1,720,960 research outputs found
VALUTAZIONE DEL FATTORE DI STRUTTURA DI EDIFICI PREFABBRICATI ESISTENTI COMPLETATI CON UN SISTEMA DI CONNESSIONE DISSIPATIVA NEI NODI
No full textOne of the most important seismic vulnerability of existing precast structures, widely used in Italy for one-storey industrial buildings, is due to the lack of mechanical connection between structural elements, as highlighted by the earthquakes that struck the Emilia region (northern Italy) in May 2012. The realization of dissipative connections is proposed as a solution for seismic rehabilitation of structures designed without anti-seismic standards, in particular for the beam-column joints. This work investigates the behavior of dissipative evices composed by carbon-wrapped steel tubes, able to guarantee a dissipative fuse effect. The aim of the study is to determine the effectiveness of the introduction of such devices in the beam-column connections. Incremental dynamic analyses have been performed on different case studies, in order to evaluate the behavior factor for structures with dissipative beam-column connections. The results of the numerical study show how the introduction of the dissipative devices produces, as expected, a significant reduction of forces transmitted to the structure, comparing the seismic response of simple structures equipped with dissipative devices with the response of the equivalent elastic systems
EFFECTIVENESS OF A DISSIPATIVE BEAM-COLUMN CONNECTION BASED ON CARBON-WRAPPED STEEL TUBES
No full textDISPOSITIVO DI COLLEGAMENTO TRA ELEMENTI DI COSTRUZIONI
No full textIl brevetto è relativo ad un elemento dissipativo per la connessione di elementi di costruzioni, con funzioni di dissipazione dell'energia, al fine di garantire protezione nei confronti degli effetti delle azioni sismich
Experimental and numerical behaviour of dissipative devices based on carbon-wrapped steel tubes for the retrofitting of existing precast RC structures
Full text linkThe 2012 Emilia earthquake (in Northern Italy) caused extensive damage to existing prefabricated reinforced concrete structures. These buildings were found being extremely vulnerable because, being designed for vertical loads only, they featured friction-based connections between structural elements, most commonly between beams and columns. Given the large diffusion of these structures, their seismic retrofit is critical. Various techniques have been proposed in the literature, in most of which friction-based connections are removed by inserting mechanical connectors that will make beam-column connections hinged. These approaches lead to a significant increase of the base shear and therefore require strengthening of columns. The paper presents dissipative devices based on carbon-wrapped steel tubes to be used as an alternative low-damage solution for the retrofit of beam-column connections. The first part of the paper presents results of experimental tests on the devices and discusses their dissipative behaviour. The succeeding parts of the paper present numerical analyses on simple structures reinforced with the proposed device. The results of the numerical study show how the introduction of the dissipative devices produces a significant reduction of forces transmitted to the structure, by comparing the seismic response of simple frame structures equipped with dissipative devices with the response of equivalent elastic systems
SEISMIC RETROFIT OF EXISTING PRECAST RC BUILDINGS WITH DISSIPATIVE DEVICES BASED ON CARBON WRAPPED STEEL TUBES
No full textThe seismic vulnerability of existing precast RC buildings not designed against seismic actions
is a well-known issue nowadays, as emerged from the aftermath of the seismic events that affected many productive areas in the Emilia region (north Italy) in 2012. This is a consequence
of the lack of structural redundancy and the widespread adoption of friction-based connections,
which can lead to collapses and significant damage to contents. Thus, the necessity of identifying suitable intervention strategies has been widely recognized by researchers, which proposed
different retrofit techniques. One of the most diffused approaches is to introduce mechanical
connectors between columns and roof elements, resulting in an increase of the base shear and
the need to strengthen the columns. To prevent this phenomenon, dissipative devices based on
Carbon-Wrapped Steel Tubes (CWST) are introduced herein for the retrofit of existing precast
RC structures, aiming at reducing the forces transmitted to columns, and providing a suitable
connection between columns and beams. To this regard, this paper discusses the seismic retrofit
of an existing precast building equipped with CWSTs. Linear and non-linear time history analyses have been conducted on two different models of the structure, one with hinged beam-column connections, and on the one with CWSTs. The yielding and the ultimate rotations of the
plastic hinges at the base of the columns as well as the cyclic shear resistance depending on
the ductility demand on each element, are defined according to Eurocode 8 prescriptions. The
paper discusses the effects of the introduction of the CWSTs in the connections in terms of forces
and proposes equivalent behavior factor values for the two structures
A Low-Damage Retrofitting Solution Based on Carbon-Wrapped Steel Tubes for Beam-Column Friction Connections of Existing Precast RC Structures
No full textThe 2012 Emilia earthquakes caused significant damages to existing precast RC structures. These buildings were found being extremely vulnerable because, being designed for vertical loads only, they featured friction-based connections between structural elements, and in particular between beams and columns. Given the large diffusion of these structures as industrial buildings, and consequently the high social and economic impact of damages, their retrofit is critical. Various techniques have been proposed in the literature; in most of them friction-based connections are removed by inserting mechanical connectors that will make beam-column connections hinged. These approaches lead to a significant increase of the base shear and therefore often require strengthening of columns and foundations.
The research presents dissipative devices based on carbon-wrapped steel tubes to be used as an alternative low-damage solution for the retrofit of beam-column friction connections able to minimize structural damages.
Firstly, the study presents results of experimental tests on the devices and discusses their innovative energy absorption mechanism and dissipative behaviour.
Then, numerical analyses carried on to investigate the effectiveness of the introduction of dissipative devices in beam-column connections of precast structures are presented. Incremental Dynamic Analyses have been performed in order to evaluate an equivalent behaviour factor for structures with dissipative devices, by comparing the seismic response of simple frame structures with dissipative connections with equivalent elastic systems. Findings of numerical investigation show how the introduction of the dissipative devices in friction-based joints provides an effective connection between structural elements and, in addition, the capability to reduce forces transmitted to the columns, improving the seismic behaviour of the entire structure.
Finally, a simplified approach to evaluate an equivalent behaviour factor for a structure equipped with dissipative devices in friction-based beam-column joints is proposed
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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