1,720,958 research outputs found
A non-linear static analysis for the seismic design of single-span integral abutment bridges
No full textIntegral abutment bridges are characterised by a monolithic connection between the deck and the abutments. Because of this connection, the seismic behaviour of the entire structure tends to be controlled by its interaction with the surrounding soil, and especially with the approach embankments. To date, methods for the seismic design of this type of bridges are still characterised by substantial uncertainties, mostly because of insufficient understanding of the dynamic response of the soil-structure system. This paper provides a contribution to the interpretation of the seismic behaviour of integral abutment bridges, focusing on a single-span structural scheme that has been receiving significant attention in recent years. The dynamic interaction between the bridge and the soil is studied with global numerical models of the soil-bridge system developed in OpenSees and subjected to a variety of ground motions. The results of the dynamic simulations, interpreted also with the aid of a modal analysis of the system, are used to develop and finally validate a simplified design procedure. This procedure is based on the capacity spectrum method, aimed at evaluating the maximum deformation and internal forces in the structure produced by the longitudinal component of the seismic motion that typically dominates the design of integral bridges
Soil-structure interaction for the seismic design of integral abutment bridges: from advanced numerical modelling to simplified procedures
No full textIntegral abutment bridges are characterised by a monolithic connection between the deck and the abutments. Because of this connection, their behaviour during a seismic
event is controlled by the interaction of the entire structure with the surrounding soil, and markedly with the approach embankment. Although this is becoming a popular design solution due its low maintenance requirements, procedures for the seismic design are still characterised by substantial uncertainties, mostly because of a lack of comprehension of the dynamic response of the soil-structure system. This study provides a contribution to the interpretation of the seismic behaviour of integral abutment bridges, focusing on a single-span structural scheme type that has received significant attention in recent years. The dynamic interaction between the bridge and the soil is studied with global numerical models of the soil-bridge systems developed in OpenSees and subjected to a variety of ground motions. The results of these dynamic calculations, interpreted also with the aid of a modal analysis of the system, are used to develop simplified design procedures aimed at evaluating the deformation and the internal forces in the structure. In details, a novel seismic design approach based on a nonlinear static analysis is provided for the longitudinal component of the seismic motion, that typically dominates the design of this type of bridges. In addition, a second simplified procedure is developed to take into account the influence of the transverse component of the seismic motion as well as of the wing walls. Two-directional time-domain analyses carried out on the full soilstructure model show that these complementary procedures lead to a seismic design of these bridges without any considerable underestimation. Finally, the possibility to use an average response spectrum prescribed by technical provisions makes this approach immediately applicable to the ordinary design
On a novel seismic design approach for integral abutment bridges based on nonlinear static analysis
No full textThis paper focuses on the seismic performance and design of a single-span inte-gral abutment bridge (IAB), as a structural system characterised by a monolithic connection between deck and abutments. Although this is becoming a popular design solution due to its low maintenance requirements, there is still the need of developing robust design criteria for such structures under seismic conditions, mainly because of the complex soil-abutment-deck interaction. This study pro-poses an application of a novel design method for IABs to a reference case study inspired by a real integral bridge recently built in Italy. In the proposed method, the seismic capacity of the bridge is obtained through a nonlinear static analysis of the entire soil-structure system, in which the soil domain is perturbed by a dis-tribution of equivalent forces aimed at reproducing the effects associated with the significant modes of the bridge. This approach is validated against the results of several dynamic analyses carried out on an advanced, full soil-structure model of the reference bridge implemented in OpenSees. Several seismic scenarios are tak-en into account, as well as the possibility to use an average response spectrum prescribed by technical provisions. This study demonstrates that the proposed de-sign approach is able to reproduce quite satisfactorily the performance of the structure, in terms of maximum internal forces and displacements, with a very low computational demand
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
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
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