Optimisation structurelle des gridshells

National audienceSee http://hal.archives-ouvertes.fr/docs/00/59/29/58/ANNEX/r_Z5N5TCL9.pd

Mapping two-way continuous elastic grid on an imposed surface: Application to grid shells

p. 989-998This paper presents a method to generate a grid shell on an imposed shape and imposed boundary conditions. The proposed method is done by mapping a two-way continuous elastic grid on an imposed surface using an explicit dynamic finite element method. An initially flat two-way grid, with free boundary conditions, is set up over a formwork like surface that has the desired shape. Then, the grid is dropped on the fixed surface. Moreover, different strategies of formfinding are presented and a comparison with other methods is done. Finally, many examples are shown to illustrate the proposed method.Bouhaya, L.; Baverel, O.; Caron, J. (2010). Mapping two-way continuous elastic grid on an imposed surface: Application to grid shells. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/696

Optimization of gridshell bar orientation using a simplified genetic approach

Gridshells are defined as structures that have the shape and rigidity of a double curvature shell but consist of a grid instead of a continuous surface. This study concerns those obtained by elastic deformation of an initially flat two-way grid. This paper presents a novel approach to generate gridshells on an imposed shape under imposed boundary conditions. A numerical tool based on a geometrical method, the compass method, is developed. It is coupled with genetic algorithms to optimize the orientation of gridshell bars in order to minimize the stresses and therefore to avoid bar breakage during the construction phase. Examples of application are shown

Des constructions innovantes en matériaux composites : Premiers prototypes de Grid Shells = Grid Shells in composite materials

National audienceLes grid shells sont des structures grille ayant la forme et la rigidité d'une coque à double courbure. Les composites sont des candidats idéaux pour ces systèmes. On s'intéresse dans notre étude à la recherche de forme de ces structures. Pour ce faire, un algorithme de relaxation dynamique a été implémenté sous Scilab™. Cela a permis la conception et la construction de premiers grid shells en matériaux composites. Une deuxième approche a été développée dans un logiciel d'éléments finis. Elle permet de générer une grille sur une surface à forme et contour imposés. Ceci est fait en maillant une grille bidirectionnelle élastique continue sur une surface imposée en utilisant une méthode d'éléments finis explicite. De nombreux exemples sont présentés pour illustrer la méthode

La traducció de manuals de congressos (anglès-català) : el cas del Gartner Symposium/ITxpo 2014 Barcelona

El present treball pretén ser una ajuda a tots aquells traductors que hagin de traduir un manual de congressos, de característiques similars al de l'empresa Gartner, que és l'objecte d'anàlisi en les següents pàgines. El present treball pretén ser una ajuda a tots aquells traductors que hagin de traduir un manual de congressos, de característiques similars al de l'empresa Gartner, que és l'objecte d'anàlisi en les següents pàgines. El present treball pretén ser una ajuda a tots aquells traductors que hagin de traduir un manual de congressos, de característiques similars al de l'empresa Gartner, que és l'objecte d'anàlisi en les següents pàginesEl presente trabajo pretende ser una ayuda a todos aquellos traductores que tengan que traducir un manual de congresos, de características similares al de la empresa Gartner, que es el objecto de análisis en las siguientes páginas. El presente trabajo pretende ser una ayuda a todos aquellos traductores que tengan que traducir un manual de congresos, de características similares al de la empresa Gartner, que es el objecto de análisis en las siguientes páginas. El presente trabajo pretende ser una ayuda a todos aquellos traductores que tengan que traducir un manual de congresos, de características similares al de la empresa Gartner, que es el objecto de análisis en las siguientes páginasThe present work aims to be a help to all those translators that ever have to translate a handbook with characteristics similar to the one of Gartner, Inc., that in this case is being analyzed. The present work aims to be a help to all those translators that ever have to translate a handbook with characteristics similar to the one of Gartner, Inc., that in this case is being analyzed. The present work aims to be a help to all those translators that ever have to translate a handbook with characteristics similar to the one of Gartner, Inc., that in this case is being analyze

