1,721,001 research outputs found
Vibration Assessment of FRP Composite Pedestrian Bridges.
Full text linkFibre reinforced polymers (FRP) are gaining momentum in bridge engineering applications, particularly where lower weight and ease of installation are important factors. Due to their reduced weight, special attention needs to be paid to dynamic behaviour and the human-structure interaction. This research investigates the vibration performance of a recently constructed FRP suspension footbridge. Initially, the bridge was analysed using FE modelling, followed by field testing which provided measurements for the frequencies, mode shapes and damping, as well as for the dynamic response induced by pedestrians. The experimental modal data were subsequently used to calibrate the FE models. The results provided information about the vibration characteristics of such bridges and better understanding regarding specific FE modelling aspects. Subsequently, this research investigated how damage affects the vibration characteristics of FRP bridges and whether it is possible to identify its location. Two GFRP beams were progressively bonded using strap joints to simulate gradual degradation of the joints. Damage assessment was carried out through specialised damage identification techniques (DIT) that utilise modal data. In addition, the calibrated FE bridge models were used to undertake a damage assessment of the structure. Several possible damage scenarios that cannot be identified by visual inspection were simulated numerically. The results showed that only certain types of damage can have a significant effect on the structure’s modal properties. However, the application of DIT was generally successful in identifying the presence and in most cases the location of damage
Assessment of debonding in gfrp joints using damage identification techniques
No full textPultruded sections are used in many different civil engineering applications involving FRP composites, including a number of footbridges. These sections are typically joined through adhesive bonding and/or mechanical interlock. The joint is clearly critical to load transfer and the avoidance of unintended failure modes. As a contribution towards studying damage identification and assessment in FRP joints, this paper examines the dynamic performance of bonded GFRP pultruded sections. Experimental testing and FE modelling were employed to model damage in the joints and to assess whether debonding can be detected through differences in the dynamic characteristics - namely frequencies and mode shapes - of the components. Debonding in the joints was simulated by progressively reducing their bonded area. Four damage identification techniques (based on modal curvature, flexibility, damage index and the curvature of the flexibility-based uniform load surface) were used to assess damage. The results show that significant damage has to be present before debonding can be identified through changes in resonant frequencies and mode shapes. Once such levels are present, damage identification techniques can be applied effectively to locate damage. It is concluded that vibration-based damage assessment methods should be used in conjunction with other non-destructive evaluation techniques
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
Compressive properties of granular foams of adhesively bonded steel hollow sphere blocks
Full text linkSteel hollow spheres adhesively bonded together as a granular composite metal foam, is a special type of porous metal that aims to combine low weight, with ductility and energy absorption. Hollow spheres comprising steel foam shells were coated with a thermally activated epoxy in order to form different specimen geometries upon moulding and curing. The collapse propagation and energy absorption of steel hollow sphere blocks, comprising spheres of different sizes, was investigated experimentally, quantifying quasi-elastic and nonlinear properties of the steel hollow sphere assemblies in compression and comparing them with analytical and semi-empirical rules based on porous metal density and sphere packing. The results identify the initiation and nature of damage and highlight the merits of the material in absorbing high compressive deformations without significant loss of integrity
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
Integration of Probabilistic Effectiveness with a Two-stage Genetic Algorithm Methodology to Develop Optimum Maintenance Strategies for Bridges
No full textreventative Maintenance (PM) measures can be used to postpone/delay the initiation of corrosion from chloride attack in reinforced concrete bridges. However there are a lot of uncertainties that influence their degree of effectiveness. Also the time-application of these measures can raise a conflict between safety requirements and budgets. This paper presents a stochastic approach for estimating the effectiveness of different PM measures. Additionally a two-stage optimisation methodology using the principles of Genetic Algorithms (GA) is developed to address the problem of the timeapplication by linking the effectiveness with the cost to produce optimum PM strategies. Futhermore, the role of the presented time-dependent probabilistic approach in the proposed two-stage GA methodology for obtaining optimum PM strategies is demonstrated
- …
