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2021 Journal article Embargo

Morphogenesis of a bundled tall building: Biomimetic, structural, and wind-energy design of a multi-core-outrigger system combined with diagrid
Laccone F., Casali A., Sodano M., Froli M.
Skyscrapers are among the most distinctive building types of the modern age. Since many resources are attributed to these buildings, their design should consider a proper performance-based construction economy and environmental sustainable development. This research introduces a new concept for a bundled tall building founded on the use of a multi-core-outrigger system, which is additionally enriched with diagrid structures. The concept is inspired by the bamboo plant and follows the biomimetic design principles for the structural organization and performance-based criteria for optimizing the lateral stiffness and for shaping the cross section. Particularly, the incident wind speed is maximized to exploit Vertical Axis Wind Turbines (VAWTs), which are located along the whole building height at the center of the bundled towers. The building morphogenesis is accomplished by a multistep methodology that is fully developed in a parametric environment and includes structural and computational fluid dynamic analyses. With the aim of validating the proposed concept, a case study of a 320-m-tall three-core building has been designed for the city of Pisa, Italy. The use of VAWTs results in an annual emissions reduction of about 10 kgCO(2)/m(2).Source: The structural design of tall and special buildings 30 (2021). doi:10.1002/tal.1839
DOI: 10.1002/tal.1839

See at: The Structural Design of Tall and Special Buildings Restricted | The Structural Design of Tall and Special Buildings Restricted | The Structural Design of Tall and Special Buildings Restricted | The Structural Design of Tall and Special Buildings Restricted | CNR ExploRA Restricted


2021 Journal article Open Access OPEN

Integrated computational framework for the design and fabrication of bending-active structures made from flat sheet materiall
Laccone F., Malomo L., Pietroni N., Cignoni P., Schork T.
This paper introduces an integrated computational design framework for the design and realization of arbitrarily-curved bending-active architectural structures. The developed framework consists of a series of methods that enable the production of a complex 3D structures composed of a set of flat 2D panels whose mechanical properties are locally tuned by varying the shape of embedded spiraling patterns. The resulting panels perform as variable stiffness elements, and they are optimized to match a desired target shape once assembled together. The presented framework includes all the steps for the physical delivery of architectural objects, including conception, static assessment, and digital fabrication. The developed framework has been applied to an architectural scale prototype, which demonstrates the potential of integrating architectural design, computational simulation, structural engineering, and digital fabrication, opening up several possible novel applications in the building sector.Source: Structures (Oxford) 34 (2021): 979–994. doi:10.1016/j.istruc.2021.08.004
DOI: 10.1016/j.istruc.2021.08.004

See at: ISTI Repository Open Access | CNR ExploRA Restricted | www.sciencedirect.com Restricted


2021 Journal article Open Access OPEN

Experimental and numerical investigation on a passive control system for the mitigation of vibrations on SDOF and MDOF structures: mini Tribological ROCKing Seismic Isolation Device (miniTROCKSISD)
Giresini L., Puppio M. L., Laccone F., Froli M.
This paper illustrates the results of an experimental campaign performed on a scale prototype of a base dissipator called Mini Tribological ROCKing Seismic Isolation Device. This device allows a smooth, controlled and damped rocking by means of frictional layers and viscous elastic springs, which aim at decoupling the frequencies of the superstructure, at dissipating energy during motion and at re-centering the system once the external action vanishes. Four superstructures are tested - a shear type frame, braced and unbraced, a multi-story frame and a SDOF oscillator - with 96 ambient vibration and impulsive tests. An analytical model is illustrated and validated by the experimental tests. The reduction of relative displacement demand is analyzed for all the cases together with the reduction of the acceleration demand, showing positive effects of the base dissipator on the dynamic behavior of all the superstructures.Source: Journal of earthquake engineering (2021). doi:10.1080/13632469.2021.1964646
DOI: 10.1080/13632469.2021.1964646

See at: ISTI Repository Open Access | CNR ExploRA Restricted | www.tandfonline.com Restricted


