1,720,969 research outputs found
Structural health monitoring of historical buildings in Italy: applications and uncertainty overview
Full text linkStructural Health Monitoring (SHM) is currently more and more considered (and applied) in It- aly for the study of Cultural Heritage (CH) buildings, as a key activity to increase the knowledge on their structural behavior and to have a deeper insight on their actual conditions, reducing uncertainties connected to material properties and structural capacity. In recent years the research group at the University of Padua, in collaboration with public administrations, has installed several SHM systems on heritage structures: two case studies are presented and discussed within this paper. The Arena of Verona and the Cathedral of Conegliano are excellent examples of ongoing monitoring activities, performed through static and dynamic approaches. In parallel to the application of innovative monitoring techniques, statistical models and data processing proce- dures have been developed and applied in order to eliminate uncertainties and exploit monitoring results for an effective assessment and protection of historical constructions
Structural health monitoring: a tool for managing risks in sub-standard conditions
No full textIn the last decade the number of structural health monitoring (SHM) systems designed and implemented on historic structures increased exponentially. Monitoring perfectly meets principles and guidelines of the recently issued Italian and European seismic codes as it is considered a strategic activity in the knowledge process of historic buildings, in order to understand their structural behavior and have a deeper insight on their health conditions. Thanks to SHM it is possible to intervene on buildings with more confidence (and only when necessary), but also to prevent the execution of intrusive strengthening interventions, in full compliance with the minimum intervention principle, so important in the restoration field. The object of monitoring is to identify, locate and classify type and severity of damages induced by external actions or degradation phenomena and to assess their effects on the structural performance. In this way it is possible to take appropriate measures to reduce the danger of collapse and, when necessary, perform strengthening interventions to improve the structural and seismic capacity. Motivated by the above reasons, the paper provide a contribution to the application of integrated methodologies and techniques, based on SHM, for the assessment and protection of cultural heritage (CH) buildings and existing structures. Selected case studies, equipped with distributed sensors and acquisition systems, allowed the definition and successive validation of SHM as a knowledge-based assessment tool, implemented to: (1) avoid the execution of unnecessary interventions and assess structural vulnerabilities; (2) evaluate intervention needs, following an incremental approach during their execution; (3) control the damage states of buildings in a post- seismic scenario. Monitoring data, automatically processed through dedicated software for static monitoring and automated algorithms for modal parameters extraction, are then used for the assessment of the health conditions and the identification of active damaging processes based on numerical simulations and robust statistical models
Uncertainty quantification in structural health monitoring: applications on cultural heritage buildings
Full text linkIn the last decades the need for an effective seismic protection and vulnerability reduction of cultural heritage buildings and sites determined a growing interest in structural health monitoring (SHM) as a knowledge-based assessment tool to quantify and reduce uncertainties regarding their structural performance. Monitoring can be successfully implemented in some cases as an alternative to interventions or to control the medium- and long-term effectiveness of already applied strengthening solutions. The research group at the University of Padua, in collaboration with public administrations, has recently installed several SHM systems on heritage structures. The paper reports the application of monitoring strategies implemented to avoid (or at least minimize) the execution of strengthening interventions/repairs and control the response as long as a clear worsening or damaging process is detected. Two emblematic case studies are presented and discussed: the Roman Amphitheatre (Arena) of Verona and the Conegliano Cathedral. Both are excellent examples of on-going monitoring activities, performed through static and dynamic approaches in combination with automated procedures to extract mean- ingful structural features from collected data. In parallel to the application of innovative monitoring techniques, statistical models and data processing algorithms have been developed and applied in order to reduce uncertainties and exploit monitoring results for an effective assessment and protection of historical constructions. Processing software for SHM was implemented to perform the continuous real time treatment of static data and the identification of modal parameters based on the structural response to ambient vibrations. Statistical models were also developed to filter out the environmental effects and thermal cycles from the extracted features
Seismic analyses and interventions design of a historic building in Jerusalem: the Cenacle and the tomb of David
Full text linkStructural health monitoring and diagnostic investigations of the Scrovegni chapel, Italy
Full text linkThe Scrovegni Chapel represents without doubt a masterpiece in the history of