Efficiency-based design of bending-active tied arches

[EN] Active bending is recently attracting considerable attention as a new paradigm to build lightweight structures both in research and practice. While there are many references dealing with form-finding methods for bending-active structures, the literature on their performance in relation to their shape and member proportioning is still scarce. This paper addresses the relationship between configuration finding and structural performance in bending-active tied arches: planar arches composed of a bent (active) rod, lower spanning cables and secondary struts that are joined to the rod and act as cable deviators. This simple bending-active arrangement allows to state key relationships between shape, proportion and performance. Starting from the fact that rod segments between struts behave as elastica segments, and selecting the mechanical slenderness of the rod as key parameter, scale-independent relationships between rise-to-span ratio, rod slenderness and stresses after activation have been established for a three-strut tied arch. The limitations posed by keeping stresses in cables after the activation within an acceptable range have been also addressed. Span-deflection ratios corresponding to Eurocode loads for the serviceability limit state have been obtained for a set of three-strut configurations using a non-linear structural model. Results have been represented in terms of rod slenderness, cable slenderness and rise-to-span ratio. The same procedure has been used to determine and represent proper utilization ratios for rod cross-sections in ultimate limit state. All the results have been combined to show the design space corresponding to the given constraints and to exemplify how to extract from it a suitable structural configuration. Finally, we explain how to extend the proposed method to design bending-active tied arches with an arbitrary number and proportion of deviators.The authors gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through grant BIA2015-69330-P (MINECO) and the support from CALTER Ingenieria and SOFiSTiK AG for providing a software license.Bessini, J.; Lazaro, C.; Casanova Colón, J.; Monleón Cremades, S. (2019). Efficiency-based design of bending-active tied arches. Engineering Structures. 200:1-11. https://doi.org/10.1016/j.engstruct.2019.109681S11120

Structural optimization of Gridshells

Le terme gridshell désigne une coque discrète qui est obtenue par déformation élastique d'une grille bidirectionnelle continue plane sans rigidité en cisaillement puis rigidifiée par une troisième direction de barres. Ainsi défini, un gridshell a un potentiel structural intéressant et peut répondre à des exigences architecturales complexes. La recherche de forme de ces structures a été menée à travers l'histoire principalement par deux méthodes, la méthode du filet inversé et la relaxation dynamique. Ces deux méthodes permettent d'obtenir une forme approchée de celle proposée par l'architecte, dérivant d'une grille à plat et de conditions aux limites partiellement ou complètement imposées. Dans le cadre de cette thèse, nous nous sommes intéressés à générer un gridshell sur une surface à forme et contours imposés. Un outil numérique se basant sur la méthode du compas a été développé. Il permet de mailler un réseau de Tchebychev sur une surface connaissant son équation cartésienne. Un autre outil permettant le maillage se basant sur un calcul en éléments finis explicite a été mis en œuvre. La particularité de cette technique est de pouvoir tenir en compte des propriétés mécaniques de la structure et de simuler le comportement du gridshell. Des applications des deux méthodes sur des formes architecturalement intéressantes ont permis de voir les limitations de la possibilité de mailler une forme avec un réseau de Tchebychev. La méthode du compas a ensuite été couplée à des algorithmes métaheuristiques types génétiques. L'algorithme résultant permet d'optimiser un gridshell en minimisant la courbure dans les barres et donc les contraintes dans la structure introduites lors de la mise en forme. Il a été mis en œuvre et testé pour plusieurs surfacesGridshells are often defined as structures that have the shape and rigidity of a double curvature shell but they consist of a grid and not a continuous surface. They are obtained by elastic deformation of a two-way grid initially flat. The deformed grid is then rigidified using a third direction of bars. Thus, a gridshell has an interesting structural potential and can respond to complex architectural requirements. Two methods have been used through out history for the form finding of gridshells, the inversion method and the dynamic relaxation method. Both techniques lead to a deformed grid which is a result of calculations. The form obtained is closed to the one proposed by the architect. A numerical tool based on the compass method is developed in this thesis. It allows mapping aTchebychev net on an imposed form and imposed boundary conditions.Another tool based on an explicit dynamic finite element calculationis proposed. The particularity of this technique is to be able to take into account the mechanical properties of the structure and to simulate the gridshell behavior. Applications of both methods on differents forms show the limitations of mapping a Tchebychev net on an imposed form. The compass method has been coupled with geneticalgorithms. The algorithm optimizes the gridshell by minimizing the curvature in bars in order not to break the bars during the construction. It has been implemented and tested on several surface

