1,721,527 research outputs found
Seismic risk assessment using machine learning for the automatic identification of building features
No full textIn nations with a high seismic hazard and a significantly vulnerable built heritage, seismic risk assessment represents a serious challenge. In particular, when seismic risk needs to be analyzed on large scales, vulnerability and exposure evaluations can lead to time-consuming and expensive investigations. In this work, artificial intelligence techniques are leveraged to address this issue. Specifically, Convolutional Neural Networks (CNNs) are trained to automatically collect data about buildings from satellite imagery and street views. In this work, three CNNs are trained to recognize the following features: building height, material, and construction period, deemed to be the essential parameters for associating a specific seismic vulnerability level to a building. The following step of this study involves the combination of vulnerability and exposure with seismic hazard to evaluate seismic damage and risk. The latter is represented by potential losses in terms of reconstruction costs, number of unusable buildings, and displaced people. Emergency management organizations may find the results of this work useful for setting priority standards for seismic retrofit operations, as well as for allocating rescue resources after an earthquake
Analytical model to predict the out-of-plane response of masonry infill walls
No full textThe use of brick masonry infill walls is a common practice in reinforced concrete (RC) frames. These, classified as non-structural elements and often overlooked in design models, strongly influence the seismic behaviour of RC frames by increasing the overall structural stiffness. In addition, they can lead to significant structural irregularities and be the cause of brittle failure mechanisms, such as soft-floor mechanisms.
This paper aims to present a recently developed analytical model for estimating the lateral out-of-plane (OOP) response of various masonry infill walls. This model implements vertical and horizontal arch mechanisms, including the deformability of the RC frame elements surrounding the panel (i.e., upper beam and columns), the possible presence of external strengthening solutions, and considering different failure mechanisms. The model is calibrated on the results of previous experimental campaigns for thin and thick infill walls, reinforced and unreinforced, also considering previous in-plane damage.
Finally, a parametric analysis based on this model is presented, which is useful for discussing the role of the main vulnerability parameters of infills on their OOP capacity
New Φ method in EN1996 for the verification of second-order effects in load-bearing masonry walls
No full textThe Eurocode 6 (EC6) revision work carried out in recent years within the “CEN/TC 250/SC 6 – Masonry Structure” was an opportunity to reconsider verification methods for unreinforced masonry (URM) walls when subjected to combined vertical and out-of-plane loading and with significant second-order effects. The method proposed in the previous version of EC6 was based on an axial load capacity reduction factor (φm), the values of which were derived from an approximate model, fairly conservative for a wide range of wall stiffnesses. In addition, the previous version of EC6 did not require explicit verification in terms of lateral flexural capacity for URM walls subjected to significant lateral loads (e.g., seismic actions), when it would be appropriate and rational. For the latter verification, which should also take into account second-order effects, a reduction factor similar to φm can be defined for bending capacity reduction (φM). Therefore, this paper aims to show the scientific derivation of the new criteria adopted in the current version of EC6 (EN1996-1-1:2022) for the verification of second-order effects in URM walls. In particular, the numerical procedure for quantifying the φ factors is presented, which has improved the estimates previously available in the literature. Based on these numerical results, prediction models of these φ factors are proposed, which are also used to demonstrate the one-to-one correspondence between φm and φM. Then, validation comparisons are shown between the predicted values of the reduction factors and the relevant experimental and numerical values previously available in the literature. Finally, the calibration of the models proposed in the new version of EC6 is shown for both φm and φM
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
Metasedimentary and igneous xenoliths from the volcano of Tallante (Betic Cordillera, Spain): a reappraisal based on isotopic analyses
No full textDeep seated xenoliths entrained by volcanics provide information on the composition, thermal regime and physical properties of deep inaccessible lithologies. Unfortunately, the approach of study is somewhat limited because: i) xenoliths are rare and not ubiquitous in all volcanic centers; ii) in each volcanic center the xenolith population is often monotonous, i.e. mainly represented by a prevalent lithology. The homogeneity of xenolith suites from distinct volcanic sites is ascribed to the uptake mechanism, mainly related to fluid release and bubble nucleation, which trigger discrete event of crack formation and breaking of the surrounding deep rocks. The specific depth of xenolith formation is distinctive of each magma type, and usually Cenozoic alkaline basalts of the Mediterranean region entrain xenoliths from either the uppermost lithospheric mantle (30-50 Km depth) or the lower crust, and sampling from different depths is rare. In this view, the volcano of Tallante (Pliocene) in the Betic Cordillera (Spain) represents a peculiar occurrence, where alkaline basalts uprising from mantle sources exhumed an extremely heterogeneous xenolith association, including protogranular peridotites, felsic metasedimentary rocks, as well as diverse cumulitic igneous rocks such as amphibole-clinopyroxenites and norite-gabbros. Noteworthy, the numerous studies available in the literature mainly focused on the peridotite xenoliths and failed to consider in a coherent framework the total xenolith suite of Tallante and to explain its extreme variability. Only recently, Bianchini et al. (2013) proposed that the extreme xenoliths heterogeneity recorded at Tallante could be related to the specific geodynamic setting, located along a collisioned belt, where the crust-mantle boundary is possibly characterized by an intimate association of crustal and subcrustal lithologies, interlayered as result of orogenic processes. This contribution presents new Sr-Nd isotopic analyses carried out on metasedimentary and igneous xenoliths, as well as in-situ U-Pb dating of a zircon grain from a gabbroic xenolith. The new data, discussed taking into account the most recent geophysical evidence (Thurner et al., 2014) give insights to refine the pre-existing petrological hypotheses, in the general geological framework of the Betic orogenic belt.
