1,722,211 research outputs found
Timber-concrete composite structures | Design according to ONR CEN / TS 19103:2021 with a focus on long-term deformation
Get PDFDas Kriechen und Schwinden von Holz und Beton sowie Temperatur- und Feuchteänderungen haben einen großen Einfluss auf die Langzeitverformung von Holz-Beton-Verbundkonstruktionen. Die einzelnen Komponenten von Holz-Beton-Verbundkonstruktionen dehnen sich aufgrund dieser Effekte unterschiedlich aus und so genannte „unelastische Dehnungen“ sind dadurch die Folge. Die aktuelle Fassung des Eurocode 5 ermöglicht keine genaue Berücksichtigung dieser Dehnungen bei der Ermittlung der Verformung der Holz-Beton-Verbundkonstruktionen nach mehreren Jahren. Generell ist die Bemessung von Holz-Beton-Verbundkonstruktionen im Eurocode 5 nicht vertreten. Der aktuelle Normenentwurf der ONR CEN/TS 19103/A „Eurocode 5: Bemessung und Konstruktion von Holzbauten – Berechnung von Holz-Beton-Verbundbauteilen – Allgemeine Regeln und Regeln für den Hochbau“ (Ausgabe 2022-04-01) schafft hier Abhilfe und ermöglicht die Bemessung solcher Verbundbauteile. Ziel dieser Arbeit ist es, diesen Normentwurf im Hinblick auf die Langzeitverformung anhand von durchgeführten Langzeitversuchen an Holz-Beton-Konstruktionen aus der Literatur zu validieren und festzustellen, ob der Normenentwurf Werte für die Langzeitdurchbiegung auf der sicheren oder unsicheren Seite bzw. generell realitätsnahe Verformungen nach mehreren Jahren liefert. Hierfür wird zuerst ein kurzer Überblick über die theoretischen und bemessungstechnischen Grundlagen der einzelnen Komponenten von Holz-Beton-Verbundkonstruktionen im Hinblick auf die Kurzzeitverformung wiedergegeben. Anschließend widmet sich diese Arbeit der Beschreibung der Langzeitverformung der einzelnen Verbundpartner und wie die Langzeiteffekte (vor allem Schwinden und Kriechen bzw. Temperatur- und Feuchteänderungen) in der Bemessung nach dem Normentwurf der ONR CEN/TS 19103 berücksichtigt werden. Ausgewählte Langzeitversuche von Holz-Beton-Verbundkonstruktionen und deren Ergebnisse werden in weiterer Folge zusammenfassend dargestellt und mit der ONR CEN/TS 19103 nachgerechnet. Die Ergebnisse nach ONR CEN/TS 19103 werden mit jenen aus dem Versuch verglichen, um Aussagen bezüglich der Genauigkeit der prognostizierten Werte nach neuen Normentwurf zu treffen. Die Nachrechnung der Versuche hat gezeigt, dass mit der ONR CEN/TS 19103 die Langzeitverformungen teils auf der konservativen Seite aber auch auf der unsicheren Seite prognostiziert werden. Dafür sind die Vorhersagen der Durchbiegung sowohl für den Zeitpunkt „nach 3 bis 7 Jahren“ als auch nach 50 Jahren realitätsnah und demnach kann die Verwendung der ONR CEN/TS 19103 empfohlen werden. Wichtig bei der Berechnung ist dabei die genaue Angabe der max. und min. Holzfeuchte sowie von Holzfeuchteschwankungen während des Betrachtungszeitraums, da die Holzfeuchte einen großen Einfluss auf die endgültige Verformung hat. Die Holzfeuchte stellt ein wichtiges Kriterium dar, um eine gute qualitative Übereinstimmung von experimentellem und nach ONR CEN/TS 19103 berechnetem analytischen Verlauf der Langzeitverformung zu gewährleisten. Bei Langzeitversuchen sollte die Holzfeuchte deswegen auch über den gesamten Betrachtungszeitraum gemessen und beobachtet werden. Zusätzlich konnte auch gezeigt werden, dass der Einfluss von schwindarmem Beton auf die Verformung durch die ONR CEN/TS 19103 gut abgebildet wird. Weiters stellte sich heraus, dass auch die Langzeitverformung von Holz-Beton-Verbundbalken mit Nagelplatten als Verbindungsmittel, welche nicht in den Anwendungsbereich der ONR CEN/TS fallen, mit dem neuen Normenentwurf realitätsnah prognostiziert werden können. Diese Verbindungsmittelart sollte demnach genauer untersucht und eventuell in die ONR CEN/TS eingearbeitet werden.The creep and shrinkage of timber and concrete as well as temperature and humidity changes have a major impact on the long-term deformation of timber-concrete composite structures. Due to these effects the individual components of timber-concrete composite constructions expand differently, and so-called "inelastic strains" are the result. The current version of Eurocode 5 does not allow these expansions to be taken into account precisely when determining the deformation of timber-concrete composite structures after several years. In general, the design of timber-concrete composite structures is not represented in Eurocode 5. The current working draft of ONR CEN/TS 19103/A "Eurocode 5: Design of Timber Structures – Structural design of timber-concrete composite structures – Common rules and rules for buildings" (edition 2022-04-01) provides a remedy and enables the design of such composite structures. The aim of this work is to validate this working draft with regard to long-term deformation based on long-term tests carried out on timber-concrete structures from the literature and to determine whether the working draft provides values for long-term deflection on the safe or uncertain side or generally realistic deformations after several years. For this purpose, a brief overview of the theoretical and design fundamentals of the individual components of timber-concrete composite structures regarding the short-term behavior is given first. Subsequently, this work is devoted to the description of the long-term behavior of the individual composite partners and how the long-term effects (especially shrinkage and creep or temperature and humidity changes) are taken into account in the design according to the working draft of ONR CEN/TS 19103.Selected long-term tests of timber-concrete composite structures and their results are summarized below and recalculated with ONR CEN/TS 19103. The results according to ONR CEN/TS 19103 are compared with those from the long-term test in order to make statements about the accuracy of the forecast values according to the new working draft. The recalculation of the tests has shown that with the ONR CEN/TS 19103 the long-term deformations are partly predicted on the conservative side but also on the uncertain side. However, the predictions of the deflection are realistic both for the time "after 3 to 7 years" and after 50 years, and therefore the use of ONR CEN/TS 19103 can be recommended. When making the calculation, it is important to specify the max. and min. timber moisture content as well as timber moisture fluctuations during the period of examination, since the timber moisture content has a major influence on the final deformation. The timber moisture content is an important criterion to ensure a good qualitative agreement between the experimental and the analytical course of the long-term deformation calculated according to ONR CEN/TS 19103. Therefore, the timber moisture content should be measured and observed over the entire observation period of long-term tests. In addition, it could also be shown that the influence of low-shrinkage on the deformation concrete is well represented by the ONR CEN/TS 19103. Furthermore, it was found that the long-term deformation of timber-concrete composite beams with nail plates as fasteners, which do not fall within the scope of ONR CEN/TS, can also be realistically predicted with the new draft standard. This type of connector should therefore be investigated in more detail and possibly incorporated into ONR CEN/TS
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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