This research project, conducted at the University of Montreal School of Architecture, presents an innovative approach to the construction of reticulated structures, focusing on the development and application of a novel ultralight aluminium node. The node, constructed from a folded, laser-cut, 1mm aluminium sheet, is designed to accommodate wooden linear members with varied rectangular sections, making it adaptable to bespoke geometries and low valence nodes. This innovative design offers a solution to the long-standing challenge in the construction industry of balancing cost, customization, and weight for reticulated structures through node optimizations.
The present project showcases the node design in a large-scale structural prototype, a pavilion built in an academic setting in the Fall of 2022. The pavilion serves as a practical demonstration of the use of the nodes to incorporate reclaimed construction timber into complex reticulated structures, showcasing the potential of this innovative approach in real-world applications. The research behind the project involved two main concurrent thrusts: network optimization and node construction.

The environmental impact of the construction industry (CI) is no longer a matter of debate. On the other hand, society is in a constant race to build bigger and more audaciously. To mitigate these competing directions CI is turning to geometry and computation to reduce new material consumption and to improve the structural properties of buildings. Aluminum with its remarkable weight to stiffness ratio and its natural anti-corrosive properties is at the forefront of this endeavour. For structural applications aluminum is mainly used in its extruded form while the rolled (sheet) material is preferred for architectural finishing and non-structural applications due to its low stiffness. However, with the advent of computational design and ubiquitous 2d CNC cutting, sheet metal can be used for bespoke architectural applications that combine aesthetic, structural, and environmental innovations. This paper will present two research projects developed in an academic setting at University of Montreal’s School of Architecture that use low thickness aluminium sheet to build bespoke architectural structures. The first project highlights an innovative use of surface discretization and assembly tabs to induce stiffness in large scale doubly curved architectural surfaces and thus produce complex, free-standing aluminum surfaces with no support structure. The second project introduces a new folded low-tech, ultralight aluminum node (300-400 gr) that is used to produce complex reticular wooden structures with nonstandard angles, using reclaimed 2×4 wooden studs. Both projects culminated with full scale research demonstrators, architectural pavilions exhibited on the university campus in 2021 and 2022.

This paper presents a new construction technique for large complex curved surfaces built from very low thickness sheet materials, reinforced through the structural activation of the dedicated assembly parts. The proposed technique works in several steps. 1. A large architectural curved surface is evaluated using FEA for local buckling and bending under self-weight and the assumption that it will be built from thin sheet material and without an additional structure or reinforcements. 2. The graphical representation of the principal bending moment stress field in the surface is simplified and used as the basis for the generation of a discretization pattern. 3. The discretization pattern is used to generate assembly elements (i.e., flaps) normal to the base surface. 4. The flaps are connected through a system of fins that engage them into a cellular structural system aligned both with the discretization and the stress patterns of the surface.

Whereas on a global scale, more than one billion people live in precarious housing situations, many construction materials are often sent to landfill sites or, worse, burned. However, these rejected materials represent a richness whose reallocation would lead to a significant economy of resources. Therefore, reusing materials from the construction industry could eventually be part of the solution. In this paper, we will present the results of a study carried out within the framework of a master’s thesis project, which attempts to establish an architectural response to this issue. The proposed solution involves a constructive system that allows the assembly of temporary shelters using a wide range of reclaimed materials. This approach implies the use of digital tools to generate a form resulting from the analysis of locally salvaged materials. The algorithm developed in this project can generate multiple formal configurations optimized for the available resources. Any shape obtained in this manner will be composed of a low number (3-5) of unique edge lengths. This rationalization strategy also limits the unique triangle typologies in the structure to a manageable number. The different elements, whether planar or linear, are then joined using low-tech metal nodes that can be easily assembled and disassembled. Because the standardized edge lengths and triangle types are compatible, the proposed workflow unlocks mixed material reuse for complex reticulated structures. The resulting flexibility allows for several variations or even a partial or complete reconfiguration of the initial shape, thus further supporting the implementation of the circular economy principles for the construction of complex architectural structures.

