1,721,037 research outputs found
“Performance of connections for prefabricated timber-concrete composite floors.”
No full textTimber–concrete composite beams and slabs require interlayer connectors, which provide composite action in the cross-section. A range of
mechanical connectors is available on the market
with an extensive variety of stiffness and strength properties, which are fundamental design parameters
for the composite structure. Another crucial parameter
is the cost of the connector, including the labour cost, that if too high may prevent the use of the composite system. In order to reduce the construction cost and make timber–concrete structures more widespread on the market, it is believed that a high degree of prefabrication should be achieved. For a simple and cost effective construction process, the use of ‘‘dry’’ connections, which do not require the pouring and curing of concrete on site, may represent a possible solution. This paper reports the outcomes of an experimental programme aimed to investigate a number of different mechanical ‘‘dry–dry’’ connectors previously embedded into a prefabricated
concrete slab. Direct shear tests on small blocks made
of a glulam segment connected with a prefabricated concrete slab were performed. The shear force relative
slip relationships were measured and all the
relevant mechanical properties such as slip moduli
and shear strengths were calculated. It was found that
some of the new developed connection systems for
prefabricated concrete slab can perform as satisfactorily
as those for cast-in-situ slabs, with the additional benefit of being relatively inexpensive
"Laboratory tests and numerical analyses of prefabricated timber-concrete composite floors."
No full textThis paper describes tests on a novel composite floor system constructed by connecting prefabricated concrete slabs to timber
joists. Seven types of shear connectors have been developed and tested: lag screws, either alone or combined with a notch cut from each timber joist; metal plates embedded in the concrete slab and either nailed or glued to the joists; dowels embedded in the concrete and glued to the timber; and toothed metal plates embedded in the concrete and pressed into the timber. Four-point bending tests to failure were performed on five, full-scale, 4.8 m long specimens connected with lag screws or metal plates nailed to the timber. Values of deflection and relative slip between the concrete slab and the timber obtained in these tests showed high correspondence with values obtained from a uniaxial finite element model developed for nonlinear analyses of composite beams. The model was also used to perform a numerical analysis to failure of composite beams with the other four connection systems that were developed but not tested on full-scale specimens. The outcomes of the experimental tests and numerical analyses show that the newly developed system can provide good
structural performance, especially if connections with coach screws and notches in the timber are used. The economic advantages of
prefabrication and the possibility to disassemble the structure and reuse the timber beams and concrete panels at the end of the service life make the proposed floor system very promising
“Prefabricated stabilising timber walls anchored with glued-in rods – Experimental tests and preliminary design.”
No full textA new beam and post system for multi-storey timber buildings has been developed in Sweden. The building is braced with timber walls constructed from two Kerto-Q
LVL boards glued and screwed onto a glulam frame. The
walls are prefabricated off-site and can be connected to the foundation using either glued-in steel rods with metric thread or nail plates. Introductory racking tests of full scale walls anchored with glued-in threaded rods were performed. The paper presents the results of the experiments and discusses the
use of the transformed section method to predict racking capacity of the anchored wall. To evaluate the strength of the glued-in rods, a newly proposed model was employed. An analytical study was conducted to investigate the role of the
sheathing and the contribution of the axial force on the racking
capacity of the walls. The wall panels tested in this experimental programme showed high strength and stiffness under racking load. The anchoring joints with glued-in steel rods with metric thread demonstrated a high load-carrying capacity
with, however, large scatter and a brittle failure mode characterized by pull-out from the timber member. The transformed section method was successfully used to predict the racking capacity of timber walls anchored with glued-in steel rods
"Provisions for ductile behavior of timber-to-steel connections with multiple glued-in rods"
No full textConnections with glued-in rods are very efficient, high-strength joints and can be successfully used, for example, for the anchorage
of vertical timber elements to a foundation. Although extensive research was done on the pullout strength of single rods, few references can be found on the behavior of multiple glued-in rods. This paper presents the results of an experimental program carried out on timber-to-steel connections with multiple glued-in rods. Two series of 10 specimens with four large-diameter, glued-in rods made from mild steel (Series GB) and 10 specimens with 12 small-diameter, high-grade glued-in rods (Series GS) were tested to failure under monotonic tensile load. Both types of connections ultimately failed in a brittle manner; however, the GB series developed some plastic deformations prior to failure which was caused
by the pullout of two rods and longitudinal splitting of the timber member. By comparing the experimental results with the analytical predictions, no significant group effect could be detected in the GB test series, and an overall acceptable approximation was found. In the GS test series, no final conclusion on the group effect could be drawn as several rods failed by nut-stripping. A parametric study using analytical formulas
was carried out to investigate the effect of rod strength, rod diameter, glued length, and timber density on the connection performance.
Based on the results of the parametric study and experimental tests, it can be concluded that the use of mild steel as well as more rods of larger diameter, properly spaced from each other, and from the edges are all effective measures to increase the connection ductility. Furthermore, by
leaving a suitable length of rod unbonded between the steel plate and the glued length, it is possible to control ductility, providing all brittle failure modes have a higher strength capacity than the rod-yielding force. Special care should be taken during the manufacturing process to
ensure good quality of gluing (required glued length and amount of adhesive) and rod alignment
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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