Determinación de la capacidad resistente de la madera estructural de gran escuadría y su aplicación en estructuras existentes de madera de conífera

El objetivo principal de esta Tesis es la caracterización estructural de madera de gran escuadría, para lo cual desarrolla y propone una metodología que permite ampliar estudios posteriores. Se dirige principalmente a la evaluación de estructuras existentes. El estudio se ha desarrollado sobre un total de 117 piezas de madera de gran escuadría procedentes de diferentes edificios antiguos, todas ellas de madera de pino silvestre o pinaster, que formaron parte de las estructuras de cubiertas o forjados. Se ha realizado la clasificación visual con las normas UNE 56544 y DIN 4074. La aplicación estricta de estas normas en estructuras antiguas conduce a un elevado número de rechazos. Por ello, en este trabajo se han utilizado diferentes parámetros de clasificación o grupos de parámetros que permitan rendimientos altos con niveles de seguridad aceptables. Se aconseja la clasificación por criterios de nudos y desviación de la fibra en una sola calidad que reúna todas las piezas que no son rechazadas según la especificación de la norma. En ese caso es posible asignar propiedades mecánicas al 85 % (UNE) y al 93 % (DIN) de las piezas. Las clases resistentes asignadas varían entre una C14 (por resistencia), una C18 (por rigidez) y una C30 (por densidad). Por otro lado se ha aplicado la técnica de ultrasonidos definiendo una clase de velocidad superior a 4.100 m/s a la que se puede asignar una clase resistente C18 (por rigidez) para el 95 % de las piezas. Por resistencia se obtienen valores excesivamente bajos. Se han complementado ambas técnicas (visual y ultrasonidos), de manera que permiten asignar mejores propiedades mecánicas aunque con menor rendimiento. Las ventajas de estas técnicas son su relativa facilidad de aplicación en obra y la respuesta fiable en los resultados. Finalmente se proponen una reglas para la clasificación visual adaptadas a las circunstancias particulares de la madera estructural de gran escuadría de estructuras antiguas y se define una sola calidad a la que se asigna un clase resistente específica definida de la forma F14/E18/D30 (valores de resistencia de la clase C14, valores de rigidez de la C18 y valores de densidad de la C30). Si se complementa la técnica con ultrasonidos, la clase resistente sería de la forma F16/E22/D30. SUMMARY: The main object of this study is the structural characterization of gross cross section timber, designing a methodology that allows to increase the volume of data in future research actions. It is focused to the structure of old timber buildings. A total quantity of 117 gross cross section timber pieces from several old buildings have been tested. They are of Redwood and Maritime pine and come from roof and floor joists structures. Visual strength grading according to UNE 56544 and DIN 4074 standards have been used with different grading parameters or group of parameters to obtain high performance and with acceptable safety level. It is recommended that visual grading would be based on knots size and slope of grain in only one grade including all pieces not rejected by the standard. In this case, it is possible to assign mechanical properties to 85 % (UNE) and 93 % (DIN) of pieces. Strength classes come from C14 (strength criteria), C18 (stiffness criteria) and C30 (density criteria). On the other hand, ultrasonic measures have been used to define a velocity class over 4.100 m/s to which it is possible to assign a strength class C18 (stiffness criteria) for 95 % of pieces. In strength criteria the results are too low. Both systems (visual grading and ultrasonic measures) have been joint in order to assign higher mechanical properties but with lower performance. The advantage of these methods are the easiness to apply in situ and the reliability of results. Finally, visual strength rules are proposed for the special circumstances of structural gross cross section timber placed at the building and only one grade are established with a strength class defined as F14/E18/D30 (strength class C14, stiffness class C18 and density class C30). Joining both methods (visual grading and ultrasonic measures), the strength class would be F16/E22/D30

Make-or-buy configurational approaches in product-service ecosystems and performance

This research examines firm boundary configurations for manufacturers' product-service offerings. We argue that the building of a product-service ecosystem through collaboration with service providers in certain types of business services can increase performance as a result of the superior knowledge-based resources coming from specialized partners. By using fuzzy set qualitative analysis on a sample of 370 multinational manufacturing enterprises (MMNEs), the results reveal that effective servitization is heterogeneous across manufacturing industries and across business service offerings. The findings indicate that most industries achieve their highest performance through collaborations with value-added service providers in two out of three of the service continuum stages (Base and Intermediate services); while keeping the development of Advanced services in-house. The results help to contextualize the best practices for implementing service business models in MMNEs by detailing which service capabilities should be retained in-house and which should be outsourced to specialized partners in various industrial contexts.Peer ReviewedPreprin

