1,721,011 research outputs found
Experimental Investigation on Bond Behavior of Cement-Matrix–Based Composites for Strengthening of Masonry Structures
No full textExperimental investigation on masonry arches strengthened with PBO-FRCM composite
No full textIn the last two decades, Fiber Reinforced Polymer (FRP) composites were effectively used for increasing the load-carrying capacity of masonry arches and for improving their mechanical response against the most critical arch failure mechanisms.
More recently, Fabric Reinforced Cementitious Matrix (FRCM) composites are appearing significantly promising for the strengthening of masonry arches, providing an alternative to the FRP composites, but only few experimental contributions are available to date.
In the present paper, the structural performance of masonry arches strengthened both at intrados and at extrados by using a polybenzoxazole (PBO) fabric reinforced cementitious mortar composite was experimentally investigated. Results, in terms of load-carrying capacity, post peak behavior and failure mechanism, were compared with those determined by using a Carbon Fiber Reinforced Polymer (CFRP) composite. The present experimental study contributes to improve the knowledge of the innovative PBO- FRCM composites and it provides mechanical data useful for defining masonry strengthening design guidelines
Intrados strengthening of brick masonry arches with different FRCM composites: Experimental and analytical investigations
No full textThis paper examines the structural behavior of masonry arches strengthened at the intrados with fabric reinforced cementitious matrix (FRCM) composites. Textiles made of poliparafenilenbenzobisoxazole (PBO) and carbon fibers are considered. The experimental results are compared with those obtained on unstrengthened arches and arches strengthened with a carbon fiber reinforced polymer (CFRP) composite.
The arches tested are analyzed with the approach of the limit analysis of the collapse mechanisms. For the FRCM strengthened arches the maximum fibers strain has been assumed equal to the maximum strain attained by the fibers during double shear bond tests previously performed, while for the FRP strengthened arches the maximum fibers strain has been assumed equal to the debonding strain evaluated according to the CNR (Italian National Research Council) guidelines.
The employed approach allowed to accurately estimate the collapse load of the arches strengthened with FRP material, while the collapse loads of the arches strengthened with FRCM materials evaluated based on the results of the double shear tests underestimate the failure loads of the arches
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
Carbon-FRCM materials for structural upgrade of masonry arch road bridges
No full textNumerous bridges of the Italian arterial road network were designed for live loads significantly lower than those produced by the current vehicular traffic. Many of them are masonry arch bridges whose load carrying capacity should be assessed for defining the necessary strengthening in-terventions. In the present paper the design criteria for strengthening masonry bridges with carbon fiber reinforced cementitious matrix (C-FRCM) materials are presented with reference to a masonry arch road bridge built right after the second world war.
Methods: The structure is analyzed both in its original and in its strengthened configuration following the approach of the collapse mechanisms. The considered approach allows to capture the strengthening effect of the C-FRCM material in terms of modification of the collapse mechanism and increase of the load collapse multiplier. Two different configurations of C-FRCM strengthening material applied at the extrados have been considered. In the first configuration the ends of the C-FRCM material are anchored at the vaults imposts, while in the second configuration they are not anchored at the imposts. Results: To obtain load collapse multipliers greater than one three layers of C-FRCM strengthening material have to be applied at the extrados of all the three vaults in the case of end anchored strengthened material, while in the case of unanchored strengthening material four layers of C-FRCM strengthening material have to be applied at the extrados of all the three vaults
Strengthening Masonry Arches with Lime-Based Mortar Composite
Get PDFIn recent decades, many strengthening interventions on masonry elements were performed by using fiber reinforced polymers (FRPs). These advanced materials proved to be effective to increase the load-carrying capacity of masonry elements and to improve their structural behavior, avoiding the most critical failure modes. Despite the advantages of this technique compared to more traditional methods, FRP systems have disadvantages related to their low resistance to high temperatures, impossibility of application on wet surfaces, low permeability, and poor compatibility with masonry supports. Therefore, composite materials made of a fiber textile embedded in an inorganic matrix were recently proposed as alternatives to FRPs for strengthening historic masonry constructions. These composite materials are easier to install, have higher resistance to high temperatures, and permit higher vapor permeability than FRPs. The inorganic matrix is frequently a cement-based mortar, and the composite materials made of a fiber textile embedded in a cement-based mortar are usually identified as FRCM (fabric reinforced cementitious matrix) composites. More recently, the use of natural lime mortar as an inorganic matrix has been proposed as an alternative to cement-based mortars when historic compatibility with the substrate is strictly required, as in case of restoration of historic buildings. In this paper, the effectiveness of a fabric made of basalt fibers embedded in lime mortar matrix (Basalt-FRLM) for the strengthening of masonry arches is investigated. An experimental investigation was performed on 1:2 scaled brick masonry arches strengthened at the extrados with a layer of Basalt-FRLM and tested under vertical load. The results obtained are compared with previous results obtained by the authors by testing masonry arches strengthened at their extrados with FRCM and FRP composites. This investigation highlights the effectiveness of Basalt-FRLM in increasing load-currying and the displacement capacities of masonry arches. The Basalt-FRLM-strengthened arch exhibited higher displacement capacity when compared to arches strengthened with polymeric and cementitious matrix composites
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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