1,720,963 research outputs found
Integrating Plastic Waste into Concrete: Sustainable Solutions for the Environment
Full text linkPlastic waste management has received significant attention in recent decades due to the urgent global environmental crisis caused by plastic pollution. The versatile and durable nature of plastic has led to its widespread usage across various sectors. However, its nonbiodegradable nature contributes to unsustainable production practices, leading to extensive landfill usage and posing threats to marine ecosystems and the food chain. To address these environmental concerns, numerous challenges have been recently addressed through investigating alternative approaches for disposing of plastic waste, with the construction sector emerging as a promising option. Incorporating plastic waste materials into concrete not only offers economic benefits but also provides a valid alternative to conventional disposal methods. This paper presents the results of different experimental studies, some of them available in the literature and others new, discussing the feasibility of integrating plastic waste into concrete and its impact on mechanical properties. The influence of different sizes, natures, treatments, and percentages of plastic waste in the concrete mixtures is dealt with in order to provide further data for helping to understand the nonunivocal results in the literature, under the conviction that only further observations can help to understand the mechanics of concrete with plastic aggregates. The experimental investigation highlighted that one parameter that is better than others and can be considered to compare different experimental investigations is the variation in weight (due to the effective volume of plastics in the mix), determining a sort of increasing of porosity that degrades the mechanical characteristics. However, this seems inconsistent in some cases. Therefore, the need for further research is highlighted to refine production methods and optimize mix designs
Experimental Characterization of Fabric-Reinforced Cementitious Matrix (FRCM) Systems Applied on Calcarenite Stone: Adoption of Non-Standard Setup for Double-Shear Bond Tests
Full text linkThe use of Fabric-Reinforced Cementitious Matrix (FRCM) systems is an innovative method
for strengthening structures, particularly masonry, while addressing environmental and economic
concerns. Despite their widespread use, characterizing FRCM composites poses challenges due to
their complex mechanical behavior and considerable variability in properties. The available standardized
testing methods exhibit some inconsistencies, underscoring the need for reliable characterization
procedures. This paper presents an experimental study on the bond behavior between FRCM materials
and calcarenite stone using a non-standard setup for double shear bond tests. Different FRCM
systems are considered, varying the matrix composition and fabric nature. The experimental results
are evaluated in terms of maximum stress, slip and data dispersion, alongside comparisons with
double shear tests on larger samples and single-lap shear. These findings provide insights into how
the mortar nature influences the stress-slip curves, strength, ductility and failure modes. The experimental
study demonstrates the repeatability and robustness, particularly in terms of peak strength,
of the non-standard setup configuration utilized in the study. The study highlights the importance of
reliable characterization procedures for FRCM materials, especially in bond behavior assessments,
emphasizing the need for further research to enhance our understanding of their application in
structural reinforcement
Monte Carlo analysis of masonry structures under tsunami action: Reliability of lognormal fragility curves and overall uncertainty prediction
Full text linkTsunami vulnerability of coastal buildings has gained more and more interest in recent years, in the consciousness of what losses may be caused. The improvement of the available approaches for the quantitative estimation of the probability of building damage and for defining possible strategies for risk mitigation is an actual goal. In this framework, several authors have provided empirical fragility curves based on field surveys after tsunamis. Nevertheless, a predictive approach based on analytical fragility curves, which can be extended to many classes of buildings, is essential for the scopes of civil protection and risk mitigation. In this paper, an approach for the construction of fragility curves, proposed for masonry structures under tsunami waves, is discussed and refined in the part regarding the assignment of the uncertainties. Further, an assessment of the reliability of the lognormal fragility distribution is carried out based on a Monte Carlo simulation applied to 4 classes of buildings. Here, it is shown that Monte Carlo analysis allows a direct evaluation of the uncertainties without the need to resort to ambiguous regression analyses and rules of combination of the uncertainties of demand and capacity based on the regression analysis results or other uncertainty estimation approaches
Preliminary results of experimental study on the diagonal compression behaviour of masonry panels retrofitted with FRCM
No full textThe use of composite fibre grids embedded in an organic matrix, namely Fabric Reinforced Cementitious Matrix (FRCM) and fibre mesh in a mortar plaster, e.g., Composite Reinforced Mortar (CRM), were increasingly applied in structural retrofitting applications and already known by the scientific community. Both systems have promising results in improving the structural performances of masonry members, such as walls, arches, and vaults. This is due to their load-carrying capacity and their great compatibility with masonry substrates, compared to other types of organic matrix composite materials. However, the literature on these strengthening systems is still quite limited, and limited research is available regarding their mechanical properties and the behaviour of strengthened masonry members.
In this work, preliminary results and considerations of the experimental campaign are presented, with the goal of examining the effectiveness of various strengthening options for increasing the in-plane shear behaviour of masonry. Single-leaf masonry panels reinforced with FRCM and CRM systems using various fibre typologies and arrangements are tested under diagonal compression tests. Masonry panels are made of calcarenite stone units, a material typically used in historic Sicilian (in the South of Italy) constructions. The mortar used as a matrix is a fibre-reinforced lime-based mortar which is medium-grained and suitable for structural work on stone and brick masonry, even where there are historical and architectural constraints. Concerning the type of fibre, a glass grid and a carbon grid are used for the FRCM system, while a Glass-FRP grid is used for the CRM system.
The planned experimental campaign involves the construction of masonry panels with different retrofitting systems, including control specimens, panel retrofitted with FRCM, and panels reinforced with the CRM system. The main objective is to evaluate the gains in shear strength and ductility of retrofitted masonry panels and to compare the results for different system types and configurations, also in terms of failure
A numerical study on the effect of the interface material model on the tensile behaviour of FRCM strips
No full textFibre Reinforced Cementitious Matrix (FRCM) composites are becoming increasingly popular for strengthening
masonry structures for which the compatibility of the inorganic matrix with the chemical and physical properties of
the support makes it advantageous to adopt such systems.
However, despite the large use of FRCMs for strengthening applications, the characterization and modelling of the
mechanical response in tension of these systems is an open issue. In fact, the constitutive tensile law of the
composite shows to be affected by different variables, such as the clamping system adopted during tensile test, the
gauge length used for recording strains, the number of yarns and the planarity of the textile within the composite
thickness. In addition to these parameters, which influence the experimental tensile characterization, few
information is available on the constitutive law that rules the fibre-matrix interface, which is essential for
evaluating the load transfer during the post-crack stage of the composite, as already shown in the literature. For
these reasons, the studies that provide indications on analytical or numerical modeling of the tensile behaviour of
FRCM materials are still limited.
This study presents the results of a series of FE numerical simulations, aimed at evaluating the tensile behaviour of
FRCM composites. The elaborations are carried out through an appropriate definition of the sliding laws between
the components (fibres and mortar) and a parametric analysis is performed by varying the type of fibre, the
mechanical characteristics of the mortar and the interface bond law. The purpose of the study is to provide
indications on the modeling of the tensile response of FRCMs, with particular regards to the evaluation of the fibrematrix
interface behaviour. The numerical results are validated through comparison with some experimental data
selected from the literature. The performed analyses allow evaluating the influence of the selected parameters and
obtaining a qualitative comparison on the mechanical performances of different types of reinforcement in terms of
maximum tensile strength and ultimate strain
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
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