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2025
Journal article
Open Access
Optimizing free‐form grid shells with reclaimed elements under inventory constraints
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
We propose a method for designing 3D architectural free-form surfaces, represented as grid shells with beams sourced from inventories of reclaimed elements from dismantled buildings. In inventory-constrained design, the reused elements must be paired with elements in the target design. Traditional solutions to this assignment problem often result in cuts and material waste or geometric distortions that affect the surface aesthetics and buildability. Our method for inventory-constrained assisted design blends the traditional assignment problem with differentiable geometry optimization to reduce cut-off waste while preserving the design intent. Additionally, we extend our approach to incorporate strain energy minimization for structural efficiency. We design differentiable losses that account for inventory, geometry, and structural constraints, and streamline them into a complete pipeline, demonstrated through several case studies. Our approach enables the reuse of existing elements for new designs, reducing the need for sourcing new materials and disposing of waste. Consequently, it can serve as an initial step towards mitigating the significant environmental impact of the construction sector.Source: COMPUTER GRAPHICS FORUM
DOI: 10.1111/cgf.70047
Project(s): Future Artificial Intelligence Research
Metrics:
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
We propose a method for designing 3D architectural free-form surfaces, represented as grid shells with beams sourced from inventories of reclaimed elements from dismantled buildings. In inventory-constrained design, the reused elements must be paired with elements in the target design. Traditional solutions to this assignment problem often result in cuts and material waste or geometric distortions that affect the surface aesthetics and buildability. Our method for inventory-constrained assisted design blends the traditional assignment problem with differentiable geometry optimization to reduce cut-off waste while preserving the design intent. Additionally, we extend our approach to incorporate strain energy minimization for structural efficiency. We design differentiable losses that account for inventory, geometry, and structural constraints, and streamline them into a complete pipeline, demonstrated through several case studies. Our approach enables the reuse of existing elements for new designs, reducing the need for sourcing new materials and disposing of waste. Consequently, it can serve as an initial step towards mitigating the significant environmental impact of the construction sector.Source: COMPUTER GRAPHICS FORUM
DOI: 10.1111/cgf.70047
Project(s): Future Artificial Intelligence Research
Metrics:
See at:
CNR IRIS 
| onlinelibrary.wiley.com | CNR IRIS 
2024
Journal article
Restricted
Bending-reinforced grid shells for free-form architectural surfaces
Laccone F, Pietroni N, Cignoni P, Malomo L
We introduce a new method for designing reinforcement for grid shells and improving their resistance to out-of-plane forces inducing bending. The central concept is to support the base network of elements with an additional layer of beams placed at a certain distance from the base surface. We exploit two main techniques to design these structures: first, we derive the orientation of the beam network on a given initial surface forming the grid shell to be reinforced; then, we compute the height of the additional layer that maximizes its overall structural performance. Our method includes a new formulation to derive a smooth direction field that orients the quad remeshing and a novel algorithm that iteratively optimizes the height of the additional layer to minimize the structure's compliance. We couple our optimization strategy with a set of constraints to improve buildability of the network and, simultaneously, preserve the initial surface. We showcase our method on a significant dataset of shapes to demonstrate its applicability to cases where free-form grid shells do not exhibit adequate structural performance due to their geometry.Source: COMPUTER AIDED DESIGN, vol. 168
DOI: 10.1016/j.cad.2023.103670
Metrics:
Laccone F, Pietroni N, Cignoni P, Malomo L
We introduce a new method for designing reinforcement for grid shells and improving their resistance to out-of-plane forces inducing bending. The central concept is to support the base network of elements with an additional layer of beams placed at a certain distance from the base surface. We exploit two main techniques to design these structures: first, we derive the orientation of the beam network on a given initial surface forming the grid shell to be reinforced; then, we compute the height of the additional layer that maximizes its overall structural performance. Our method includes a new formulation to derive a smooth direction field that orients the quad remeshing and a novel algorithm that iteratively optimizes the height of the additional layer to minimize the structure's compliance. We couple our optimization strategy with a set of constraints to improve buildability of the network and, simultaneously, preserve the initial surface. We showcase our method on a significant dataset of shapes to demonstrate its applicability to cases where free-form grid shells do not exhibit adequate structural performance due to their geometry.Source: COMPUTER AIDED DESIGN, vol. 168
DOI: 10.1016/j.cad.2023.103670
Metrics:
See at:
CNR IRIS | CNR IRIS | CNR IRIS | www.sciencedirect.com
2024
Journal article
Open Access
Procedural generation of geometric patterns for thin shell fabrication
Scandurra E., Laccone F., Malomo L., Callieri M., Cignoni P., Giorgi D.
This paper addresses the design of surface shells as assemblies of tileable, flat geometric patterns with predictable performance in response to mechanical stimuli. We design a family of tileable and fabricable patterns represented as triangle meshes, which can be assembled for creating surface tessellations. First, a regular recursive subdivision of the planar space generates different geometric configurations for candidate patterns, having interesting and varied aesthetic properties. Then, a refinement step addresses manufacturability by solving for non-manifold configurations and sharp angles that would produce disconnected or weak patterns. We devise a strategy for creating continuous variations on the geometry of individual patterns, in both aesthetics and behavior, to enrich the catalog of available designs. Finally, we simulate our patterns to evaluate their mechanical response when loaded in different scenarios targeting out-of-plane bending. Through a simple browsing interface, we show that our patterns span a variety of different bending behaviors. The result is a catalog of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our design-to-fabricate approach, we show fabricated 3D objects with different curvatures, and compare physical and simulated experiments.Source: COMPUTERS & GRAPHICS, vol. 122 (issue 103958)
DOI: 10.1016/j.cag.2024.103958
Project(s): NextGenerationEU programme under the funding schemes PNRR-PE-AI scheme (M4C2, investment 1.3, line on AI) FAIR (Future Artificial Intelligence Research), Social and hUman ceNtered XR
Metrics:
Scandurra E., Laccone F., Malomo L., Callieri M., Cignoni P., Giorgi D.