painting in Italy and Europe in the 14th century and it is considered the most complete series
of frescos executed by Giotto in his mature age. Given the crucial importance of the building
from a cultural point of view, in 1995 a systematic research campaign started, including the
execution of studies on the structural health state of the Chapel. The final aim is to guarantee
optimal preservation conditions on the occasion, and in direct continuation, of the restoration
of the Giotto’s frescoes performed in 2001-2002. The investigation plan, based on nondestructive
techniques, includes punctual tests, periodically repeated, and continuous monitoring,
direct measurements and indirect identifications (back-analysis) of relevant structural
parameters. Although the structural layout of the chapel is apparently simple, the protection
of the monument is strongly connected to the fact that its historic and artistic value cannot be
separated from the structure itself and the effects of strengthening interventions carried out in
the last 150 years need to be carefully evaluated. In this framework a structural health monitoring
system has been recently installed by the authors. A network of static and dynamic sensors
controls the relevant parameters related to the structural safety of the monument and the
protection of the artistic content. The paper describes the diagnostic investigations carried
out, including ambient vibration tests, crack pattern survey and identification of possible ongoing
degradation phenomena. Then the installed monitoring equipment is presented focusing
on the algorithms developed and implemented into a processing software to perform the
online automatic analysis of static data and the identification of modal parameters. Relevant
features extracted from monitoring data are then used as inputs for the application of damage
detection algorithms and the numerical calibration of a finite element model of the structure
Operating conditions of an ancient Roman bridge: inspections and vibration analysis
Full text linkObject of the research activities reported within this paper is one of the best-preserved and famous roman structures of Padova: San Lorenzo bridge. It was built between 47 and 30 BC on the river Medoacus (the old flow of the Brenta river) and over its long history it was gradually incorporated into medieval and modern structures. Thanks to the archaeological excavations carried out in 1938 it was totally rediscovered and currently it is located below the modern roadway. In July 2013, after the survey of some detachments of stone from the intrados of the arch bridge, the municipality gave the task to the University of Padova to carry out an investigation campaign to study its health state. Aim of this work was to define the structural conditions of the bridge, control its degradation state and define possible actions to be implemented. Starting from historical research and geometrical survey, it was possible to investigate the past interventions and define a detailed damage pattern. Thermographic and georadar tests were per- formed confirming the high level of humidity affecting the structure due to water infiltrations. In addition, a dynamic monitoring system was installed in order to control the vibration level transmitted by the traffic on the masonry structures of the roman bridge. Time histories collected over about 20 days were processed and used for vibration analysis and verifications according to national and European standards (UNI 9916, DIN 4150). The outcomes of vibration monitoring gave the possibility to identify the type of vehicles that induce higher levels of vibrations and to control the daily and weekly intensity of traffic over the structure. The work constitutes the basis for any actions to be implemented in agreement with Padova municipality and the ministry of Cultural Heritage for an effective maintenance and conservation plan of the monument
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
Monitoring of orthotropic steel decks for experimental evaluation of residual fatigue life
No full textOrthotropic steel decks, directly subjected to traffic loads, are very sensitive to fatigue: defects mainly appear as cracks, which affect the top plates, longitudinal ribs and cross-beams of the deck. In this kind of bridges, structural health monitoring can be effectively adopted in characterising the safety threshold of the ongoing fatigue damage. This paper estimates the residual fatigue life of an existing orthotropic box-girder bridge, using experimental data from long-term monitoring of real traffic-induced effects. The bridge in question, less than 25 years old, is located on one of Italy’s busiest toll highways and evidenced fatigue damage due to deficiencies in original design and detailing. After preliminary visual inspections, the dynamic identification of the bridge was investigated by operational modal analysis, and a long-term monitoring campaign of strain measurements was subsequently carried out, involving series of strain gauges located on the most critical bridge sections. According to stress cycles recorded at these points, unlimited life verification was carried out according to EN 1993-1-9, and estimates of the residual fatigue life of the various elements were then derived by extrapolation of the experimental data. The proposed method can effectively be applied to fatigued steel bridge decks so that residual fatigue life and the real urgency of retrofitting interventions can be evaluated in operational conditions
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
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