Design of Load-Bearing Systems for Open-Ended Downstream Reuse

This paper discusses the design of load-bearing systems for buildings with regard to their current lack of open-ended reusability. The reason for dismantling load-bearing systems today tends to be less related to material degradation than to a loss of functional fit with an evolving building program. It can therefore be expected that load-bearing components are reused in other systems, which extends their service life and avoids the manufacture of other components. Common design strategies to ensure the actual reusability of components consist in guaranteeing that the assembly is durable, versatile, modular, reversible, and adaptable. This paper (a) reviews these features, (b) illustrates by means of case studies that, without minimum threshold, they do not guarantee the repurpose of components into different, unforeseen systems, and (c) describes opportunities and challenges related to the design of more open-ended sets of load-bearing elements, i.e. sets whose element types allow for a substantially large number of diverse assemblies, in terms of floor plans, spans, loads, support layouts, connection types, architectural language, and integration with other building systems

Constraint-Based Graphic Statics - A geometrical support for computer-aided structural equilibrium design

This thesis introduces “constraint-based graphic statics”, a geometrical support for computer-aided structural design. This support increases the freedom with which the designer interacts with the plane static equilibriums being shaped. Constraint-based graphic statics takes full advantage of geometry, both its visual expressiveness and its capacity to solve complex problems in simple terms. Accordingly, the approach builds on the two diagrams of classical graphic statics: a form diagram describing the geometry of a strut-and-tie network and a force diagram vectorially representing its inner static quilibrium. Two new devices improve the control of these diagrams: (1) nodes — considered as the only variables — are constrained within Boolean combinations of graphical regions; and (2) the user modifies these diagrams by means of successive operations whose geometric properties do not at any time jeopardise the static equilibrium of the strut-and-tie network. These two devices offer useful features, such as the ability to describe, constrain and modify any static equilibrium using purely geometric grammar, the ability to compute and handle multiple solutions to a problem at the same time, the ability to switch the hierarchy of constraint dependencies, the ability to execute dynamic conditional statements graphically, the ability to compute full interdependency and therefore the ability to remove significantly the limitations of compass-and-straightedge constructions and, finally the ability to propagate some solution domains symbolically. As a result, constraint-based graphic statics encourages the emergence of new structural design approaches that are highly interactive, precognitive and chronology-free: highly interactive because forces and geometries are simultaneously and dynamically steered by the designer; precognitive because the graphical region constraining each points marks out the set of available solutions before they are even explored by the user; and chronology-free because the deductive process undertaken by the designer can be switched whenever desired

Automatic generation of diverse equilibrium structures through shape grammars and graphic statics

This article presents a computational design methodology that integrates generative (architectural) and analytical (engineering) procedures into a simultaneous design process. By combining shape grammars and graphic statics, the proposed methodology enables the following: (1) rapid generation of diverse, yet statically equilibrated discrete structures; (2) exploration of various design alternatives without any biases toward pre-existing typologies; (3) customization of the framework for unique formulations of design problems and a wide range of applications; and (4) intuitive, bidirectional interaction between the form and forces of the structure through reciprocal diagrams. Design tests presented in this article illustrate the creative potential of the proposed approach and demonstrate the possibility for unbiased explorations of richer and broader design spaces during early stages of design, with much more trial and less error

Environmental Benefits when Reusing Load-Bearing Components in Office Buildings: A Case Study.

This case study applies life-cycle assessment methods to the preliminary design of an office building in order to quantify the benefits achieved when reusing its load-bearing components. Results show that the production of the load-bearing system would account for 40% of the global warming potential indicator. The slabs are responsible for 65% of the environmental impacts among all structural elements and should be considered for reuse first. Compared to traditional constructions built from first-use material, a fictitious reuse of undamaged load-bearing components over three consecutive use cycles would reduce the global warming potential indicator by 25%. The global warming potential of reuse is eventually computed according to three repartition methods, highlighting the need to separate the life-cycle footprints related to production, use, and end-of-life more systematically

Geometric Optimization of a Reciprocal Floor-Framing System with Self-Weight and Area-Loading Considerations

This paper explores the geometric optimization of a planar reciprocal frame (RF) floor framing structure, focusing on the triangular topology. The structural performance of the frames is computed and plotted against the geometric parameters for various load cases. The load cases modelled include both symmetric and asymmetric loading on a hypothetical surface supported by the frame, and the loads are distributed to the members based on tributary areas. The two key geometric parameters studied are the rotation angle of the members at the unit RF level which defines the geometry, and the total number of members in the grid which defines the grid density. The structural performance is deduced from the total strain energy in the grid. Results show that smaller rotation angles at the unit RF level produce more structurally efficient RF grids. Depending on the grid density and load case, the optimal angle lies between 4 and 8.2 degrees. To some extents, these values mean that optimum geometries for RF under area-loading considerations tend to reduce lever-arms to a minimum. It is also found that the optimal angle remains relatively unchanged for a given grid density between the symmetric and asymmetric load cases

