El pasado 14 de enero, se reunió en la Escuela de Ingenieros Agrónomos de la Universidad Politécnica de Madrid el tribunal designado para evaluar la tesis doctoral desarrollada por D. Jorge Fernandez-Lavandera y dirigida por D. José Luis Fernández Cabo. Dicho tribunal estuvo compuesto por los siguientes miembros:
- Presidente: D. Ramón Argüelles Álvarez
- Secretario: D. José Miguel Ávila Jalvo
- Vocal: D. Manuel Guaita Fernández
- Vocal: D. João Henrique Jorge de Oliveira Negrão
- Vocal: D. Javier Benlloch Marco
Tras la presentación de la tesis y responder a las cuestiones planteadas por los miembros del tribunal y el numeroso público presente, el tribunal, tras unas breves deliberaciones decidió otorgar a D. Jorge Fernández-Lavandera, el título de Doctor con el grado máximo que contempla la legislación académica, Cum Laude.
Ciete S.A. en su estrategia de fomento de la I+D+i, ha apoyado siempre a los miembros de su equipo para el desarrollo de labores de investigación por lo que felicitamos a D. Jorge Fernández-Lavandera por la consecución de este gran logro que dignifica y llena de orgullo a toda la organización.
Abstract of Ph. D. Thesis "Composite structure with timber: efficiency with flexible connection"
The work is oriented to the composite structure with timber, and especially to the case of timber-concrete composite beam; even though most of the content can be generally applied.
The typical connection systems used in the timber composite beams are flexible, i.e. there is a slip at the connection. This slip influences the overall structural behavior, and leads to a reduction at the composite effect.
The work covers the next general goals: conceptual revision, analytical models, the study of the main parameters which control the efficiency and compilation of the simplified model for the professional practices.
The used procedures are analytics, within the context of first order theory. Conceptually, the simple bending is isolated as the unique state bounded by the connection, and the ways for understanding its behavior is proposed. On this basis, a model considering the gap between pieces, a variable arrangement and a non-linear behavior of the connection, and the moisture/temperature induced stresses, is presented.
The behavior with flexible connection is addresses on basis of the structural efficiency, considering as reference point the upper and lower bounds; i.e. the state with a completely stiff connection and the case without connection.
It is considered a typical arrangement at the connection system, at least uniform in part of the beam. If the separation of the connection is fixed at its minimum, they offer the maximum stiffness, the threshold for its use.
A model of direct application is used for the case of uniform separation of the connection, which favors the study of its efficiency. This is a practical tool for searching the key parameters that control the preliminary design of the beam.
The efficiency is controlled only by two non-dimensional parameters, and the simple analytical relationship is shown. Moreover, for most of cases, only one of these parameters is needed. The equations show that, on basis to these non-dimensional parameters, it exists a point from where a increase of the connection does not mean a gain in the efficiency, a key concept for the preliminary design.
A first analytical continuous model is after extended for developing the stiffness matrix of a composite beam element; reflecting then the same two non-dimensional parameters. The matrix is arranged as typically in the matrix analysis of beams, but using a degree of freedom for the slip at the connection, and separating the state with pure axial force without the influence of the connection. A simple and an approximate relationship are offered; the last one connected with the parameters used at the annex B of the Eurocode 5.
The question of long term deflection is not still a closed item at the research field. The used model at the standards is a notably simplification. A protocol is proposed according the current state of art.
A effort was made for transferring information from the research to the professional field. This way, a state of art of the current connection systems is presented, as also recommendations for the design and construction. This is scattered information, which compilation was needed. A personal professional experience was important for filtering and arranging the information.
The work allows the use of different models for future additional needed works, both at the theoretical and empirical field.
Acerca de D. Jorge Fernández-Lavandera
D. Jorge Fernández-Lavandera es ingeniero agrónomo por la Universidad Politécnica de Madrid desde el año 1988. Es especialista en ingeniería rural, estructuras, obras hidráulicas y estudios del medio físico. Su carrera profesional ha estado ligada siempre a Ciete S.A. aunque ha realizado numerosas colaboraciones docentes y científicas.