1,721,000 research outputs found
Modelli osservazionali di fragilità sismica per serbatoi di stoccaggio
No full textNumerosi impianti di processo si trovano in are sismicamente attive come, ad esempio, le raffinerie nelle coste di Giappone, California, Perù, Alaska e Turchia. Il ventesimo secolo ha visto un notevole aumento di tali installazioni che però sono state sovente sede di disastri a seguito di terremoti. Gli impianti di processo sono costituiti da numerosi componenti, tra i quali i serbatoi di stoccaggio si possono annoverare tra i più pericolosi per le grandi quantità di sostanze in essi stoccate. Tra gli esempi di disastri sismo indotti (incidenti NaTech) nei quali sono stati danneggiati serbatoi si possono citare, tra gli altri, i terremoti di Kern County del 1952, di Niigata del 1964, di Kocaceli nel 1999 e di Tohoku del 2011. A seguito di tutti questi
eventi si sono generati incendi o esplosioni le cui conseguenze in alcuni casi sono state molto gravi sia dal punto di vista delle perdite di vite umane sia da quello ambientale. Tra le diverse tipologie di serbatoi, una tra le più diffuse per il contenimento di liquidi è costituita dai serbatoi atmosferici in acciaio. Numerosi studi sono stati condotti per comprendere
il comportamento di tali strutture quando sottoposte ad azioni sismiche approfondendo in particolare la problematica dell’interazione fluido-struttura (Calvi et Nascimbene, 2011). Inoltre in letteratura sono stati proposti alcuni modelli di fragilità sismica (O’Rourke et So, 2000; Salzano et al., 2003). Questi modelli forniscono la probabilità di superare diversi livelli
di danneggiamento, o di entità del rilascio delle sostanze contenute, in funzione dell’intensità dello scuotimento sismico alla base, tipicamente espressa in termini di accelerazione di picco del terreno (Buratti et al., 2017). Essi costituiscono un fondamentale strumento per le valutazioni quantitative del rischio industriale (Antonioni et al., 2009; Buratti et al., 2012; Fabbrocino et al., 2005). Tali modelli sono comunemente basati su raccolte di dati osservazionali relativi al
livello di danneggiamento riscontrato in serbatoi a seguito di terremoti, pertanto la loro qualità è strettamente legata a quella dei dati utilizzati. Recentemente sono stati proposti alcuni modelli ottenuti tramite modelli numerici, ma la loro generalità è limitata. La presente memoria propone modelli di fragilità parametrici ottenuti a partire da una nuova base dati sul danneggiamento dei serbatoi, creata dagli autori analizzando criticamente ed ampliando quanto già disponibile in letteratur
Dynamic identification of a railway bridge with prestressed concrete box beams
No full textDynamic monitoring of infrastructures has become increasingly important in the last decade because of their ageing and deterioration, and the need to evaluate their safety levels and rationally plan maintenance activities. The current paper presents the dynamic identification of a railway bridge with prestressed concrete box girders, based on acceleration recordings performed in operating conditions. Through the analysis of experimental data, natural frequencies, damping factors and mode shapes of the main modes were estimated. A finite element model was then defined in order to simulate the experimental data. The paper presents a comparison between the predictions of this model and experimental data and discusses their accuracy
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Empirical seismic fragility of different typologies of precast RC industrial buildings
No full textIn the present economy, seismic loss estimation is extremely important for planning civil protection strategies and
for predicting costs for restoring or retrofitting damaged buildings after earthquakes. Fragility curves are a fundamental tool for seismic risk assessment. They can be obtained using different approaches, mainly statistical analysis of observational damage data or numerical modelling. Observational damage data from past earthquakes are commonly used worldwide for the development of new empirical fragility curves or for validating existing ones based on mechanical models. The present paper focuses on the definition of observational fragility curves for RC precast buildings using damage data collected for almost 1800 buildings after the Emilia seismic sequence that struck the north of Italy in 2012. In particular, the building stock was subdivided into six main typologies with homogenous features. Parametric fragility curves for the different typologies and for different damage states, allowed to distinguish the fragility of the different typologies
Seismic fragility assessment of masonry aggregates with identical structural units in row
No full textIn civil engineering field, it is a common simplification to consider a building as isolated, even if it belongs to an aggregation of structural units. Thus, the first part of this work is focused on the fragility analysis of masonry structural units, considered as a part of a row aggregate and analyzed at first as isolated. Some variabilities and uncertainties involved in the problem are considered, generating a set of simulations through the Response Surface statistical procedure. The data obrained from the simulations were used to plot the fragility curves, by applying the Monte Carlo method. Afterwards, the masonry structural units have been aggregated in row in order to compare their seismic fragility with that of the isolated ones. The reults showed relevant differencies if different directions of the seismic action and different positions of the structural unit along the aggregate are considered
Stratigraphy and sedimentation setting of the Triassic Gokdere-type pelagic succession in western Taurides (southern Turkey)
No full textThe article is focused on the Upper Triassic volcano-sedimentary succession (western Taurids, ) . Integrated sedimentary and organic facies point to an epicontinental basinal environment for the late Triassic Gokdere-type pelagic sediments, which evolution was controlled by relative sea level fluctuations. The in situ palynomorphs confirm a late Carnian-Norian age for the Gokdere-type pelagic succession. The relative good preservation degree and TAI data of recycled sporomorphs and the presence of quartz of sedimentary provenance indicate unmetamorphosed Palaeozoic sandstones and shales as source area. According to the present knowledge on regional geology the Palaeozoic reworked debris could be originated from Sultandagi Region, at the northern part of the Anamas-Akseki Autochthonous
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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