Bonding shear strength in timber and GFRP glued with epoxy adhesives

The bonding quality of epoxy glued timber and glass fibre reinforced polymers (GFRP) was evaluated by means of compression loading shear test. Three timber species (Radiata pine, Laricio pine and Oak) and two kinds of GFRP (plates and rods made with polyester resin reinforced with mat and roving glass fibre) were glued and tested using three epoxy formulations. The increase in shear strength with age after the setting of epoxy formulations and the effect of surface roughness on timber and GRP gluing (the planing of the surface of timber and the previous sanding of GRP) were studied. It can be concluded that the mechanical properties of these products make them suitable for use in the reinforcement of deteriorated timber structures, and that a rough timber surface is preferable to a planed one, while the previous sanding of GRP surfaces is not advantageous

Territorial servitization and the manufacturing renaissance in knowledge-based economies

The analysis of how the development of knowledge-intensive business service (KIBS) sectors in certain territories contributes to rebuild the competitive advantage of manufacturing businesses—a process described as territorial servitization—has increasingly drawn scholarly and policy attention. The collection of nine papers in this special issue brings new insights into how institutional and spatial as well as socio-economic and industry-specific attributes underpin the development of territorial servitization. By adopting a multidisciplinary perspective that combines a variety of frameworks (organizational, place-based, economic geography), the mechanics and the relationships underlying territorial servitization as well as its territorial economic repercussions are developed. This editorial note first portrays territorial servitization as a local hybrid value chain and argues that effective territorial servitization requires a value adding fit between manufacturers and KIBS. Also, we provide a number of yet unresolved topics that deserve academic attention.Peer ReviewedPostprint (author's final draft

Give me a KIBS: Policy instruments mediating the relationship between service knowledge firms and sustainable manufacturing supply chains

In addition to product offering, the provision of advanced services is of growing importance for manufacturing businesses to maintain competitive advantage, a phenomenon best known as servitization. Mainstream servitization literature follows different approaches to describe the success of manufacturing companies in integrating services with their corporate clients. However, literature is still silent on how new manufacturing companies, which cannot internalize service offering, generate these services through Knowledge Intensive Business Service firms (KIBS). This research contributes to this literature stream by exploring how relevant industry characteristics—in our case, stock of manufacturing firms and total number of freights transported—mediate the relationship between KIBS and employment created by new manufacturers. By using multiple data sources—Global Entrepreneurship Monitor (GEM), Spanish Institute of Statistics and Eurostat—we created a panel data comprising information for the 17 Spanish regions for the period 2006-2012 to test the proposed hypotheses. The results strongly support the view that territories with a vigorous manufacturing business environment benefit from a virtuous circle which connects new KIBS and new manufacturers’ performance through the economic activity of incumbent manufacturing businesses. The work offers value insights for scholars and policy makers on how to implement specific policies that facilitate the interaction between manufacturing and KIBS businesses, thus fuelling territorial development.Peer ReviewedPostprint (published version

Product-service innovation systems—opening-up servitization-based innovation to manufacturing industry

The objective of this special issue is to produce theoretical and empirical work that provokes and fertilizes the scholarly debate on product-service innovation (PSI) systems, that is, the adoption of externalized service-augmented strategies by manufacturing businesses. With this end goal at the center of our priorities, we expect to advance our understanding of the connection between PSI and the innovation trajectories of manufacturers, as well as of the mechanics underlying external PSI systems in terms of their formation, evolution and performance.Peer ReviewedPostprint (author's final draft

Territorial Servitization: exploring the virtuous circle connecting knowledge-intensive services and new manufacturing businesses

