1,720,958 research outputs found
Plastic Waste for Concrete Mixture: Advanced Strategies and Solutions
No full textIn recent years, various waste recycling strategies have emerged emphasizing the utilization of plastic waste in concrete mixtures. This practice offers a dual advantage by decreasing the demand for traditional aggregates, like sand and gravel, or lightweight aggregates while mitigating plastic accumulation in landfills and oceans, promoting a circular economy. Although high plastic content may worsen mechanical characteristics, proper mix designs can optimize concrete containing plastic aggregates to be lighter and beneficial for weight-sensitive applications. This study investigates the influence of plastic waste on concrete mechanical characteristics, incorporating different types of plastic waste in varying percentages to identify potential applications. Experimental results indicate that incorporating plastic waste does not significantly compromise concrete strength. Despite promising findings, challenges associated with using plastic waste in concrete must be addressed to optimize this practice and overcome drawbacks. These efforts align with sustainable waste management and eco-friendly construction practices, underscoring the importance of refining the use of plastic waste in concrete
Effect of a non-uniform distribution of mortar strength on the bond behavior of FRCM composites: Numerical study and experimental verification
Full text linkRecent experimental research on the constitutive behavior of Fabric Reinforced Cementitious Matrix (FRCM) composites has shown that usually the failure modes and the crack evolution often differ from expectations. This is due to the several uncertainties usually related to the mechanical properties of the constituent materials adopted. This study aims to investigate the bond behavior of FRCM-to-masonry assemblies with uncertain mechanical properties.
In a first step he tensile strength of the mortar only was considered as a probabilistic variable, and random values were assigned along the length of the sample based on different possible distributions. In a second step, the relationship between the interface behavior and mortar mechanical parameters was taken into account by varying both constituent behaviors. To study the effects on the global response, Monte Carlo analyses were also performed. A simplified Finite ELement (FE) model that had already been implemented and validated was used to perform these analyses. This research is supported by an experimental investigation carried out by the authors, including double shear pulling tests on various combinations of FRCM using cementitious or lime matrices and basalt or glass fiber fabrics. The results show how the variability of the mortar tensile strength and the interface maximum tangential stress, applied to the simplified model, modify global and local behavior and crack pattern, highlighting the importance of accounting these effects
Structural health monitoring of masonry structures using stress sensors: Experimental induced damage tests and proposed approach for real-time monitoring
No full textThe paper presents an experimental and numerical study investigating the effectiveness of two innovative stress sensors, i.e. piezoelectric and capacitive stress sensors, for use in Structural Health Monitoring (SHM). These sensors are installed within the mortar bed-joints and can measure vertical stress variations. The capability of the sensors in revealing stress state variations due to external events is experimentally tested by performing induced damage tests on two half-scale masonry wall specimens made of three piers and monitored by both the typologies of stress sensors. Two types of masonry, clay brick and calcarenite brick, are investigated. Experimental tests provided damage simulation by progressively reducing the cross-section of the central pier of the specimens by keeping the vertical load constant. Experimental sensor outputs are compared to those resulting from a reference refined finite element micro-model simulating the experimental tests. Simplified fiber-section equivalent frame modelling of masonry is finally proposed and tested as a computationally effective approach for real time monitoring. Results show that vertical stress variations in masonry structures can be effectively detected by the investigated sensors and potentially interpreted for the early prediction of structural stress-state modifications that can be eventually related to an ongoing damage
Preliminary validation of an innovative stress sensor for the Structural Health Monitoring of masonry buildings
Full text linkStructural Health Monitoring (SHM) of existing masonry constructions is a challenging topic widely studied by the scientific
community. In this paper, the use of a low-cost Capacitive Stress Sensors (CSSs) is investigated as an effective tool for the detection
of the compression state level in mortar joints of masonry structures. The study is conducted by means of Finite Element (FE)
simulations aimed at reproducing the mechanical response of a prototype of innovative CSS, recently patented, subjected to
compression forces typical of masonry buildings under serviceability conditions. The constitutive behaviour of the sensor is
