Manuel Guaita

• Professor
• Managing Director at University of Santiago de Compostela

Engineered wood product (EWP) offers an improvement in performance and mechanical properties over the use of sawn timber. This is mainly due to the fact that these products can eliminate defects such as knots, splits, etc. The removal of these defects has been achieved through the development of the finger-joint technique. This technique makes it p...

In timber structures, knowledge of the splitting capacity of beams loaded perpendicular to the grain by dowel-type connections is of primordial importance since brittle failure can occur. In the present work, single-and double-dowel-type connections following different loaded edged distance arrangements are experimentally investigated to derive the...

Elastic timber gridshells are lightweight structures whose stiffness is highly dependent on multiple factors, such as boundary conditions and the semi-rigidity and eccentricity of the joints. Their structural analysis requires calibrated numerical models that incorporate all aspects influencing stiffness. Unfortunately, very little research on expe...

The design of gridshells always requires an iterative process between architecture and engineering with accurate adjustment of different parameters from early stages, which causes a great deal of effort. This paper presents five parametrized generative algorithms developed in Grasshopper® which integrate and provide, in real time, essential informa...

The use of rounded dovetail connections has gained popularity in timber floor and ceiling structures due to the advance in computerized numeric control machinery. However, European building regulations for fire safety in timber structures from Eurocode 5 standard does not provide a specific method to calculate the fire performance of this kind of c...

Many buildings in Spain constructed with "pitch pine" beams are, nowadays, under rehabilitation processes. In some cases the decision on maintaining, or not, the existing timber structure is a key issue. The commercial name "pitch pine" comprises several species in the group of Southern Yellow Pines, being the "Longleaf pine" or "Georgia pitch pine...

This work establishes the main guidelines to produce high-performance Eucalyptus globulus Labill fingerjointed solid timber and glued laminated timber laths and analyse their potential for application in mul-tilayer strained gridshells. To this end, a proposal for strength grading of eucalyptus solid timber is firstly provided, combining visual and...

Eucalyptus globulus Labill stands out as one of the hardwood species produced in Europe with prominent mechanical properties, which is undergoing a growing interest in extending added value. The development of engineered wood products with this species and its application in timber structures involving numerical finite element simulations requires...

Roof structures comprising of heavy timber trusses and purlins made of glued laminated timber, as well as dowels and metal plates used as mechanical joints, are widely employed, among others, in agro-industrial settings that require large open areas. This paper presents the economic optimisation of such roof structures through the use genetic algor...

The objective is to promote sustainable construction through the use of natural low embodied energy materials. It explores the potential of local species with high mechanical performance such as Eucalyptus globulus to be used in shell structures made with elastically curved laths. The project and construction of the eucalyptus triaxial gridshell...

The objective is to promote sustainable construction through the use of natural low embodied energy materials. It explores the potential of local species with high mechanical performance such as Eucalyptus globulus to be used in shell structures made with elastically curved laths. The project and construction of the eucalyptus triaxial gridshell...

Elastic timber gridshells are built by bending small cross-section, long and good quality timber laths on site to the desired shape. This procedure enables double curvature structures of great aesthetic appearance and high structural efficiency. Despite their interest, few structures of this type have been built since the first realizations due to...

En este trabajo se presenta una visión general de los objetivos y acciones planteados en el proyecto Life Lugo+Biodinámico. El foco de atención se centra en aquellas acciones destinadas a desarrollar productos estructurales de madera con especies forestales gallegas y su aplicación en proyectos de edificación. En particular, se presentan los trabaj...

This paper presents a new elastic timber gridshell built to cover a wood storage area at the Timber Engineering Laboratory of the University of Santiago de Compostela in Spain. It is the first permanent elastic timber gridshell to be built in the country and the first in the world to be made of Eucalyptus globulus Labill. It includes various novelt...

