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Buckling of GFRP pultruded built-up columns
No full textPresented are the test results of an experimental campaign to investigate the buckling behaviour of pultruded built-up columns subjected to concentric loading. The specimens tested are assembled using four C-shape (off-the-shelf) GFRP pultruded profiles, having the same detailing as strut members in a large FRP structure that was executed in 2009 for restoration activities at the Santa Maria Paganica church in L’Aquila (Italy). This church had partially collapsed walls and no roof after the 2009 L’Aquila earthquake. A total of five columns have been characterised with two different configurations for the bolted connections joining together the C-shapes into the built-up member. Test results are discussed and a comparison is made with closed form solutions for flexural buckling resistance and with Eigenvalue buckling predictions from a (linear elastic) finite element analysis
Time-dependent effects on critical buckling load of pultruded column
No full textIt is well known that the performance of pultruded structural elements is influenced by the viscoelastic behavior of the based-polymer material that are not affected by aging effects.
In what concerns buckling of pultruded columns, creep causes a time-dependent decrease of the critical load or, in other words, a time-dependent induced buckling due to the evolution in time of the lateral deformations due to initial imperfections or load eccentricity. The numerical and experimental analyses have been carried out on pultruded column that have been used in a large all-GFRP (Glass Fiber Reinforced Polymers) structure built in L'Aquila, Italy.
The critical load is firstly evaluated using the well known Euler formulas; secondly, the long-term critical load is evaluated, - on the base of the same formulas - adopting a reduced value for the elastic constants, taking into account the creep behavior of the material. Finally, a geometrically non linear analysis of the column is carried on, taking into account creep deformations and transversal deformability.
A possible application of the numerical computations is to find a value of the constant applied load that causes the time-dependent buckling of the column for limited load duration that can be analyzed in an experimental campaign, in order to compare the results and to define the parameters of viscoelastic law
Buckling of built-up columns of pultruded fiber-reinforced polymer C-sections
Get PDFThis paper presents the test results of an experimental investigation to evaluate the buckling behavior of built-up columns of pultruded profiles, subjected to axial compression. Specimens are assembled by using four (off the shelf) channel shaped profiles of E-glass fiber-reinforced polymer (FRP), having similar detailing to strut members in a large FRP structure that was executed in 2009 to start the restoration of the Santa Maria Paganica church in L’Aquila, Italy. This church had partially collapsed walls and no roof after the April 6, 2009, earthquake of 6.3 magnitude. A total of six columns are characterized with two different configurations for the bolted connections joining the channel sections into a built-up strut. Test results are discussed and a comparison is made with closed-form equation predictions for flexural buckling resistance, with buckling resistance values established from both eigenvalue and geometric nonlinear finite element analyses. Results show that there is a significant role played by the end loading condition, the composite action, and imperfections. Simple closed-form equations overestimate the flexural buckling strength, whereas the resistance provided by the nonlinear analysis provides a reasonably reliable numerical approach to establishing the actual buckling behavior
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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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