1,720,965 research outputs found
Criteria for monitoring in mixed models maintenance of building estate
No full textThe relevance of the control and/or monitoring of the buildings is now emphasized by both the existing legislation and by the increasingly advanced equipment for diagnosis. However, poorly developed integration still exists between the scope of interventions and that of controls, which are usually seen as two separate worlds and lack the necessary interrelationships. In the maintenance plan, which is part of the executive project, two documents entirely without reciprocal links coexist: the sub-program of the controls and the sub-program of the interventions. The application of most popular software shows that these two documents sometimes produce even paradoxical situations, precisely because of the lack of interaction. Therefore a methodology with the aim of highlighting how to achieve a far greater effectiveness of the maintenance plan will be exposed. It won’t be neglected, moreover, that the preventive maintenance strategy that is more suited to the buildings is the condition-based one, founded - precisely - on a rigorous planning of the activities of the component performance monitoring
VALUTAZIONE SPERIMENTALE DELLA DURABILITÀ DI SISTEMI DI RINFORZO CON CALCESTRUZZO AUTOCOMPATTANTE
No full textL’obiettivo della ricerca è di valutare il comportamento nel tempo di sistemi di blindatura degli elementi strutturali in calcestruzzo ordinario mediante gusci in SCC, un intervento ormai largamente diffuso.
Con riferimento ad un caso studio di particolare interesse, è stata condotta una sperimentazione strutturata in due fasi:
a. valutazione comparativa del comportamento del calcestruzzo ordinario e di quello autocompattante mediante sperimentazioni di laboratorio, al fine di stimare il ciclo di vita di quest’ultimo, così articolata:
- valutazione delle caratteristiche meccaniche mediante prove sclerometriche (UNI EN 12504-2 ) e ultrasoniche (UNI EN 12504-4);
- valutazione delle caratteristiche meccaniche mediante prove a compressione (UNI EN 12390-2, 3, 4) e a trazione (UNI EN 12390- 2, 5);
- valutazione delle caratteristiche chimico-fisiche mediante prove di carbonatazione accelerata (UNI EN 13295 – 2) e prove di porosità aperta e assorbimento d’acqua per immersione totale (RILEM, 25 PEM).
b. applicazione dei modelli desumibili dalla letteratura scientifica (Andrade, Parrot, ecc.) per una validazione di quanto ricavato dalla fase a e per la messa a punto di un modello previsionale
Experimental evaluation of the contribution of coatings to the durability of concrete
No full textNell’ambito generale degli studi sul ciclo di vita dei componenti edilizi, ed in particolare della durabilità del calcestruzzo, è stata condotta una sperimentazione finalizzata a valutare il ruolo dei rivestimenti costituiti da intonaci tinteggiati, rispetto al problema della carbonatazione delle strutture in c.a., con particolare riguardo al patrimonio edilizio del dopoguerra, per il quale questa soluzione tecnica rappresenta effettivamente per la maggior parte l’unica protezione dagli agenti atmosferici.
La sperimentazione è stata comparativamente condotta su quattro tipi di provini prismatici (dim. 70x470x160 mm) confezionati con calcestruzzo ordinario non rivestito, e con calcestruzzo ordinario rivestito (spessore 1,5 cm.) con tre differenti soluzioni, in accordo con le procedure proposte della norma UNI EN 13295. Sono state eseguite prove di carbonatazione accelerata, mediante l’impiego di una cella termostatica, esponendo i campioni ad un’atmosfera con 2% di CO2 e misurando le profondità di carbonatazione a tre step significativi.
I risultati mostrano, con evidenza, quali siano le soluzioni di rivestimento con migliori prestazioni nei confronti del fenomeno della carbonatazione. E dunque possono costituire un’utile indicazione per gli interventi manutentivi da eseguire su quegli edifici che per loro natura e caratteristiche originaria hanno le strutture in c.a. maggiormente sottoposte all’aggressione dell’atmosfera
HYPOTHESIS FOR AN APPLICATION OF THE FACTOR METHOD TO REINFORCED CONCRETE
No full textThe research is collocated in the general field of the studies on life cycle management for building components and especially on the durability of reinforced concrete. In particular, in reference to Factor Method, introduced in norm ISO 15686 for the ESL prediction, the objective of this study is to suggest a methodology aimed to the reduction of subjectivity in the determination of the multiplying factor for this specific component.