The double-step joint is among the most frequently used layouts, within carpentry joints, for transmitting higher forces that would allow a single notch. They are especially effective in heavy timber structures. Nowadays, computer-aided manufacturing is being used more often, demanding further progress in its understanding. The conventional design...

Timber lattice shells are multi-layered structures of great interest for medium and long span lightweight solutions in structural and aesthetic terms. They are constructed by bending initially straight laths. This curving process can lead to high initial stresses in the laths and the possibility of overstressing under service loads. However, these...

This paper presents a new elastic timber gridshell that has been built to cover a wood store facility at the Timber Engineering Laboratory of the University of Santiago de Compostela. It is the first permanent elastic timber gridshell built in Spain and the first worldwide made with Eucalyptus globulus L. It comprises various novelties for timber g...

The prediction of the fracture behaviour through reliable and practical criteria in the design of structural timber elements and connections has become of great importance and demands a proper fracture characterization of the material. Eucalyptus globulus Labill is envisioned as a hardwood species with great potential for high performance structura...

Dispositivo para ensayos de relajación de tensiones a flexión en láminas de madera curvadas con radio constante. La presente invención se refiere a un dispositivo que permite la realización de ensayos de materiales y estructuras. El dispositivo comprende una estructura soporte (102); una pareja o más de elementos de sujeción y curvado (104) de lámi...

In this paper, the finite element method (FEM) is used in order to develop a simulation of the mechanical performance of timber rounded dovetail connections between joists and beams under a fire event. The simulation is developed using the commercial FEM software ANSYS, and it is validated using the results of several experimental tests. These expe...

Early selection of trees allows acceleration of genetic improvement, as well as processes related to forest management, to improve the quality of the wood produced; however, to reach this objective, it is necessary to know which parameters can be used as predictors of a tree’s aged condition. The objective of this research was to study parameters t...

Traditional notched joints can be used in timber structures to connect two structural parts under compression loads that concur at a somehow diagonal angle. They can be used to connect the top-chord and the tie-beam of timber trusses, which have been widely in use as roofs in buildings, agricultural and industrial service constructions. Computer-ai...

The design of engineering high value-added products and timber structures analysis requires reliable elastic characteristics related to a theoretical model that describes the elastic behavior of wood material. The present research focuses on determining the elastic constants of Eucalyptus globulus Labill., which allow their implementation as input...

Timber gridshell structures get their shape by curving on site initially straight timber laths. This curving process produces stresses in the laths that can easily reach values close to the allowable ones. These initial bending stresses are partially reduced over time due to the rheological behavior of the material. This phenomenon, known as stress...

Eucalyptus globulus is one of the hardwood species growing in Europe with the best mechanical properties and great natural durability. In high performance engineered laminated products, finger-joints play a key role. The aim of this research is developing high strength finger-joints of eucalyptus using 1C-PUR adhesive. The influence of geometric an...

The aim of this study is to obtain the elastic constants of Eucalyptus globulus Labill required for any numerical model. Two methods were used for this: the propagation of ultrasound waves and mechanical compression tests. The same test specimens were used in both procedures and no significant differences were found. The elastic parameters obtained...

The present research focus on the performance of finger-joints for the development of novel engineered laminated products made of Eucalyptus globulus using 1C-PUR adhesive type I suitable for outdoor use, taking the advantages of the high mechanical properties and great natural durability that this species offers. The influence of the elastic modul...

This paper presents the optimisation by genetic algorithms of the members and joints of heavy timber trusses fastened by mechanical joints with dowels and metal plates. This is achieved by programming in Matlab twenty-four elitist genetic algorithm models which, in combining different variables, provide an estimate of the geometry of the truss, the...

The stress distribution of timber tenoned scarf joint subjected to tension force was analysed by means of finite element method. This analysis was compared and validated with results from an experimental work on 42 specimens of Scots pine wood (Pinus sylvestris L.) with 48 × 148 mm in cross-section and 1932 mm, in length, manufactured with a tenone...

