820 research outputs found
Introduzione a [Ermanna Chiozzi (1920-2020). Arte e vita, pane e colore]
No full textIl territorio di Copparo è particolarmente ricco di patrimonio culturale nelle sue molteplici forme, esito di una lunga storia che ha lasciato consistenti tracce archeologiche, architettoniche e artistiche, il cui valore e interesse supera ampiamente i confini amministrativi locali e si pone come fulcro di richiamo ben più vasto. Per queste ragioni, il Dipartimento di Architettura dell’Università degli Studi di Ferrara e il Comune di Copparo da alcuni anni sono impegnati, in forza di accordi di collaborazione, in attività didattiche e scientifiche che sono state concordemente riconosciute come fondamento indispensabile per ogni azione di conservazione e valorizzazione dei beni e delle risorse che caratterizzano questa interessante realtà.
L’iniziativa della mostra dedicata alla figura di Ermanna Chiozzi costituisce un ulteriore, fondamentale tassello nella collaborazione tra istituzioni e nella messa in valore di un patrimonio culturale, e in questo caso precipuamente artistico oltre che fortemente radicato nel territorio, racchiuso nell’opera trasmessa a noi da una donna speciale, impegnata, attenta e vivace al tempo stesso, che ha fuso con passione quasi totalizzante il suo fare artistico con la propria vita quotidiana, il vissuto personale con una dimensione sociale ben più vasta, la sua terra con la terra di tutti.
In sinergia con la curatrice della mostra, professoressa Chiara Guerzi, che si è fortemente impegnata per portare all’attenzione l’eredità artistica di Ermanna Chiozzi, si è dunque lavorato per supportare l’allestimento museografico della esposizione di un buon numero di opere, circoscritto rispetto all’innumerabile produzione dell’artista, ma in grado di portare al pubblico il forte carattere visivo e il messaggio impresso in ogni suo dipinto. Con viva soddisfazione possiamo affermare di avere collaborato per offrire allo sguardo di molti un ulteriore importante frutto artistico scaturito qui, e non altrove, ma in grado di parlare a tutti
Multiscale topology optimization with embedded TPMS architected materials
No full textTopology optimization has emerged as a critical computational tool for designing lightweight, robust, resilient and efficient structures. Recent advances in additive manufacturing technologies enable the production of complex objects across multiple scales, fostering the development of novel architectures endowed with diverse topologies and material classes, tailored to specific performance requirements. In this work we explore the use of Triply Periodic Minimal Surface (TPMS) architected materials, which mimic natural and biological systems to achieve exceptional mechanical efficiency and scalability. To this aim, we present a multiscale, multi-material topology optimization framework that leverages a gradient-based scheme to minimize compliance under multiple volume constraints. TPMS microstructures are generated via the Fourier Series Function (FSF) method, seamlessly integrated into the optimization process through homogenization theory. The Solid Isotropic Material with Penalization (SIMP) model is coupled with Discrete Material Optimization (DMO) interpolation, introducing a continuation parameter that transitions smoothly from a convex problem to a non-convex problem. To handle volume constraints effectively, the ZPR-BFGS design variable update scheme is adapted to the continuum setting, allowing constraints to be updated independently, sequentially, or in parallel. This framework enables flexible volume constraints, which can govern either all or a subset of materials at both global and local scales. Additionally, we introduce a voxel-based post-processing strategy to ensure scalable designs, smooth material transitions, and tunable scale separation. Key insights are illustrated through meaningful numerical examples, demonstrating the effectiveness of the proposed framework. The methodology highlights the versatility of TPMS-based architectures in achieving optimal material distribution with arbitrary geometric complexity
A general NURBS-based method for kinematic limit analysis of masonry vaults
No full textThe present contribution proposes a new NURBS-based approach for the limit analysis of masonry vaults based on an upper bound formulation. A given masonry vault geometry can be represented by a NURBS (Non-Uniform Rational B-Spline) parametric surface. A NURBS mesh of the given surface can be generated. Each element of the mesh is a NURBS surface itself and can be idealized as a rigid body. An upper bound limit analysis formulation, which takes into account the main characteristics of masonry material is deduced, with internal dissipation allowed exclusively along element edges. The approach is capable of well predicting the load bearing capacity of any masonry vault of generic shape. It is proved that, even by using a mesh constituted by very few elements, a good estimate of the collapse load multiplier is obtained provided that the initial mesh is adjusted by means of a meta-heuristic approach (i.e. genetic algorithms) in order to enforce that element edges accurately approximate the actual failure mechanism