2020 Journal article Open Access OPEN

TVT(delta) concept for long-span glass-steel footbridges
Froli M., Laccone F., Natali A.
Transparency and structural lightness are inspiring ideas in the design of footbridges. Glass is the most performing transparent material to be used for structural purposes because of its high compressive strength, chemical stability, and absence of fatigue and viscosity phenomena at room temperature. However, its fragility constitutes a challenging limit in structural applications. This research provides and discusses a specific concept named TVT? (Travi Vitree Tensegrity) for lightweight long-span beam-like footbridges made of structural glass. Hence, two design approaches of fail-safe design (FSD) and damage avoidance design (DAD) are applied to guarantee adequate safety levels and postcracking serviceability, respectively, with low damages on the main components. FSD provides the adoption of structural collaboration between glass and steel. Following DAD, glass is segmented into triangular panels, and reciprocal diffuse prestress is performed by steel tendons. This strategy assures low rehabilitation costs because only collapsed elements should be replaced once failed. At ultimate limit state (ULS), the TVT? footbridge attains a global ductile behavior in which the yielding of steel tendons occurs before any fragile failure. Such result is achieved through a hierarchic calibration of the chain of failures. In glass panels, which are mostly precompressed, the buckling failure, representing the main risk, is delayed by the mutual stabilization of the panels' compressed edges with steel clamping. However, because an accidental event may cause a localized or diffuse brittle failure of glass components, the system is designed to maintain a residual load bearing capacity in this scenario. At the serviceability limit state (SLS), the TVT? footbridge is highly stiffened by the presence of glass panes, partially encased in metallic frames. Crack initiation is delayed by precompression.Source: Journal of bridge engineering (Online) 25 (2020). doi:10.1061/(ASCE)BE.1943-5592.0001514
DOI: 10.1061/(asce)be.1943-5592.0001514

See at: ascelibrary.org Open Access | ISTI Repository Open Access | CNR ExploRA Open Access | Journal of Bridge Engineering Restricted | Journal of Bridge Engineering Restricted | Journal of Bridge Engineering Restricted


2020 Journal article Restricted

Glass-steel triangulated structures: parametric nonlinear finite-element analysis of in-plane and out-of-plane structural response of triangular laminated glass panels
Laccone F., Louter C., Froli M.
Glass exhibits brittle failure behavior. Therefore, redundancy is a fundamental design requirement when using glass as a main structural material. On this basis, a novel structural concept has been developed for hybrid glass-steel posttensioned triangulated structures, where the two materials collaborate. In forming such lattice structure, local fracture must be avoided. This paper presents a parametric study that highlights the influences of mechanical and geometrical parameters on the in-plane and out-of-plane static behaviour of laminated triangular glass panels. The resulting data set constitutes a useful source for the designer to select the most appropriate component. The main sensitivity parameters are panel length, laminate thickness, and interlayer stiffness.Source: Journal of architectural engineering (2020). doi:10.1061/(ASCE)AE.1943-5568.0000374
DOI: 10.1061/(asce)ae.1943-5568.0000374

See at: Journal of Architectural Engineering Restricted | ascelibrary.org Restricted | Journal of Architectural Engineering Restricted | Journal of Architectural Engineering Restricted | CNR ExploRA Restricted


2020 Journal article Open Access OPEN

A bending-active twisted-arch plywood structure: computational design and fabrication of the FlexMaps Pavilion
Laccone F., Malomo L., Pérez J., Pietroni N., Ponchio F., Bickel B., Cignoni P.
Bending-active structures are able to efficiently produce complex curved shapes from flat panels. The desired deformation of the panels derives from the proper selection of their elastic properties. Optimized panels, called FlexMaps, are designed such that, once they are bent and assembled, the resulting static equilibrium configuration matches a desired input 3D shape. The FlexMaps elastic properties are controlled by locally varying spiraling geometric mesostructures, which are optimized in size and shape to match specific bending requests, namely the global curvature of the target shape. The design pipeline starts from a quad mesh representing the input 3D shape, which defines the edge size and the total amount of spirals: every quad will embed one spiral. Then, an optimization algorithm tunes the geometry of the spirals by using a simplified pre-computed rod model. This rod model is derived from a non-linear regression algorithm which approximates the non-linear behavior of solid FEM spiral models subject to hundreds of load combinations. This innovative pipeline has been applied to the project of a lightweight plywood pavilion named FlexMaps Pavilion, which is a single-layer piecewise twisted arch that fits a bounding box of 3.90x3.96x3.25 meters. This case study serves to test the applicability of this methodology at the architectural scale. The structure is validated via FE analyses and the fabrication of the full scale prototype.Source: SN Applied Sciences 2 (2020). doi:10.1007/s42452-020-03305-w
DOI: 10.1007/s42452-020-03305-w
Project(s): EVOCATION via OpenAIRE