This paper addresses the design of surface shells as assemblies of tileable, flat geometric patterns with predictable performance in response to mechanical stimuli. We design a family of tileable and fabricable patterns represented as triangle meshes, which can be assembled for creating surface tessellations. First, a regular recursive subdivision of the planar space generates different geometric configurations for candidate patterns, having interesting and varied aesthetic properties. Then, a refinement step addresses manufacturability by solving for non-manifold configurations and sharp angles that would produce disconnected or weak patterns. We devise a strategy for creating continuous variations on the geometry of individual patterns, in both aesthetics and behavior, to enrich the catalog of available designs. Finally, we simulate our patterns to evaluate their mechanical response when loaded in different scenarios targeting out-of-plane bending. Through a simple browsing interface, we show that our patterns span a variety of different bending behaviors. The result is a catalog of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our design-to-fabricate approach, we show fabricated 3D objects with different curvatures, and compare physical and simulated experiments.Source: COMPUTERS & GRAPHICS, vol. 122 (issue 103958)
DOI: 10.1016/j.cag.2024.103958
Project(s): NextGenerationEU programme under the funding schemes PNRR-PE-AI scheme (M4C2, investment 1.3, line on AI) FAIR (Future Artificial Intelligence Research), Social and hUman ceNtered XR
Metrics:
See at:
Computers & Graphics | IRIS Cnr | IRIS Cnr | CNR IRIS
2024
Conference article
Open Access
Single-instance, multi-target learning of 3D architectural gridshells for material reuse and circular economy
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
We propose a learning-based method for the assisted design of 3D architectural free-form gridshells which reuse elements from dismantled, old buildings. Given a gridshell design as input, the output is a learned gridshell whose shape has been modified to reuse as many stock elements as possible, while preserving the design intent and optimizing for statics performance. The main idea is to perform multi-target shape optimization as a single-instance machine learning task, featuring differentiable losses that account for both structural and stock constraints. Since our approach enables the reuse of existing elements for new designs, it reduces the need for sourcing new materials and for disposing waste. Therefore, it contributes to switch to a circular economy and alleviate the environmental impact of the construction sector. © 2024 Copyright for this paper by its authors.Source: CEUR WORKSHOP PROCEEDINGS, vol. 3762, pp. 470-475. Naples, Italy, 29-30/05/2024
Project(s): NextGenerationEU programme under the funding schemes PNRR-PE-AI scheme (M4C2, investment 1.3, line on AI) FAIR (Future Artificial Intelligence Research)
Favilli A., Laccone F., Cignoni P., Malomo L., Giorgi D.
We propose a learning-based method for the assisted design of 3D architectural free-form gridshells which reuse elements from dismantled, old buildings. Given a gridshell design as input, the output is a learned gridshell whose shape has been modified to reuse as many stock elements as possible, while preserving the design intent and optimizing for statics performance. The main idea is to perform multi-target shape optimization as a single-instance machine learning task, featuring differentiable losses that account for both structural and stock constraints. Since our approach enables the reuse of existing elements for new designs, it reduces the need for sourcing new materials and for disposing waste. Therefore, it contributes to switch to a circular economy and alleviate the environmental impact of the construction sector. © 2024 Copyright for this paper by its authors.Source: CEUR WORKSHOP PROCEEDINGS, vol. 3762, pp. 470-475. Naples, Italy, 29-30/05/2024
Project(s): NextGenerationEU programme under the funding schemes PNRR-PE-AI scheme (M4C2, investment 1.3, line on AI) FAIR (Future Artificial Intelligence Research)
See at:
ceur-ws.org | CNR IRIS | CNR IRIS
2024
Journal article
Open Access
Computational design of segmented concrete shells made of post-tensioned precast flat tiles
Laccone Francesco, Menicagli Sandro, Cignoni Paolo, Malomo Luigi
This paper introduces a novel structural concept for free-form shells, in which the shape is decomposed into flat concrete tiles to be assembled sequentially with the help of falseworks. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the assembly is completed, the tiles are post-tensioned through a network of cables to minimize tension and avoid detachment. The top surface can finally be completed with an in situ cast layer that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains a jagged aesthetics. The paper presents the automatic pipeline supporting the computational design of these shells, from an input shape to its fabrication. The segmentation of the input shape is guided by a field-aligned quad mesh derived from the principal stresses of the thin shell. The tiles are flattened individually and extruded along the normal of the best-fitting plane. In this configuration, only edge midpoints of adjacent tiles share a contact point. Thus, forces can mainly flow along the tiles’ cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced model of the shell as a network of beams. Six different input shapes are tested to demonstrate the applicability of the proposed design method. The working hypotheses are validated through a higher-resolution nonlinear Finite Element Analysis. The fabrication pipeline is assessed utilizing a reduced-scale 3D-printed replica.Source: STRUCTURES, vol. 62 (issue 106156)
DOI: 10.1016/j.istruc.2024.106156
Metrics:
Laccone Francesco, Menicagli Sandro, Cignoni Paolo, Malomo Luigi
This paper introduces a novel structural concept for free-form shells, in which the shape is decomposed into flat concrete tiles to be assembled sequentially with the help of falseworks. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the assembly is completed, the tiles are post-tensioned through a network of cables to minimize tension and avoid detachment. The top surface can finally be completed with an in situ cast layer that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains a jagged aesthetics. The paper presents the automatic pipeline supporting the computational design of these shells, from an input shape to its fabrication. The segmentation of the input shape is guided by a field-aligned quad mesh derived from the principal stresses of the thin shell. The tiles are flattened individually and extruded along the normal of the best-fitting plane. In this configuration, only edge midpoints of adjacent tiles share a contact point. Thus, forces can mainly flow along the tiles’ cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced model of the shell as a network of beams. Six different input shapes are tested to demonstrate the applicability of the proposed design method. The working hypotheses are validated through a higher-resolution nonlinear Finite Element Analysis. The fabrication pipeline is assessed utilizing a reduced-scale 3D-printed replica.Source: STRUCTURES, vol. 62 (issue 106156)
DOI: 10.1016/j.istruc.2024.106156
Metrics:
See at:
IRIS Cnr | IRIS Cnr | IRIS Cnr | Structures | CNR IRIS | CNR IRIS
2024
Journal article
Open Access
Holistic performance assessment of gridshells: methodological framework and applications to steel gridshells
Raffaele L., Bruno L., Laccone F., Venuti F., Tomei V.
