ingeniería Industrial ,Arquitectura - Abstract
El presente documento es un estudio sobre el estado de conservación de la cubierta de madera del martinete de Navafría. El martinete de Navafría fue declarado Bien de Interés Cultural por la Junta de Castilla y León en 1998. Es el último martinete de cobre que queda en Europa y en él se realizaban calderos, braseros, calienta-camas y demás enseres de cobre. Se ha realizado una croquización de la cubierta del martinete y se han registrado las dimensiones de todas y cada una de las piezas. Se ha realizado una inspección de cada una de las piezas. En esta inspección se han descrito todas las patologías encontradas y se han generado unos croquis donde se representa el grado de ataque. Se han empleado Técnicas No Destructivas (TND) para determinar el grado de ataque de las diferentes patologías y para estimar las características estructurales de la madera. El grado de ataque que presenta la estructura es muy elevado y una de las cuatro vigas principales presenta una rotura total. Una vez analizado el estado de las patologías se ha modelizado la estructura para calcular los índices de agotamiento y comprobar si cumple con la normativa. Se ha obtenido que los índices de agotamiento son superiores a los permitidos. Por lo que no se puede garantizar la seguridad de la estructura. Después de todo el análisis se han redactado unas conclusiones y se han realizado una propuestas de actuación. Estas medidas se han planteado para mejorar la conservación y solucionar los problemas observados. Se ha realizado una propuesta de una nueva cubierta empleando materiales más ligeros y manteniendo el diseño estructural original. Se ha conseguido disminuir el peso de la cubierta un 27 %. Con estas nuevas cargas se ha recalculado de nuevo la cubierta y se ha comprobado que no cumple con las exigencias de la normativa vigente. Por ello es necesario un nuevo diseño que se adapte a la normativa y se recomienda que busque el mantener el aspecto original.
- Published
- 2012
46. Influencia de la humedad de la madera en la evaluación de las propiedades mecánicas del pino silvestre mediante técnicas no destructivas
- Author
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Mata Jiménez, Jaime de la, Íñiguez González, Guillermo, and Esteban Herrero, Miguel
- Subjects
Física ,Ingeniería Civil y de la Construcción ,Arquitectura - Abstract
El presente Proyecto Fin de Carrera estudia la influencia que tiene el contenido de humedad de la madera en la evaluación de sus propiedades mecánicas mediante ensayos no destructivos (END), llevados a cabo mediante métodos acústicos y análisis de vibración, analizando y comparando los valores obtenidos. Actualmente, las técnicas no destructivas son métodos muy usados en la evaluación de materiales maderables. Para ello, se seleccionan 26 probetas de madera aserrada de pino silvestre (Pinus sylvestris L.) cuya procedencia es El Espinar, Segovia, con una dimensión nominal de 3000 mm x 150 mm x 100 mm. Posteriormente se trasladan al laboratorio de maderas del CIFOR – INIA, donde van a permanecer a medida que se van secando. Se clasifica visualmente el lote a medida que se produce su secado según la norma UNE 565444: 2009, observando la evolución de las probetas, referente a las clases visuales, a lo largo del proceso. El contenido de humedad se determina a través del método de la resistencia eléctrica de la madera según la norma española UNE- EN 13183-2: 2002, haciendo uso de diferentes tipos de electrodos previamente introducidos en las probetas. Este método es el más común en la determinación del contenido de humedad de la madera en aserradero o puesta en obra. A medida que transcurre el proceso de secado se miden las diferentes variables relacionadas con el contenido de humedad y con las técnicas END: al principio la pérdida de humedad es más rápida y las mediciones son más frecuentes y, posteriormente, el espaciamiento entre días de medición es mayor. Una vez que la madera alcanza el contenido de humedad de equilibrio se procede a ensayar a flexión, cuyos resultados se comparan con los END, para ver si es posible predecir el comportamiento mecánico de la madera a través de estas últimas. Resultan buenos coeficientes de correlación en módulo de elasticidad (R2 de 0,71 para onda ultrasónica, 0,67 para onda sónica y 0,81 para el análisis de vibraciones).