See at: link.springer.com Open Access | SN Applied Sciences Open Access | ISTI Repository Open Access | CNR ExploRA Open Access | SN Applied Sciences Restricted | SN Applied Sciences Restricted | SN Applied Sciences Restricted | SN Applied Sciences Restricted


2020 Conference article Open Access OPEN

Automated Design and Analysis of Reinforced and Post-Tensioned Glass Shells
Laccone F., Malomo L., Pietroni N., Froli M., Cignoni P.
Shells made of structural glass are beautiful objects from both the aesthetics and the engineering point of view. However, they pose two significant challenges. The first one is to assure adequate safety and redundancy concerning possible global collapse. Being single-layered, in a shell made of structural glass, the brittle cracking of a single pane can lead to a sudden propagation of failure, up to instability. The second one is to guarantee cheap replacing possibilities for potentially collapsed components. This research explores a novel concept to address both requirements, where glass is both post-tensioned and reinforced and develops the research on TVT post-tensioned glass beams. Following the Fail-Safe Design (FSD) principles, a steel reinforcement relieves glass deficiencies (i.e. brittleness and low tensile strength). Following the Damage Avoidance Design (DAD) principles, glass segmentation and post-tensioning avoid the propagation of cracks. Up to now, glass-steel systems were limited to mono-dimensional elements (such as beams and columns) or simple bi-dimensional elements (arches, domes, barrel vaults). Instead, massive structures are usually realized as grid shells, where glass is used as simple cladding. This research investigates piecewise triangulated glass shells to enable the creation of 3D free-form glass-steel systems, where glass is load-bearing material. Hence, laminated glass panels are mechanically coupled with a filigree steel truss, whose elements are placed at the edges of the panel and act as an unbonded reinforcement. In a performance-based perspective, these steel trusses can be sized to bear at least the weight of all panels in the occurrence of simultaneous cracks (worst-case scenario). The panels are post-tensioned using a set of edge-aligned cables that add beneficial compressive stress on glass to prevent crack initiation. The cable placement and accompanying pre-loads are derived with an optimization strategy that minimizes the tensile stress acting on the shell. This optimization procedure also considers the practical constraints involved in the process. The results obtained through this automated procedure are later investigated using nonlinear FE analyses. The resulting structures optimize the total material usage providing contemporarily both transparency and load-bearing capabilities. Posttensioned shells excel in static performances, achieving high stiffness and good redundancy for the worst-case scenario, and improve the structural lightness and the visual impact with respect to state-of-the-art competitors.Source: Challenging Glass 7 Conference on Architectural and Structural Applications of Glass, Ghent University, September 2020

See at: journals.open.tudelft.nl Open Access | ISTI Repository Open Access | CNR ExploRA Open Access


2020 Journal article Restricted

Conceptual design and FEM structural response of a suspended glass sphere made of reinforced curved polygonal panels
Froli M, Laccone F.
The paper introduces a novel concept for structural glass shells that is based on the mechanical coupling of double curved heat-bent glass panels and a wire frame mesh, which constitutes a grid of unbonded edge-reinforcement. Additionally, this grid has the purpose of providing redundancy. The panels have load-bearing function, they are clamped at the vertices and dry-assembled. The main novelty lies in the use of polygonal curved panelswith a nodal force transfer mechanism. This concept has been validated on an illustrative design case of a 6 m-diameter suspended glass sphere, in which regular pentagonal and hexagonal spherical panels are employed. The good strength and stiffness achieved for this structure is demonstrated by means of local and global FE models. Another fundamental feature of the concept is that the reinforcement grid provides residual strength in the extreme scenarios in which all panels are completely failed. A quantitative measure of redundancy is obtained by comparing this scenario with the ULS.Source: Glass Structures & Engineering (2020). doi:10.1007/s40940-020-00130-w
DOI: 10.1007/s40940-020-00130-w