The structural behaviour of halved and tabled tenoned scarf joint subjected to tensile stresses was experimentally analysed to find the different failure modes. A total of 42 specimens of Scots pine wood (Pinus sylvestris L.) were made. Specimens were divided into 8 groups corresponding to different joint geometries. Three different failure modes w...

Traditional diagonal front notched timber joints can be used in timber structures to connect two structural parts under compression loads that concur at a somehow diagonal angle. For example, they can be used to connect the top-chord and the tie–beam of traditional timber trusses, which have been widely in use as roof in hangar and agricultural ser...

The goal of this paper was to analyze the mechanical properties of Castanea sativa determined using an ultrasonic wave method. The results were compared with those obtained using the traditional static compression and bending methods with the same sample. The results were also compared with expected values for this species, and relationships betwee...

The influence of different types of knots and fiber deviations on the bending of wood, as managed using visual grading standards, was analytically discussed in this research by means of the finite element method. The effect of each geometrical variable on the strength and stress distribution has been studied individually. This was accomplished afte...

In 2011 the collapse of one of the timber pillars that form the structure of the centuries-old warehouse of maceration that the firm "Bodegas Bilbaínas, S. A." helds in the town of Haro (La Rioja), occurred.This paper describes the most significant pathological processes existing in this nave, associated mainly to its wooden components.Then, accord...

Bending strength, modulus of elasticity and density were obtained for 981 specimens of Spanish Sweet Chestnut (Castanea sativa Mill.) sawn timber from 5 provenances. Four-points bending tests were made three sizes (40x100x2500, 40x150x3500 and 70x150x3500 mm) according to EN 408 (CEN EN 408:2011).Visual grading criteria were established, resulting...

Background Pinus pinaster Aiton, Pinus radiata D. Don and Castanea sativa Mill. are the main timber species in Asturias. Intensive forest management, including pruning and thinning allows to produce higher value wood products. However there is little knownledge about the influence of both silvicultural treatments on the timber properties of these s...

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The finite element method was used to investigate the influence of size and position of cylindrical knots on load capacity considering the elasticeplastic constitutive law of Scots pine timber. A finite element model for a four points bending test was generated considering four different knot conditions in the beams: without knot; knot as a hole; l...

The purpose of this study is to determine the stress distribution in the carpentry joint of halved and tabled scarf joint with the finite element method (FEM) 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 re...

Linear regression models were constructed for chestnut beams of Spanish origin (Asturias, Galicia, Catalonia and Extremadura) using the global modulus of elasticity (MOE g ) and bending strength (MOR), both obtained by destructive tests, as dependent variables, and the results of non-destructive measurements, visual grading parameters and density a...

The objective of this paper is to develop a twodimensional numerical model to simulate the response of Scots pine (Pinus sylvestris L.) defect free timber members in order to predict the behaviour of these members when subjected to external forces. For this purpose, data of the mechanical properties of Scots pine were obtained by performing experim...

This article presents a three-dimensional wood material model implemented in finite element (FE) software which is capable of predicting the behavior of timber at the macro-scale taking into account the effect of any type of knot. The model was built in Ansys using the ansys parametric design language, such that the whole simulation process, includ...

This paper presents 64 different deterministic approaches and criteria to predict the failure load in mesostructrally heterogeneous models of wood. The knots and the grain deviation can generate singular stress concentrations in wood as the notches or the cracks would do it in fracture mechanics. The average stress approach proposed by Landaelius a...

In this research it is proposed a 3D material model for simulating the behavior of wood at macroscale when considering the effect of the mesoscale in terms of the knots and grain deviation. The fibre deviation was estimated by applying the theory of the flow-grain analogy in 3D around the real complex shape of the knots, and regardless of the finit...

A finite element model was used to simulate timber beams with defects and predict their maximum load in bending. Taking into account the elastoplastic constitutive law of timber, the prediction of fracture load gives information about the mechanisms of timber failure, particularly with regard to the influence of knots, and their local grain deviati...

