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Papers by Antonio michele Tralli
Archives of Computational Methods in Engineering, 2019
XVII Congresso AIMeTA, 2005
In the present work the problem of thin surface coatings of an elastic layer subject to a residua... more In the present work the problem of thin surface coatings of an elastic layer subject to a residual thermal stress is analytically investigated. The system adopts a curvature as a result of the misfit strain due to the different thermal expansivities of the layer and coatings. The problem is governed by a singular integral equation which can be reduced to a linear algebraic system by approximating the unknown interfacial shear stress via series expansion of Chebyshev polynomials. The present analysis is developed in order to assess the mechanical behaviour of a crystalline undulator designed for obtaining high emission radiations through channelling phenomeno
Nel presente lavoro vengono presentati alcuni modelli analitici sviluppati per descrivere la comp... more Nel presente lavoro vengono presentati alcuni modelli analitici sviluppati per descrivere la complessa interazione dinamica fra il terreno e una paratia incastrata alla base. A differenza dei metodi pseudostatici, suggeriti dagli Eurocodici, i modelli sviluppati consentono di tenere conto della effettiva rigidezza della paratia, delle proprietà elastiche e di permeabilità del terreno ed inoltre di simulare il comportamento dinamico dell’insieme terreno-opera di sostegno in presenza di una forzante comunque variabile nel tempo, applicando la trasformata discreta di Fourier (D.F.T.). La risposta dinamica dell’opera viene modellata con riferimento a due diversi tipi di terreno, tipici dei siti alluvionali interessati dal progetto della Idrovia Ferrarese (Lanzoni et al., 2005); l’uno di tipo limo-argilloso con bassa permeabilità per cui viene considerata una equazione costitutiva di tipo visco-elastico, l’altro per i terreni a grana grossa con elevata permeabilità per cui viene sviluppa...
This paper presents a critical review of several analytical and numerical models that may be adop... more This paper presents a critical review of several analytical and numerical models that may be adopted for studying the out-of-plane behaviour of masonry structures having regular texture, with particular attention to the case of historical masonry, that is characterized by rigid blocks connected by mortar joints modelled as elastic interfaces. Discrete model, Love-Kirchhoff and Reissner-Mindlin plate models and a full three-dimensional heterogeneous finite element model are considered. The elastic parameters of both plate models are based on an existing compatible identification between a three-dimensional discrete model and two-dimensional plate models. Numerical tests are carried on by defining four case studies and paying attention to an in-plane scale factor, representing the size of heterogeneity of the masonry pattern, and to an out-of-plane scale factor, representing the thickness of the structure. Numerical tests show that the existing discrete model is simple and effective for representing masonry behaviour, especially when the magnitude of the heterogeneity is large with respect to the overall size of the panel. Increasing the in-plane scale factor, both plate models converge to the discrete one, but the Reissner-Mindlin plate model shows a better convergence and also allows the adoption of a simple plate finite element for performing numerical analysis
American Journal of Engineering and Applied Sciences, 2016
Journal of Engineering Mechanics, 2017
Engineering Structures, 2016
ABSTRACT Continuum micro-polar models are employed for modeling masonry based on a compatible ide... more ABSTRACT Continuum micro-polar models are employed for modeling masonry based on a compatible identification procedure. The sensitivity of micro-polar models to the representative elementary volume (REV) chosen is discussed, moreover a discrete element model is proposed to verify reliability of several micro-polar solution. The discrete model allows to verify the influence of micro-rotations in masonry wall behavior. A comparison between discrete and F.E. Model in which constitutive functions are obtained from identification procedure is presented in some meaningful cases.
Rivista Italiana di …, 2005
Journal of Engineering Mechanics, 2005
International Journal of Engineering Science, 2008
International Journal of Architectural Heritage, 2012
In the present paper, a comparative numerical study on a 12 century masonry tower located in the ... more In the present paper, a comparative numerical study on a 12 century masonry tower located in the northern Italy is described. To assess the safety of the tower under seismic loads, different numerical analyses have been performed: non-linear static, limit and non-linear full dynamic analyses. In the first two cases, a full 3D detailed FE model is adopted, changing the seismic load direction and assuming different hypotheses for the interconnection between the core and the external walls. When dealing with the FEM incremental analysis, a commercial code is utilized assuming for masonry a smeared crack isotropic model. For limit analysis, a non-commercial full 3D code developed by the authors is utilized. It provides limit good estimates of limit loads and failure mechanisms, to compare with standard FEM results. The dynamical analyses have been performed by a specific 2D RBSM (Rigid Body and Spring Model), accounting for the asymmetries along the thickness and the irregularities changes of thickness of both the external and internal walls in an approximate but realistic way. Four different accelerograms are utilized –passing from low to high seismicity zones- to evaluate the performance of the tower under dynamic loads. From numerical results, the role played by the actual geometry of the tower is envisaged, as well as a detailed comparison of failure mechanisms provided by the incremental FEM and limit analysis is provided. In all cases, the numerical analysis has given a valuable picture of possible damage mechanisms providing useful hints for the introduction of structural monitoring.
