1,720,974 research outputs found
The Italian guidelines on risk classification and management of bridges: Applications and remarks on large scale risk assessments
Get PDFBridges are essential for guaranteeing the functioning of transportation systems since their failure can cause serious threats to the safety, well-being and economy of modern communities, especially in emergency conditions. Following recent bridge failures, among which include the Morandi bridge in 2018, specific guidelines on risk classification and management, safety assessment and monitoring of existing bridges have been issued in Italy by the Minister of Infrastructure as a mandatory code. They pay particular attention to the evaluation of the residual life span of critical transportation infrastructure dating back to the 1950s and 1960s of the last century. Being a newly issued tool, the Guidelines need to be applied and tested in order to find possible drawbacks and to point out the main factors influencing their results. Therefore, in this study, after a short description of the Italian Guidelines, pointing out some differences with other approaches adopted worldwide, some advantages and disadvantages are discussed by an application to a bridge stock located in the Basilicata region (Italy). Data needed to apply the Guidelines are gathered by a purposely set up procedure that exploits existing databases on road infrastructure (OpenStreetMap) complemented by additional data retrieved by means of public image repositories (Google Street View). By accounting for the qualitative nature of the risk classification results obtained by applying the lower analysis levels of the Guidelines, a prioritization method is proposed for ranking bridges for higher assessment levels and possible interventions, as well as consequent funds allocation. The application shows that the Guidelines’ approach tends to provide conservative results. In fact, even in case of bridges with low degradation levels, the final risk classification induces actions undertaken for preliminary or detailed assessment; thus, normal operation (with periodic inspections) would not be possible anymore
Structural analysis of dapped-end beams through machine learning techniques
Get PDFDapped-end beams (or half-joints) are extensively used in both reinforced concrete bridge structures and roofs and flooring for prefabricated buildings. Due to their geometric configuration, they represent discontinuity regions where high stresses concentrate. Therefore, it is crucial to evaluate the load-bearing capacity of these elements which may depend on various parameters, such as the strength of materials, the quantity and the different layouts of the used reinforcements which also significantly influence their failure mode. For this purpose, a literature review led to the creation of an experimental tests database used to conduct an in-depth statistical analysis, considering the influence of various parameters on the ultimate load capacity and failure mode of dapped-end beams. The collected database has been also used to train a regression model with supervised machine learning techniques in order to predict the ultimate capacity of dapped-end beams
Post-earthquake rehabilitation of healthcare buildings: The case study of the mirandola hospital
Get PDFRecent earthquakes in Italy and other countries have shown the fragility of hospital complexes which resulted in many cases unusable due to structural and non-structural damage. Depending on the extent of damage, unusable hospitals were reopened after some weeks/months, or affected by long rehabilitation intervention or demolished. In order to allow for a prompt resumption of the social activities of the local communities, the usability evaluation carried out in the immediate aftermath of a seismic event is a crucial step to address the short-term countermeasures and to obtain a gross estimate of the economic losses. After the first weeks, it is often necessary a more detailed assessment which allows for a more accurate evaluation of damage and, more importantly, about the reparability of the structure along with the study of feasible intervention strategies. This latter activity needs detailed analyses based on increased knowledge of the structure. Keeping in mind the objectives of detailed post-earthquake assessment and reparability evaluations, the Santa Maria Bianca hospital of Mirandola, damaged by the Emilia 2012 earthquake, has been analyzed as a case study. Analyses were devoted to defining an upgrading strategy to match the code serviceability limit states (damage limitation and occupancy). The selected strategy included solutions to carry out most of the work from outside, to limit the downtime of the building as well as reconstruction of demolished non-structural elements. Further analyses were made in order to check the effects of the upgrading strategy under the seismic actions recorded during the 2012 Emilia earthquake. These analyses highlighted that even the upgraded hospital building could not be able to remain operational after a new seismic event having the same intensity as the 2012 event, underlining the need of more stringent design criteria for strategic structures like hospitals that are requested to provide healthcare services even more when strong earthquakes occur
Effetto della levosulpiride e della metoclopramide sulla cinetica colecistica in soggetti diabetici, insulinodipendenti con neuropatia autonomica
