1,720,966 research outputs found
Alcune considerazioni sul comportamento meccanico di cupole storiche
No full textQuesta ricerca si propone di analizzare il comportamento statico di alcune cupole storiche mediante il metodo dell’analisi membranale e dell’analisi limite. Viene pertanto proposta una breve trattazione in cui vengono inizialmente illustrati alcuni metodi storicamente utilizzati per l’analisi tecnico-strutturale delle cupole e successivamente vengono proposti alcuni casi studio che sono stati analizzati sia con il metodo dell’analisi membranale sia con l’analisi limite. Infine vengono proposte alcune considerazioni sul comportamento strutturale delle medesime cupole in caso di sisma
Multi scale procedures for the structural identification of historic Masonry Bell Towers by innovative monitoring and structural modelling techniques
No full textA Procedure to Investigate the Collapse Behavior of Masonry Domes : Some Meaningful Cases
Full text linkMasonry domes represent an important part of the architectural heritage. However, the literature
about domes analysis seems less consistent than that referred to other masonry structures. The
collapses that have happened in recent years as a consequence of seismic actions or lack of
maintenance show the need for detailed studies. Here a limit analysis to evaluate the masonry
domes behavior is presented. An algorithm based on the kinematic approach has been developed
to evaluate the geometric position of the hinges that determine the minimum collapse load
multiplier. The proposed procedure is validated by a comparison with some meaningful cases—
the collapse of Anime Sante Church in L’Aquila, the collapse of San Nicolò Cathedral in Noto, the
crack pattern of San Carlo Alle Quattro Fontane Church in Rome, and the analysis developed on
Hagia Sofia in Istanbul. The comparison with real cases shows a good agreement between the
model results and the phenomenological crack patterns
Analisi modale del campanile di Santa Maria Gloriosa dei Frari: un caso studio di struttura muraria come materiale composito
No full textLa ricerca propone lo studio mediante l’analisi modale tridimensionale, sviluppata in ambito lineare elastico del campanile di Santa Maria Gloriosa dei Frari.
Il campanile dei Frari è costituito da una struttura portante in muratura. Come noto, la muratura è un materiale composito, costituito da giunti di malta e blocchi in laterizio, disposti con tessitura più o meno regolare, usata per molti secoli come materiale costruttivo. Le azioni dinamiche spesso rappresentano il rischio maggiore di collasso per edifici in muratura e, nonostante il progredire delle conoscenze tecniche e meccaniche, la valutazione del rischio sismico degli edifici così costituiti rappresenta ancora un tema di ricerca. In linea generale, gli edifici in muratura sottoposti all’azione sismica, possono subire danni secondo due diversi meccanismi: nel piano e fuori piano. Il primo meccanismo è caratterizzato da deformazioni geometriche e quadri fessurativi, mentre il secondo può causare il ribaltamento di intere parti murarie. Diversi studi sono stati eseguiti sia sui modelli numerici che sui parametri fisici che possono essere presi in considerazione (Kingsley et al. 1996, Magenes e Calvi 1997, Gambarotta e Lagomarsino 1997, Brasile e Casciaro 2009, Baraldi e Cecchi 2014).
In questo lavoro, si propone di valutare la sensibilità dei modelli numerici in relazione al variare dei parametri geometrici, alla presenza di aperture, allo spessore della sezione muraria. A questo scopo sono stati sviluppati quattro modelli agli elementi finiti: i) modellazione del paramento esterno e del nucleo interno del campanile con reali caratteristiche geometriche ; ii)modellazione del solo paramento esterno del campanile con reali caratteristiche geometriche; iii) modellazione del paramento esterno del campanile semplificato quale trave a sezione scatolare di spessore costante e del nucleo interno; iv)modellazione del solo paramento esterno del campanile semplificato quale trave a sezione scatolare di spessore costante.