The re-use of existing buildings is gaining importance worldwide in the context of the carbon reduction efforts. In the case of Québec City there is a large number of heritage buildings that are currently unused. There are ongoing projects to breathe new life in these buildings, mainly by converting them in residential units. At the same time there is a growing preoccupation in Québec province towards energy efficiency and proper daylighting in both new and existing buildings. This is reflected in the emergence of new regulations concerning new buildings. In relation to existing buildings there are no regulations, but optimal daylight is a desired feature that can contribute significantly to the quality and attractiveness of newly designed spaces in the existing premises. In the case of heritage buildings, the additional conceptual challenge is to create properly daylit spaces while maintaining the character defining elements of the building, including facades and openings. Therefore, a digital workflow was developed to be integrated in the earliest schematic phase of design to ensure an equitable distribution of existing daylight in the newly created spatial units of heritage buildings. The method is based on an adapted constrained K-means clustering algorithm that works on daylight simulation data.

The present research introduces a novel parametric approach for the construction of PPE, a face mask inspired from takeaway food packaging and kirigami techniques. The technique requires only foldable planar material with no gluing or binding. The design is customizable to the users face using an augmented reality application and automatic processing in the Grasshopper environment. Using the proposed workflow, a personal mask can be constructed from a cutting and folding pattern printed on any household 2d printer. This makes it one of the most affordable and fast techniques for artisanal PPE existent now.

@inproceedings{Nejur_Balaban_2022, title={The A(fin)ne Pavilion – Pandemic adapted architectural studio fabrication}, url={http://papers.cumincad.org/cgi-bin/works/paper/ecaade2022_52}, abstractNote={This paper presents the didactical and research process of a pandemic-adapted digital fabrication, material-driven research master studio held at University of Montreal School of Architecture in early 2021 that concluded with the construction of a large-scale research pavilion assembled by the students with hand tools only. The paper focuses on the structure of the studio and how the research was re-oriented to permit material investigations using limited physical interaction between the participants, intermittent access to on-campus fabrication facilities, limited financial resources, and a cohort of students with near-zero computational design experience.}, booktitle={Pak, B, Wurzer, G and Stouffs, R (eds.), Co-creating the Future:  Inclusion in and through Design – Proceedings of the 40th Conference on Education and Research in Computer Aided Architectural Design in Europe (eCAADe 2022) – Volume 2, Ghent, 13-16 September 2022, pp. 507–516}, publisher={CUMINCAD}, author={Nejur, Andrei and Balaban, Thomas}, year={2022} }

Sustainable temporary architecture seems like a dichotomy but should be a major concern for the construction industry. Now aware of its impact, architecture must contribute to a more sustainable management of resources and despite their short time frame, ephemeral structures should be no exception to the rule. This work aims to develop a simpler and more accessible computational workflow based on the particle system tool Kangaroo inside Grasshopper to match design intent with available material stock. The proposed research examines the potential of combining raw or reused materials, such as wood and plastic, with easily accessible architectural technologies and tools to generate temporary and sustainable constructions. The workflow allows for many design variations using only simple and intuitive tools in both its digital and physical stages and aims to support the simple development non-standard, responsible temporary architecture that fully implements the principles of a circular economy.

In this paper, we introduce a structural form finding plugin called PolyFrame for the Rhinoceros software. This plugin is developed based on the methods of 3D Graphic Statics and Polyhedral Reciprocal Diagrams. The computational framework of this plugin uses new robust and efficient algorithms for the creation and modification of complex funicular, compression-only structural forms and is freely available for students, designers, researchers, and practitioners in the fields of architecture, structural engineering, mechanical engineering, and material science. The geometry-based structural design methods are one of the most intuitive yet powerful structural design methods that have recently been extended to 3D based on the Principles of the Equilibrium of Polyhedral Frames. Still, the increased geometrical complexities of the polyhedral diagrams hinder more in-depth practical applications and the research in this field. The framework proposed in this paper can manage, in near real-time, the creation and transformation of reciprocal polyhedral diagrams with a large number of elements as form and force diagrams for structural design purposes. The paper also introduces a hybrid object-oriented data structure that extends and generalizes the previously proposed approaches and thus allows the users to incorporate a variety of different geometric constraints, including edge lengths and the location of the supports from the initial stages of design. Additionally, a new parallel manipulation algorithm is introduced that is capable of transforming polyhedral diagrams while preserving the edge directions and face normal. As a result, a designer can effectively manipulate both structural form and its force distribution without breaking their reciprocity.