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A sustainable solution for the seismic strengthening of RC existing buildings through the HPDF system (HPDF): A case study
No full textThe large number of existing buildings for which seismic rehabilitation interventions are required highlights the need of sustainable techniques able to reduce costs and downtime. To this purpose, a new strengthening technique named High-Performance Dissipating Frame (HPDF) was developed. It consists of new framed structures applied from the outside thus reducing the impact and relocation needs of tenants. This is even more important for strategic (e.g. hospitals) and other public buildings (e.g. schools) due to the social and economic effects deriving from their interruption of use. HPDF system consists of external precast RC frames (i.e. exoskeletons) rigidly connected to the existing structure and equipped with both shear and flexural damper devices to provide a high dissipation capacity in case of seismic actions and then to protect existing building. In the paper, the HPDF system has been applied to a Reinforced Concrete (RC) school building designed only to gravity loads. After a brief description of the building under study and the HPDF system, the stiffness, strength, and dissipation properties have been determined using an iterative displacement-based design procedure purposely set up. Results show that the considered strengthening technique increases seismic performance of the existing building according to different targets involving both structural and non-structural components, also avoiding any other local intervention
Analysis of a large database of concrete core tests with emphasis on within-structure variability
Get PDFIn reinforced concrete (RC) structures, the compressive strength of concrete can play a crucial role in seismic performance and is usually difficult to estimate. Major seismic codes prescribe that concrete strength must be determined essentially from in situ and laboratory tests. Mean values obtained from such tests are the reference design values when assessing existing structures under seismic actions. The variability of concrete strength can also play an important role, generally requiring that various homogeneous domains are identified in a single structure, in each of which a specific mean value should be assumed as representative. This study analyzes the inter- and intra-variability of the concrete strength of existing buildings using a very large database made up of approximately 1600 core tests extracted from RC buildings located in the Basilicata region (Southern Italy). The analysis highlighted that concrete strength variability was dependent on the structures' dimensions as well as on the number of storeys. Moreover, the concrete strength of cores extracted from columns was found to be, on average, lower than that from beams, thus justifying the usual practice to extract cores mainly from columns, which results in a conservative approach as well as a more feasible one. Finally, some case studies were analyzed, specifically focusing on the effects of the within-storey variability. Conservative strength values, to be used especially in the case of vertical members subjected to high axial loads, are suggested
Experimental and numerical evaluation of coring effects in reinforced concrete columns
Get PDFThe knowledge of in-situ material properties is the first step in the assessment process of existing structures and, where needed, in the design of the consequent strengthening interventions. In order to achieve this goal, destructive (DT; e.g., cores) and non-destructive (NDT; e.g., ultrasonic, rebound) test methods are generally adopted, either alone or combined. Although many literature papers and guidelines propose to minimize the number of cores in the estimation of the concrete strength in reinforced concrete structures, the European and Italian codes prescribe that the estimation of in-situ strength has to be mainly based on cores drilled from the structure (DT). In this framework, the paper reports results of an experimental program aimed at evaluating the effects of core tests on RC columns, as well as the effectiveness of the structural restoration of drilling holes. Specifically, three sets of column specimens have been considered: (i) drilled columns, (ii) drilled and subsequently restored columns, and (iii) reference not drilled (as-built) columns. Compression tests have been carried out on each column and the results have been compared with the prediction based on codes or other literature approaches. This helped to recognize the main phenomena affecting the column members behavior under axial loads. At the same time, the authors calibrated detailed finite element models based on the experimental results of the tests carried out on column specimens. An advanced Fem tool was used to set-up 3D models. Numerical simulations aimed at better understanding the failure mechanism, especially in the presence of the hole related to the core extraction. The role of longitudinal and transverse reinforcement has been evaluated, highlighting that concrete crushing in the areas around the hole causes the early buckling of rebars, leading to premature failure of drilled column specimens
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
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