Factor Method currently represents the instrument that is probably used the most for the estimation of the life cycle of building components, also thanks to its adaptability and simplicity. Yet, the most frequent critics that are moved against this method are indeed tied – in addition to those against the criteria for RSL determination – to the excessive subjectivity for the appreciation of multiplying factors.
In view of mandatory and voluntary legislation of the last years (referring, for example to UNI-EN 206-1 and to UNI 11104 which derived from it, or to D.M. 14/01/2008 and to EC2:2005) which contributed to provide useful elements of comparative and absolute evaluation, but also on the spur of some suggestions that were formulated during recent years in the worldwide scientific scene, the research suggests – in the aim of evaluating service life for structures in reinforced concrete – in its first part the definition of a set of values of reference (among which the values to use for the specific case can be chosen) corresponding to the parameters that are considered to have influence on each multiplying factor. Then, in the second part, in order to simplify the assignment of the scores to the users, the conditions of unitary value for each parameter have been identified, considering the results of direct observations carried out on the field in the last decades. Eventually, starting from unitary values, a complete grid of values has been defined, containing the values to attribute to worsening and improving conditions.
The results obtained in the research can represent for designers a possibility of application of Factor Method without risks of oscillation between too distant and subjective values, due to the uncertainty in adopting more appropriate scores
DETERMINING IN THE EXECUTIVE PROJECT THE DURATION OF WORKS OF A NEW BUILDING
No full textIn the execution of public works, the failure of the contractual compliance time is more expensive for the Contracting Authority due
to the onset of disputes, the failure to fruition on schedule, etc. Several studies carried out in recent years have found that the actual
duration of the works is higher than contract in 90% of cases. In the executive project, not by knowing the actual characteristics of the
contracting firm, for estimating the duration of the works, not well certain resources - based only on the labor incidence indicated in the
price lists - are assumed. The paper proposes a methodological approach that allows the technician, in executive project phase, the estimation of aduration of the works so-called conventional, setting some parameters according to experimental observations and considering only deemed critical activities. Starting, in fact, from the comparison of the two methods commonly used (calculation of men-day and Circ. n. C/175 Cassa per il Mezzogiorno 02/03/1982), through processing of the parameters contained in them, an algorithm that can be a useful reference for determining the duration of the works has been achieved, even with limitations and by means of further studies
Durability of Mortars Packaged with Production Waste of Autoclaved Aerated Concrete
Full text linkThe building sector is responsible for the introduction of about 40% of the waste in the environment (60 Mtons per year in Italy), with serious consequences for our future. Therefore, the statistics of the last few years have induced many researchers and many companies to investigate more sustainable products and technologies. Among these strategies, the re-use of waste materials has been widely encouraged. Many solutions have been proposed in the field of mortars for which the use of waste products such as ceramic materials, polystyrene, clay, concrete, has been tried out. The results have often been encouraging, especially for masonry mortars. Nevertheless, very few attempts have been made to place this type of products on the market. Moreover, the “younger” building materials such as Autoclaved Aerated Concrete have not been fully investigated in their potential use as recycled aggregates. The goal of this research was to evaluate the characteristics of mortars packaged with different percentages of production waste of Autoclaved Aerated Concrete components as aggregates, in order to assess the possible use of these conglomerates as masonry mortars or as plasters. The first campaign included tests for determining mechanical resistance, density, capillary water absorption, adherence to substrate, resistance to carbonation. The tested mortars had satisfactory mechanical characteristics and generally exhibited a good capacity to withstand the actions of atmospheric agents. Finally, the results highlighted the direct connection between Autoclaved Aerated Concrete percentage and mechanical and durability properties
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
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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