Niels De Temmerman

Scissor-hinged retractable membrane structures

This paper introduces scissor-hinged retractable membrane structures, a system for retractable membrane roofs that require a fully retractable supporting structure and multiple stable roof-configurations. A vaulted, foldable, supporting structure is developed consisting of two scissor-hinged frames that can retract towards opposite sides of the space below. Structural membranes are spanned in these frames in a ridge-and-valley configuration to form the roofs outer surface. Actuators are integrated to control the tension in the membrane surface in different roof-configurations. Transformation from one configuration to another is controlled by cables running through the supporting structure over series of pulleys. The characteristics of these components are discussed, and their implementation illustrated with a design for a retractable roof over a tennis arena. The structural behaviour of this roof is analysed under representative load conditions. A procedure for such analyses using conventional software tools for the design and analysis of tensile surface structures is presented.

The universal scissor component: Optimization of a reconfigurable component for deployable scissor structures

Deployable scissor structures are well equipped for temporary and mobile applications since they are able to change their form and functionality. They are structural mechanisms that transform from a compact state to an expanded, fully deployed configuration. A barrier to the current design and reuse of scissor structures, however, is that they are traditionally designed for a single purpose. Alternatively, a universal scissor component (USC)—a generalized element which can achieve all traditional scissor types—introduces an opportunity for reuse in which the same component can be utilized for different configurations and spans. In this article, the USC is optimized for structural performance. First, an optimized length for the USC is determined based on a trade-off between component weight and structural performance (measured by deflections). Then, topology optimization, using the simulated annealing algorithm, is implemented to determine a minimum weight layout of beams within a single USC component.

Life Cycle Costing as an Early Stage Feasibility Analysis: The Adaptable Transformation of Willy Van Der Meeren's Student Residences☆

Abstract Understanding and exploiting the future value of existing buildings is an opportunity for property owners, developers and designers to be sustainable and offer advantages rather than burdens to successiveusers. However, although several assessment methods have been studied to quantifythe future value of buildings, more cases are needed to illustrate their usefulness. Commissioned by theVrijeUniversiteit Brussels administration we studied the feasibility of the transformation of 352 student residences that have become obsolete. In order to compose a thorough advice, architectural explorations and life cycle assessments have been conducted. This paper reports on the result of Life Cycle Costingon this case in particular. Through Life Cycle Costing, the initial costs of distinct transformation strategies, conventional as well as adaptable, were put in a long term perspective.By combining assessments at element and building level,it was possible to detect the particular value of the residences’ load bearing structure and the conditions under which adaptable building can increase that value. These findings allowed us to formulate straightforward advises in an early project stage. They are useful to both the universitys administration and the architectural designers that will be commissioned. Nevertheless, in this paper we alsoexpressthe technical and methodological optimizationthat is necessary.

Geometric service life modelling and discounting, a practical method for parametrised life cycle assessment

PurposeTo evaluate the long-term advantage of reusing building elements, including reduced material consumption and waste production, life cycle assessments are purposeful. To translate these assessments in relevant design advices, it is necessary to model accurately the service life of the considered elements and acknowledge the related uncertainties. Practical methods to do this are nevertheless lacking. In reaction, this paper proposes a new assessment method: geometric service life modelling and discounting.MethodsThe developed method is extensively parametric. Its formulas express an element’s service life in terms of a limited number of variables. This facilitates the evaluation of large series of elements as well as the automation of uncertainty analyses. Further, the method tackles different modelling complexities such as the interaction between replacements and refurbishments. Taking into account these complexities aligns the assessments with realistic service lives. For the presentation of the developed method, a focus on life cycle costing is chosen.Results and discussionIn this paper, the outcomes of the newly developed method are compared to those of an existing calculation method and benchmarked with the manual modelling and assessment of 390 simplified building elements. This comparison is based on three indicators characterising the methods’ accuracy: the number of interventions, their individual impact and their resulting net present value. For each indicator, geometric discounting led to a considerable increase of accuracy compared to the existing method.ConclusionsFrom this comparison, it is concluded that geometric service life modelling and discounting offers not only a well-defined procedure for parametrised life cycle assessment studies, this method is also more accurate than the existing one. Moreover, the uncertainty analyses it facilitates illustrate how detailed assessment outcomes and relevant design advices about the effectiveness of element reuse can be obtained. Nevertheless, further research about the method’s practical implementation is required.

Computational modelling methods for pliable structures based on curved-line folding

Abstract Curved-line folding, the act of folding paper along a pattern of curved lines to obtain a 3D shape, is an interesting starting-point for the design of innovative pliable structures. There exists a kinematic connection between two surfaces linked through a curved crease that can be used to generate a folding motion. However, due to the interdependency of geometry, forces and material properties the design of pliable structures based on curved-line folding is very complex. To facilitate the design process, adequate computational modelling methods are essential. This paper presents two ways of modelling: a geometric modelling method based on discretisation of the crease pattern and a method based on Finite Element Analysis (FEA). The proposed methods are validated by means of a case study in which a physical model is compared to digital ones. It can be concluded that the method based on FEA corresponds very well with the physical model, proving its potential. The accuracy of the geometric modelling is improved by the introduction of a set of guidelines based on the direction of the principal bending moments in the pliable structure. Furthermore, the case study exposes how the material-dependent behaviour of pliable structures increases the complexity of the design and should certainly be part of future research.

An Automated Structural Optimisation Methodology for Scissor Structures Using a Genetic Algorithm

We developed a fully automated multiobjective optimisation framework using genetic algorithms to generate a range of optimal barrel vault scissor structures. Compared to other optimisation methods, genetic algorithms are more robust and efficient when dealing with multiobjective optimisation problems and provide a better view of the search space while reducing the chance to be stuck in a local minimum. The novelty of this work is the application and validation (using metrics) of genetic algorithms for the shape and size optimisation of scissor structures, which has not been done so far for two objectives. We tested the feasibility and capacity of the methodology by optimising a 6źm span barrel vault to weight and compactness and by obtaining optimal solutions in an efficient way using NSGA-II. This paper presents the framework and the results of the case study. The in-depth analysis of the influence of the optimisation variables on the results yields new insights which can help in making choices with regard to the design variables, the constraints, and the number of individuals and generations in order to obtain efficiently a trade-off of optimal solutions.