@article{Nejur_Akbarzadeh_2021, title={PolyFrame, Efficient Computation for 3D Graphic Statics}, volume={134}, ISSN={00104485}, url={https://linkinghub.elsevier.com/retrieve/pii/S0010448521000142}, DOI={10.1016/j.cad.2021.103003}, journal={Computer-Aided Design}, author={Nejur, Andrei and Akbarzadeh, Masoud}, year={2021}, month={May}, pages={103003}, language={en} }

This paper presents the didactical and research process of a pandemic-adapted digital fabrication, material-driven research master studio held at University of Montreal School of Architecture in early 2021 that concluded with the construction of a large-scale research pavilion assembled by the students with hand tools only. The paper focuses on the structure of the studio and how the research was re-oriented to permit material investigations using limited physical interaction between the participants, intermittent access to on-campus fabrication facilities, limited financial resources, and a cohort of students with near-zero computational design experience.

@inproceedings{Nejur_Szentesi-Nejur_2021, address={Hong Kong}, title={The F8LD mask – Parametrized on-body design for personal protection.}, url={http://papers.cumincad.org/cgi-bin/works/paper/caadria2021_341}, DOI={10.52842/conf.caadria.2021.1.503}, author={Nejur, Andrei and Szentesi-Nejur, Szende}, year={2021}, pages={503–512} }

The proposed paper presents the methodology and the outcomes of an intensive conception studio taught by the authors at the School of architecture of the University of Montreal having as objective the introduction of 3rd year architecture students to environmental evaluation and optimization techniques linked by the parametric design and the generative creation of architectural object. As opposed to mostly analysis-based approaches, an integration with architectural and urban design concepts was considered to be a more efficient method to initiate architecture students in environmental performance-driven design. The novelty of the course lays in the development of an integrative teaching method having as educational goals the development of environmental analysis skills, the creative use of digital tools, the conception of a coherent optimization process and the ability to represent a performance-driven design process.

@inproceedings{Szentesi-Nejur_De Luca_Nejur_2021, address={Novi Sad, Serbia}, title={Integrated Architectural and Environmental Performance-Driven Form-Finding – A teaching case study in Montreal}, url={http://papers.cumincad.org/cgi-bin/works/paper/ecaade2021_197}, DOI={10.52842/conf.ecaade.2021.2.105}, author={Szentesi-Nejur, Szende and De Luca, Francesco and Nejur, Andrei}, year={2021}, pages={105–114} }

This paper presents a method for the manipulation of groups of polyhedral cells that allows geometric transformation while preserving the planarity constraints of the cells and maintaining the equilibrium direction of the edges for the reciprocity of the form and force diagrams. The paper expands on previously investigated single-cell manipulations and considers the effects of these transformations in adjacent cells and the whole system. All the transformations discussed in this paper maintain the initial topology of the input system. The result of this research can be applied to both form and force diagrams to investigate various geometric transformations resulting in convex or complex (self-intersecting) polyhedra as a group. The product of this research allows intuitive user interaction in working with form and force diagrams in the early stages of geometric structural design in 3D.

@inproceedings{nejur2018constrained, title={Constrained manipulation of polyhedral systems}, author={Nejur, Andrei and Akbarzadeh, Masoud}, booktitle={Proceedings of IASS Annual Symposia}, volume={2018}, number={16}, pages={1–8}, year={2018}, organization={International Association for Shell and Spatial Structures (IASS)} }

Daylight standards are one of the main factors for the shape and image of cities. With urbanization and ongoing densification of cities, new planning regulations are emerging in order to manage access to sun light. In Estonia a daylight standard defines the rights of light for existing buildings and the direct solar access requirement for new premises. The solar envelope method and environmental simulations to compute direct sun light hours on building façades can be used to design buildings that respect both daylight requirements. However, no existing tool integrates both methods in an easy to use manner. Further, the assessment of façade performance needs to be related to the design of interior layouts and of building clusters to be meaningful to architects. Hence, the present work presents a computational design workflow for the evaluation and optimisation of high density building clusters in urban environments in relation to direct solar access requirements and selected types of floor plans.

@inproceedings{De Luca_Nejur_Dogan_2018, address={Łódź, Poland}, title={Facade-Floor-Cluster – Methodology for Determining Optimal Building Clusters for Solar Access and Floor Plan Layout in Urban Environments}, url={http://papers.cumincad.org/cgi-bin/works/paper/ecaade2018_329}, DOI={10.52842/conf.ecaade.2018.2.585}, author={De Luca, Francesco and Nejur, Andrei and Dogan, Timur}, year={2018}, pages={585–594} }

Although geometry-based structural design methods like 3D Graphic Statics (3DGS) allow for exploring a variety of spatial funicular geometry and their force equilibria. However, the material properties are not involved in the geometric form finding and there is no experimental data on the actual mechanical behavior of such systems. This paper will explore the structural performance of a funicular polyhedral geometry using experimental testing. The geometry of the physical prototype for the presented study is designed using 3DGS method. The specimen is constructed as a cast-in-place concrete structure, and the geometry of the sample is comparable to the standard concrete cylindrical test. High-performance, self-consolidating concrete is used for casting. Experimental results validated the 3DGS force distribution in the structure and showed that the magnitude of internal force in the members of the sample can be accurately predicted by 3DGS as long as the ultimate strength of the specimen is known.