Gridshells are a paradigmatic example of the intricate concept and analysis of building structures. Their design should simultaneously take into account different goals and meet final performances, by referring to multiple disciplinary competences such as the ones of architects, engineers, builders, and experts in mathematics and computer graphics. The present study provides a deep insight into a new framework for the holistic performance assessment of gridshells. The overall performance is quantitatively expressed as the linear combination of three partial metrics, referring to structural response, buildability and sustainability. Each partial metric combines multiple goal metrics, some defined in the current state of the art, others proposed by the Authors. The proposed method is tested with reference to three gridshells with their spring line partially unconstrained, and to their fully-constrained counterparts. This application is intended to shed light on the scarcely investigated mechanical behaviour of free- edge gridshells, and to be inspirational for future proposals of design/optimization solutions within the newborn FreeGrid international benchmark.Source: JOURNAL OF BUILDING ENGINEERING, vol. 90 (issue 109406)
DOI: 10.1016/j.jobe.2024.109406
Project(s): IMPACT - Integrated Manufacture of Polymers and Conductive Tracks
Metrics:
Raffaele L., Bruno L., Laccone F., Venuti F., Tomei V.
Gridshells are a paradigmatic example of the intricate concept and analysis of building structures. Their design should simultaneously take into account different goals and meet final performances, by referring to multiple disciplinary competences such as the ones of architects, engineers, builders, and experts in mathematics and computer graphics. The present study provides a deep insight into a new framework for the holistic performance assessment of gridshells. The overall performance is quantitatively expressed as the linear combination of three partial metrics, referring to structural response, buildability and sustainability. Each partial metric combines multiple goal metrics, some defined in the current state of the art, others proposed by the Authors. The proposed method is tested with reference to three gridshells with their spring line partially unconstrained, and to their fully-constrained counterparts. This application is intended to shed light on the scarcely investigated mechanical behaviour of free- edge gridshells, and to be inspirational for future proposals of design/optimization solutions within the newborn FreeGrid international benchmark.Source: JOURNAL OF BUILDING ENGINEERING, vol. 90 (issue 109406)
DOI: 10.1016/j.jobe.2024.109406
Project(s): IMPACT - Integrated Manufacture of Polymers and Conductive Tracks
Metrics:
See at:
Journal of Building Engineering | Archivio Istituzionale della Ricerca - Università degli Studi di Cassino | Publications Open Repository TOrino | IRIS Cnr | IRIS Cnr | CNR IRIS
2023
Conference article
Open Access
FreeGrid: a benchmark on design and optimisation of free-edge gridshells
Bruno L, Cignoni P, Gabriele S, Grande E, Imbimbo M, Laccone F, Marmo F, Mele E, Raffaele L, Tomei V, Venuti F
FreeGrid is meant to offer a common benchmark to test and compare different approaches to the design and optimization of steel gridshells, from man-based heuristic design to AI-based one. FreeGrid sets three design baseline problems: a barrel vault, a paraboloidal dome, and a hyperbolic paraboloid, having their spring line partially not constrained (free-edge) and subjected to symmetric and asymmetric load conditions. Participants are called to modify the baseline gridshell(s) in order to improve their structural performances, buildability, and sustainability, all three of them weighted in a single, bulk quantitative performance metric. Participants shall comply with a limited number of design constraints, while any other design solution is allowed. Baseline setups, performance metrics and design constraints will be fully detailed in technical specifications made publicly available. The full data of the baseline structures will be offered to participants according to an Open Data policy, together with postprocessing utilities intended to align the procedure to obtain the performance metrics. The FreeGrid benchmark will be launched within the IASS Symposium 2023 in Melbourne.
Bruno L, Cignoni P, Gabriele S, Grande E, Imbimbo M, Laccone F, Marmo F, Mele E, Raffaele L, Tomei V, Venuti F
FreeGrid is meant to offer a common benchmark to test and compare different approaches to the design and optimization of steel gridshells, from man-based heuristic design to AI-based one. FreeGrid sets three design baseline problems: a barrel vault, a paraboloidal dome, and a hyperbolic paraboloid, having their spring line partially not constrained (free-edge) and subjected to symmetric and asymmetric load conditions. Participants are called to modify the baseline gridshell(s) in order to improve their structural performances, buildability, and sustainability, all three of them weighted in a single, bulk quantitative performance metric. Participants shall comply with a limited number of design constraints, while any other design solution is allowed. Baseline setups, performance metrics and design constraints will be fully detailed in technical specifications made publicly available. The full data of the baseline structures will be offered to participants according to an Open Data policy, together with postprocessing utilities intended to align the procedure to obtain the performance metrics. The FreeGrid benchmark will be launched within the IASS Symposium 2023 in Melbourne.