References
- Bianchini G., Braga R. & Langone A., 2013. Crustal xenoliths from Tallante (Betic Cordillera, Spain): insights into the crust–mantle boundary. Geol. Magaz. 150, 952-958.
- Thurner S., Palomeras I., Levander A., Carbonell R., & Lee C.-T. Ongoing lithospheric removal in the western Mediterranean: Evidence from Ps receiver functions and thermobarometry of Neogene basalts (PICASSO project). Geochem. Geophy. Geosyst. 10.1002/2013GC005124
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
Monazite dissolution-reprecipitation in medium-grade metasedimentary rocks from the northern Apennines, Italy
No full textFluid-induced dissolution of parent phases and precipitation of products is a fundamental process in metamorphism
(Putnis & Austrheim, 2010). Here we present the dissolution-reprecipitation behaviour of monazite, one of the main
rare-earth element (REE)-bearing accessory minerals useful for obtaining geochronological and geochemical
information from a wide range of Ca-poor crustal rocks. The reactions involving monazite were studied in a micaschist
recovered from the Pontremoli 1 well (Tuscany) and the implications of fluid-controlled monazite breakdown on age
dating were discussed (Lo Pò et al., 2016). The micaschist belongs to the Variscan basement of the Northern Apennines.
In this rock monazite, either disseminated in the matrix or included in white mica and chlorite partially replacing garnet,
is surrounded by coronitic microstructures consisting of concentric shells of apatite + Th-silicate, allanite, epidote.
Studies of the element partitioning between garnet and accessory minerals and the garnet inclusion mineralogy suggest
that monazite was partially dissolved and replaced by apatite, allanite and epidote during garnet breakdown to chlorite
and muscovite. This stage was associated with the retrograde and decompressional evolution of the micaschist at fluidpresent
conditions. Through thermodynamic modelling, we determined the P-T conditions of the monazite partial
dissolution and replacement process at 510 ± 35°C, during a nearly isothermal decompression path from 8 kbar to 2-3
kbar. Fluid-induced alteration of monazite also resulted in a partial resetting of the monazite ages, which were
determined to be between 294 and 19 Ma. The maximum extent of the alteration process occurred in monazite located
within retrogressed garnet rims. In this microstructural site, Pb in the Variscan monazite was lost.
Lo Pò, D., Braga, R., Massonne, H.-J., Molli, G., Montanini, A., Theye, T. (2016): Fluid-induced breakdown of monazite in mediumgrade
metasedimentary rocks of the Pontremoli basement (Northern Apennines, Italy). J. Metamorph. Geol., 34, 63-84.
Putnis, A. & Austrheim, H. (2010): Fluid-induced processes: metasomatism and metamorphism. Geofluids, 10, 254-269
Monazite dissolution-reprecipitation in medium-grade metasedimentary rocks from the Northern Apennines, Italy.
No full textFluid-induced dissolution of parent phases and precipitation of products is a fundamental process in metamorphism
(Putnis & Austrheim, 2010). Here we present the dissolution-reprecipitation behaviour of monazite, one of the main
rare-earth element (REE)-bearing accessory minerals useful for obtaining geochronological and geochemical
information from a wide range of Ca-poor crustal rocks. The reactions involving monazite were studied in a micaschist
recovered from the Pontremoli 1 well (Tuscany) and the implications of fluid-controlled monazite breakdown on age
dating were discussed (Lo Pò et al., 2016). The micaschist belongs to the Variscan basement of the Northern Apennines.
In this rock monazite, either disseminated in the matrix or included in white mica and chlorite partially replacing garnet,
is surrounded by coronitic microstructures consisting of concentric shells of apatite + Th-silicate, allanite, epidote.
Studies of the element partitioning between garnet and accessory minerals and the garnet inclusion mineralogy suggest
that monazite was partially dissolved and replaced by apatite, allanite and epidote during garnet breakdown to chlorite
and muscovite. This stage was associated with the retrograde and decompressional evolution of the micaschist at fluid-
present conditions. Through thermodynamic modelling, we determined the P-T conditions of the monazite partial
dissolution and replacement process at 510 ± 35°C, during a nearly isothermal decompression path from 8 kbar to 2-3
kbar. Fluid-induced alteration of monazite also resulted in a partial resetting of the monazite ages, which were
determined to be between 294 and 19 Ma. The maximum extent of the alteration process occurred in monazite located
within retrogressed garnet rims. In this microstructural site, Pb in the Variscan monazite was lost.
Lo Pò, D., Braga, R., Massonne, H.-J., Molli, G., Montanini, A., Theye, T. (2016): Fluid-induced breakdown of monazite in medium-
grade metasedimentary rocks of the Pontremoli basement (Northern Apennines, Italy). J. Metamorph. Geol., 34, 63-84.
Putnis, A. & Austrheim, H. (2010): Fluid-induced processes: metasomatism and metamorphism. Geofluids, 10, 254-269
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