Archives of Computational Methods in Engineering, 2019
XVII Congresso AIMeTA, 2005
In the present work the problem of thin surface coatings of an elastic layer subject to a residua... more In the present work the problem of thin surface coatings of an elastic layer subject to a residual thermal stress is analytically investigated. The system adopts a curvature as a result of the misfit strain due to the different thermal expansivities of the layer and coatings. The problem is governed by a singular integral equation which can be reduced to a linear algebraic system by approximating the unknown interfacial shear stress via series expansion of Chebyshev polynomials. The present analysis is developed in order to assess the mechanical behaviour of a crystalline undulator designed for obtaining high emission radiations through channelling phenomeno
Nel presente lavoro vengono presentati alcuni modelli analitici sviluppati per descrivere la comp... more Nel presente lavoro vengono presentati alcuni modelli analitici sviluppati per descrivere la complessa interazione dinamica fra il terreno e una paratia incastrata alla base. A differenza dei metodi pseudostatici, suggeriti dagli Eurocodici, i modelli sviluppati consentono di tenere conto della effettiva rigidezza della paratia, delle proprietà elastiche e di permeabilità del terreno ed inoltre di simulare il comportamento dinamico dell’insieme terreno-opera di sostegno in presenza di una forzante comunque variabile nel tempo, applicando la trasformata discreta di Fourier (D.F.T.). La risposta dinamica dell’opera viene modellata con riferimento a due diversi tipi di terreno, tipici dei siti alluvionali interessati dal progetto della Idrovia Ferrarese (Lanzoni et al., 2005); l’uno di tipo limo-argilloso con bassa permeabilità per cui viene considerata una equazione costitutiva di tipo visco-elastico, l’altro per i terreni a grana grossa con elevata permeabilità per cui viene sviluppa...
This paper presents a critical review of several analytical and numerical models that may be adop... more This paper presents a critical review of several analytical and numerical models that may be adopted for studying the out-of-plane behaviour of masonry structures having regular texture, with particular attention to the case of historical masonry, that is characterized by rigid blocks connected by mortar joints modelled as elastic interfaces. Discrete model, Love-Kirchhoff and Reissner-Mindlin plate models and a full three-dimensional heterogeneous finite element model are considered. The elastic parameters of both plate models are based on an existing compatible identification between a three-dimensional discrete model and two-dimensional plate models. Numerical tests are carried on by defining four case studies and paying attention to an in-plane scale factor, representing the size of heterogeneity of the masonry pattern, and to an out-of-plane scale factor, representing the thickness of the structure. Numerical tests show that the existing discrete model is simple and effective for representing masonry behaviour, especially when the magnitude of the heterogeneity is large with respect to the overall size of the panel. Increasing the in-plane scale factor, both plate models converge to the discrete one, but the Reissner-Mindlin plate model shows a better convergence and also allows the adoption of a simple plate finite element for performing numerical analysis
American Journal of Engineering and Applied Sciences, 2016
Journal of Engineering Mechanics, 2017
Engineering Structures, 2016
ABSTRACT Continuum micro-polar models are employed for modeling masonry based on a compatible ide... more ABSTRACT Continuum micro-polar models are employed for modeling masonry based on a compatible identification procedure. The sensitivity of micro-polar models to the representative elementary volume (REV) chosen is discussed, moreover a discrete element model is proposed to verify reliability of several micro-polar solution. The discrete model allows to verify the influence of micro-rotations in masonry wall behavior. A comparison between discrete and F.E. Model in which constitutive functions are obtained from identification procedure is presented in some meaningful cases.