See at:
CNR IRIS | iass2023.org.au | CNR IRIS
2023
Contribution to conference
Open Access
Static- and fabrication-aware concrete shells segmented into flat tiles
Laccone F, Menicagli S
The design of freeform concrete shells has gained popularity recently, pushed by computational tools that allow manipulating and exploring complex shapes interactively. However, their actual fabrication, even on a small scale, still poses challenges of feasibility and cost. Continuous shells require accurate and dense formworks, while segmented shells offer a low prefabrication rate, especially in the case of variable curvature. We propose a novel structural concept for freeform shells, in which the shape is decomposed into flat tiles, touching each other at the midpoint of the edges. Once assembled, the tiles are post-tensioned to minimize the resulting tension on the structure under service load. The outer surface is finally completed with an in situ cast that fills the gaps and activates the entire shell behavior. The bottom surface presents a jagged aesthetic due to gaps and misalignments at the seams. We developed an automatic pipeline to manage the design process from a general input shape to fabrication. The input shape is segmented based on a field-aligned quad mesh computed from the principal stress of the thin shell. The flat tiles are obtained by extruding each face along the normal of the associated checkerboard mesh, i.e., a mesh whose 'solid' parts are the planar rhomboids with vertices on each quad edge's midpoint. The contact between adjacent tiles is ensured only at their edge midpoints so that forces can flow along the cross directions, namely the principal directions. Candidate post-tensioning paths are found by clustering the segments linking pairs of opposite midpoints of the tiles' edges. We discard paths that do not terminate on the boundary, closed loops, or paths with significant kinks, to avoid localized shear on the surface.
Laccone F, Menicagli S
The design of freeform concrete shells has gained popularity recently, pushed by computational tools that allow manipulating and exploring complex shapes interactively. However, their actual fabrication, even on a small scale, still poses challenges of feasibility and cost. Continuous shells require accurate and dense formworks, while segmented shells offer a low prefabrication rate, especially in the case of variable curvature. We propose a novel structural concept for freeform shells, in which the shape is decomposed into flat tiles, touching each other at the midpoint of the edges. Once assembled, the tiles are post-tensioned to minimize the resulting tension on the structure under service load. The outer surface is finally completed with an in situ cast that fills the gaps and activates the entire shell behavior. The bottom surface presents a jagged aesthetic due to gaps and misalignments at the seams. We developed an automatic pipeline to manage the design process from a general input shape to fabrication. The input shape is segmented based on a field-aligned quad mesh computed from the principal stress of the thin shell. The flat tiles are obtained by extruding each face along the normal of the associated checkerboard mesh, i.e., a mesh whose 'solid' parts are the planar rhomboids with vertices on each quad edge's midpoint. The contact between adjacent tiles is ensured only at their edge midpoints so that forces can flow along the cross directions, namely the principal directions. Candidate post-tensioning paths are found by clustering the segments linking pairs of opposite midpoints of the tiles' edges. We discard paths that do not terminate on the boundary, closed loops, or paths with significant kinks, to avoid localized shear on the surface.
2023
Conference article
Open Access
A geometry-preserving shape optimization tool based on deep learning
Favilli A, Laccone F, Cignoni P, Malomo L, Giorgi D
In free-form architecture, computational design tools have made it easy to create geometric models. However, obtaining good structural performance is difficult and requires further steps, such as shape optimization, to enhance system efficiency and material savings. This paper provides a user interface for form-finding and shape optimization of triangular grid shells. Users can minimize structural compliance, while ensuring small changes in their original design. A graph neural network learns to update the nodal coordinates of the grid shell to reduce a loss function based on strain energy. The interface can manage complex shapes and irregular tessellations. A variety of examples prove the effectiveness of the tool.Source: LECTURE NOTES IN CIVIL ENGINEERING, vol. 437, pp. 549-558. Torino, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_57
Project(s): Future Artificial Intelligence Research
Metrics:
Favilli A, Laccone F, Cignoni P, Malomo L, Giorgi D
In free-form architecture, computational design tools have made it easy to create geometric models. However, obtaining good structural performance is difficult and requires further steps, such as shape optimization, to enhance system efficiency and material savings. This paper provides a user interface for form-finding and shape optimization of triangular grid shells. Users can minimize structural compliance, while ensuring small changes in their original design. A graph neural network learns to update the nodal coordinates of the grid shell to reduce a loss function based on strain energy. The interface can manage complex shapes and irregular tessellations. A variety of examples prove the effectiveness of the tool.Source: LECTURE NOTES IN CIVIL ENGINEERING, vol. 437, pp. 549-558. Torino, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_57
Project(s): Future Artificial Intelligence Research
Metrics:
See at:
CNR IRIS | link.springer.com | CNR IRIS | CNR IRIS
2023
Conference article
Open Access
Static- and fabrication-aware segmented concrete shells made of post-tensioned precast flat tiles
Laccone F, Menicagli S, Cignoni P, Malomo L
This paper introduces a novel structural concept for freeform shells, in which the shape is decomposed into flat tiles to be assembled sequentially with the help of falseworks. Once the structure is completed, the tiles are post-tensioned to minimize the tension forces and avoid detachment. The entire design process, from an input shape to fabrication, is managed by an automatic pipeline. The input shape is segmented into a field-aligned quad mesh, computed from the principal stress of the thin shell. The flat tiles are obtained by extruding each face along the normal of the best-fitting plane per face. The contact between adjacent tiles is ensured only at their edge midpoints so the forces can mainly flow along the cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced beam model of the shell. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the structure is completed, the top surface is finally completed with an in situ cast that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains its jagged aesthetics.Source: LECTURE NOTES IN CIVIL ENGINEERING, vol. 437, pp. 1-10. Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_1
Metrics:
Laccone F, Menicagli S, Cignoni P, Malomo L
