1,720,979 research outputs found
Corrosion of fasteners in concrete: Literature review and discussion of current test methods
No full textCorrosion damage may impair functioning and capacity of fasteners, hence affecting structures durability. The aim of this paper is to present the existing knowledge on fasteners’ corrosion behavior in concrete. The paper investigates the available literature and discusses the most significant test methods currently in use for the evaluation of fastener’s corrosion performance in concrete (i.e., hydrogen embrittlement, salt spray and sulfur dioxide tests). In this context, design standards and product norms often provide inconsistent requirements, while assessment procedures of non-zinc coatings are left to case-by-case implementation. Moreover, the study of existing test methods revealed that, beside the hydrogen embrittlement test for concrete screws, none of the other considered test methods are specifically conceived to investigate the fastener’s corrosion behavior at the steel-to-concrete connection scale, nor they account for service conditions. Therefore, the significance for both designers and manufacturers of the remarks pointed out in this paper
Low-cycle behavior of wood screws under alternating bending
No full textEarthquake-resistant timber structures may be designed accounting either for the dissipative or low-dissipative structural behavior, depending on the relevant ductility class. A timber structure belonging to a given ductility class shall meet specific requirements especially in the type and rotational ductility capacity of connections, since the timber members themselves shall be regarded as behaving elastically. In addition, Eurocode 8 prescribes that only materials and mechanical fasteners providing appropriate low-cycle fatigue behavior may be used in joints regarded as dissipative zones. In this context, the properties of dissipative zones may be determined by tests either on single joints, or on whole structures in accordance with EN 12512. At the same time, the appropriate fastener’s low-cycle behavior is currently deemed to be satisfied if the connectors are sufficiently slender with respect to the thickness of the joined members. Nowadays, this assumption may not be sufficiently reliable because of the actual trends in fasteners technology, which consists in providing heavily hardened connectors in order to achieve higher resistances and ease of insertion into timber. The aim of this study is to investigate the low-cycle behavior of modern wood screws by means of three-point alternating bending tests. The paper describes a new testing apparatus, the related test procedure and assessment criteria specifically designed for this purpose. A preliminary investigation of the low-cycle behavior of different wood screws currently on the market is then carried out and the related test results are discussed
Impact performance of thin glass-polycarbonate composite panels
No full textSafety glass is usually the proper designer choice when glazing may be subjected to the impact of a person. In order to avoid people injuries, glass products must comply with appropriate safety practices. Existing technical standards classify safety glass products by mode of breakage and post-breakage behavior. Critical demanding applications in terms of self-weight saving, like high efficiency elevator cars in buildings or aircrafts and other means of transportation interiors in aerospatial and automotive industries, are currently driving the innovation in the development of safety glass. In this framework, glass-polycarbonate composite panels offer a lightweight alternative which is at once able to preserve the aesthetic and safety aspects of traditional laminated safety glass. The aim of this paper is to present an experimental investigation on the performance under impact of thin glass layer with a cellular polycarbonate backing joined together by an auto-adhesive interlayer film. Different coatings (mirror and paint) at the glass-adhesive interface are also taken into account
SEISMIC DESIGN AND EXPERIMENTAL INVESTIGATION OF A NEW TIMBER HOLD-DOWN CONNECTION
No full textTimber connections made with hold-down are usually adopted for timber wall to foundation connection at the edges of
the wall to restraint the possible overturning moment (due to rocking) which can occur by applying a horizontal force to
the panel (e.g. under seismic action). The main components of the connection are the steel plate fastened to the panel
via threaded screws or nails and the anchor system to the concrete foundation. As such, the connection behavior under
seismic loading is characterized by the contemporarily contribution of different resistant mechanisms, i.e. (i) laterally
loaded timber screws or nails; (ii) axially loaded steel plate; (iii) axially loaded anchor in concrete. The former has been
basically neglected in past investigations having anchored the hold-down with steel bolt directly to the strong floor.
However, the design of the anchor should be considered as crucial when it comes to capacity design, especially in case
of narrow foundations (edge failure) and post-installed anchors when the resistance is highly reduced with respect to
steel bolt capacity. Moreover, the overall dissipative performance might be affected by the anchor’s displacement. An
innovative hold-down connection has been designed to promote steel failure of the axially loaded plate. The plate’s
geometry has been optimized such that capacity design rules according to Eurocode 8 can be applied. Additionally, a
target displacement requirement is addressed, and the stretch length is defined accordingly. The whole connection is
tested against cyclic loading and results show enhanced performances with respect to standard configuration. In
particular, brittle mechanism such as concrete-cone failure of the anchors and splitting of timber are prevented. The
paper discusses the experimental results for different type and size of the anchor, also the size of the optimized steel
plate is considered as a parameter
The effect of edge processing in thin glass for cold bending applications
No full textCold bent glass is nowadays of primary importance both for industrial and civil applications. In fact, thin glass with a maximum thickness of 1.5 mm is often part of a wide range of technological devices and architectural surfaces (e.g. touchscreens, displays, mirrors, optical instruments, claddings and building interiors). The manufacturing process of cold bent glass is generally considered faster and less demanding in terms of necessary equipment with respect to hot bending or casting techniques. On the contrary, both the design of the manufacturing procedure and of the products are still a challenge and they are mainly based on a trial and error approach. Generalized defects and imperfections are always present on the surface of the raw glass product, while another significant source of flaws is usually localized at the edges and it is associated with the specific cutting technique and edges processing. The aim of this work is to experimental investigate the influence of the edge processing on the failure strength of 1.5 mm glass plates by means of four point bending tests. Two edge conditions are taken into account: manual diamond cut and ground by hand-operated tool which introduces randomly diffused small-size flaws. Test results are then statistically assessed and compared with the stresses that arise during the cold bending process due to the imposed curvature. In the end, grinding somehow increases the level of damage as it increases the number of flaws. On the contrary, the improved uniformity of the damage leads to less scattered resistance values. These allows to achieve smaller curvature radii or, for a given design radius, it reduces accidental failures during the cold bending process
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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