1,720,996 research outputs found
Prediction of Early Age Cracking of Steel-Concrete Composite Beams in Partial Interaction
No full textHydration heat and shrinkage of concrete at early age can be responsible for cracking phenomena developing in steel-concrete composite beams. Predicting these phenomena is a rather difficult task, as material properties and the actual interaction between the concrete slab and the steel profile evolve in time. Moreover, few contributions are actually available in the scientific literature and the recom-mendations adopted by design codes are generally simplistic. Therefore, this work deals with de-termining the time evolution of stresses and strengths in concrete at early age. Two different ap-proaches assuming either full or partial interaction between the concrete slab and the steel profile are considered. The results obtained by applying the two alternative approaches to a steel-concrete com-posite bridge assumed as a case-study are finally compared and discusse
EVALUATION OF FRAGILITY OF INFILLED FRAME STRUCTURES SUBJECT AFTERSHOCKS BY MEANS OF DOUBLE INCREMENTAL DYNAMIC ANALYSIS APPROACH
No full textThe paper investigates the role of masonry infill walls on the seismic fragility of reinforced concrete structures
subject to mainshock/aftershock sequences. An assessment framework aimed at determining aftershock fragility
curves of bare frames and infilled frames is presented. The framework is based on a Double Incremental
Dynamic Analysis (D-IDA) approach, which provides the adoption of ground motions defined by combining a
fixed intensity mainshock with a set of variable intensity aftershocks. Mainshock (MS) intensity is scaled several
times and combined with the same set of aftershocks (AS). Chord-rotation and shear limit states are specifically
defined to consider the influence of masonry infills within frames. The OpenSees software platform is used to
carry out simulations by means of a fully fiber-section model of a reinforced concrete (RC) prototype structure.
Fragility curves and residual capacity diagrams obtained show that masonry infills can provide significant
additional capacity seismic to resist further shakings in comparison with bare frames, if reinforced concrete
members have sufficient shear resistance
Out of plane fragility of infill walls with and without prior in-plane damage
No full textThe paper presents the results of a probabilistic assessment framework aimed at evaluating out-of-plane fragility curves of infill walls which have suffered (or not) prior in-plane damage. Out-of-plane incremental dynamic analyses are performed based on a suite of 22 ground motion records. A recently developed in-plane / out-of-plane macroelement model is used to model masonry infills within frames. The outcomes show fragility curves representing the probability of exceeding out-of-plane collapse at a given earthquake intensity as a function of a different combination of geometrical and mechanical parameters, in-plane damage level and supporting conditions
Multi-axial stress sensor for structural health monitoring
Full text linkAll civil structures experience aging and deteriorate with time. To ensure structural integrity, civil structures should thus be equipped with sensors for Structural Health Monitoring (SHM) with the aim of developing automated monitoring systems and facilitate inspections for damage detection. Nowadays, optical sensors and accelerometer are mostly used for SHM [1]. However, it has been shown that stress sensors could improve the reliability of monitoring systems as well as the accuracy of damage identification [2]. Of course, these stress sensors should be low cost to be spread within the structure. MEMS technology is therefore the most promising technology. Existing MEMS stress sensors have very limited full-scale and they are unable to separate the contributions of normal and shear stresses at material-package interface.
This paper presents a multi-axial stress sensor based on thick film piezo-resistive ink [3] that is capable of measuring both the out-of-plane and the in-plane internal stresses of the structures being monitored. By decoupling the two components of stress, the sensor is insensitive with respect to the variation of the surrounding material properties and boundary/installation conditions. The proposed stress sensor consists of three layers of ceramics, two thick protection layers and a thin middle layer bonded together by means of a bonding glass. The top surface of the middle layer contains the piezo-resistive gauges that are connected to form two Wheatstone bridges: one bridge senses in-plane strains and the other one senses both in-plane and out-of-plane strains [4]. The design of the sensor and the position of the sensing elements were optimized by means of a commercial Finite Element software.
A series of prototypes were produced and tested in laboratory by means of compression tests, imposing different boundary conditions and materials, up to a compression force of 5 kN that corresponds to a normal pressure of 10 MPa. Also, the influence of working temperature was assessed. By linearly combining the two bridge outputs, the influence of boundary conditions on the compression stress component can be minimized. Inserting the sensor in standardized concrete samples having size of 15x15x15 cm the influence of inclusions close to the sensor can be also assessed. Again, the influence of inclusions on the compression stress is shown to be negligible unless the inclusion is very close to the 3D resistors
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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