Reciprocal Frame (RF) Structures are three-dimensional grid structures consisting of mutually supporting beams, where no more than two beams are connected at a time adding to simplicity of assembly and construction. The ReciPlyDome is a novel structural system based on utilizing bending-active principles and combining them with RF polyhedral morphologies and simple connections. The result is a lightweight plywood kit-of-parts dome, fabricated from flat plywood panels, cut and pre-bent to form the active-bent dome structure designed for disasembly. ReciPlySkin is a step further in the development and is a partially enclosed shelter structure clad with a membrane attached internally to the plywood beams of the ReciPlyDome. Building on the work already done on RF emergency shelters, this paper describes the ReciPlyDome and ReciPlySkin governing principles in the context of transformability. It presents the challenges and opportunities of these structures outlining the methods and process needed for their development. More specifically the investigation, design, optimization, fabrication and construction process of a full-scale dome demonstrator exhibited at the recent Circular Economy exhibition in Denmark, are shown. A reflection on how to develop the principles further is offered with some further research and design directions identified. Lastly, possible applications are also discussed.@en

Bending-active reciprocal structures consist of elastically bent beams in a mutually supporting weave pattern in which each connection joins only two beams. Aside from the advantages for fabrication and assembly, this system has an extensive geometric potential, allowing reuse and reconfiguration. However, the load-bearing behaviour of these structures is limited by the required flexibility of the components. This paper discusses the impact of geometric parameters on the stiffness of bending-active reciprocal geometries for two cases: single-layered domes and double-layered components. It concludes by illustrating the use of the double-layered component for the development of a kit-of-parts structure: the ReciPlyDome. Thanks to the elastic capacity of the components and the very simple connections, the ReciPlyDome can be very easily and rapidly assembled and manufactured. This in contrast with the high technical complexity of many other kit-of-parts or grid structures. The analyses underline the importance of the form-force relationship when developing bending-active reciprocal structures and show the potential of active bending for the development of pre-assembled beam components. This research is framed within the wider scope of developing lightweight, transformable and temporary structures.@en

While transformable structures allow rapid assembly, reuse and reconfiguration, their technical complexity and related production or cost issues often hinder architectural application. Yet, vernacular or nomadic structures, like teepees or yurts, show how reversibility and transportability can be achieved with low-tech structural systems. The project presented in this paper is part of a broader research that investigates how material understanding and manipulation through elastic deformation can contribute to the development of low-tech and rapidly assembled kit-of-parts structures. More specifically, the ReciPlyDome project combines the concepts of bending-active and reciprocal structures. The parametric design and modelling of the system are based on regular polyhedra to guarantee uniformity and allow reconfiguration of the components. While this works from a design perspective, the structural performance is limited by the flexibility of the components. Therefore, we developed a double-layered component to increase the structural height and improve the stiffness of the structure. Preliminary FEM analyses provide assessment of this layering and stress stiffening, i.e. the stiffening effect of the residual stress. A full-scale prototype illustrates the rapid and low-tech manufacturing and assembly process. Through design, analysis and finally construction, this project illustrates the potential of active-bending in developing more low-tech and rapidly assembled structures.@en

As mutually supported beam structures, reciprocal frames limit the number of components that are joined at each connection to two. However, this system of intermediate connections introduces undesirable bending moments in the beam elements. By utilising elastic deformation to create curved geometries, bending-active structures show the potential of bending as a formation process. Moreover, the curved geometries showcase an increased resistance to bending. Despite the apparent potential, only a few geometric explorations of bending-active reciprocal structures exist. Therefore, we investigated the principle by developing a design methodology based on polyhedral shapes. As this work is part of a research on transformable, rapidly assembled structures, the focus lies on simplicity of the connections, uniformity of the components and reconfigurability. This paper discusses the development of a kit of parts of reciprocal bending-active components based on a selection of polyhedral dome types. To simplify the assembly of the structures and avoid the manual bending of the components on site, we introduce the concept of a double-layered, pre-bent component. Finally, this paper presents the development, fabrication and assembly of the ReciPlyDome, a full-scale prototype of a bending-active reciprocal dome with double-layered components. Preliminary analyses of the load-bearing behaviour show the potential of these systems for material-efficient, lightweight structures. The research presented in this paper contributes to the understanding of bending-active reciprocal frames as a structural principle for temporary and rapidly assembled structures.@en

Curved-line folding is the act of folding a flat sheet of material along a curved crease pattern in order to create a three-dimensional shape. It is a creative and innovative way to produce lightweight and geometrically stiff components using only sheet materials. The pavilion presented in this paper integrates this principle in a kit-of-parts system. After being cut out of flat plates, the components get their 3D shape by folding them along a set of predefined curved lines. This deformed geometry, variable in its degree of bending, results in a structurally efficient ‘building block’ that can be combined into different structural configurations depending on its mode of assembly. The components form a weave pattern by connecting them ‘flap to leg’ respectively. As such, adjacent components lock each other into their rigid three-dimensional configuration and a modular shell structure is obtained. When composed of identical components, the obtained structure combines the advantages of rapid fabrication and assembly with an extensive reuse of components. However, the pavilion demonstrates that more geometrically and aesthetically challenging compositions, consisting of a series of custom-made components, are also possible and manageable when using digital fabrication techniques. Furthermore, this paper presents and discusses the digital modelling methods used for the design of the pavilion, as well as the lessons learned by real scale fabrication and assembly.@en