This paper introduces a novel structural concept for freeform shells, in which the shape is decomposed into flat tiles to be assembled sequentially with the help of falseworks. Once the structure is completed, the tiles are post-tensioned to minimize the tension forces and avoid detachment. The entire design process, from an input shape to fabrication, is managed by an automatic pipeline. The input shape is segmented into a field-aligned quad mesh, computed from the principal stress of the thin shell. The flat tiles are obtained by extruding each face along the normal of the best-fitting plane per face. The contact between adjacent tiles is ensured only at their edge midpoints so the forces can mainly flow along the cross directions. The best configuration of cable paths and pre-loads is found by solving a constrained optimization problem exploiting a reduced beam model of the shell. All tiles can be prefabricated in the shop with an adaptable and reusable molding system. Once the structure is completed, the top surface is finally completed with an in situ cast that fills the gaps and activates the entire shell behavior. In contrast, the bottom surface maintains its jagged aesthetics.Source: LECTURE NOTES IN CIVIL ENGINEERING, vol. 437, pp. 1-10. Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_1
Metrics:
See at:
CNR IRIS | link.springer.com | ISTI Repository | CNR IRIS | CNR IRIS
2023
Conference article
Open Access
Statics and stability of bending-optimized double-layer grid shell
Laccone F, Pietroni N, Froli M, Cignoni P, Malomo L
Grid shell structures are optimal when considering their aesthetics and lightness, but their efficiency is highly reduced when their shape deviates from a pure membrane. Many contemporary architectures possess a freeform shape, conceived mostly on aesthetics and functional criteria. In these cases, finding an efficient grid shell often requires substantial shape modifications. This work addresses a new kind of doublelayer structure that aims to preserve the desired shape design. The structural system comprises a quad-meshed grid shell aligned to the target shape and enriched with an additional reinforcement layer that adds bending stiffness. This additional layer, going inward and outward of the main surface, presents variable height and discontinuous elements based on the required bending strength. The obtained structural system differs from both grid shells, as these latter may be very deformable in this setup, and from classic double-layer structures (space frames), which are heavier and redundant. In this paper, we show how the presented system compares with grid shell and double-layer competitors in terms of statics and stability. We highlight the pros and cons based on a systematic comparative analysis run on selected freeform shapes.Source: LECTURE NOTES IN CIVIL ENGINEERING, pp. 569-578. Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_59
Metrics:
Laccone F, Pietroni N, Froli M, Cignoni P, Malomo L
Grid shell structures are optimal when considering their aesthetics and lightness, but their efficiency is highly reduced when their shape deviates from a pure membrane. Many contemporary architectures possess a freeform shape, conceived mostly on aesthetics and functional criteria. In these cases, finding an efficient grid shell often requires substantial shape modifications. This work addresses a new kind of doublelayer structure that aims to preserve the desired shape design. The structural system comprises a quad-meshed grid shell aligned to the target shape and enriched with an additional reinforcement layer that adds bending stiffness. This additional layer, going inward and outward of the main surface, presents variable height and discontinuous elements based on the required bending strength. The obtained structural system differs from both grid shells, as these latter may be very deformable in this setup, and from classic double-layer structures (space frames), which are heavier and redundant. In this paper, we show how the presented system compares with grid shell and double-layer competitors in terms of statics and stability. We highlight the pros and cons based on a systematic comparative analysis run on selected freeform shapes.Source: LECTURE NOTES IN CIVIL ENGINEERING, pp. 569-578. Turin, Italy, 26-28/06/2023
DOI: 10.1007/978-3-031-44328-2_59
Metrics:
See at:
CNR IRIS | link.springer.com | ISTI Repository | CNR IRIS | CNR IRIS
2023
Conference article
Open Access
Computational design of fabricable geometric patterns
Scandurra E, Laccone F, Malomo L, Callieri M, Cignoni P, Giorgi D
This paper addresses the design of surfaces as assemblies of geometric patterns with predictable performance in response to mechanical stimuli. We design a family of tileable and fabricable patterns represented as triangle meshes, which can be assembled for creating surface tessellations. First, a regular recursive subdivision of the planar space generates different geometric configurations for candidate patterns, having interesting and varied aesthetic properties. Then, a refinement step addresses manufacturability by solving for non-manifold configurations and sharp angles which would produce disconnected or fragile patterns. We simulate our patterns to evaluate their mechanical response when loaded in different scenarios targeting out-of-plane bending. Through a simple browsing interface, we show that our patterns span a variety of different bending behaviors. The result is a library of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our approach, we show a pair of fabricated 3D objects with different curvatures.DOI: 10.2312/stag.20231297
Metrics:
Scandurra E, Laccone F, Malomo L, Callieri M, Cignoni P, Giorgi D
This paper addresses the design of surfaces as assemblies of geometric patterns with predictable performance in response to mechanical stimuli. We design a family of tileable and fabricable patterns represented as triangle meshes, which can be assembled for creating surface tessellations. First, a regular recursive subdivision of the planar space generates different geometric configurations for candidate patterns, having interesting and varied aesthetic properties. Then, a refinement step addresses manufacturability by solving for non-manifold configurations and sharp angles which would produce disconnected or fragile patterns. We simulate our patterns to evaluate their mechanical response when loaded in different scenarios targeting out-of-plane bending. Through a simple browsing interface, we show that our patterns span a variety of different bending behaviors. The result is a library of patterns with varied aesthetics and predefined mechanical behavior, to use for the direct design of mechanical metamaterials. To assess the feasibility of our approach, we show a pair of fabricated 3D objects with different curvatures.DOI: 10.2312/stag.20231297
Metrics:
See at:
diglib.eg.org | CNR IRIS | ISTI Repository | CNR IRIS
2023
Journal article
Open Access
Geometric deep learning for statics-aware grid shells
Favilli A, Laccone F, Cignoni P, Malomo L, Giorgi D
This paper introduces a novel method for shape optimization and form-finding of free-form, triangular grid shells, based on geometric deep learning. We define an architecture which consumes a 3D mesh representing the initial design of a free-form grid shell, and outputs vertex displacements to get an optimized grid shell that minimizes structural compliance, while preserving design intent. The main ingredients of the architecture are layers that produce deep vertex embeddings from geometric input features, and a differentiable loss implementing structural analysis. We evaluate the method performance on a benchmark of eighteen free-form grid shell structures characterized by various size, geometry, and tessellation. Our results demonstrate that our approach can solve the shape optimization and form finding problem for a diverse range of structures, more effectively and efficiently than existing common tools.Source: COMPUTERS & STRUCTURES, vol. 292
DOI: 10.1016/j.compstruc.2023.107238
Project(s): Future Artificial Intelligence Research, SUN
Metrics:
Favilli A, Laccone F, Cignoni P, Malomo L, Giorgi D