Rivista Italiana di …, 2005
Journal of Engineering Mechanics, 2005
International Journal of Engineering Science, 2008
International Journal of Architectural Heritage, 2012
In the present paper, a comparative numerical study on a 12 century masonry tower located in the ... more In the present paper, a comparative numerical study on a 12 century masonry tower located in the northern Italy is described. To assess the safety of the tower under seismic loads, different numerical analyses have been performed: non-linear static, limit and non-linear full dynamic analyses. In the first two cases, a full 3D detailed FE model is adopted, changing the seismic load direction and assuming different hypotheses for the interconnection between the core and the external walls. When dealing with the FEM incremental analysis, a commercial code is utilized assuming for masonry a smeared crack isotropic model. For limit analysis, a non-commercial full 3D code developed by the authors is utilized. It provides limit good estimates of limit loads and failure mechanisms, to compare with standard FEM results. The dynamical analyses have been performed by a specific 2D RBSM (Rigid Body and Spring Model), accounting for the asymmetries along the thickness and the irregularities changes of thickness of both the external and internal walls in an approximate but realistic way. Four different accelerograms are utilized –passing from low to high seismicity zones- to evaluate the performance of the tower under dynamic loads. From numerical results, the role played by the actual geometry of the tower is envisaged, as well as a detailed comparison of failure mechanisms provided by the incremental FEM and limit analysis is provided. In all cases, the numerical analysis has given a valuable picture of possible damage mechanisms providing useful hints for the introduction of structural monitoring.
The aim of this paper is to present a critical comparative review of different models that may be... more The aim of this paper is to present a critical comparative review of different models that may be adopted for modelling the mechanical behaviour of masonry, with particular attention to microstructured models. Several continuous and discrete models are discussed. Such models are based on the following assumptions: i) the structure is composed of rigid blocks; ii) the mortar is modelled as an elastic material or an elastic interface. The rigid block hypothesis is particularly suitable for historical masonry, in which stone blocks may be assumed as rigid bodies. For this type of masonry, mortar thickness is negligible if compared with block size, hence it can be modelled as an interface. Masonry-like materials may be modelled taking into account their heterogeneity by adopting a heterogeneous Finite Element Model (FEM) or a Discrete Element Model (DEM). The former seems to be more representative of masonry, but it is computationally onerous and results interpretation may be difficult; the latter is limited to rigid block assumption and mortar joints modelled as interfaces. For this reason, continuous equivalent models may be suitable to investigate masonry behaviour. Continuum equivalent models provide, in an analytical form, constitutive functions, but Cauchy model may be not suitable to describe masonry behaviour due to not negligible size of heterogeneity (block size) with respect to masonry panel size. For this reason, micropolar equivalent continuum may be adopted. By reference to the existing literature, a simple and effective DEM is adopted, in which masonry is modelled as a ‘skeleton’ having a behaviour depending on forces and moments transferred between blocks through the interfaces (mortar joints). Moreover for the micropolar equivalent continuum, an ad hoc enriched homogenised FEM is formulated by means of triangular elements. The proposed numerical models represent two possible simple approaches for solving heterogeneous problems. Such models are developed both by means of fast numerical routines and do not require specific computer codes, whereas the heterogeneous FEM may be studied by adopting a traditional FE code. DEM and heterogeneous FEM are adopted to verify reliability and application field of Cauchy and micropolar continua. Moreover, sensitivity of micropolar model to the Representative Elementary Volume (REV) chosen is discussed. For these purposes, ad hoc FE models are adopted, with constitutive functions obtained from an identification procedure (both for Cauchy and micropolar continua). An extensive comparison between DEM, heterogeneous FEM and equivalent homogenous FEM is presented in some meaningful cases, taking into account also the effect of heterogeneity size on models behaviour.
In this paper a free modal analysis for the Frari historical bell tower in Venice is described. T... more In this paper a free modal analysis for the Frari historical bell tower in Venice is described. Three-dimensional finite element models and an analytical model are proposed. The proposal is to evaluate the sensitivity of the models to several geometric parameters, i.e. geometric irregularities, the presence of openings, different thicknesses of external walls. With this aim four models are proposed: i) a model of external and internal walls with real geometric parameters; ii) a model of the only external walls with real geometric parameters; iii) a simplified model of external and internal walls represented as a rectangular girder; iv) a simplified model of the only external walls represented as rectangular girder. The analytical simplified model is proposed as a comparative example. The analysis shows interesting results: i) frequencies are strongly connected to the internal nucleus; ii) mass participation is not uncoupled and always are present both flexural and torsional mode, due to geometric non-alignment to the vertical axis. Geometric irregularities entail only a part of the whole mass, which is involved in the flexural mode, while a torsional component is entailed into the mass participation. This changes entire structural behaviour. For this reasons, dynamic analysis must take into account actual geometry: effective thickness related to mass distribution, opening presence and vertical inclination.
Continuum micro-polar models are employed for modeling masonry based on a compatible identificati... more Continuum micro-polar models are employed for modeling masonry based on a compatible identification procedure. The sensitivity of micro-polar models to the representative elementary volume (REV) chosen is discussed, moreover a discrete element model is proposed to verify reliability of several micro-polar solution. The discrete model allows to verify the influence of micro-rotations in masonry wall behavior. A comparison between discrete and F.E. Model in which constitutive functions are obtained from identification procedure is presented in some meaningful case.