1,720,957 research outputs found
Axial Compressive Behavior of Bubble-size Plastic Straw Waste FRP Composites-confined Circular Short Concrete Columns: An Alternative on Managing Single-use Plastic Waste after COVID-19 Pandemic
No full textOne of the crucial problems caused by the COVID-19 pandemic is the increase in the number of disposable plastic wastes, especially bubble-size plastic straw waste. The use of recycled fiber as a material of fiber-reinforced polymer composites for concrete strengthening can be an alternative to recycling disposable plastic wastes, especially in Indonesia. The use of fiber-reinforced polymer made from woven bubble-size plastic straw waste fibers that are bonded with epoxy has been found to be able to alternate the axial deformability and ultimate compressive strength of confined circular concrete. Adding more FRP layers also significantly improved the axial deformability and ultimate compressive strength. Based on test results from this study for bubble-size plastic straw waste fiber-reinforced polymer, new models are created to forecast both the ultimate compressive strength and strain. The results of the experimental analysis have shown that four layers application of bubble-size plastic straw waste fiber-reinforced polymer confined circular concrete is effective enough to increase the strength of concrete up to around 50% of the initial strength of concrete
Development of Green Sustainable Water Hyacinth Bio Epoxy Resin FRP Composite Used for External Concrete Strengthening under Axial and Flexural Loading
No full textThis study examines the effect of Water Hyacinth Bio Epoxy Resin (WHBR) FRP as an external reinforcement for concrete columns and beams. WHBR FRP is an environmentally friendly fiber-reinforced polymer composed of water hyacinth stem fibers as the fiber phase and commercial bio epoxy resin as the matrix phase, with a fiber volume fraction of 31.5%, applied through the hand-layup method. For concrete columns, variations were made based on corner radius and the number of FRP layers. A larger corner radius enhances compressive capacity by optimizing lateral confining pressure and preventing the knife effect. Additionally, increasing the number of FRP layers improves stiffness, resulting in a capacity increase of approximately 25-70%. For concrete beams, variations were based on beam type (plain or reinforced) and the number of FRP layers used for flexural reinforcement. In plain beams, FRP improves capacity but remains less effective than longitudinal reinforcement, while in reinforced concrete beams, FRP further enhances capacity. Similar to columns, adding more layers increases stiffness, with capacity improvements ranging from 10-70%. Economically, WHBR FRP remains more expensive than synthetic FRP (such as GFRP) when measured in IDR/MPa, with a price difference reaching 15,000-20,000 IDR/MPa due to the greater capacity enhancement provided by synthetic FRP. However, in terms of life cycle analysis, WHBR FRP development—from raw materials to decomposition—results in a relatively low carbon footprint of 40.16 kg CO₂ eq, which can be reduced to 2 kg CO₂ eq if developed using equipment without oil-based or electrical energy sources
Stress-Strain Model of Concrete Columns Externally Collared with Steel Angles Subjected to Axial Compression
Full text linkRC Structures with poorly confined columns have been known to have poor performance during earthquake events. Brittle failures of columns with low ductility can lead to progressive overall building collapses. Many confining techniques have been proven to be successful in retrofitting circular columns. However, for square or rectangular columns, providing effective confining stress be the external retrofitting method is not a simple task due to the high stress concentration occurring at the columns corners. In this paper, an analytical model for the axial stress-strain relationship of square columns confined only by external steel collars has been developed. The combined effect of conventional internal stirrups and the external steel collars on the improved stress-strain relationship has been also developed analytically and proposed as the retrofit design approach. Comparison with experimental results has shown that the axial stress-strain relationship of square RC columns could be well predicted be the proposed retrofit design approach
Performance of Externally Steel Angle-Collared Concrete Columns Under Axial Compressive Load
Full text linkDeficient Reinforced Concrete (RC) columns and higher demands of new codes are the
main reasons for retrofit works for RC columns. One of the deficiencies involves the lack of confining
elements which leads to poor ductility. Confining stress conventionally provided by transverse
reinforcement has been recognized to enhance the strength and ductility of RC columns. Nowadays,
the confinement method has been further developed to be applied externally which is more suitable
for retrofit works. In square or rectangular columns, providing effective confining stress is not as
simple as that of circular columns. In this research, displacement controlled compressive test on a
set of square RC columns retrofitted by steel angle collars is presented. The volumetric ratio of the
confining elements is the main parameter to investigate the effectiveness of the retrofitting technique.
Enhancement of axial strength and ductility are observed as the confining element volumetric ratio
increases
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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