See at: Glass Structures & Engineering Restricted | Glass Structures & Engineering Restricted | link.springer.com Restricted | Glass Structures & Engineering Restricted | Glass Structures & Engineering Restricted | CNR ExploRA Restricted


2019 Journal article Open Access OPEN

Automatic design of cable-tensioned glass shells
Laccone F., Malomo L., Froli M., Cignoni P., Pietroni N.
We propose an optimization algorithm for the design of post-tensioned architectural shell structures, composed of triangular glass panels, in which glass has a load-bearing function. Due to its brittle nature, glass can fail when it is subject to tensile forces. Hence, we enrich the structure with a cable net, which is specifically designed to post-tension the shell, relieving the underlying glass structure from tension. We automatically derive an optimized cable layout, together with the appropriate pre-load of each cable. The method is driven by a physically based static analysis of the shell subject to its service load. We assess our approach by applying non-linear finite element analysis to several real-scale application scenarios. Such a method of cable tensioning produces glass shells that are optimized from the material usage viewpoint since they exploit the high compression strength of glass. As a result, they are lightweight and robust. Both aesthetic and static qualities are improved with respect to grid shell competitors.Source: Computer graphics forum (Online) 39 (2019): 260–273. doi:10.1111/cgf.13801
DOI: 10.1111/cgf.13801

See at: ISTI Repository Open Access | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | onlinelibrary.wiley.com Restricted | Computer Graphics Forum Restricted | Computer Graphics Forum Restricted | CNR ExploRA Restricted


2019 Journal article Open Access OPEN

Dynamics of a new seismic isolation device based on tribological smooth rocking (TROCKSISD)
Froli M., Giresini L., Laccone F.
A novel isolation device is introduced to seismically protect slender structures or historic assets within the philosophy of Damage Avoidance Design (DAD). This device is conceived to allow smooth, controlled and damped rocking thanks to spherical contact surfaces, elastic springs which ensure re-centering, frictional layers and viscous elastic dampers able to dissipate energy during motion. The conceptual framework of the device is analyzed, and corresponding equations of motions obtained for the equivalent two degrees-of-freedom system. The proposed Performance Based Approach allows identifying geometric and mechanical features of the system. Extensive dynamic analyses with spectra-compatible ground motions are performed and the primary contribution of friction, developed by the relative slip of the two spherical surfaces, is discussed. Finally, the dynamic response under selected earthquakes is evaluated by comparing the isolated and the corresponding not isolated response, to highlight the beneficial effects produced by the proposed isolation technique.Source: Engineering structures 193 (2019): 154–169. doi:10.1016/j.engstruct.2019.05.014
DOI: 10.1016/j.engstruct.2019.05.014

See at: ISTI Repository Open Access | Engineering Structures Restricted | Engineering Structures Restricted | Engineering Structures Restricted | CNR ExploRA Restricted | Engineering Structures Restricted


2019 Conference article Open Access OPEN

FlexMaps Pavilion: a twisted arc made of mesostructured flat flexible panels
Laccone F., Malomo L., Perez J., Pietroni N., Ponchio F., Bickel B., Cignoni P.
Bending-active structures are able to eciently produce complex curved shapes starting from flat panels. The desired deformation of the panels derives from the proper selection of their elastic properties. Optimized panels, called FlexMaps, are designed such that, once they are bent and assembled, the resulting static equilibrium conguration matches a desired input 3D shape. The FlexMaps elastic properties are controlled by locally varying spiraling geometric mesostructures, which are optimized in size and shape to match the global curvature (i.e., bending requests) of the target shape. The design pipeline starts from a quad mesh representing the input 3D shape, which denes the edge size and the total amount of spirals: every quad will embed one spiral. Then, an optimization algorithm tunes the geometry of the spirals by using a simplied pre-computed rod model. This rod model is derived from a non-linear regression algorithm which approximates the non-linear behavior of solid FEM spiral models subject to hundreds of load combinations. This innovative pipeline has been applied to the project of a lightweight plywood pavilion named FlexMaps Pavilion, which is a single-layer piecewise twisted arc that ts a bounding box of 3.90x3.96x3.25 meters.Source: FORM and FORCE, IASS Symposium 2019 60th Anniversary Symposium of the International Association for Shell and Spatial Structures Structural Membranes 2019 9th International Conference on Textile Composites and Inflatable Structures, pp. 498–504, Barcelona, 7-10/10/2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access


