1,720,982 research outputs found
Periodic variation of the transferable load at the FRP-masonry interface
No full textThis work sheds light into the effect of the periodic pattern of bricks and mortar joints on the stress transfer at the interface between fiber-reinforced polymer (FRP) composites and masonry. Experimental evidence is used to highlight that the fracture process at the FRP-masonry interface depends on the characteristics of the constituent materials and the geometry of the masonry. Two simplified cohesive material laws are proposed for the FRP-brick and FRP-mortar interfaces, which are associated with finite effective bond lengths of the two interfaces. The aforementioned simplified interfacial laws are employed to compute the load response of the FRP-masonry interface, which is compared with the experimental one. The results indicate that length of the stress-transfer zone of, and the transferable load at, the FRP-masonry interface vary periodically in accordance with the periodic pattern of bricks and mortar joints
Relationship between Results of Tensile Test of FRCM Composites and the Fiber-Matrix Bond Properties
No full textThe mechanical properties of fiber-reinforced cementitious matrix (FRCM) composites are derived from tensile tests of composite coupons and shear tests of composite strips bonded to the substrate. Different test set-ups are used for tensile coupons, which lead to different tensile responses depending on the mechanical properties of the matrix and bond properties of the fiber-matrix interface. Direct shear tests are employed to study the stress-transfer between the composite and the substrate onto which the composite is bonded. These tests can be employed to obtain the cohesive material law (CML) that describes the bond behavior at various interfaces, such as the matrix-substrate, matrix-matrix, and fiber-matrix interface. In this paper, the cohesive material law associated with the fiber-matrix interface of a polyparaphenylene benzo-bisoxazole (PBO) FRCM composite is employed in an analytical model to reproduce the tensile response of the FRCM composite, when the fibers are gripped directly. The results of the model are compared with corresponding experimental results of tensile tests of the same FRCM composite employed to calibrate the CML. The experimental work includes digital image correlation (DIC) analysis of the cracking process. A comparison between the analytical and the experimental results is performed in terms of load response focusing on the coupon deformation and opening of the cracks
Experimental analysis on bond between PBO-FRCM strengthening materials and concrete
Full text linkThe effectiveness of externally bonded strengthening for reinforced concrete (RC) elements strongly depends on the bond between the strengthening material and the concrete and on the mechanical properties of the concrete cover. In this paper the bond between fiber reinforced cementitious matrix (FRCM) materials made out of a poliparafenilenbenzobisoxazole (PBO) net embedded in a cement based matrix and the concrete is experimentally analyzed. Experimental results of double shear tests involving different
bond lengths and fibers cross sections are presented. The results allow to estimate the effective anchorage length and evidence that the debonding occurs at the fibers/matrix interface after a considerable fibers/matrix slip. They also confirms the effectiveness of the FRCM materials as external reinforcements for concrete. The obtained experimental results can be used to calibrate a local bond-slip relation to be used in the design of the external reinforcement
Bond-Slip Relations for PBO-FRCM Materials Externally Bonded to Concrete
Full text linkExisting reinforced concrete (RC) structures often need to be repaired, strengthened and upgraded to satisfy current code requirements. In recent years many interventions have been done bonding composite materials to the surface of existing RC elements. The structural effectiveness of these interventions strongly depends on the bond between the strengthening material and the concrete and on the mechanical properties of the concrete cover. In this paper the bond between fiber reinforced cementitious matrix (FRCM) materials made out of a poliparafenilenbenzobisoxazole (PBO) net embedded in a cement based matrix and the concrete is analytically analyzed with reference to the approach generally adopted for the fiber reinforced polymers (FRP) materials, which is based on the local bond-slip relation between the strengthening fibers and the supporting concrete. A local bond-slip relation is calibrated on the base of
the results of an experimental investigation previously performed by the authors. The bond-slip relation is essential in the modeling of the structural behavior of RC elements strengthened with PBO-FRCM, in
that it allows to calculate the force that can be transferred to the concrete, the effective anchorage length, the concrete cracks distance and opening
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
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
- …