This paper introduces a novel method for shape optimization and form-finding of free-form, triangular grid shells, based on geometric deep learning. We define an architecture which consumes a 3D mesh representing the initial design of a free-form grid shell, and outputs vertex displacements to get an optimized grid shell that minimizes structural compliance, while preserving design intent. The main ingredients of the architecture are layers that produce deep vertex embeddings from geometric input features, and a differentiable loss implementing structural analysis. We evaluate the method performance on a benchmark of eighteen free-form grid shell structures characterized by various size, geometry, and tessellation. Our results demonstrate that our approach can solve the shape optimization and form finding problem for a diverse range of structures, more effectively and efficiently than existing common tools.Source: COMPUTERS & STRUCTURES, vol. 292
DOI: 10.1016/j.compstruc.2023.107238
Project(s): Future Artificial Intelligence Research, SUN
Metrics:
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CNR IRIS | ISTI Repository | www.sciencedirect.com | CNR IRIS
2023
Journal article
Open Access
Exploring new frontiers in gridshell design: the FreeGrid benchmark
Bruno L, Gabriele S, Grande E, Imbimbo M, Laccone F, Marmo F, Mele E, Raffaele L, Tomei V, Venuti F
Gridshell structures require an intricate design activity that shall comply with several design goals of diverse nature. This design phase can be approached with different methods and strategies and usually requires multiple competencies from different scientific fields. In this context, a common benchmark, called FreeGrid, is proposed to the scientific and practitioners' communities in order to test and compare different approaches to the design and optimization of steel gridshells on the bases of ad-hoc defined performance metrics. FreeGrid sets three design baseline problems: a barrel vault, a parabolic dome, and a hyperbolic paraboloid, having their spring line partially not constrained (free-edge) and subjected to uniform and piecewise uniform load conditions. Participants are called to modify the baseline gridshell(s), observing a limited number of design constraints (related to geometry, external constraints and material), in order to improve their structural, buildability, and sustainability performances through the maximization of a bulk quantitative performance metric. Specifically, the structural performance metric accounts for both ultimate and serviceability behavior, through the calculation of the critical Load Factor and maximum vertical displacement; the buildability performance metric includes the evaluation of face planarity, uniformity of structural joints and members; the sustainability performance metric is based on the structure embodied carbon. This paper describes the baseline gridshells setups, the proposed performance metrics and the recommended method for performance assessment. The complete data of the baseline structures are made available according to an Open Data policy, together with postprocessing utilities intended to align the procedure to obtain the performance metrics.Source: STRUCTURES, vol. 58
DOI: 10.1016/j.istruc.2023.105678
Metrics:
Bruno L, Gabriele S, Grande E, Imbimbo M, Laccone F, Marmo F, Mele E, Raffaele L, Tomei V, Venuti F
Gridshell structures require an intricate design activity that shall comply with several design goals of diverse nature. This design phase can be approached with different methods and strategies and usually requires multiple competencies from different scientific fields. In this context, a common benchmark, called FreeGrid, is proposed to the scientific and practitioners' communities in order to test and compare different approaches to the design and optimization of steel gridshells on the bases of ad-hoc defined performance metrics. FreeGrid sets three design baseline problems: a barrel vault, a parabolic dome, and a hyperbolic paraboloid, having their spring line partially not constrained (free-edge) and subjected to uniform and piecewise uniform load conditions. Participants are called to modify the baseline gridshell(s), observing a limited number of design constraints (related to geometry, external constraints and material), in order to improve their structural, buildability, and sustainability performances through the maximization of a bulk quantitative performance metric. Specifically, the structural performance metric accounts for both ultimate and serviceability behavior, through the calculation of the critical Load Factor and maximum vertical displacement; the buildability performance metric includes the evaluation of face planarity, uniformity of structural joints and members; the sustainability performance metric is based on the structure embodied carbon. This paper describes the baseline gridshells setups, the proposed performance metrics and the recommended method for performance assessment. The complete data of the baseline structures are made available according to an Open Data policy, together with postprocessing utilities intended to align the procedure to obtain the performance metrics.Source: STRUCTURES, vol. 58
DOI: 10.1016/j.istruc.2023.105678
Metrics:
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CNR IRIS | ISTI Repository | www.sciencedirect.com | CNR IRIS
2022
Conference article
Open Access
Exploratory study on a segmented shell made of recycled-HDPE plastic
Laccone F, Manolas I, Malomo L, Cignoni P
Recycled HDPE plastic can be obtained from up to 100% waste material and can be produced in the shape of panels and rods. The aim of this work is to explore the possibility to employ this material for structural purposes. The proposed concept for segmented shells is based on the cassette system, namely a spatial waffle structure clamped by inner and outer plates, and a shaping strategy of the shell cross section targeted on bending. The concept is applied on translational surfaces, in which the transverse cross section serves as the shaping objective. A digital workflow is implemented to explore the possible solutions and to evaluate the shells' feasibility from both a fabrication and a structural point of view. A case study of 5.2 meters is further explored with nonlinear analysis.Source: PROCEEDINGS OF THE IASS ANNUAL SYMPOSIUM, pp. 1859-1870. University of Surrey, UK, 23-27/08/2021
DOI: 10.15126/900337
Project(s): EVOCATION
Metrics:
Laccone F, Manolas I, Malomo L, Cignoni P
Recycled HDPE plastic can be obtained from up to 100% waste material and can be produced in the shape of panels and rods. The aim of this work is to explore the possibility to employ this material for structural purposes. The proposed concept for segmented shells is based on the cassette system, namely a spatial waffle structure clamped by inner and outer plates, and a shaping strategy of the shell cross section targeted on bending. The concept is applied on translational surfaces, in which the transverse cross section serves as the shaping objective. A digital workflow is implemented to explore the possible solutions and to evaluate the shells' feasibility from both a fabrication and a structural point of view. A case study of 5.2 meters is further explored with nonlinear analysis.Source: PROCEEDINGS OF THE IASS ANNUAL SYMPOSIUM, pp. 1859-1870. University of Surrey, UK, 23-27/08/2021
DOI: 10.15126/900337
Project(s): EVOCATION
Metrics:
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CNR IRIS | ISTI Repository | openresearch.surrey.ac.uk | CNR IRIS
2022
Journal article
Open Access
Automated generation of flat tileable patterns and 3D reduced model simulation
Manolas I., Laccone F., Cherchi G., Malomo L., Cignoni P.
