1,720,973 research outputs found
Structural Behavior of Arch Models Strengthened Using FRP Strips of Different Lengths
No full textThe authors address the structural behavior of masonry arches strengthened through carbon-fiber-reinforced polymer (CFRP) strips at intrados or extrados surfaces and subjected to horizontal forces. The paper reports and compares results from experimental tests on 1:2-scale arches and from an analytical model that considers no-tensile strength, infinite rigid, and infinite compressive strength material. Under the assumption that the structure fails because of the formation of a four-hinge collapse mechanism, the model allows the calculation of the collapse load and the evaluation of the load-displacement diagram. The model is based on the equilibrium conditions and considers finite displacements. Results provide an evaluation of the dependence of arch structural behavior on the length of CFRP strengthening. In particular, the postpeak behavior is evaluated in the perspective of performance-based seismic design criteria, which regard the ultimate displacement as a key parameter for seismic capacity. The evaluation shows that, for the considered case study, an increase of intrados reinforcement length produces an increase of maximum load but a decrease of the ultimate displacement
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
Influence of Different Mortar Matrices on the Effectiveness of FRCM Composites for Confining Masonry Columns
No full textIn the past, steel hoops were applied over the height of columns to increase their load-bearing capacity. Currently, innovative strengthening techniques, namely fiber-reinforced composites, are successfully replacing traditional systems. Although fiber-reinforced polymers were demonstrated to be effective in the confinement of columns, the use of fabric-reinforced cementitious matrix (FRCM) systems is preferred in the case of masonry columns belonging to architectural heritage buildings because of the compatibility with the masonry substrate as well as the reversibility of the intervention. In this paper, the influence of different matrices on the effectiveness of confinement of masonry columns is investigated both experimentally and analytically. Three different matrices are considered to assemble the composite: a natural lime mortar with poor mechanical properties, a cement mortar, and a commercial mortar with high compression strength. The FRCM system was obtained by embedding a polyparaphenylenebenzobisoxazole fabric within these matrices. Results of axial compression tests demonstrate the effectiveness of confinement in all cases, highlighting the different increases in the load-bearing capacity and ductility of the columns provided by the use of different matrices. The main predictive formulas available in the literature were used to compute the increase in the load-bearing capacity of the tested columns, providing values very different than those obtained experimentally. For this reason, the authors believe that these formulas, which are affected by coefficients fine-tuned by the various authors based on their experimental results, need to be further calibrated and tuned to be successfully used in practical applications. Accordingly, the use of two different equations in the case of matrices having a compression strength higher or lower than the strength of the unconfined column is proposed
Numerical investigation on the use of flat-jack test for detecting masonry deformability
No full textCorrect determination of masonry deformability is fundamental for evaluating the seismic response of masonry structures. For existing buildings, double flat-jack tests are largely used to estimate elastic modulus, but many problems arise for a reliable interpretation of the test outcomes. Formulas provided by standards or available in the literature follow different approaches, the results of which are strongly variable. Furthermore, these formulas do not take into consideration important practical aspects of the test apparatus, like the position of the measurement reference points in the masonry sample. The arrangement of the gauge points can influence the displacement measurements and, consequently, the value of elastic modulus. This work aims at numerically investigating-through finite element (FE) models- the effects of the position of the gauge points on the outcomes of a double flat-jack test. In particular, a continuous FE mode is adopted, in which the concrete damage plasticity model implemented in Abaqus code is used to model the nonlinear behavior of the masonry. This study provides recommendations on the correct way to determine reliable values of elastic modulus from double flat-jack testing. Furthermore, numerical results and their comparison with experimental data allow for important considerations with regard to both the research field and professional and practical activities
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
Experimental study on thermal matrix composite for seismic-energy upgrade of masonry buildings
No full textThe existing building stock consists mainly of masonry constructions built long before modern seismic regulations and the issue
of energy saving. As a result of the well-known problems related to climate change and the need to reduce energy consumption,
the issues of sustainability and reducing the environmental impact of the construction industry have become increasingly relevant.
In this context, the present research addresses an integrated way for both structural and energy upgrade of masonry buildings.
Specifically, innovative fibre-reinforced composite materials assembled by using lime-based thermal matrices combined with a
balanced high-strength basalt fibre were experimentally investigated at the Laboratory of the University of Florence. These
composite materials are identified by the acronym FRLM (Fiber Reinforced Lime Matrix). Initial work involved the selection of
thermally efficient and compatible matrices, and then, the composite materials were investigated through tensile tests and single
shear tests in order to evaluate their bond performance. Different bond lengths were considered with the goal of identifying the
effective one
Reliability of different test setups and influence of mortar mixture on the fabric-reinforced cementitious matrix-to-brick bond response
No full textThe results of four different bond tests, conducted on specimens made of bricks and fabricreinforced cementitious matrix (FRCM) composite strips, are presented in this article. The composites consisted of a basalt textile embedded in four types of inorganic matrices: a commercial product made of lime mortar and three different mortars properly prepared in the laboratory. Bond tests were carried out to highlight variations in the bond behavior of the four composites. The experimental campaign, for all the tested composites, confirmed that the debonding mechanism occurs at the textile-matrix interface with large differences, in terms of load carrying capacity, between the four typologies of FRCM composite. In particular, composites made up of a commercial matrix were demonstrated to be the best ones to fully exploit the tensile strength, whereas composites made up of cement-lime mortar showed the worst bond behavior. Furthermore, the results of the four bond tests conducted on the same type of composite were compared to evaluate the reliability of the different types of bond tests. Among the apparatus used to conduct the four bond tests, the single shear test was demonstrated to be the most effective for determining the actual bond performances of FRCM composites
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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