Fragility functions for masonry infill walls with in-plane loading
No full textRecent seismic events have provided evidence that damage to masonry infills can lead not only to large economic losses but also to significant injuries and even fatalities. The estimation of damage of such elements and the corresponding consequences within the performance-based earthquake engineering framework requires the construction of reliable fragility functions. In this paper, drift-based fragility functions are developed for in-plane loaded masonry infills, derived from a comprehensive experimental data set gathered from current literature, comprising 152 masonry infills with different geometries and built with different types of masonry blocks, when tested under lateral cyclic loading. Three damage states associated with the structural performance and reparability of masonry infill walls are defined. The effect of mortar compression strength, masonry prism compression strength, and presence of openings is evaluated and incorporated for damage states where their influence is found to be statistically significant. Uncertainty due to specimen-to-specimen variability and sample size is quantified and included in the proposed fragility functions. It is concluded that prism strength and mortar strength are better indicators of the fragility of masonry infills than the type of bricks/blocks used, whose influence, in general, is not statistically significant for all damage states. Finally, the presence of openings is also shown to have statistically relevant impact on the level of interstory drift ratio triggering the lower damage states
A Genetic Algorithm NURBS-based new approach for fast kinematic limit analysis of masonry vaults
No full textThe present paper proposes a new Genetic Algorithm NURBS-based approach for the limit analysis of masonry vaults based on an upper bound formulation. A given masonry vault geometry can be represented by a NURBS (Non-Uniform Rational B-Spline) parametric surface and a NURBS mesh of the given surface can be generated. Each element of the mesh is a NURBS surface itself and can be idealized as a rigid body. An upper bound limit analysis formulation, which takes into account the main characteristics of masonry material is deduced, with internal dissipation allowed exclusively along element edges. The approach is capable of well predicting the load bearing capacity of any masonry vault of generic shape. It is proved that, even by using a mesh constituted by very few elements, a good estimate of the collapse load multiplier is obtained provided that the initial mesh is adjusted by means of a meta-heuristic approach (i.e. a Genetic Algorithm, GA) in order to enforce that element edges accurately represent the actual failure mechanism. The proposed method turns out to be both accurate and much less computationally expensive than existing methods for the limit analysis of masonry vaults
Base isolation of heavy non-structural monolithic objects at the top of a masonry monumental construction
No full textThe present paper deals with the relevant topic of seismic protection of heavy non-structural monolithic objects, which are usually placed at the top of masonry monumental constructions for mainly decorative purposes, like pinnacles and heavy artwork. Even if, after seismic events, most of the losses are due to structural collapse of buildings and other structural systems, heavy non-structural objects of the kind considered in the present work represent a serious potential hazard for both human lives and cultural heritage. During earthquakes, such objects undergo large base accelerations, which may eventually cause their collapse by rocking and overturning. In the present contribution, the seismic protection of eleven ancient marble decorative pinnacles placed at the top of the three-arched masonry city gate in Ferrara (Italy) is illustrated as a case study. In particular, a method for assessing the safety level of these systems under the action of seismic excitations is outlined and base isolation is proposed as a very promising technique for the seismic retrofit of heavy non-structural monolithic objects. The dynamical response to seismic actions of the underlying masonry construction is assessed through time-history dynamic analyses and the amplification of the ground accelerations at the base of the pinnacles is evaluated. Furthermore, the pinnacles are modeled as rigid bodies and their rocking behavior under base excitations is discussed. Finally, the effectiveness of the proposed base isolation system is assessed through non-linear dynamic numerical simulations
Multi-scale topology optimization for innovative 3D-printed walls and shell structures
