Recherches

Louvain-La-Neuve

Robert Maillart’s structural design process

Robert Maillart’s Chiasso Shed (1924)

Swiss engineer Robert Maillart (1872-1940) designed visually striking structures that are remarkable for their efficiency. However, for many years his methods were considered fanciful and approximate. Following work initiated by David Billington in the 1970s, current research shows that his approach can be considered an elaborate method leading to exceptional designs. By first examining clues pointing to the structural problem, Maillart devised the adapted structural response (behaviours) and then worked out how to implement it, resulting in concrete being considered differently depending on the structural mechanisms employed. Maillart went on to assemble the various constituent structural mechanisms into the final arrangement, it being evident that the choice of appropriate mechanisms depends on the context of the problem, particularly the site, leading to differentiated and contextualised designs on each occasion. Given the results obtained by his approach, in which the work of the structure’s design –structural choices, the best structural course of action, the efficiency of the form, the adaptation or construction of the form according to constraints associated with the site or with the functionality of the construction, the integration of constructive parameters and the aesthetics of the structures – plays its full part and achieves the objectives. This study allows the work of the engineer to be reconsidered with an approach incorporating all the dimensions of an integrated and successful structure.

Collaborators:
Denis Zastavni | Corentin Fivet | Jean-Philippe Jasienski
Selected publications:
– Purely geometrical considerations during the design of bridges in the early 20th century – The case of R. Maillart
– Load path and prestressing in conceptual design related to Maillart’s Vessy Bridge
– Typological decision-making tree for the design of arch bridges from historical studies
– Géométrie et conception de la dalle en béton chez Maillart : une simplicité toute relative
– Robert Maillart’s Innovative use of Concrete.
– Robert Maillart’s key methods from the Salginatobel bridge design process (1928).
– The structural design of Maillart’s Chiasso Shed (1924): A graphic procedure.
– What ideas does Maillart’s eighty-year-old approach give us about how a concrete structure could be designed in the 21st century?
– What was truly innovative about Maillart’s designs using reinforced concrete?
– La conception chez Robert Maillart : morphogenèse des structures architecturales (PhD Thesis)

Constraint-Based Graphic Statics

Constraint-Based Graphic Statics (CBGS) is a computer-aided environment aimed at assisting designers during the very first stages of the structural design process. Taking full advantage of geometry both its visual expressiveness and its capacity to solve complex problems in simple terms, it gives designers the opportunity to build and modify interactively geometric constraints that control the structural shape and its static equilibrium simultaneously and in an entirely graphical way.
More precisely, its allows to describe, constrain and modify any static equilibrium using purely geometric grammar, to compute and handle multiple solutions to a problem at the same time, to switch the hierarchy of constraint dependencies in a non-destructive way, to execute dynamic conditional statements graphically, and to compute interdependent constraints. As a result, CBGS encourages the emergence of new structural design approaches that are highly interactive, that do not impose a specific sequence of resolution and that qualifies all the solution domains before they are even explored.
More than a tool, this framework is also a fundamental theoretical background that paves the way for a new understanding of what a bearing structure is and how to describe its inner distribution of forces.

Collaborators:
Corentin Fivet | Denis Zastavni

Selected publications:
– Interactive Shaping of Forces
– A Fully Geometric Approach for Interactive Constraint-Based Structural Form-Finding.
– Constraint-based Graphic Statics: New paradigms of computer-aided structural equilibrium design.
– Constraint-based graphic statics (PhD thesis)

Evaluating constitutive elements of structural robustness [within the context of Graphic Statics]

Geometrical domains characterising the degrees of freedom of a structural system within the context of Maxwell’s reciprocal representation of force and geometry are likely to provide indicators of the constitutive elements of structural robustness. Structural robustness is defined as the “insensitivity to local failure”. This definition emphasises the structure’s capacity for force redistribution and the possibility of finding alternative load paths in a structure. Features linked to resistance and the redistribution of forces are likely to be modelled by load path, struts and ties or thrust lines, close to geometrical thinking.
Since most methods proposed today for assessing the robustness of structures are based on probabilistic approaches, they are of limited interest for the design phase. Of the few approaches that have adopted a deterministic formulation, all provide a type of survey that is based on an in-depth analysis of the structure once it has been designed, according to specific scenarios. A central challenge should be to manage the issue of robustness earlier during the design process, or even to be able to interact with a model of the future structure in order to adjust the features of robustness. This paper explores the ability of geometrical domains to assess some of the relevant elements of structural robustness in terms of design in order to characterise the capacity of structures to redistribute forces. It compares indicators linked to the area of these domains. Based on case studies, this quantification of the structural provision is then compared with indices of deterministic and energetic criteria currently proposed in literature to quantify structural robustness.

Collaborators:
Aurelie Deschuyteneer | Denis Zastavni | Corentin Fivet

Selected publications:
– Admissible geometrical domains within the context of Graphic Statics for evaluating constitutive elements of structural robustness
– A geometrical approach to evaluating constitutive elements of structural robustness

Analysis and comments on tools and methods for structural design

Structural design is both a difficult science and a difficult art when attempts are made to practise it while incorporating all the necessary dimensions. The following constraints lead to an exploration of any new design approach in order to reduce the element of risk or uncertainty:
– dangers in contemporary structural practices (free architectural forms / computerised structural studies with the risk of poor structural performance)
– accidents (an area linked tostructural robustness)
– potential architectural ambitions if structural processes are controlled
– issue of sustainable development (well thought-out and efficient management of resources)
– (control of construction costs)
– innovation and possibilities for innovation
– extensive involvement of the S&T team in teaching.
Starting from the limits encountered in traditional approaches and making use of the experience gained from historical investigations and contact with some of the most creative contemporary engineers around, this research area combines critical analysis, theoretical tests, promotional publications and theoretical, methodological and practical explorations of structures.