Optimisation structurelle des gridshells

Gridshells are often defined as structures that have the shape and rigidity of a double curvature shell but they consist of a grid and not a continuous surface. They are obtained by elastic deformation of a two-way grid initially flat. The deformed grid is then rigidified using a third direction of bars. Thus, a gridshell has an interesting structural potential and can respond to complex architectural requirements. Two methods have been used through out history for the form finding of gridshells, the inversion method and the dynamic relaxation method. Both techniques lead to a deformed grid which is a result of calculations. The form obtained is closed to the one proposed by the architect. A numerical tool based on the compass method is developed in this thesis. It allows mapping aTchebychev net on an imposed form and imposed boundary conditions.Another tool based on an explicit dynamic finite element calculationis proposed. The particularity of this technique is to be able to take into account the mechanical properties of the structure and to simulate the gridshell behavior. Applications of both methods on differents forms show the limitations of mapping a Tchebychev net on an imposed form. The compass method has been coupled with geneticalgorithms. The algorithm optimizes the gridshell by minimizing the curvature in bars in order not to break the bars during the construction. It has been implemented and tested on several surfacesLe terme gridshell désigne une coque discrète qui est obtenue par déformation élastique d'une grille bidirectionnelle continue plane sans rigidité en cisaillement puis rigidifiée par une troisième direction de barres. Ainsi défini, un gridshell a un potentiel structural intéressant et peut répondre à des exigences architecturales complexes. La recherche de forme de ces structures a été menée à travers l'histoire principalement par deux méthodes, la méthode du filet inversé et la relaxation dynamique. Ces deux méthodes permettent d'obtenir une forme approchée de celle proposée par l'architecte, dérivant d'une grille à plat et de conditions aux limites partiellement ou complètement imposées. Dans le cadre de cette thèse, nous nous sommes intéressés à générer un gridshell sur une surface à forme et contours imposés. Un outil numérique se basant sur la méthode du compas a été développé. Il permet de mailler un réseau de Tchebychev sur une surface connaissant son équation cartésienne. Un autre outil permettant le maillage se basant sur un calcul en éléments finis explicite a été mis en œuvre. La particularité de cette technique est de pouvoir tenir en compte des propriétés mécaniques de la structure et de simuler le comportement du gridshell. Des applications des deux méthodes sur des formes architecturalement intéressantes ont permis de voir les limitations de la possibilité de mailler une forme avec un réseau de Tchebychev. La méthode du compas a ensuite été couplée à des algorithmes métaheuristiques types génétiques. L'algorithme résultant permet d'optimiser un gridshell en minimisant la courbure dans les barres et donc les contraintes dans la structure introduites lors de la mise en forme. Il a été mis en œuvre et testé pour plusieurs surface

Simplified Environmental Study on Innovative Bridge Structure

International audienceThe aim of this paper is to present a simplified life cycle assessment on an innovative bridge structure, made of wood and ultra high performance concrete, which combines mechanical performance with minimum environmental impact The environmental analysis was conducted from cradle to grave using the Life Cycle Assessment method. It was restricted to energy release and greenhouse gas emissions. Assumptions are detailed for each step of the analysis. For the wood end-of-life, three scenarios were proposed: dumping, burning, and recycling. Results show that the most energy needed is in the production phase, which represents 73.4% of the total amount Analysis shows that the renewable energy is about 70% of the production energy. Wood, through its biomass CO2, contributes positively to the environmental impact. It was concluded that no scenario can be the winner on both impacts. Indeed, the end-of-life wood recycling gives the best impact on CO2 release, whereas burning wood, despite its remarkable energy impact, is the worst According to the emphasis given to each impact, designers will be able to choose one or the other

Structural Optimization of Gridshells

International audienceGridshells are often defined as structures that have the shape and rigidity of a double curvature shell but they consist of a grid and not a continuous surface. They are obtained by elastic deformation of a two-way grid initially flat. This paper presents a method to generate a gridshell on an imposed shape and imposed boundary conditions. A numerical tool based on the compass method is developed. It is then coupled with genetic algorithms to optimize the gridshell by minimizing the curvature in bars in order not to break the bars during the construction. Examples of application of this method are shown