1,721,028 research outputs found
Building Techniques and Structural Damage of Historical Constructions Detected Through the Point Cloud Survey
Full text linkThe study of historical constructions belonging to the cultural and architectural heritage is often challenging as, in most cases, it is very complex to reach a full understanding and description of them, due to the long-lasting history and the numerous modifications throughout the centuries. Many instruments today available allow gathering information on the current state of these buildings and contemporarily can provide some evidence on their history and constructive techniques. As a matter of fact, data taken from the modern technique of laser scanning, applied to architectural heritage, can provide important information not only on the present deformed configuration of each building, but also on the construction techniques related to its components, their geometries and possible structural problems. By juxtaposing the slices taken from the point cloud survey, indeed, the correspondences or the differences of the profiles might prove either the regularities or the incongruences characterizing each building. The present study will prove the significance of such an investigation technique with reference to the case study provided by Santa Fosca church on Torcello Island. This is a Venetian-Byzantine church, dated back to the 11th century, very peculiar both from the structural and architectural point of view and subject to numerous interventions throughout the centuries
Relative clauses from the input: Syntactic considerations on a coorpus based analysis of Italian
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Modelli generativi e sintassi generativa
No full textIn this short paper we present the results of four experiments assessing various degree of morphosyntactic and semantic linguistic competence in three very large language models (LLMs), namely davinci (GPT-3/ChatGPT), davinci-002 and davinci-003 (GPT-3.5 with different training options). We focused on (i) acceptability, (ii) complexity and (iii) coherence judgments on 7-point Likert scales and on (iv) syntactic development by means of a forced choice task. The datasets used are taken from available test-sets presented in shared tasks by the NLP community or from linguistic tests. The results suggest that, despite a rather good performance overall, these LLMs cannot be considered competence models since they do not qualify neither as descriptively nor explanatorily adequate
Damage evolution in churches due to repeated earthquake shocks
Full text linkMany ancient masonry churches reported considerable damage in the earthquakes that occurred in Italy in the last decades. In order to protect this heritage, dedicated research projects collected the effort of a large research community, producing methods for vulnerability assessment and damage classification, and criteria for seismic improvement. Considerations deriving from different surveys carried out by the authors on churches damaged in the recent Central Italy, 2016, earthquake are reported here. The surveys have been performed in the Region Marche at different times. Some churches inspected at the beginning of October 2016, after the first strong earthquake shocks, could be revisited in Spring 2017 after the strong events at the end of October and in January 2017. These surveys offered the opportunity of observing the evolution of damage and to assess some effects of the structural improvement interventions that had been carried out prior to the earthquake. In summary, the seismic events that arrived after the first surveys increased the damage on these already weakened structures, developing further the damage mechanisms that had been identified. In some instance the situation evolved into localized collapse, but in most cases the global stability was maintained. While further investigations including numerical modeling are in progress, observations confirmed that simple and low-impact interventions are effective in limiting some damage typologies; in some of these cases, however, damage developed moving to different elements, most likely for a higher level of action
Semi-automatic calibration of numerical models for the seismic safety assessment of masonry towers embedded in building aggregates
No full textThe present work addresses the topic of automated calibration of numerical models starting from the experimental characterization of the structure's dynamic behaviour. The importance of the topic is well known in the literature, especially in cases where it is necessary to have at disposal validated numerical models, necessary for the correct evaluation of the safety of existing buildings. Generally, the calibration problem is developed with a manual approach (manual tuning), with a positive outcome whenever there is a good knowledge of the boundary and internal constraint conditions and the elastic mechanical properties of the construction's constituent materials. Conversely, the positive outcome is particularly difficult to achieve manually when there are non-homogeneous and/or complex structures, as in the cases of historic masonry structures, which are often the result of constructions carried out at different times, organized in aggregates whose interaction between the portions is not simple to understand. For this purpose, the present work, using commercial software and specially prepared routines, illustrates a semi-automatic procedure, which employs genetic algorithms, suitable for the optimized identification of the numerical model that best represents the structure's experimental dynamic behaviour. The procedure is presented with reference to two case studies: the Gabbia Tower historic masonry aggregate in Mantua and the bell tower of the Monastery of the Ursuline nuns in Capriolo, Brescia. In the first case, in addition to the experimental dynamic characterization, a good instrumental characterization of the tower's masonry mechanical properties is available. In the second case, alongside a good experimental dynamic characterization, only a qualitative estimate of the masonry mechanical properties, based on visual inspections, is available. The two case studies allow for testing the validity of the numerical models’ calibration procedure, necessary for their application in the field of safety checks. Finally, for the case studies analysed the work presents an assessment of seismic vulnerability starting from the models identified with the semi-automatic procedure. The seismic vulnerability assessment was obtained using non-linear static analysis following the N2 method
Interpretation of collapse modalities for a timber roof truss
No full textRoof structures in historical buildings are often based on complex timber trusses; this is typically the situation of theatre buildings, where a wide room is present and large spans have to be covered. Several studies have been done on such structural systems showing that, in the case of complex roof systems, connections between timber elements were conceived in the past mainly to resist vertical loads corresponding to symmetrical patterns, with no consideration of eccentric loads and horizontal forces. In the paper, this problem is investigated with reference to the specific case study offered by a theatre, where a queen post truss was adopted for the roof system and the sudden collapse of one truss has occurred. The theatre, which is located in northern Italy, was built at the beginning of the 19th century. Although some modifications were made through time, the roof structure has preserved the original configuration. A precise identification of the real structural conditions has been obtained on the basis of the results of laser scanning and photogrammetric surveys. On this basis, numerical models have been developed in order to analyse a variety of load scenarios compatible with the observed structural collapse, with the final purpose of highlighting possible deficiencies in the original structural configuration, in line with the collection of similar cases which are reported in the literature
COMPARISON OF THE RECORDED SEISMIC SIGNALS FOR THE 2012 EMILIA AND 2016 CENTRAL ITALY SEISMIC SEQUENCES WITH THE DESIGN EARTHQUAKES BASED ON THE PSHA APPROACH
No full textThe recent seismic sequences occurred in 2012 in the Emilia region and in 2016 in Central Italy have confirmed the high level of vulnerability typical of masonry historical buildings and historical centres. Among these, the historical centre of Amatrice was razed to the ground and most of the historical buildings of municipalities in the epicentral area suffered partial or total collapse. Ground motion recordings highlighted a remarkable difference with the design earthquakes provided by the national seismic hazard map, which is based on the PSHA (Probabilistic Seismic Hazard Assessment) approach. Specifically, the response spectra of the signals recorded at Finale Emilia and Mirandola (2012) and at Norcia and Amatrice (2016) have been compared to the design spectra prescribed by the national building code; from comparison, the strong underestimation of the design spectral accelerations is evident, especially for the historic centre of Amatrice, due to the additional effect of local amplification. All recent Italian earthquakes (L'Aquila 2009, Emilia 2012, Central Italy 2016) and many others around the world, have shown that the PSHA approach does not provide reliable results in case of severe events. On the contrary, the technical literature shows that the NDSHA (Neo-Deterministic Seismic Hazard) approach generally provides reliable results. The need to update the seismic regulations, therefore, is clear in view of a preventive policy against the collapse of historic centres and monuments, based on the correct definition of seismic hazard levels. In the present contribution the analysis of the above seismic events is presented, being part of a wider analysis on the effects produced on the built heritage by seismic sequences
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