RESUMEN La madera de castaño de procedencia española no está presente como material estructural en la norma europea EN 1912, y por lo tanto no está asignada a ninguna clase resistente como sí lo están otras especies españolas. Por ello, en el presente trabajo se realizó una caracterización de madera aserrada de castaño de Asturias con fines estruct...

En el presente trabajo se desarrolla una metodología para poder determinar los coeficientes de fricción tanto estático como dinámico aplicable a diferentes especies de madera. Para desarrollar dicha metodología se utilizan las instalaciones que posee la Plataforma de Enxeñería da Madeira Estructural (PEMADE) donde hay una mesa que permite la realiz...

La simulación numérica de cualquier material requiere del conocimiento de sus propiedades. En el caso de las uniones tradicionales, el coeficiente de rozamiento del material es fundamental en el comportamiento de la misma y habitualmente su valor es tomado de bibliografía de referencia. En el presente trabajo se diseñó un ensayo de determinación de...

En situación de incendio, los elementos estructurales de madera laminada encolada (“MLE”) sufren una degradación térmica que les lleva a una pérdida de sección portante. El Código Técnico de la Edificación cuantifica esta pérdida en 0,55 - 0,70 mm/min por cada cara sometida a carga, según especie y densidad, pero no propone una metodología específi...

RESUMEN En el presente trabajo se desarrolla una metodología para poder determinar los coeficientes de fricción tanto estático como dinámico aplicable a diferentes especies de madera. Para desarrollar dicha metodología se utilizan las instalaciones que posee la Plataforma de Enxeñería da Madeira Estructural (PEMADE) donde hay una mesa que permite l...

This is the project of a suspension footbridge over the Ulla River. It has a span of about 36 meters. The beauty of the natural surroundings where it is located guided the design to the option of a clear and simple proposal with the aim of achieving an integrated project for the area. The footbridge tries to be as invisible as possible with the pur...

The present research has developed a specific finite element model using ANSYS software that simulates timber beams with defects and predicts its maximum load in bending. This model predicts the fracture load, which gives information about the mechanisms of timber failure, particularly with regard to the influence of knots on the fracture. The comm...

This paper presents an analysis of carpentry joints between structural timber members based on numerical simulation. In conventional design, simplifying assumptions of the stress distribution and the transmission of forces on the contacting surfaces are made, and the effect of contact friction between surfaces is neglected. Whereas a number of auth...

A three-dimensional finite element analysis was made of the filling of cylindrical silos having an eccentric hopper, using different boundary conditions—silos supported at the transition or on discrete columns. The analysis included the options of the presence or absence of reinforcement in the transition and walls. The results for the pressures on...

This paper presents a finite-element-based analysis of carpentry joints between structural timber members. Currently, the design of these joints is conducted by using simplifying assumptions of the stress distribution and of the distribution of forces on the contacting surfaces, and neglects the effect of contact friction between surfaces. Such unr...

This work presents the simulated filling of two cylindrical silos, one with a concentric hopper and the other with an eccentric hopper, both with flexible walls supported on columns. The results showed that, for both types of hopper, the presence of columns led to local increases in pressure just above the junction of the cylinder and hopper, and d...

The influence of hopper eccentricity on silo discharge has always concerned researchers. Eccentric discharge brings about asymmetries in the distribution of normal pressures, the values of which are not known with precision. This study presents a three-dimensional model of the dynamic discharge of a silo with an eccentric hopper, considering the Dr...

The use of numerical methods in the design of silos requires properties that describe the behavior of materials that are commonly stored in silos. Variations in the values of these parameters can result in the risk of failures in this type of structure. Because of the lack of existing data in the literature, the goal of this research was to: (1) pr...

This study presents a model for the analysis of silo discharge with the finite element method. The proposed model incorporates the Drucker-Prager plasticity model, a metal wall, and surface-to-surface contact using a dynamic analysis. This study reports the results obtained for discharge from a silo with a flexible wall and compares these results w...

