1,721,062 research outputs found
A POSSIBLE RE-USE OF SHEEP WOOL IN CONCRETE
No full textConcrete is widely used for the construction. However, the concrete production determinates a great amount of CO2 production. It is nowadays important to find waste materials to introduce in the concrete mix. In this paper it is considered the problem that every year a great amount of the wool obtained by the sheep shearing is not accepted by textile companies, because of too low quality, determinating a great ecological problem: a possible re-use of it in the concrete would be a great result in the objective of the circular economy. In this paper the intention of the author is to provide an overview of the principal mechanical properties of the concrete obtained with the addition of several percentage of sheep wool, and to find a possible optimum mix design: in fact it has found that the addition of sheep wool in the concrete mix increases the ductility of the concrete, but reduces its workability. The possibility of re-use the sheep wool in the concrete mix would be a step in the research addressed to the ecological transition of the construction sector, in the direction of a more sustainable design practice
Expression for calculating the compressive strength of concrete containing rice husk ash
No full textConcrete is widely used for the construction of various types of structures and is made by materials that come all from the earth’s crust. However, the resource of these natural materials is depleting, and it is nowadays important to find a substitute to them. A solution of this problem can be the use of agricultural waste materials that can be locally available. For example, Rice Husk Ash (RHA) is the residue of completely incinerated rice husk, that is the covering part of the grain of rice. Rice husk is abundant in many parts of the world, and is classified as a highly reactive pozzolana, so it can be used as a partial replacement of cement. During the years, researchers have studied the mechanical properties and the durability of the concrete incorporating different percentage of RHA. The objective of the study presented in this paper is not only to find the "perfect percentage" of RHA replacement, but also to find a new expression for calculating the concrete compressive strength, considering the percentage of RHA replacement. From the comparison on the experimental studies done by other researchers on the concrete compressive strength, the reliability of the here proposed expression is evaluated, and it has found to be in better agreement with the test results, indicating that the here proposed expression has certain universality and can accurately describe the effect of the RHA replacement on concrete strength
Resistance of axially and eccentrically loaded steel column at high temperature: A simple expression
Full text linkThe study of the behaviour of steel structures at elevated temperature has become more and more important in structural design in recent years. Nevertheless, there are few design Code provisions and researcher expressions for predicting the steel column resistance on local buckling under fire conditions. In this paper a rather simple expression for predicting the resistance of steel column subjected to both axial and eccentrical load under high temperature is proposed. This expression considers the dependence of the steel column resistance on the relative slenderness at the collapse temperature. The steel column resistance values at high temperature obtained with the here proposed expression has been compared with those outcoming from other researchers and Code expressions, with respect to the test results found in the literature. The proposed expression has found to lead not only the most accurate but also the most uniform prediction of the column resistance under fire loads. It is also important to point out that the here proposed expression is very simple and easily applicable also by engineers in the practical design
Evaluation of the Bond Stress Transfer Mechanism in CFSTs
Full text linkThis paper studies the non-linear distribution of bond–slip behavior in the steel concrete interface of a Concrete Filled Steel Tube (CFST). Specifically, it concerns the regions of geometric discontinuity occurring in composite beams of CFST column-frame connection points. The study was conducted through an analytical model that represented the bond stress transfer mechanism within these areas. The resulting deductions were drawn up on the basis of the elasticity theory and the non-linear bond–slip relationship between the steel jacket and the confined concrete. This paper highlights how the model proposed here was able to obtain, not only the closed-form analytical expression of the transferring length involved in the bond stress transfer mechanism in CFSTs but also the expressions of concrete and steel jacket stresses and strains. In addition, the procedure also obtained the bond stress and slip trend in the above-mentioned length for rectangular and circular concrete filled steel tubes. The use of this model also resulted in an analytical expression for the calculation of the ultimate load in CFSTs. In this paper, the ultimate load predictions were compared with the experimental results obtained from 97 tests carried out on circular concrete filled tubes (CCFTs) and 35 tests on rectangular concrete filled tubes (RCFTs). The predictions drawn up with this model have been found to be the most accurate and uniform in comparison with those obtained from models proposed by other authors and Eurocode. With reference to the experimental-to-analytical load value ratio, the AVG and COV values obtained from the model proposed here are 0.86 and 0.42, and 1.06 and 0.57 for CCFT and RCFT analyses, respectively
Experimental investigation of flare groove weld stiffness in lattice girder beams by means of push-out tests
No full textWith the purpose to investigate the behaviour of the lattice girder composite slab (LGCS) at construction stage, a push-out experimental investigation has been carried out on 9 lattice girder specimens having not only different diameters of web bars, top and bottom chords, but also different heights. The results obtained from tests are here presented and analysed. The paper focuses on the behaviour of the flare groove welds among web bar and bottom and top chords. For each tested specimen a F.E.M. model has been developed, schematizing the stiffness of the flare groove welds by local springs, whose stiffness has been calibrated by means of the load-displacement curves obtained from tests. A chart that allows to estimate the aforesaid stiffness of a lattice girder beam in function of the triad of top, bottom chords and web bar diameters, and in function of the inclination between the web bar and the beam horizontal transversal axis is proposed. This paper highlights that the chart proposed here provides stiffness values with which numerical models can more accurately predict the behaviour of LGCS during construction. Furthermore, this paper highlights that the weld stiffness of the flare groove influences the buckling length of the web bar
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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