No full textTopology optimization is a computational design tool that allow to optimize specific properties in a design domain imposing a priori conditions. A common topology optimization formulation adopted for civil engineering problem is the minimization of compliance, which is equivalent to maximize the stiffness. In this work, we propose a homogenization-based multiscale approach with a compliance minimization formulation for large-scale 3D printing of innovative in-plane loaded walls and shells for building engineering. This approach entails a two-dimensional structural optimization scheme, that accounts for the presence of predefined microstructures and different material properties. Afterwards, the three-dimensional layout of the optimized structure is reconstructed at the micro-scale starting from the obtained optimal layout by means of a specifically tailored 2.5-D post-processing algorithm. The proposed multiscale topology optimization approach is demonstrated by several meaningful numerical examples
A fast and general upper-bound limit analysis approach for out-of-plane loaded masonry walls
No full textA new general approach for the limit analysis of out-of-plane loaded masonry walls based on an upper bound formulation is presented. A given masonry wall of generic form presenting openings of arbitrary shape is described through its Non-Uniform Rational B-Spline (NURBS) representation in the three-dimensional Euclidean space. A lattice of nodes is defined in the parameters space together with possible fracture lines. An initial set of rigid elements initially subdividing the original wall geometry is identified accordingly. A homogenized upper bound limit analysis formulation, which takes into account the main characteristics of masonry material such as very low resistance in traction and anisotropic behavior is deduced. Moreover the effect of vertical loads and membrane stresses is considered, assuming internal dissipation allowed exclusively along element edges. A number of technically meaningful examples prove that a good estimate of the collapse load multiplier is obtained, provided that the initial net of yield lines is suitably adjusted by means of a meta-heuristic approach (i.e. a Genetic Algorithm, GA) in order to enforce that element edges accurately represent the actual failure mechanism
Fast kinematic limit analysis of FRP-reinforced masonry vaults. I: General genetic algorithm-NURBS-based formulation
No full textA new approach for the limit analysis of masonry vaults retrofitted with fiber-reinforced polymers (FRP) based on an upper bound formulation is presented in this paper. In particular, a new genetic algorithm (GA)-nonuniform rational b-spline (NURBS)-based general framework for the limit analysis of curved masonry structures tailored upon an upper bound formulation is discussed thoroughly in the present Part I. A given FRP-reinforced masonry vault can be geometrically represented by a NURBS parametric surface, and a NURBS mesh of the given surface can be generated. Each element of the mesh is a NURBS surface itself and can be idealized as a rigid body. An upper bound limit analysis formulation, which takes into account the main characteristics of masonry material and FRP reinforcement, is deduced, with internal dissipation allowed exclusively along element interfaces. The approach is capable of well predicting the load-bearing capacity of any reinforced masonry vault of arbitrary shape, provided that the initial mesh is adaptively adjusted by means of a metaheuristic approach (i.e., a suitable GA) to enforce that element edges accurately approximate the actual failure mechanism. The approach is validated and discussed in Part II, which is devoted to presenting a number of structural analyses of FRP-reinforced vaults
Fast kinematic limit analysis of FRP-reinforced masonry vaults. II: Numerical simulations
No full textA new approach for limit analysis of masonry vaults retrofitted with fiber-reinforced polymers (FRPs) based on an upper bound formulation is presented. Part I of this paper was devoted to detailing the theory on which this approach relies. The main idea consists of exploiting properties of nonuniform rational b-spline (NURBS) functions to develop a computationally efficient adaptive limit analysis procedure, which allows quick evaluation of the collapse load multiplier of any given FRP-reinforced masonry vault starting from its three-dimensional (3D) model, which can be generated within any free-form modeler natively working with NURBS entities. A suitably devised genetic algorithm (GA) governs mesh adaption. The present Part II is devoted to validating and discussing through numerical simulations the proposed GA-NURBS procedure. Several structural examples of masonry vaults, including two distinct arches (a straight parabolic barrel vault and a skew parabolic arch, respectively), a hemispherical dome, and both cloister and cross vaults are investigated. Each example is analyzed considering both the unreinforced configuration and the presence of FRP reinforcements. Moreover, comparisons with both nonlinear finite-element (FE) simulations and data collected from experiments (where existing) are presented to assess the proposed GA-NURBS limit analysis procedure. It is shown that, for all cases analyzed, this model allows reliable prediction of both collapse mechanisms and failure loads. The present GA-NURBS approach turns out to be a promising tool that may be conveniently used by practitioners who seek a quick and reliable way to evaluate the outcome of restoration interventions based on the application of FRP composites
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