The computational fabrication community is developing an increasing interest in the use of patterned surfaces, which can be designed to show ornamental and unconventional aesthetics or to perform as a proper structural material with a wide range of features. Geometrically designing and controlling the deformation capabilities of these patterns in response to external stimuli is a complex task due to the large number of variables involved. This paper introduces a method for generating sets of tileable and exchangeable flat patterns as well as a model-reduction strategy that enables their mechanical simulation at interactive rates. This method is included in a design pipeline that aims to turn any general flat surface into a pattern tessellation, which is able to deform under a given loading scenario. To validate our approach, we apply it to different contexts, including real-scale 3D printed specimens, for which we compare our results with the ones provided by a ground-truth solver.Source: COMPUTERS & GRAPHICS, vol. 106, pp. 141-151
DOI: 10.1016/j.cag.2022.05.020
Project(s): EVOCATION
Metrics:
Manolas I., Laccone F., Cherchi G., Malomo L., Cignoni P.
The computational fabrication community is developing an increasing interest in the use of patterned surfaces, which can be designed to show ornamental and unconventional aesthetics or to perform as a proper structural material with a wide range of features. Geometrically designing and controlling the deformation capabilities of these patterns in response to external stimuli is a complex task due to the large number of variables involved. This paper introduces a method for generating sets of tileable and exchangeable flat patterns as well as a model-reduction strategy that enables their mechanical simulation at interactive rates. This method is included in a design pipeline that aims to turn any general flat surface into a pattern tessellation, which is able to deform under a given loading scenario. To validate our approach, we apply it to different contexts, including real-scale 3D printed specimens, for which we compare our results with the ones provided by a ground-truth solver.Source: COMPUTERS & GRAPHICS, vol. 106, pp. 141-151
DOI: 10.1016/j.cag.2022.05.020
Project(s): EVOCATION
Metrics:
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CNR IRIS | ISTI Repository | www.sciencedirect.com | CNR IRIS
2022
Journal article
Open Access
Design and construction of a bending-active plywood structure: the Flexmaps Pavilion
Laccone F, Malomo L, Callieri M, Alderighi T, Muntoni A, Ponchio F, Pietroni N, Cignoni P
Mesostructured patterns are a modern and efficient concept based on designing the geometry of structural material at the meso-scale to achieve desired mechanical performances. In the context of bending-active structures, such a concept can be used to control the flexibility of the panels forming a surface without changing the constituting material. These panels undergo a formation process of deformation by bending, and application of internal restraints. This paper describes a new constructional system, FlexMaps, that has initiated the adoption of bending-active mesostructures at the architectural scale. Here, these modules are in the form of four-arms spirals made of CNC-milled plywood and are designed to reach the desired target shape once assembled. All phases from the conceptual design to the fabrication are seamlessly linked within an automated workflow. To illustrate the potential of the system, the paper discusses the results of a demonstrator project entitled FlexMaps Pavilion (3.90x3.96x3.25 meters) that has been exhibited at the IASS Symposium in 2019 and more recently at the 2021 17th International Architecture Exhibition, La Biennale di Venezia. The structural response is investigated through a detailed structural analysis, and the long-term behavior is assessed through a photogrammetric survey.Source: JOURNAL OF THE INTERNATIONAL ASSOCIATION FOR SHELL AND SPATIAL STRUCTURES, vol. 63 (issue 2), pp. 98-114
DOI: 10.20898/j.iass.2022.007
Metrics:
Laccone F, Malomo L, Callieri M, Alderighi T, Muntoni A, Ponchio F, Pietroni N, Cignoni P
Mesostructured patterns are a modern and efficient concept based on designing the geometry of structural material at the meso-scale to achieve desired mechanical performances. In the context of bending-active structures, such a concept can be used to control the flexibility of the panels forming a surface without changing the constituting material. These panels undergo a formation process of deformation by bending, and application of internal restraints. This paper describes a new constructional system, FlexMaps, that has initiated the adoption of bending-active mesostructures at the architectural scale. Here, these modules are in the form of four-arms spirals made of CNC-milled plywood and are designed to reach the desired target shape once assembled. All phases from the conceptual design to the fabrication are seamlessly linked within an automated workflow. To illustrate the potential of the system, the paper discusses the results of a demonstrator project entitled FlexMaps Pavilion (3.90x3.96x3.25 meters) that has been exhibited at the IASS Symposium in 2019 and more recently at the 2021 17th International Architecture Exhibition, La Biennale di Venezia. The structural response is investigated through a detailed structural analysis, and the long-term behavior is assessed through a photogrammetric survey.Source: JOURNAL OF THE INTERNATIONAL ASSOCIATION FOR SHELL AND SPATIAL STRUCTURES, vol. 63 (issue 2), pp. 98-114
DOI: 10.20898/j.iass.2022.007
Metrics:
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2022
Other
Restricted
Statics-aware 3D gridshells: a differential approach towards shape optimization
Favilli A, Giorgi D, Laccone F, Malomo L, Cignoni P
In the context of architecture, gridshells are three-dimensional frame structures in which loads are entirely born by edges, or beams. Our contribution is to draw the way to a computational method that, given an input gridshell provided by a designer, slightly changes the input to ensure good static performance. The changing is induced by structure node repositioning. If the gridshell is represented as a surface mesh, the problem boils down to finding a proper vertex displacement. The vertex displacement should strike a happy medium between structure rigidity, with load deformation as low as possible, and structure resistance, preventing stress caused breaks. In this report, we introduce a shape optimization strategy based on automatic differentiation of a loss function, which embeds the static equilibrium problem of a girdshell.DOI: 10.32079/isti-tr-2022/017
Metrics:
Favilli A, Giorgi D, Laccone F, Malomo L, Cignoni P