Living in an age of rapid changes, designers are challenged to create solutions that remain sustainable in a continuously evolving environment. Since most of our earth's resources are finite, these solutions should incorporate efficient material use and reuse. Buildings and structures are always in transition. Facilitating these transformations is vital to the sustainable development of our built environment. With our group we study, develop and assess transformable structures on different scales, in different contexts and for various time-spans and purposes. This paper presents our work on transformable structures, based on four case studies: a kinetic curved-line folding component, a temporary and rapidly assembled structure, a dynamic wall assembly and a BIM tool for material flow assessment of adaptable buildings. Although varying in scale or purpose, these cases demonstrate the same key principles of transformability. Reducing the complexity of the connections and structural system facilitates an easy and rapid assembly, but also allows users and locals to participate in the assembly, maintenance, reconfiguration and deconstruction of the structure. Apart from benefits during the assembly and adaptability, it is important to assess transformable structures and building solutions on their material and cost effectiveness. With BIM tools it is possible to incorporate this assessment already in the conceptual design phases of a project, as illustrated in the fourth case.@en

In the event sector, where there is a search for architectural constructions with an innovative morphology, reuse is key to strive towards more sustainable events. Designing modular structures and detailing them for easy disassembly and re-assembly is an ideal way to encourage and facilitate reuse. This way a longer lifespan is assured for the used components. However, temporary (event) structures are often hard to assemble, which can compromise their reusability. The difficulties of assembly are usually induced by the morphology of the modules or by using certain types of connections. Therefore these structures require optimization in terms of assembly while remaining resource efficient. The main objective of this research is to reimagine a developed structure, the ReciPlyDome, and optimize it in terms of assembly. The ReciPlyDome is a reciprocal dome structure based on a rhombic triacontahedron, whereby all elements are identical (except for the five elements that touch the ground). During the assembly phase of the first version of the ReciPlyDome, torsion in the components appeared to hinder efficient construction. To eliminate this, the dome was reviewed, which led to the development of a new connection system and an improved shape for the beams. A new full-scale version of the dome has been built, showing the positive effect of the improved connection system and the optimised beam position. In-situ measurements were made after construction, illustrating good correspondence between the digital and built model. Further research will focus on the covering of this modular reciprocal dome for outdoor use.@en

In a dynamic context of rapidly evolving user needs, transformable structures anticipate and respond to changing demands in minimal time, with minimal effort. Innovative structural concepts should supplement the design of transformable structures to increase their structural and functional efficiency. Therefore, we defined transformable active bending as a combination of the principles of mobility and rapid assembly of transformable structures, and the utilisation of bending deformations in bending-active structures. Although it is the availability of state-of-the-art design modelling techniques and structural modelling tools that facilitate design exploration and form-finding of bending-active structures, accurate modelling of the complex relation between their geometry and bending behaviour remains challenging. This paper presents two principles for the design of transformable bending-active structures, respectively based on design for disassembly and deployability. Furthermore and illustrated by two case studies the paper introduces two digital modelling techniques. Further research on transformable bending-active structures will focus on their realisation and structural performance.@en

Utilising the inherent elasticity of their flexible components, bending-active struc-tures can easily be produced from planar or linear components. Although the components and their fabrication can be very simple, the deformation behaviour is often complex and can result in complex structural geometries. Parametric tools allow modelling such geometries by including material properties and behaviour early on in the design process. While this can potentially lead to an entirely new structural and morphological design vocabulary, functional requirements often demand regularity and compatibility from the structure and its components. This paper presents an approach for the development of bending-active kit- of-parts systems. Consisting of regular sets of identical or compatible components, these systems generate apparent geometric complexity though very simple geometric patterns and component connectivity. The resulting structures are reconfigurable and can be adapted to multiple uses, locations and spatial requirements. Theoreti-cal insights are supported by two applied cases: reciprocal bending-active structures and kinetic curved-line folding structures. Both use the flexibility of their components to develop structural diversity through a simple geometric system. Illustrated by two built structures, these cases show how a well- integrated design that considers manufacturing and assembly can lead to an efficient construction process. Moreover, using reversible connections, the structures allow reuse and even reconfiguration.@en

In a context of rapid changes, resource depletion and augmenting waste production, transformable structures facilitate reuse on a structural and component level. Increasing the transformational capacity of spatial structures enables speed and ease of erection and lowers the stacking volume during transportation. Thanks to its unique ability to use structural members under different curvatures and return bent elements to their initial straight or planar geometry, active bending has the potential to expand the existing morphology of transformable structures. Therefore, the authors defined ‘transformable active bending’, integrating high bending deformations in the kinematic systems of transformable structures and thus complementing the transformational capacity of the structure with a bending transformation of the components. However, active bending is essentially a structural principle. Therefore we conducted a parameter study to assess the structural behaviour of a bending component under different curvatures. This paper presents the results of this study along with the case of a bent scissor-arch that illustrates the potential applicability of transformable active bending in mobile architectural applications. The study shows that a range of curvatures exists in which active bending components are structurally efficient, thus allowing transformation or reconfiguration. The kinematic concept thus allows application in structural systems, which will be developed in the scope of future research.@en