125,356 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
FIGURE 2. A. Sepals. B. Petals. C. Stamens and pistils. D in A new species of Aquilegia (Ranunculaceae) from Sardinia (Italy)
No full textFIGURE 2. A. Sepals. B. Petals. C. Stamens and pistils. D. Anther; E. Staminodes. F. Staminodes and pistils. G. Pistil. H. Stigma. I. Follicles. J. Seed. Illustration by Salvatore Brullo based on Bacchetta, Fenu & Mattana s.n. (CAT).Published as part of Bacchetta, Gianluigi, Brullo, Salvatore, Congiu, Angelino, Fenu, Giuseppe, Garrido, José Luis & Mattana, Efisio, 2012, A new species of Aquilegia (Ranunculaceae) from Sardinia (Italy), pp. 59-64 in Phytotaxa 56 (1) on page 62, DOI: 10.11646/phytotaxa.56.1.9, http://zenodo.org/record/506127
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Dynamic Performance Analysis of a Curved Cable-Stayed Bridge Based on the Direct Method and the Sensitivity-Based Iterative Method
No full textCurved cable-stayed bridges have been regularly accepted due to their ability to cross long spans, and a number of studies have been conducted to investigate the mechanical or dynamic performance of them. Meanwhile, currently just a few studies focus on the curved composite cable-stayed bridges. In this study, an operational modal testing and finite element model updating of a conventional straight bridge with the steel-concrete composite girder were conducted to investigate the performance of the potential methods for the model updating, which included the direct method and the sensitivity-based iterative method. Then, dynamic tests were performed for one typical curved steel-concrete composite cable-stayed bridge as the key case study. A highly refined finite element model of the bridge was developed and then calibrated based on the aforementioned methods in reference to the experimental results. Finally, the dynamic behavior of the curved steel-concrete composite cable-stayed bridge was studied based on the model. It is found that the solution accuracy of the finite element model can be improved significantly by employing the structural health monitoring technique. Moreover, by using the iterative method, the solutions of the updating parameters are generally more accurate compared with the solutions of the direct method. Nevertheless, when the appropriate choices are made for the algorithmic parameters, both methods can lead to the updated models with satisfactory numerical analysis results as compared to the experimental data
Experimental study on joint resistance and failure modes of concrete filled steel tubular (CFST) truss girders
No full textConcrete Filled Steel Tubular (CFST) structures are increasingly used not only for columns in tall buildings but also in the arch trusses of many arch bridges and in the truss girders of buildings and bridge decks. Therefore, the chords of Circular Hollow Section (CHS) truss arches and girders are increasingly filled with concrete, effectively making them CFST structures. In addition to the strength and stiffness of the CFST members, the failure mode of the CFST joint connecting them to the tubular member is also affected by the concrete filling. In this study, truss girders with different web arrangements were tested, and their behaviour investigated. The girders were not slender because they were designed to attain the peak limiting state for joint failure rather than chord failure due to bending moments. Moreover, two other types of girders were tested: one without concrete-filled chords (CHS girder) and another with only the upper chord filled with concrete; thus allowing an investigation of how a concrete-filled chord affects joint failure mode. The geometry of the CHS girder joints was such that only chord face failure and punching shear failure could occur. The former required an inward deformation that was prevented by the concrete filling in a CFST girder with similar geometry. Finally, the study considers extending the Eurocode 3 and the AWS D1.1 code formulae, originally proposed for CHS joints, to calculate the resistance of CFST joints
Numerical simulation and simplified calculation of the effective slab width for composite cable-stayed bridges
No full textWith the advent of progressively large and complex structures, the simultaneous presence of axial forces and bending on bridge decks is emerging as a recurring and increasingly concerning phenomenon. In the design of steel–concrete composite cable-stayed bridges, the combination of the axial force, mainly induced by the inclination of the cables, and bending is being increasingly considered to realize long spans that can bear the weight of the structure while ensuring a high rigidity of the deck. Despite its importance, this aspect is not sufficiently treated in the design codes, e.g., Eurocode specifications do not consider the axial force and its shear lag effects; therefore, the design rules are specified exclusively for the case of bending. From a practical standpoint, this deficiency can entail design complications due to the use of complicated FE models (shell and brick elements), which incur significant computational loads and design effort. In this study, a simple methodology for the design and verification of a girder composite deck subjected to combined compression and bending is developed. The methodology is based on a parametric study performed using finite element (FE) models that are valid for a generic girder composite deck. The stress distribution on the composite deck can be assessed while accounting for the axial force and bending moments associated with the deck by considering the results obtained using universal beam models. The proposed methodology is applied to an existing cable-stayed bridge
Curved shell-supported footbridges
No full textAfter Maillart's curved bridges, the improved building technologies in structural concrete and steel work led designers to realize different typologies of curved bridges. Jörg Schlaich's contribution in the design of curved bridges has been fundamental, through developing different typologies of suspended and cable-stayed curved bridges. In the '60s of the past century, Sergio Musmeci gave another innovative contribution to bridge design, by shaping shell supported bridges with minimal shell surface, and finally realizing the Basento Bridge in Potenza, Italy, a concrete shell bridge considered as his masterpiece. Accounting for Schlaich's and Musmeci's work on, respectively, curved and shell bridges, a curved footbridge supported by an anticlastic concrete shell with minimal surface is herein studied. The influence of the boundary conditions on bridge shape, and the advantages of prestressing the ring girder supporting the cantilevered deck are studied
Static behaviour of a prestressed stone arch footbridge
No full textA twin-arch rib footbridge constructed with innovative use of prestressed stone ashlars is designed and its static behavior is investigated by finite element method. Through FE spatial and plane models, general deformation modes, contact-sliding behavior of the interface between stone element and mortar layer, as well as stresses in the stone arch ribs under crowd load are investigated. It is revealed that FE plane model can accurately analyze the bridge's general deformation. Conversely, from the analysis of FE spatial models, no separation or sliding between stone element and mortar layer has been found under critical load cases. Moreover, stress control in the different materials is also achieved. Finally, both geometry and structural layout of the new-type structure are technologically feasible
Curved deck arch bridges supported by an inclined arch
No full textCurved arch bridges with curved deck supported by an inclined arch either through web members or without are studied. Reference to shell-supported bridges is first made. It must be taken into account that even if the deck is supported by a shell, its bottom free edge (usually stiffened) is described by a thrust line, so that the shell connects the curved deck (that is a horizontal arch) with an inclined 3D funicular arch. A limit case is that the ring girder of the curved deck and the funicular arch merge dividing the shell into two parts, so that, if shell thickness tends to zero, no shell connects them. This is the case of curved bridges supported only at mid-span by an inclined arch. The efficiency of different arches is compared. Moreover, the deck can be supported not only at mid-span but also by web members connecting deck girder and inclined arch. In this latter case, the most appropriate form of the inclined arch is obtained
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