@inproceedings{Bolhassani_Ghomi_Nejur_Furkan_Bartoli_Akbarzadeh_2018, title={Structural Behavior of a Cast-in-Place Funicular Polyhedral Concrete: Applied 3D Graphic Statics}, volume={2018}, abstractNote={Although geometry-based structural design methods like 3D Graphic Statics (3DGS) allow for exploring a variety of spatial funicular geometry and their force equilibria. However, the material properties are not involved in the geometric form finding and there is no experimental data on the actual mechanical behavior of such systems. This paper will explore the structural performance of a funicular polyhedral geometry using experimental testing. The geometry of the physical prototype for the presented study is designed using 3DGS method. The specimen is constructed as a cast-in-place concrete structure, and the geometry of the sample is comparable to the standard concrete cylindrical test. High-performance, self-consolidating concrete is used for casting. Experimental results validated the 3DGS force distribution in the structure and showed that the magnitude of internal force in the members of the sample can be accurately predicted by 3DGS as long as the ultimate strength of the specimen is known.}, booktitle={Proceedings of IASS Annual Symposia}, author={Bolhassani, Mohammad and Ghomi, Ali Tabatabaei and Nejur, Andrei and Furkan, Mustafa Omer and Bartoli, Ivan and Akbarzadeh, Masoud}, year={2018}, month={Jul}, pages={1–8} }

The recent evolution of two-dimensional graphic statics (2DGS) into the third dimension (3DGS) has broadened the opportunity for extensive exploration into design of efficient funicular structural systems [1]. Furthermore, the design and use of structural glass has expanded significantly in recent years [2]. This research exploits the current potential to which 3DGS and computational form finding can be used to extend the boundaries of optimization in the design of glass structures. The ultimate research objective is construction of a fully-transparent, high performance pedestrian bridge composed entirely of glass plates, which are oriented in a double layer, funicular, compression-dominating configuration. The funicular form of the bridge, developed using 3DGS, maximizes structural performance and minimizes the use of materials and resources: making it both architecturally unique and structurally efficient [3].

@article{bolhassanibehavior, title={Behavior of Modular Components in a Funicular Glass Bridge}, author={BOLHASSANI, Mohammad and BYRNES, Cory and YOST, Joseph Robert and AKBARZADEH, Masoud and SCHNEIDER, Jens and NEJUR, Andrei} }

This paper investigates the relationship between the topology of a structure, load-path values and material efficiency for given boundary conditions in structural form finding using 3D Graphic Statics (3DGS) methods. Subdividing the force polyhedron is a technique in graphic statics that allows generating topologically-different structural forms for a given boundary condition. This method is used to deal with buckling problems in long members by substituting them with multiple members with shorter lengths. However, subdivision methods result in more members and nodes in the structure and this adds to the construction costs and material use. This paper investigates the effect of subdivision techniques on the change in the load-path values and local buckling load for various developed funicular polyhedral systems and the volume of the construction material. Multiple subdivision algorithms are developed to generate series of bar-node compression-only spatial structural systems for a given boundary condition, and relevant algorithms are designed to calculate the volume, load path and maximum local buckling force. The results of 41 different specimens show that by applying subdivision on global force diagram, generally the maximum local buckling force would increase, as well as load path and volume. However, the slope of increase in local buckling force is higher. Furthermore, subdividing the applied forces as well as internal forces causes a better local buckling force than the subdivision of interior geometry.

