1,720,979 research outputs found
The structural life of a Cathedral and the worksites of the Duomo di Milano
Full text linkThe life of Milan Cathedral is described with the evolution of the structural system and the restorations carried out throughout the centuries. The organization of the Veneranda Fabbrica del Duomo di Milano is outlined, with the latest restoration interventions. The case study of the construction and restorations of the Tiburio with its supporting pillars is analyzed, from the initial design to the dramatic damage in the 20th century. The rebirth of the Cathedral was the fruit of restorations preserving the structural identity of the monument up to the present. The conclusions address the study of damage and maintenance and repair operations of mon-umental heritage buildings within a life cycle perspective, in relation to the underlying socie-tal values
Monitoring an iconic heritage structure with OMA: The main spire of the Milan Cathedral
No full textOne of the most remarkable structural elements characterizing the Milan Cathedral is its Main Spire, built in Candoglia marble and completed in 1769. The Main Spire, reaching the height of about 108 m and supporting the statue of the Virgin Mary, is about 40 m high and stands on the octagonal tiburio erected around the main dome. The structural arrangement of the spire includes a central column which is connected through a spiral staircase to 8 perimeter columns and each column is stiffened by inverse flying buttress. Metallic clamps and dowels connect the marble blocks and metallic rods connect the perimeter columns to the central core. A large monitoring system was recently installed in the Milan Cathedral, including seismometers and temperature sensors at 3 levels of the Main Spire as well as a weather station at the top of the spire. After a concise historic background on the Main Spire and the description of the sensing devices installed in this structure, the paper focuses on the dynamic characteristics of the spire and their evolution during a time span of about 16 months. The presented results highlight that: (a) a high density of vibration modes is automatically detected in the frequency range 1.0-7.0 Hz; (b) the lower identified modes correspond to global modes of the cathedral; (c) the normal evolution in time of the resonant frequencies is characterized by clear fluctuations induced by the environmental effects (temperature and wind); (d) especially the dependence of resonant frequencies on temperature is very distinctive and reveals the key role of the metallic elements in the overall dynamic behavior; (e) notwithstanding the remarkable effects exerted by the changing environment on the resonant frequencies, output-only removal of environmental effects and novelty analysis allow an effective monitoring of the structural condition
Long-term monitoring for the condition-based structural maintenance of the Milan Cathedral
Full text linkThe Milan Cathedral, whose main structures were erected between 1386 and 1813, is one of the largest masonry monuments ever built. Within the traditional collaboration between Politecnico di Milano and Veneranda Fabbrica del Duomo di Milano–the historic Institution established in 1387 and responsible for the preservation and development of the Cathedral–a structural monitoring system was recently designed and implemented with the two-fold objective of assisting the condition-based structural maintenance of the Cathedral and creating a large archive of experimental data, useful to improve the knowledge of the monument. The new monitoring system, fully computer based and with efficient transmission of the collected data, includes static and dynamic measurements. The static monitoring system consists of: (a) bi-axial tilt-meters installed at the top of selected piers and at 3 levels of the Main Spire; (b) vibrating wire extensometers mounted on the iron tie-rods which are characterized by the higher tensile stress; (c) temperature and humidity sensors for the measurement of internal and external environmental parameters. The dynamic monitoring is performed through seismometers (electro-dynamic velocity sensors) installed at the top of 14 selected piers and at 3 levels of the Main Spire. After a concise historic background on the Milan Cathedral and the description of the sensing devices installed in the church, the paper focuses on the results obtained during the first months of monitoring (since October 16th, 2018) and the lessons learned in view of the Structural Health Monitoring (SHM) of the monument
Continuous monitoring of the Milan Cathedral: dynamic characteristics and vibration-based SHM
Full text linkThe traditional collaboration between Politecnico di Milano and Veneranda Fabbrica del Duomo di Milano—the historic institution established by Gian Galeazzo Visconti in 1387 and having in charge all operational aspects related to the Milan Cathedral since more than 600 years—recently focused on the design and installation of a structural monitoring system, with the objective of assisting the condition-based structural maintenance of the historic church through the continuous interrogation of sensors installed in the structure and the extraction from measured data of features which are representative of the current state of structural health. The new monitoring system of the Milan Cathedral includes different types of measurements and sensors: quasi-static acquisition of strain in selected tie-rods and biaxial tilt of selected piers and the main spire, monitoring of inner and outer environmental parameters and dynamic measurement of the velocity response at the top of 14 piers and at 3 levels of the main spire. After a concise description of the historic church and of the monitoring system, the paper focuses on the dynamic characteristics of the Milan Cathedral, their evolution during the first months of monitoring (since October 16th, 2018) and the lessons learned in view of the structural health monitoring of the monument. The presented results from the vibration monitoring highlight that: (a) 8 global modes of vibration are automatically detected in the frequency range 1.0–5.0 Hz; (b) the resonant frequencies exhibit a distinctive trend of variation, which is mainly driven by temperature; (c) the mode shapes of the cathedral do not show appreciable fluctuations associated with the environmental effects