Diversi studi sono già stati pubblicati sul campanile dei Frari (Lionello 2011), e sono inoltre disponibili in letteratura diversi lavori inerenti i modi di vibrare dei campanili, basati sulle analisi tromografiche (Teza et
al. 2014) e su analisi con modelli ad elementi finiti in ambito dinamico (Milani et al. 2012)
A Procedure for the Structural Identifcation of Masonry Towers
No full textHistoric masonry towers, as well as bell towers, minarets and chimneys, represent an important part of the Mediterranean
basin architectural heritage. Widely spread out on the Italian peninsula, the bell towers refect cultural, social and religious
aspects of the communities, thus, their conservation remains an open challenge for scientists, governments and local communities. The seismic behavior of slender masonry structures is, generally, characterized by the combination, of the static
vertical loads with dynamic loading. However, the determination of the structural behavior of masonry structures is always
a complex challenge due to the material inhomogeneity, manufacturing imperfections, geometric confguration or structural interaction between the layers in the case multi-leaf masonry structures. In this research, an expeditious and low-cost
procedure for the structural identifcation of historic masonry towers is proposed. The procedure, based on experimental
measurements and numerical modeling, aims at the estimation of the average mechanical characteristics under service loads.
In particular, the procedure proposes the acquisition of the fundamental frequency by means of a single compact digital
tromograph and successive fnite element model calibration starting from the experimental data. The whole identifcation
procedure has been at frst verifed on an elementary laboratory specimen, then applied on the historic bell tower of Basilica
dei Frari located in the historic city center of Venice
Modal Analysis of Frari Historical Bell Tower in Venice: A Comparison Between Detailed and Simplified Models
No full textIn 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
Modal Analysis for Study of Minor Historical Architecture
No full textThe cultural heritage conservation is a challenge for the contemporary society. In recent decades significant resources have been allocated for the conservation and restoration of the architectural heritage. Historical buildings were restored, protected and reinforced with the intent to limit the risks of degradation or loss, due to phenomena of structural damage and to external factors such as differential settlements, earthquake effects, etc... The wide diffusion of historic masonry constructions in Italy, Europe and Mediterranean area requires reliable tools for the evaluation of their structural safety. In this paper is presented a free modal analysis performed on a minor historical architecture located in the village of Bagno Grande, near the city of L’Aquila in Italy. The location is characterized by a complex urban context, seriously damaged by the earthquake of 2009. The aim of this work is to check the structural behavior of a masonry building characterized by several boundary conditions imposed by adjacent buildings and infrastructural facilities
Experimental and Numerical Analysis of a Historic Bell Tower
No full textIn this paper, a procedure for the evaluation of seismic behavior of slender masonry structures (towers, bell towers, chimneys, minarets, etc.) is presented. The presented procedure is based on a full three-dimensional modal analyses and frequency measurements. As well-known, masonry is a composite material formed by bricks, or stone blocks, and mortar arranged more or less regularly and adopted for many centuries as structural material.
Dynamic actions may represent the major risk of collapse of brickworks, and despite the progress achieved so far in science and mechanics; the assessment of their seismic erformance remains a challenging task. Then, reliable physical and numerical models are worthy of recommendation. In this paper, attention is paid to the historical bell tower of the Basilica of Santa Maria Gloriosa dei Frari - usually called Frari - one of the greatest churches in Venice, Italy
Limit analysis of masonry domes: the case of Hagia Sophia and Anime Sante
No full textThe conservation of cultural heritage is a challenge for the contemporary society. In recent
decades, significant resources have been allocated for the conservation and restoration of the
architectural heritage. Historical buildings were restored, protected and reinforced with the
intent to limit the risks of degradation, due to phenomena of structural damage and to external
factors such as differential settlements, earthquakes, etc. The wide diffusion of historic masonry
constructions in the Mediterranean basin requires reliable tools for the evaluation of their
structural safety.
Masonry domes represent an important part of the architectural heritage. However domes
haven’t been studied as much as other masonry structures. The collapses happened in recent
years, as a consequence of seismic actions or lack of maintenance, show the need of detailed
studies. Here a limit analysis (Milankovitch, 1907; Heymann, 1969; Livesley, 1992; Milani and
Cecchi, 2013) to the evaluation of the behavior of masonry domes is presented. An algorithm
based on the kinematic approach has been developed to evaluate the minimum collapse
multiplier and to determine the position of the hinges. The proposed method is compared with
some real cases: the collapse of Anime Sante Church in L’Aquila and the analysis developed
on Hagia Sofia in Istanbul. This comparison is useful to tune and validate the proposed method
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