Few models simulate the discharge of flat-bottom silos by using finite elements. This paper presents a new dynamic model for silo discharge using the Drucker–Prager plasticity model. The model was used to study discharge in mixed flow and mass flow silos with rigid walls. Various silos were analysed, and pressures under different flow patterns were...

The objective of this work was to perform an analysis of pressure distributions in grain silos both for the discharge and for static conditions. To this end a model based on the finite element method (FEM) was employed. In this paper, we present results for a cylindrical silo with rigid wall, Drucker- Prager material criterion and surface-to-surfac...

This paper presents a new dynamic model for silo discharge using the Drucker-Prager plasticity model, surface-to-surface contact and flexible wall. Results were compared with Eurocode 1 – part 4 actions in silos and tanks, which is the standard used in the European Union. Overpressure coefficients due to discharge were obtained in all cases. The re...

One of the main causes for failure in grain silos is due to the excessive pressures exerted on the silo wall during discharge. Within traditional theories, several attempts have been made to obtain mathematical expressions reflecting the overpressures produced due to eccentric discharge. These start from the calculation of pressures in a concentric...

Traditional methods for silos design just took into account some material properties such as the angle of internal friction, the grain to wall friction coefficient and the specific weight. Currently some of these methods are still commonly applied in different international silo design standards. However, with these methods it was not possible to a...

The objective of this work is to perform an analysis of pressure distributions in grain silos subjected to thermal effects. To this end, the commercial ANSYS program, based on the finite-element method is employed. Changes in the temperature along the silo walls produce dilatations and contractions, which cause variations both in the wall stresses...

The objective of this work is to perform an analysis of pressure distributions in grain silos for both the discharge and static conditions with eccentric outlets. To this end, the commercial ANSYS program, based on the finite-element method is employed. In this paper, results are presented for a silo with a height of 10.5 m (cylinder height 8 m, ba...

At the European level, silos are considered under the European Standards (Eurocode 1, Part 4. Actions in si/os and tanks), with no proposed method of calculation in the case of an eccentric outlet. The guidelines include a brief mention that eccentricity should not exceed 25% of the silo diameter and that in the future, attempts will be made to cov...

Different finite element models for axisymmetric silo analysis, that simultaneously considers the behaviour of the grain and the structure, are proposed in this paper. The use of commercial programmes and integration of modern theories on pressures exerted by grain are the main premises of the research. The paper presents models for both the static...

At the European level, silos are considered under the European Standards (Eurocode 1, Part 4. Actions in si/os and tanks), with no proposed method of calculation in the case of an eccentric outlet. The guidelines include a brief mention that eccentricity should not exceed 25% of the silo diameter and that in the future, attempts will be made to cov...

El nuevo Eurocódigo 1, parte 4, supone un gran avance en los métodos de cálculo de acciones del material ensilado en Europa y en España. Sin embargo, presenta aún limitaciones que deben corregirse, para lo cual resulta imprescindible incorporar los hallazgos realizados por los diferentes equipos de investigación que en todo el mundo trabajan para u...

New Eurocode 1, part 4, supposes a great advance in the calculation methods of actions of silaged materials in Europe and Spain. Nevertheless, it still displays limitations that must corrected, for which is essential to incorporate the findings made by the different research groups, which work for a better understanding of the behavior of silaged m...

Conventional approaches for the analysis of foundations consider the soil as an elastic material, without any consideration of plastic behavior or friction. Nevertheless, it is widely accepted that this is an over-simplification. In this paper, non-linear models were developed using finite element methods, and considering soil-footing interactions...

Conventional approaches for the analysis of foundations consider the soil as an elastic material, without any consideration of plastic behavior or friction. Nevertheless, it is widely accepted that this is an over-simplification. In this paper, non-linear models were developed using finite element methods, and considering soil-footing interactions...