The Graphic Statics behind the Collier Memorial

This paper reviews the various graphic statics methods applied during the early structural design of the Collier Memorial, Cambridge, MA. Built in 2015 to honor fallen MIT Police Officer Sean Collier, the monument is a vaulted assembly of massive granite blocks. They are held together with pure compression contact when under the action of gravity alone. This non-conventional structural typology has only rare contemporary precedents and its design consequently innovates in various areas. In particular, assumptions of plastic theory and graphic statics have been combined to explore the design space, to assess stability, to study collapse mechanisms and to provide factors of safety related to maximum allowed displacements and maximum allowed live load. These methods proved to be a faster and sounder alternative to conventional discrete-element methods during the conceptual design stage

Donner forme aux forces

Un outil pour manipuler géométries et efforts au sein des structures architecturales Citation : JCorentin Fivet et Denis Zastavni, "Donner forme aux forces", lieuxdits#1, juin 2011, pp.18-21. Bibliographie

The caisson – review of a unique wooden construction typology in China

The caisson is a wooden construction system that covers opera stages for rain protection and sound control. Caissons in China display a diverse range of geometric expressions, delicate manufacturing, structural behaviours, and acoustic qualities. Despite their uniqueness and patrimonial interest, very little literature is known to exist, and it lacks comprehensiveness. First, this paper attempts to compile for the first time a comprehensive list of publications on caissons. Fifteen sources are identified, among which six papers address the origin and interpretation of douba and spiral caissons. In addition, other types are here recorded, based on an original field research in Zhejiang and Shanxi provinces. Following this survey, the paper also suggests a classification for caisson types according to their geometries, construction process, and structural behaviour. This classification is further supported by the interviews with a local carpenter master who specialized in the renovation and component replacement of caissons. Considerations on carving artistries, painting, and pest control are also given eventually. As a result, this study brings forward the caisson’s diversity, fineness, and significance for the history of wood joinery construction

Prestressed ultra-high performance concrete (UHPC) beams for reusable structural systems: design and testing

With the aim to reduce the environmental footprint of buildings, this paper presents an original structural system concept for two-way slabs in residential and office buildings. The proposed system extends the best practice in terms of modularity, versatility, demountability, reusability, and durability. A finite set of elements can be used to form the main load-bearing system of multiple successively constructed buildings having different and unpredicted layouts and static systems. Ultra-High Performance Concrete (UHPC) was identified as one of the most promising materials for this application because of its high strength, extreme durability and the opportunities it opens for shape optimization and material consumption reduction. In the first part of this contribution, the main features of the new structural system and preliminary design assumptions for UHPC modules are briefly outlined. Then, the authors present and discuss the results of an experimental campaign on prestressed UHPC beams that were tested in bending and shear, under service and ultimate load conditions. Beams with transversal openings in the web were also tested to assess the influence of these openings on the cracking behavior and shear strength of the beams. Experimental results provide useful information for the subsequent modeling of the structural system. Thanks to the presence of fibers, transversal openings in the web only have a limited influence on the response of the beams, thus allowing horizontal technical shafts to pass through the structural thickness of the slab

Structural Design with Reclaimed Materials: an Elastic Gridshell out of Skis

This paper presents the design and construction of a 36m2 gridshell, the rigidity of which is achieved through the bending of an initially flat grid of 210 reclaimed skis. The generated waste for its production is near zero as it is mostly built from discarded material. Its construction process is such that it can be disassembled and reassembled multiple times without scaffolding and by means of traditional tools only. After a brief introduction on the need for reducing embodied carbon and waste in structures through reuse, the paper sets up the constraints that have driven the definition of the pavilion, the main one being the extension of the lifetime of high-performance sport equipment by reclaiming their intrinsic mechanical properties. The paper then details the encountered unusual aspects in the design process and how they have been overcome – i.e. sporadic material supply, categorization of mechanical properties, physical alteration of these properties, and uncertainties in the numerical modelling of both the structural analysis and the construction process. Eventually, we conclude that reclaimed skis as a material have the potential to be as good as conventional timber when designing elastic gridshells. A series of future directions for this emerging field of research are also laid out