validated against the results of a pilot laboratory test on a mortar cylindrical specimen endowed with CSSs and LVDTs and then
subjected to cyclic uniaxial compression. The FE model is built in order to simulate the capacitive sensor embedded within the
mortar material; therefore, a correlation analysis is performed by comparing the numerical stress-strain output of the sensor and
the experimental results. The validation procedure shows that the numerical results are in good agreement with the records obtained
by the LVDTs. Moreover, the FE model is used for developing a parametric analysis aimed at highlighting the effects of mortar
stiffness and strength on the efficacy of the SHM performed by the CSSs and the optimal serviceability configurations are
accordingly identified
Experimental testing of two novel stress sensors for SHM of masonry structures
Full text linkThe paper presents an experimental study on the performance of two types of
stress sensor for their possible use in structural health monitoring (SHM) of masonry
constructions. Ceramic piezoelectric sensors and capacitive sensors were installed in mortar
bed-joints of two series of masonry specimens made of calcarenite stones and clay bricks. The
specimens were tested under uniaxial compression, assessing the effectiveness of the sensors in
recording the stress state variation in terms of vertical stresses within different types of
masonry. Experimental results show that, although both the ceramic and capacitive sensors
were initially designed to be embedded in concrete elements, their application in mortar joints
ensures a good agreement with records by standard measurement devices. Results also
demonstrate the possibility to extend the application of these devices to existing masonry
structures, where SHM becomes a challenging issu
Advances in experimental characterization and modelling of FRCM composites for structural retrofitting
Full text linkQuesta tesi presenta i risultati di una campagna sperimentale incentrata sulla caratterizzazione della trazione dei basalt e glass FRCM e della caratterizzazione del legame di aderenza composito-Calcarenite. Il lavoro sperimentale è completato dalla proposta di due modelli numerici sia per prove di trazione che per quelle di aderenza. L'indagine sperimentale è stata condotta considerando l'influenza di diversi rinforzi, matrici e metodi di prova. I risultati sperimentali consentono di valutare l'effetto della malta sulle curve sforzo-deformazione, la resistenza, la duttilità e le modalità di crisi. Inoltre, la tesi fornisce un importante contributo per valutare l'influenza di diversi metodi di prova (es. clamping e clevis come riportato da diversi standard e linee guida) sulle prestazioni dei sistemi FRCM testati a trazione.
Inoltre, la correlazione dell'immagine digitale è stata utilizzata per misurare le tensioni di trazione e per analizzare le modalità di crisi offrendo una caratterizzazione meccanica accurata. L'elemento di principale novità è l'adozione di un set-up per le prove di aderenza modificato e progettato per analizzare l'influenza della dimensione del composito sulla lunghezza e la resistenza del legame. Un'analisi approfondita dei risultati conferma l'efficacia di questo innovativo set-up. Infine, vengono presentati due modelli numerici che tentano di fornire un semplice strumento numerico per valutare il comportamento costitutivo dei sistemi FRCM. I modelli sono stati calibrati sulla base delle curve sperimentali sforzo-deformazione e carico-slittamento dimostrando di essere uno strumento efficace per prevedere il comportamento meccanico dei materiali compositi FRCM.This thesis presents the results of an experimental campaign focused on the tensile characterization of basalt and glass FRCM and composite-calcarenite bond characterization. The experimental work is complemented by the proposal of two numerical models both for tensile and bond tests. The experimental investigation was carried out considering the influence of different reinforcements, matrices and testing methods. Experimental results provide for assessing the effect of mortar grade on the stress-strain curves, strength, ductility and failure modes. Moreover, the thesis provides an important contribution to assess the influence of different testing methods (i.e.
clamping and clevis as reported by different standard and guidelines) on the performance of the FRCM systems tested in tension.
Moreover, the Digital image correlation was used to measure the tensile strains and to analyse the failure modes offering an accurate mechanical characterization. The main element of novelty is the adoption of a modified bond test set-up designed to analyse the influence of the composite size on bond length and strength. A deep analysis of the results confirms the effectiveness of this innovative set-up. Finally, two numerical models are presented attempt at providing a simple numerical tool for capturing the constitutive behaviour of the FRCM systems. The models were calibrated on the basis of the experimental stress-strain and load-slip curves showing to be an effective tool for predicting the mechanical behaviour of the FRCM composites
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
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