Continuous monitoring the cathedral of Milan: Documentary and preliminary investigations
Full text linkWithin the traditional collaboration between Veneranda Fabbrica del Duomo di Milano and Politecnico di Milano, significant efforts were recently devoted by the authors to the critical re-analysis of the past issues experienced by the Cathedral of Milan and to the evaluation of recent experimental evidences, with the objective of designing and implementing a new monitoring system, aimed at assisting the condition-based structural maintenance of the building. Appropriate strategies of Structural Health Monitoring have been developed for the continuous interrogation of sensors installed in the structure and the extraction from measured data of features which are representative of the current state of structural health. The conceptual design of the monitoring system is presented and discussed in the paper, as well as the documentary and preliminary investigations carried out to address the main choices. In summary, the new monitoring system of the Milan Cathedral includes different classes of measurements and sensors, such as: (a) quasi-static strain acquisition (through wireless vibrating wire extensometers) in the metallic tie-rods subjected to high tension loads; (b) quasi-static measurements of the biaxial tilt at the top of selected piers and along the height of the main spire (through innovative wireless tilt-meters, with high accuracy and compensation of the temperature effects); (c) quasi-static measurements of environmental parameters (through temperature and humidity sensors placed in the same points where the tilt-meters are installed); (d) dynamic measurement of the velocity at the top of selected piers and along the height of the main spire. The monitoring system is characterized by a distributed architecture, allowing easy modifications and/or adding of sensors; furthermore, all quasi-static sensors are wireless and powered through high capacity batteries
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 environmental and sound-induced vibrations on artistic stained glasses
No full textStained glasses are a key component of the artistic heritage of most European Christian cathedrals. During the last thousand years they grew in complexity and extension until they reached the size of several square meters. Therefore, artistic stained glasses are one of the elements of cultural heritage that are most exposed to environmental hazard though seldom considered until recent days. One of the modern danger sources for stained glasses are environmental vibrations and sound pressure induced vibrations. Considering the lack of modern literature on this topic, the authors carried out an experimental investigation on the Duomo di Milano stained glasses vibrations. The experimental campaign focused on the dynamic response of glasses due to both environmental vibration and to sound-induced excitation during some events which took place in the big square facing the church. As a result, a preliminary vibration analysis has been computed, thus enabling the characterization of vibrations and their effects under operating conditions. Data show that the response for this type of glass under operating conditions is limited to the 30–200Â Hz band, with a concentration of energy in the 40–80Â Hz band. Furthermore, considering a 30–200Â Hz band, the RMS vibration level due to pop/rock concerts is about 10 times higher than that due to environmental excitation
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
Effects of environmental vibration on ancient stained-glass windows
No full textAncient stained-glass windows are delicate pieces of art that need to be carefully maintained in order to be preserved over time. Several studies address the problem of stained-glass windows degradation, however, the effect of ambient vibrations on the conservation state of these artworks is not thoroughly studied and understood. In the present work, a wide and general approach was adopted to better address the problem. Two monitoring campaigns have been carried out on the stained-glass windows of the Mi- lan Cathedral, to understand the characteristics of the typical daily excitation and that of shorter duration events, like concerts taking place in the square in front of the cathedral. Starting from the gathered data, experimental tests have been performed on a facsimile window panel. The direct exposure to concert-like sound pressure waves has been reproduced with a laboratory test rig and the evolution of the window panel dynamics has been tracked through a series of measurements. Lead cames, which form the internal metallic structure of a window panel, proved to be the most critical element of a stained-glass window, rather than the glass pieces themselves. In fact, when sub- jected to a prolonged direct exposure to the pulsating actions produced by concerts or similar events, severe metal fatigue phenomena were observed. On the other hand, glass pieces remained intact during the tests. This suggests that their possible detachment is not due to their direct failure when subjected to a direct exposure to the pressure waves, rather to an improper or weakened fastening of the lead cames. The mechanical damaging processes of stained-glass windows appear to be more related to metal fatigue and subsequent glass chattering, rather than to an expected intrinsic fragility of the artwork. Nevertheless, since the windows of the façade of the Milan Cathedral are protected by an additional structure comprising glass windows, they are not directly exposed to the sound pressure waves, as a filter is introduced between the source and the window panes. This strongly mitigates the vibration levels reaching the window panels. Such an arrangement appears to be of importance for the conservation of the stained-glass windows from a mechanical point of view
- …
