1,720,982 research outputs found
Hybrid intelligence framework for optimizing shear capacity of lightweight FRP-reinforced concrete beams
Full text linkThis study rigorously assesses the shear capacity of fiber-reinforced polymer (FRP) reinforced concrete (RC) beams as a lightweight material alternative, scrutinizing the efficacy of the Eurocode and ACI design codes. Leveraging a dataset of 260 experimental FRP-RC beam cases, two distinct Artificial Neural Network (ANN) models were developed using the Levenberg-Marquardt algorithm. Beams with and without stirrups were considered, with parameters including beam width (b), depth (d), length (L), concrete compressive strength (fc′), FRP modulus of elasticity (Efr, Efs) and FRP reinforcement ratios (ρf, ρfs). Multi-objective optimization was deployed to integrate Genetic Algorithms (GA) and fmincon to optimize beam parameters for maximizing the shear capacity, Vc. Sensitivity analysis allowed to quantify the influence of each parameter, revealing that b and d significantly affect Vc, with sensitivity scores of 0.39 and 0.35, respectively. The optimization process, highlighted by a 3D scatter plot, dynamically illustrated trade-offs among key design parameters (ρf, ρfs, d), giving insights into the complex interplay in FRP beam design. The hybrid intelligence models reached superior predictive accuracy over traditional codes, achieving R2 values of 0.89. Notably, for beams without stirrups, model predictions closely matched experimental data, with a lower average ratio (1.02) compared to Eurocode (1.65) and ACI (1.58). Principal Component Analysis (PCA) has elucidated the intricate interactions among variables, thereby deepening insights into the structural dynamics of FRP-RC beams. Incorporating artificial intelligence, sophisticated optimization methodologies, and thorough statistical evaluations establishes a holistic approach for the structural examination of FRP-RC beams, providing improved precision and valuable viewpoints for the refinement of future designs
Flexural toughness of sustainable ECC with high-volume substitution of cement and silica sand
No full textThis study explores the effects of high-content fly ash and limestone filler partial replacement for portland cement and silica sand, respectively on the flexural toughness parameters of engineered cementitious composites (ECC). Various groups of mixtures having variable fly ash/portland cement ratio and different levels of limestone filler were prepared. ASTM C1609, JSCE-SF4 and the Post-Crack Strength method were employed to appraise the flexural toughness parameters of the ECC mixtures at 3, 28 and 90-d. The results show that according to ASTM C1609, JSCE-SF4 and the Post-Crack Strength method, limestone filler did not significantly affect the flexural toughness, while the flexural toughness of ECC beams decreased when the fly ash content increased. Considering deflection capacity, specimens made with a FA/OPC ratio of 1.2 without limestone filler achieved higher ductility at all curing ages. Owing to its superior crack resistance and toughness compared to normal concrete, ECC with high fly ash content and limestone filler could be a sustainable alternative construction material in diverse civil engineering applications. ECC with enhanced ductility compared to normal concrete could offer increased crack resistance, durability and better resilience. (C) 2020 Elsevier Ltd. All rights reserved
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
Performance of Structural Concrete Frames Reinforced with GFRP Grid
No full textThe use of fibre-reinforced polymers (FRP) rebar in structural applications has been getting increasing attention due to the advantages it offers over conventional reinforcement (e.g. durability, light weight, magnetic neutrality). A possible application of FRP rebar reinforcement is in the area of multi-storey structural frames. However, current design standards and detailing criteria for beam-column joints were established in the 1970’s and may be considered unsuitable for FRP reinforcement due to its different mechanical properties. During recent earthquakes, many structural collapses were initiated or caused by beam-column joint failures. There are no comprehensive seismic standards for the application of FRP materials. Consequently, research is needed to gain a better understanding of the behaviour of FRP materials and their interaction with traditional materials in such application in order to implement their use on solid grounds. In this study, two full-scale quasi-static loading tests were performed on beam-column joint specimens. The first test was performed on a joint specimen reinforced with steel and its behaviour was compared to that of a second similar test performed on a GFRP-reinforced joint specimen. It is shown that GFRP-reinforced frames can have satisfactory drift capacity, but their energy dissipation capacity is limited
Performance of x and inverted v bracing systems in controlling progressive collapse of reinforced concrete buildings
Full text linkProgressive collapse can lead to partial or total failure of structures under extreme events such as explosions or earthquakes. While brace systems effectively enhance lateral stiffness, their use in reinforced concrete (RC) buildings is limited due to detailing challenges at connection points. This study evaluates the influence of X and inverted V bracing systems on the progressive collapse behavior of RC buildings and investigates the effectiveness of optimally placed X-bracing configurations under multiple column removal scenarios. Three groups of 9-, 12-, and 15-story RC buildings, designed per the Turkish Building Earthquake Code (TBEC2018), were modeled using the Applied Element Method (AEM) in the ELS software. The first group included unbraced reference models. The second group comprised 54 fully braced models using X and inverted V configurations, subjected to three distinct column removal scenarios. The third group included 27 models with X bracing placed only in selected bays to determine optimal configurations for collapse prevention. Nonlinear dynamic analysis of 84 models revealed that both the reference buildings and those with inverted V bracing experienced progressive collapse, with maximum top displacements reaching over 65 cm. In contrast, fully braced X systems effectively prevented collapse, reducing displacements to below 10 cm. Optimized Xbracing layouts, applied to only 30-50 % of the bays, achieved comparable performance while reducing material usage and detailing complexity. This study demonstrates the superiority of RC X-bracing in enhancing progressive collapse resistance and provides practical recommendations for optimal placement in reinforced concrete (RC) buildings
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