In the context of architecture, gridshells are three-dimensional frame structures in which loads are entirely born by edges, or beams. Our contribution is to draw the way to a computational method that, given an input gridshell provided by a designer, slightly changes the input to ensure good static performance. The changing is induced by structure node repositioning. If the gridshell is represented as a surface mesh, the problem boils down to finding a proper vertex displacement. The vertex displacement should strike a happy medium between structure rigidity, with load deformation as low as possible, and structure resistance, preventing stress caused breaks. In this report, we introduce a shape optimization strategy based on automatic differentiation of a loss function, which embeds the static equilibrium problem of a girdshell.DOI: 10.32079/isti-tr-2022/017
Metrics:
2022
Other
Restricted
Geometric deep learning for statics-aware 3D gridshells
Favilli A, Giorgi D, Laccone F, Malomo L, Cignoni P
In the context of architecture, gridshells are three-dimensional frame structures in which loads are entirely born by edges, or beams. Our contribution is to draw the way to a computational method that, given an input gridshell provided by a designer, slightly changes the input to ensure good static performance. The changing is induced by structure node repositioning. If the gridshell is represented as a surface mesh, the problem boils down to finding a proper vertex displacement. The vertex displacement should strike a happy medium between structure rigidity, with load deformation as low as possible, and structure resistance, preventing stress caused breaks. In this report, we inculde a solution to solve this mesh vertex displacement learning problem with a target goal of reducing a physically-based loss function, namely the mean strain energy of a gridshell, by means of a graph neural network. We adopt several geometric input features and discuss their effects on the results.DOI: 10.32079/isti-tr-2022/016
Metrics:
Favilli A, Giorgi D, Laccone F, Malomo L, Cignoni P
In the context of architecture, gridshells are three-dimensional frame structures in which loads are entirely born by edges, or beams. Our contribution is to draw the way to a computational method that, given an input gridshell provided by a designer, slightly changes the input to ensure good static performance. The changing is induced by structure node repositioning. If the gridshell is represented as a surface mesh, the problem boils down to finding a proper vertex displacement. The vertex displacement should strike a happy medium between structure rigidity, with load deformation as low as possible, and structure resistance, preventing stress caused breaks. In this report, we inculde a solution to solve this mesh vertex displacement learning problem with a target goal of reducing a physically-based loss function, namely the mean strain energy of a gridshell, by means of a graph neural network. We adopt several geometric input features and discuss their effects on the results.DOI: 10.32079/isti-tr-2022/016
Metrics:
2022
Journal article
Open Access
Vorogrid: a static-aware variable-density Voronoi mesh to design the tube structure tessellation of tall buildings
Laccone F, Gaudioso D, Malomo L, Cignoni P, Froli M
In the context of tall building design, the tube concept represents one of the most performing systems. The diagrid is the widespread type of tube system and consists of a diagonal grid of beams that wraps the building, forming a diamond pattern. It performs as lateral bracing and is additionally able to sustain vertical loading through axial forces. Despite its efficiency, a growing interest is recently observed in alternative geometries to replace the diagrid pattern and improve the architectural impact conferred by the building skin aesthetics on the urban environment. The paper pursues the use of a Voronoimesh, in which the geometry of the cells is steered to known schemes for the structural design of a cantilever tube structure. The objective is to mimic a macroscopic structural behavior through a topology and sizemodification of the Voronoimesh that increases the density for creating resisting paths with higher stiffness. The paper proposes a novel method Vorogrid for designing a new class of tall buildings equipped with an organic-looking and mechanically sound tube structure, which makes them a valuable alternative to competitors (diagrid, hexagrid, random Voronoi). Diagrids and hexagrids still remain more efficient in terms of forces and displacements but are characterized by a more usual appearance, instead Vorogrid offers more design control and better performances on average with respect to random Voronoi structures. This method is streamed into a pipeline that includes grid initialization strategies, geometric and structural optimization to mitigate the effects of the grid randomness, and structural sizing.Source: COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING (ONLINE), vol. 38 (issue 6), pp. 683-701
DOI: 10.1111/mice.12912
Metrics:
Laccone F, Gaudioso D, Malomo L, Cignoni P, Froli M
In the context of tall building design, the tube concept represents one of the most performing systems. The diagrid is the widespread type of tube system and consists of a diagonal grid of beams that wraps the building, forming a diamond pattern. It performs as lateral bracing and is additionally able to sustain vertical loading through axial forces. Despite its efficiency, a growing interest is recently observed in alternative geometries to replace the diagrid pattern and improve the architectural impact conferred by the building skin aesthetics on the urban environment. The paper pursues the use of a Voronoimesh, in which the geometry of the cells is steered to known schemes for the structural design of a cantilever tube structure. The objective is to mimic a macroscopic structural behavior through a topology and sizemodification of the Voronoimesh that increases the density for creating resisting paths with higher stiffness. The paper proposes a novel method Vorogrid for designing a new class of tall buildings equipped with an organic-looking and mechanically sound tube structure, which makes them a valuable alternative to competitors (diagrid, hexagrid, random Voronoi). Diagrids and hexagrids still remain more efficient in terms of forces and displacements but are characterized by a more usual appearance, instead Vorogrid offers more design control and better performances on average with respect to random Voronoi structures. This method is streamed into a pipeline that includes grid initialization strategies, geometric and structural optimization to mitigate the effects of the grid randomness, and structural sizing.Source: COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING (ONLINE), vol. 38 (issue 6), pp. 683-701
DOI: 10.1111/mice.12912
Metrics:
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CNR IRIS | onlinelibrary.wiley.com | CNR IRIS | CNR IRIS