2019 Conference article Open Access OPEN

Concept and cable-tensioning optimization of post-tensioned shells made of structural glass
Laccone F., Malomo L., Froli M., Cignoni P., Pietroni N.
Shells made of structural glass are charming objects from both the aesthetics and the engineering point of view. However, they pose two signicant challenges: the rst one is to assure adequate safety and redundancy concerning possible global collapse; the second one is to guarantee the economy for replacing collapsed components. To address both requirements, this research explores a novel concept where triangular panels of structural glass are both post-tensioned and reinforced to create 3D free-form systems. Hence, the ligree steel truss, made of edges reinforcements, is sized in performance-based perspective to bear at least the weight of all panels in the occurrence of simultaneous cracks (worst-case scenario). The panels are post-tensioned using a set of edge-aligned cables that add benecial compressive stress on the surface. The cable placement and pre-loads are optimized to minimize the tensile stress acting on the shell and match the manufacturing constraints. These shells optimize material usage by providing not only a transparent and fascinating building separation but also load-bearing capabilities. Visual and structural lightness are improved to grid shell competitors.Source: FORM and FORCE, IASS Symposium 2019 60th Anniversary Symposium of the International Association for Shell and Spatial Structures Structural Membranes 2019 9th International Conference on Textile Composites and Inflatable Structures, pp. 2133–2140, Barcelona, 7-10/10/2019

See at: ISTI Repository Open Access | CNR ExploRA Open Access


2019 Conference article Open Access OPEN

A new seismic isolation device based on tribological smooth rocking (TROCKSISD)
Froli M., Giresini L., Laccone F.
In the field of seismic risk mitigation of art objects, an innovative isolation device is here il-lustrated. The device, called TROCKSISD (Tribological ROCKing Seismic ISolation Device), couples multiple components to dissipate energy and control smooth rocking: spherical con-tact surfaces with frictional layers, elastic springs ensuring re-centering and viscous elastic dampers. The conceptual idea is described and the equations of motions of the two degrees of freedom system presented, discussing the performance-based structural behaviour and the mechanical/geometric parameters involved. Moreover, dynamic analyses are performed to understand the role of the frictional layers with respect to the peripheral dampers in the miti-gation of motion under spectrum compatible seismic records. The results in terms of rocking spectra are presented and comparisons with the equivalent single degree of freedom system without the isolation device are made.Source: COMPDYN 2019 - 7th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, pp. 750–760, Crete, Greece, 24-26 June 2019
DOI: 10.7712/120119.6954.19893

See at: arpi.unipi.it Open Access | ISTI Repository Open Access | CNR ExploRA Open Access | www.eccomasproceedia.org Open Access | academic.microsoft.com Restricted


2019 Doctoral thesis Open Access OPEN

Reinforced and post-tensioned structural glass shells: Concept, morphogenesis and analysis
Laccone F.
The relationship between architecture and structure is a key point in the conceptual phase of a building or one of its components. Glass structures can be considered optimal from the material usage viewpoint because they simultaneously offer transparency, an idea always pursued by architects, and good structural performances. Transparent and free-form glass shells are fascinating objects from both the aesthetic and structural engineering point of view, but are practically difficult to realize, apart from limited favourable cases, and have a low safety level. This work explores a new structural concept for triangulated glass shells, in which the glass panels are both reinforced and post-tensioned. Hence, the net formed by the reinforcements constitutes a redundancy barrier to avoid global collapse in case of glass cracking. In order to ensure an adequate safety level, glass should be prevented from carrying tensile stresses. To this aim, a novel algorithm is developed for the automatic design of the piecewise geometry of the shell and the derivation of the optimal cables distribution with respective preloads. Global nonlinear analyses have been performed to prove the feasibility of the concept and to highlight the advantages that these structures offer with respect to the grid shells competitors. At the local level, the main components of these systems are investigated: the node is tested experimentally and its behaviour is successively described numerically, and the triangular laminated panels are explored with parametric nonlinear models. The thesis is written as a monograph. Some papers prepared during the study are included as part of the work.

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