- Published
- 2011
47. Influencia de factores físicos y geométricos en la clasificación estructural de la madera mediante técnicas no destructivas
- Author
-
Fernández Llana, Daniel and Íñiguez González, Guillermo
- Subjects
Silvicultura - Abstract
Esta tesis doctoral presenta los análisis, resultados y conclusiones de la influencia de ciertos factores (contenido de humedad, longitud de medida y posición de los sensores) en las variables no destructivas, así como, la clasificación visual de las muestras y la determinación de las propiedades físico-mecánicas (densidad, módulo de elasticidad y tensión de rotura) mediante ensayos según la norma EN 408. Además, recopila y homogeneiza resultados de ensayos con técnicas no destructivas de varios grupos de investigación españoles. Para el estudio citado se utilizaron dos muestras de madera de procedencia española de las especies: pino radiata, silvestre, laricio y pinaster. Muestra 1a: 100 piezas (25 de cada especie) y de dimensiones 100x150x3000 mm. Muestra 1b: 100 piezas de las mismas especies y de dimensiones 100x150x500 mm. Muestra 2: 120 piezas (30 de cada especie) de las mismas especies y de dimensiones 90x140x4000 mm. Se realizaron mediciones con equipos no destructivos de: ultrasonidos, ondas de impacto, vibraciones inducidas, resistencia a la penetración y resistencia al arranque de tornillo. Se estudió la influencia del contenido de humedad de la madera en las variables no destructivas medidas, obteniendo modelos de ajuste por equipo y especie, con coeficientes de corrección que, para un contenido de humedad de referencia del 12%, variaron entre 0,58 y 0,77% para las técnicas no destructivas globales (acústicas y vibración), entre 1,7 y 2,2% para la resistencia a la penetración, y entre 2,1 y 2,8% para la resistencia al arranque de tornillo. Se propusieron modelos de estimación de las propiedades físico-mecánicas mediante técnicas no destructivas, con coeficientes de determinación de hasta el 68% para la densidad, hasta el 92% para el módulo de elasticidad y hasta el 70% para la tensión de rotura. También se observó que la velocidad de los equipos de transmisión de onda a diferentes longitudes de medida no era constante, presentando una tendencia a disminuir la velocidad al aumentar la longitud de medida. Dado que la corrección está influenciada por múltiples factores (equipo, especie y calidad de la madera) no resultó posible obtener un modelo de ajuste y, por tanto, se propuso un procedimiento de corrección de dichas velocidades, que se aconseja realizar para cada caso particular. Se observó que las mediciones de velocidad de ultrasonidos realizadas colocando los sensores en la cara de la pieza, bien en la misma cara o en caras opuestas, y en los cantos, no presentaban diferencias estadísticamente significativas entre ellas, sin embargo, sí las presentaban con respecto a las mediciones de velocidad testa testa. Se propusieron modelos de ajuste entre velocidades testa-testa y el resto de posiciones de medida, con coeficientes de determinación de hasta el 97%. La clasificación visual realizada sobre la misma muestra, tanto en húmedo como en seco, mostró, que si bien existía una gran diferencia entre el porcentaje de rechazo en húmedo (hasta el 24%) y seco (hasta el 84%), en ambas situaciones se pudo realizar una discriminación del módulo de elasticidad y la tensión de rotura por calidad visual. No siendo posible, sin embargo, discriminar la densidad. La recopilación y homogeneización de datos de mediciones con equipos no destructivos portátiles de varios grupos de investigación españoles, mostró que existen hasta la actualidad datos de aproximadamente 9500 piezas de madera aserrada estructural, de las cuales, más de 3000 son de gran escuadría, y puso de manifiesto la necesidad de normalizar el uso de otras técnicas no destructivas aparte de la clasificación visual para clasificar madera. ABSTRACT This Doctoral Thesis entitled: “The influence of physical and geometrical factors on timber stress-grading by non-destructive techniques”, contains analyses, results and conclusions regarding several factors’ influence (moisture content, measurement length and sensors position) on non-destructive variables. Furthermore, visual strength grading results and physical and mechanical properties (density, modulus of elasticity and bending strength) according to the EN 408 standard are presented. The non-destructive results from several Spanish research groups are also compiled and homogenized. Two timber batches of four Spanish species (radiata pine, Scots pine, laricio pine and maritime pine) were used in these studies. Batch 1a: 100 specimens (25 of each species) with nominal dimensions of 100x150x3000 mm. Batch 1b: 100 specimens (25 of each species) with nominal dimensions of 100x150x500 mm. Batch 2: 120 specimens (30 of each species) with nominal dimensions of 90x140x4000 mm. Measurements were taken using non-destructive devices such as ultrasound waves, sonic stress waves, longitudinal vibration, penetration tester and screw withdrawal. The influence of timber moisture content on non-destructive variables was studied, and adjustment models for 12% reference moisture content by device and species were obtained. Adjustment coefficients range from: 0,58% to 0,77% for acoustic and vibration techniques, 1,7% to 2,2% for penetration resistance, and 2,1% to 2,8% for pullout resistance. Physical and mechanical properties estimation models for non-destructive techniques were proposed, with determination coefficients up to: 68% for density, 92% for modulus of elasticity and 70% for bending strength. Furthermore, no constant velocity was observed for different lengths when measured with acoustic devices. A clear tendency of velocity to decrease with increased length was found. As correction of this effect is affected by several factors (device, species and timber quality), it was not possible to obtain a correction model. A velocity correction procedure was therefore proposed. No significant statistical differences were found between face-to-face and edge-toedge direct and indirect ultrasound velocity measurements. However, significant statistical differences were found between these velocities and end-to-end velocities. Adjustment models between end-to-end and the other velocities were proposed, obtaining determination coefficients of up to 97%. Wet (up to 24% rejected) and dry (up to 84% rejected) visual strength gradings in the same batch were found to differ widely. In both moisture content situations, a correct discrimination between modulus of elasticity and bending strength was found by visual strength grade. Nevertheless, it was not possible to discriminate by density. Compilation and homogenization of non-destructive results from several Spanish research groups with circa 9500 specimens (more than 3000 of gross cross-section) showed the necessity to standardize the use of non-destructive techniques.
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