Collaborators:
Denis Zastavni | Corentin Fivet | Christophe Lootvoet

Selected publications:
– Experiment and reflexions on structural sense in design. 
– An equilibrium approach on a structural scale to structural design.
– Are Codes Misleading Designers?
– Complexity in structural design: a questioning of structural evolution through history and recent developments.
– Typological decision-making tree for the design of arch bridges from historical studies.

3-Dimensional Graphic Statics, a new method for structuralmorphogenesis

As far as structural morphogenesis is concerned, the pertinence of graphical methods has been proven over the years because of its visual way of dealing with the shape and the stresses simultaneously. As regards the equilibrium of a 3D structure, however, knowledge is still limited because it requires a new methodology to be able to deal with every typology. This PhD looks into extending graphic statics to the third dimension. It is based on the geometrical axiomatisation of graphic statics developed by Corentin Fivet (see “Constraints-based graphic statics”).

Collaborators:
Jean-Philippe Jasienski | Corentin Fivet | Denis Zastavni

Selected publications:
– Various perspectives on the extension of graphic statics to the third dimension

Mechanical behaviour of multilayers-composed historical masonry structures

In this research, Jean-François Rondeaux focuses on the possible applications of computer-aided graphic statics to ancient masonry structures in order to offer an alternative to the FEM-based methods for the analysis and assessment of common historical structures such as vaults, bridges, buttresses, walls and so forth. The main focuses are the understanding of the mechanical behavior of multilayers composed walls containing an incoherent infill and the evaluation of the factor of safety of such structures. The aim of this research is to provide architects and engineers with convenient tools for modeling this behavior and assessing their collapse factor as well as the effect of reinforcement techniques.

Collaborators:
Jean-François Rondeaux | Denis Zastavni | Jean-Louis Vanden Eynde

Analyses par champs de contraintes discontinus à nœuds quasi-hydrostatiques au sein d’assemblages bois-bois

La complexité de la modélisation de la distribution des efforts internes aux éléments en bois fait obstacle à une analyse des éléments par la théorie des poutres. La difficulté vient de la grande hétérogénéité de la réponse structurale du bois en fonction du sens des sollicitations qui lui sont appliquées (dans le sens parallèle ou perpendiculaire aux fibres ; en traction ou en compression). Les assemblages par contact ou les poutres entaillées sont des exemples de ces limites. Plus précisément, le dimensionnement des assemblages traditionnels, faisant intervenir des entures, tenons, traits de Jupiter, embrèvements ne se fait actuellement que par le biais de procédures empiriques basées sur des règles de bonnes pratiques. Elles ne permettent pas de vérifier des dispositions originales qui dérogent à ces règles traditionnelles.
Pour pallier ces limites, un travail inité par Corentin Fivet [recherche des modalités permettant l’étude des assemblages en bois par manipulation graphique de champs de contraintes discontinus] a exploré la possibilité d’étudier les assemblages par contact à l’aide de champs de contrainte discontinus, comme cela se fait dans le béton.

Collaborators:
Corentin Fivet | Denis Zastavni | Nora Poelvoorde

Selected publications:
– Recherche des modalités permettant l’étude des assemblages en bois par manipulation graphique de champs de contraintes discontinus
– Validation expérimentale d’analyse par champs de contraintes discontinus au sein d’assemblages bois-bois

Best practices in timber construction

As part of “Timber in Construction”, the academic strand of continuous education at UCL, a project passing on best practice in the use of wood in construction has been undertaken in collaboration with Hout Info Bois in order to guide designers in their approach to a construction project using wood. This project comprises an analysis of five wooden buildings, all in Wallonia. The aim of these analyses is to summarise the difficulties of ensuring a wooden building performs well if the designer’s approach has been poor. They involve different programmes and on each occasion are associated with a specific problem linked to performance. The areas covered included structure, air and water-tightness, hygrothermal performance, fire-related issues and acoustic performance. Each mini project file summarises the different aspects of one of these issues and illustrates the approach taken by the designer to achieve the desired performance. The project to pass on good practice is introduced by recommendations from experts, in summary form, in order to focus on the essentials. It highlights the advice of expert bodies in relation to the difficulties often encountered in constructing in wood. Although it covers considerable ground, this introduction has been devised as a memo rather than a manual. It is intended to draw engineers’ attention to aspects they will have to consider when designing with wood.

Collaborators:
Denis Zastavni | Damien Nyssen-Dehaye | Albert Mahy | Francis De Vos | Gilles Delaunoit | Kévin Stassen | Jeremy Haynes | Lionnel Van Obbergh | Jean-Marc Franssen | Manuel Van Damme

Related publications:
– La problématique acoustique d’un bâtiment en bois : Immeuble d’appartement Renard à Eghezee.
– La problématique des étanchéités et de la durabilité du bois : Hôtel du Val d’Amblève – Malmedy, 2008.
– La problématique hygro-thermique d’un bâtiment en bois : IFPC – Nivelles 2007.
– La problématique structurale d’un bâtiment en bois : Espace Capital et Croissance – 2008.
– La problématique incendie d’un bâtiment en bois, Maison de l’enfance ‘Les Charmettes’ – Rixensart, 2007.
– Paroles d’experts – la sécurité incendie.
– Paroles d’experts – comportement structural et dimensionnement. 
– Paroles d’experts – conception des dispositions structurales d’ensemble.
– Paroles d’experts – l’acoustique.

Related link:

Paroles d’experts et études de cas
Formation continue “Le bois dans la construction”