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In the present paper, a study is conducted on building systems associated with concrete extrusion-based additive manufacturing techniques. Specific parameters are highlighted - concerning scale, environment, support, and assembly strategies - and a classification method is introduced. The objective is to explicitly characterise construction systems based on such printing processes. A cartography of the different approaches and subsequent robotic complexity is proposed. The state of the art gathered from the literature is mapped thanks to this classification. It appears that the disruption potential brought by concrete 3D printing has not been fully embraced yet

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International audienceThe design of free-form structures is governed by structural and geometric considerations, the latter ones being closely linked to the costs of fabrication. If some construction constraints have been studied extensively, the question of the repeatability of nodes in free-form structures has rarely been addressed yet. In this paper, a family of surfaces that can be optimized regarding typical geometrical constraints and that exhibit high node congruence is proposed. They correspond to particular meshes of moulding surfaces and are called isogonal moulding surfaces by the authors. The geometrical properties of these surfaces are discussed. In particular, it is shown how to derive Edge Offset Mesh from them. It is also demonstrated that they represent all the possible meshes parallel to surfaces of revolution. Finally, the reader is introduced to some computational strategies linked to isogonal moulding surfaces

The objective of this paper is to discuss the characteristics of a family of space structures that are referred to as 'nexorades'. Typically, a nexorade is constructed from scaffolding tubes, connected together with swivel couplers. An important application of nexorades is for shelters of various sizes and shapes for temporary or permanent purposes. In such a shelter, the structural skeleton is provided by a nexorade and the cover is provided by a membrane material

While plants are primarily sessile at the organismal level, they do exhibit a vast array of movements at the organ or sub-organ level. These movements can occur for reasons as diverse as seed dispersal, nutrition, protection or pollination. Their advanced mechanisms generate a myriad of movement typologies, many of which are not fully understood. In recent years, there has been a renewal of interest in understanding the mechanical behavior of plants from an engineering perspective, with an interest in developing novel applications by up-sizing these mechanisms from the micro-to the macro-scale. This literature review identifies the main strategies used by plants to create and amplify movements and anatomize the most recent mechanical understanding of compliant engineering mechanics. The paper ultimately demonstrates that plant movements, rooted in compliance and multi-functionality, can effectively inspire better kinematic/adaptive structures and materials. In plants, the actuators and the deployment structures are fused into a single system. The understanding of those natural movements therefore starts with an exploration of mechanisms at the origins of movements. Plant movements, whether slow or fast, active or passive, reversible or irreversible, are presented and detailed for their mechanical significance. With a focus on displacement amplification, the most recent promising strategies for actuation and adaptive systems are examined with respect to the mechanical principles of shape morphing plant tissues.

Gridshells are defined as structures that have the shape and rigidity of a double curvature shell but consist of a grid not a continuous surface. This study concerns those obtained by elastic deformation of an initially flat two-way grid. This paper presents a method 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 bar breakage during the construction phase. Examples of application are shown.Keywords: Gridshell, Formfinding, Compass method, Genetic algorithms. IntroductionGridshells are often defined as structures that have the shape and rigidity of a double curvature shell but consist of a grid rather than a continuous surface. In this work, they are obtained by elastic deformation of an initially flat two-way grid. This reduces the grid's shear stiffness allowing large deformations. The deformed grid is then rigidified using a third direction of bars or panels. A gridshell thus has interesting structural potential and can respond to complex architectural requirements. A dozen gridshells have been constructed Two methods have been used in gridshell formfinding, one experimental, the inversion method [5]; and one numerical, principally the dynamic relaxation method [6-7-8-9]. The inversion method is based on the assumption that the flexural stiffness of the grid elements is negligible. This method was used in the design of the Mannheim Bundesgartenschau gridshell in Germany, the first and largest timber gridshell ever built.The second method, the dynamic relaxation method, is a numerical tool that uses dynamic calculation to find the static equilibrium state of a mechanical system. The Downland museum gridshell in the United Kingdom and the two prototypes of gridshell in composite materials at the Ecole des Ponts ParisTech were designed using this method. Both techniques, the inversion method and the dynamic relaxation method, lead to a deformed grid through calculation. The shape obtained is close to the one proposed by the architect but is difficult to control. These methods are described in the first part of the paper.In this paper, the first aim is to focus on the generation of gridshells on an imposed form and under imposed boundary conditions. By definition, mapping a gridshell on a form is equivalent to drawing two-way parallel and equidistant curved axes, i.e. parallelograms, on the surface. Mathematically speaking, those nets are called Tchebychev nets [10][11]. The problem is very similar to that encountered with fabric draping. Among the methods used for composite forming, a geometrical method, the fishnet algorithm, was introduced by Van Der Waëen [12]. Other mechanical approaches are described by Boisse in [13][14]. A method for mapping a two-way elastic grid using finite element simulations was inspired from those approaches and was introduced previously in [15].A geometrical me...

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