1,720,957 research outputs found
Impact Dipping Pyramidal-Prismatic Piles and their Resistance to Pressure and Horizontal Load
Full text linkThe results of experiments carried out in the field with the use of large-scale models of reinforced concrete driven pyramidal - prismatic piles with different lengths of the pyramidal part are presented. The impact capacity of piles were evaluated of their bearing capacity to the action of indentation and horizontal static loads. It has been established that the driving of pyramidal-prismatic piles is accompanied by both large (by 1.10–1.60 times) and lower (by 8.0–37.0 %) energy consumption for their driving in comparison with conventional pris-matic and pyramidal piles. It was also revealed that under the action of a vertical indentation load, the bearing capacity of the pyramidal-prismatic piles is 1.09–1.48 times, and under the action of a horizontal static load, it is 1.17–1.80 times higher than that of a prismatic pile. It has been established that with an increase in the length of the pyramidal part of the test piles, there is an increase in their bearing capacity by 1.12–1.34 times. Formulas are proposed for determining the bearing capacity of pyramidal-prismatic piles. The research results serve as the basis for the development of recommendations for the calculation and design of pyramidal-prismatic piles
Equations Used to Calculate Vertical Bearing Capacity of Driven Piles with Shaft Broadenings
Full text linkIn a pile foundation setting practice driven piles with an unconventional (variable) longitudinal shape of surface are widely used. Such piles are made with various slopes of the side faces, may have different types of broadenings, thickenings, etc. The effectiveness of such piles is due to their design features, allowing full use of the natural bearing capacity of the soil base without additional reinforcement. The obvious advantages of these piles make it relevant to study the features of their interaction with the soil stratum, especially the bearing capacity of piles. This study was aimed to investigate vertical bearing capacity of driven reinforced concrete piles with several broadening of the shaft. Numerical calculations and experimental studies of the bearing capacity of piles with broadening under the static loading have been carried out. Equations for calculating the bearing capacity of piles with broadenings are proposed and their verification is performed. The equations include a coefficient that takes into account the features of soil behavior underneath of the pile broadening during palification. Correlation dependence is presented which makes it possible to determine the values of that coefficient depending on the number of pile broadening and the liquidity index of soil. A correlation that makes allow calculations the bearing capacity of piles with broadening via the bearing capacity of a prismatic pile is proposed. The equations are recommended to be used at the stage of variant design of piles with broadening as part of the pile foundations of buildings and structures
Strength Properties of Various Types of Fiber-Reinforced Concrete for Production of Driven Piles
No full textThis paper presents the results of static and dynamic tests of fiber-reinforced and unreinforced concrete samples under laboratory conditions. Concrete samples reinforced with steel and non steel fibers were tested. The dynamic tests were carried out on the stand by applying falling weight impacts on the concrete samples. The impact testing of samples included two stages of deformation: until the first defects appeared in the samples and until their complete destruction. The impact resistance of the samples was evaluated according to the energy input of the hammer with registration of the type, size and volume of the defects. It was revealed that the type of fibers has a different effect on the static and impact resistance of fiber concrete. Correlational dependencies used for predicting the strength and energy parameters of fiber concrete in their comparative evaluation have been obtained. It has been determined that the static strength and impact resistance of fiber concrete may not be identical, i.e., a high static strength in fiber concrete does not always provide a high impact resistance. The impact resistance of fiber concrete when tested before the first defects appear is always lower than when tested before complete failure
The Influence of Backfill on the Driving Energy Intensity and Axial Load Resistance of Piles with Shaft Widenings: Modeling Research
No full textThis article is dedicated to addressing the current challenge of augmenting the load-bearingcapability of pile foundations. This predicament is most effectively addressed by employing piles with unconventional geometries along with atypical methodologies for installing these foundation piles. The primary objective of the research wasto examine the impact of various fill materials (including both soil and rigid substances) on the energy consumption during pile driving and the resistance to static loads by piles with multiple shaft expansions. The findings derived from model-based investigations demonstrate that the load-bearing capacity of piles with shaft expansions installed with bulk material filling surpassed that of conventional piles (prismatic and pyramidal) by a factor ranging from 1.5 to 4.6. Furthermore, the research outcomes also indicated greater energy consumption (1.14–1.66 times) and enhanced load-bearing capacity (1.15–1.68 times) for piles with shaft expansions driven with backfill in comparison to piles installed without backfill. It is noteworthy that the type of backfill material significantly influenced the energy consumption during pile driving and their stability under axial static loads. The correlation relationships can be applied to approximate projection of the energy-related and structural parameters of piles with shaft expansions embedded with the addition of bulk materials
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
The Influence of the Fine Earth Composition of the Soil Mixture on the Parameters of Its Filtration, Moisture Content, and Density
No full textThe article presents the results of laboratory studies on the patterns of change in the filtration coefficient of the fine-grained component (fine earth) of the soil mixture from a number of influencing factors. The study was conducted to assess the impact of the fine earth fractional composition of a soil mixture on its filtration parameters and density-moisture state. The experiments were conducted using a compression device, the use of which is regulated by the standard of the Republic of Kazakhstan. One hundred and twenty-six fine earth samples were tested, containing 50 to 75% (by weight) of various fractions with particle sizes smaller than 5 mm. An analysis of the test results revealed that for large fractions (with particle sizes of 5 mm or less, but more than 1 mm), the filtration coefficient of fine earth increases as the weight content of fractions in it increases (from 50 to 75%), while for small fractions (with particle sizes of 1 mm or less), it decreases. It was determined that similar patterns are characteristic of the increase in moisture content and increase in the density of fine earth, which occur when water is filtered through it. The scientific novelty of the research lies in the fact that, based on the identified patterns, correlation dependencies were established between the filtration coefficient and the weight content of various fractions, as well as the increase in moisture content and the increase in the density of fine earth. Correlation dependencies of the filtration coefficient on the weight content of various fractions, as well as on the increase in moisture content and increase in the density of fine earth, were established. Based on the established relationships, formulas were developed for predicting the filtration coefficient, moisture content, and density of fine earth, which adds practical value to the research. These formulas are recommended for use in selecting optimal fine earth compositions for soil mixtures used in dam construction
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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