@inproceedings{ghomi2018effect, title={Effect of Subdivision of Force Diagrams on the Local Buckling, Load-Path and Material Use of Founded Forms}, author={Ghomi, Ali Tabatabaie and Bolhassani, Mohammad and Nejur, Andrei and Akbarzadeh, Masoud}, booktitle={Proceedings of IASS Annual Symposia}, volume={2018}, number={16}, pages={1–8}, year={2018}, organization={International Association for Shell and Spatial Structures (IASS)} }

This paper presents progress in the development of practical applications for graph representations of meshes for a variety of problems relevant to generative architectural design (GAD). In previous work (Nejur and Steinfeld 2016), the authors demonstrated that while approaches to marrying mesh and graph representations drawn from computer graphics (CG) can be effective within the domains of applications for which they have been developed, they have not adequately addressed wider classes of problems in GAD. There, the authors asserted that a generalized framework for working with graph representations of meshes can effectively bring recent advances in mesh segmentation to bear on GAD problems, a utility demonstrated through the development of a plug-in for the visual programming environment Grasshopper. Here, we describe a number of implemented solutions to mesh segmentation and transformation problems, articulated as a series of additional features developed as a part of this same software. Included are problems of mesh segmentation approached through the creation of acyclic connected graphs (trees); problems of mesh transformations, such as those that unfold a segmented mesh in anticipation of fabrication; and problems of geometry generation in relation to a segmented mesh, as demonstrated through a generalized approach to mesh weaving. We present these features in the context of their potential applications in GAD and provide a limited set of examples for their use.

@inproceedings{Nejur_Steinfeld_2017, address={Cambridge (Massachusetts), USA}, title={Ivy: Progress in Developing Practical Applications for a Weighted-Mesh Representation for Use in Generative Architectural Design}, url={http://papers.cumincad.org/cgi-bin/works/paper/acadia17_446}, DOI={10.52842/conf.acadia.2017.446}, author={Nejur, Andrei and Steinfeld, Kyle}, year={2017}, pages={446–455} }

Mesh segmentation has become an important and well-researched topic in computational geometry in recent years (Agathos et al. 2008). As a result, a number of new approaches have been developed that have led to innovations in a diverse set of problems in computer graphics (CG) (Sharmir 2008). Specifically, a range of effective methods for the division of a mesh have recently been proposed, including by K-means (Shlafman et al. 2002), graph cuts (Golovinskiy and Funkhouser 2008; Katz and Tal 2003), hierarchical clustering (Garland et al. 2001; Gelfand and Guibas 2004; Golovinskiy and Funkhouser 2008), primitive fitting (Athene et al. 2004), random walks (Lai et al.), core extraction (Katz et al.) tubular multi-scale analysis (Mortara et al. 2004), spectral clustering (Liu and Zhang 2004), and critical point analysis (Lin et al. 20070, all of which depend upon a weighted graph representation, typically the dual of a given mesh (Sharmir 2008). While these approaches have been proven effective within the narrowly defined domains of application for which they have been developed (Chen 2009), they have not been brought to bear on wider classes of problems in fields outside of CG, specifically on problems relevant to generative architectural design. Given the widespread use of meshes and the utility of segmentation in GAD, by surveying the relevant and recently matured approaches to mesh segmentation in CG that share a common representation of the mesh dual, this paper identifies and takes steps to address a heretofore unrealized transfer of technology that would resolve a missed opportunity for both subject areas. Meshes are often employed by architectural designers for purposes that are distinct from and present a unique set of requirements in relation to similar applications that have enjoyed more focused study in computer science. This paper presents a survey of similar applications, including thin-sheet fabrication (Mitani and Suzuki 2004), rendering optimization (Garland et al. 2001), 3D mesh compression (Taubin et al. 1998), morphin (Shapira et al. 2008) and mesh simplification (Kalvin and Taylor 1996), and distinguish the requirements of these applications from those presented by GAD, including non-refinement in advance of the constraining of mesh geometry to planar-quad faces, and the ability to address a diversity of mesh features that may or may not be preserved. Following this survey of existing approaches and unmet needs, the authors assert that if a generalized framework for working with graph representations of meshes is developed, allowing for the interactive adjustment of edge weights, then the recent developments in mesh segmentation may be better brought to bear on GAD problems. This paper presents work toward the development of just such a framework, implemented as a plug-in for the visual programming environment Grasshopper.

@inproceedings{Nejur_Steinfeld_2016, address={Ann Arbor (Michigan), USA}, title={Ivy: Bringing a Weighted-Mesh Representations to Bear on Generative Architectural Design Applications}, url={http://papers.cumincad.org/cgi-bin/works/paper/acadia16_140}, DOI={10.52842/conf.acadia.2016.140}, author={Nejur, Andrei and Steinfeld, Kyle}, year={2016}, pages={140–151} }