The mainstream servitization literature mostly describes the success of manufacturing firms in integrating services for their corporate clients. However, the literature is relatively silent on how territories capitalize on the potential interconnectedness between manufacturing firms and the knowledge-intensive business service (KIBS) sector. The analysis of the outcomes that result from the mutually dependent associations between manufacturing businesses and KIBS firms, a process that we call Territorial Servitization, is of great relevance for academics and policy makers. This research hypothesizes that there is a positive symbiotic and bidirectional link between the growth in KIBS activity and employment generation by manufacturing sector start-ups. Furthermore, we scrutinize the mediating role over this relation of relevant industry characteristics, in our case the stock of manufacturing firms and the total number of freights transported. The empirical application considers a unique dataset created from multiple sources—the Global Entrepreneurship Monitor (GEM), the Spanish Institute of Statistics and Eurostat—for the 17 Spanish regions during the period 2006-2012. The results support the view that territorial servitization contributes to employment creation in manufacturing sectors. Territories with a vigorous manufacturing base benefit from a virtuous circle in which KIBS start-ups and newly formed manufacturers are connected through the economic activity of incumbent manufacturing firms. The study offers valuable insights for scholars and policy makers on how to implement specific policies—e.g., the development of digital infrastructures—that facilitate the interaction between manufacturing and KIBS businesses, thus fuelling territorial development.Peer ReviewedPostprint (published version

Conformance and performance roles of bank boards: the connection between non-performing loans and non-performing directorships

This study evaluates how non-performing loans and different types of board turnover—which we link to performing directorship (natural turnover) and non-performing directorship (forced turnover)—impact the economic performance (ROA) of banks. The proposed model and hypotheses, based on the conformance and performance roles of boards, are tested on a rich sample that includes all banking firms operating in Costa Rica between 2000 and 2012. The results indicate that the negative effect of non-performing loans on ROA is significantly greater in banks with non-performing directorship associated with high rates of unexpected changes in the board. The findings of this study highlight the importance of balancing financial and non-financial goals if superior governance and economic performance are the objectives pursued by organisations.Peer ReviewedPreprin

Análisis del estado de tensiones en uniones carpinteras de empalme de llave por el método de los elementos finitos

El objeto del presente trabajo es la determinación de la distribución de tensiones en la unión carpintera de empalme de llave mediante el método de los elementos finitos y su comparación con los valores obtenidos mediante la teoría de Resistencia de Materiales. Se analizan las zonas donde se produce concentración de tensiones y se estudia la influencia del refino de la malla sobre los resultados con el fin de determinar el tamaño que proporciona los valores de tensión más ajustados a la teoría. En las zonas donde la concentración de tensiones es menor, distintos tamaños de la malla muestran valores de tensión similares. Los resultados muestran una simetría central de la distribución de isotensiones donde el centro de simetría se corresponde con el centro geométrico de la unión. En las zonas donde se produce concentración de tensiones, los valores de las mismas aumentan considerablemente con el refino de la malla. La comparación de los niveles de tensiones normales obtenidos por el MEF y la teoría clásica muestran diferencias reducidas, excepto en los puntos de concentración de tensiones. The purpose of this study is to determine the stress distribution in the joint carpenter of halved and tabled joint with the finite element method and its comparison with the values obtained using the theory of Strength of Materials. The stress concentration areas where analyzed and the influence of mesh refinement was studied on the results in order to determine the mesh size that provides the stress values more consistent with the theory. In areas where stress concentration is lower, different mesh sizes show similar stress values. The results show a central symmetry of the isobar lines distribution where the centre of symmetry corresponds to the geometric centre of the joint. In areas where stress concentration occurs, the same values increase considerably with the refinement of the mesh. Comparison of normal stress levels obtained by the FEM and the classical theory shows small differences, except at points of stress concentration

The influence of sensor placement on in-situ ultrasound wave velocity measurement.

Ultrasound wave velocity was measured in 30 pieces of Spanish Scots pine (Pinus sylvestris L.), 90 x 140 mm in cross-section and 4 m long. Five different sensor placement arrangements were used: end to end (V0), face to opposite face, edge to opposite edge, face to same face and edge to same edge. The pieces were successively shortened to 3, 2 and 1 m, in order to obtain these velocities and their ratios to reference value V0 for different lengths and angles with respect to the piece axis for the crossed measurements. The velocity obtained in crossed measurements is lower than V0. A correction coefficient for crossed velocities is proposed, depending on the angle, to adjust them to the V0 benchmark. The velocities measured on a surface, are also lower than V0, and their ratio with respect to V0 is close to 0.97 for distances equal to or greater than 18 times the depth of the beam