1,720,999 research outputs found
Effects of structural deterioration and infrastructure upgrading on the life-cycle seismic resilience of bridge networks
No full textThe life-cycle seismic resilience of aging bridges and road transportation networks is investigated considering the long-term effects of bridge structural deterioration and network upgrading interventions under uncertainty. The proposed methodology is applied to a highway network with spatially distributed reinforced concrete (RC) bridges exposed to chloride-induced corrosion and different earthquake scenarios. A new road segment including a bridge is added over the lifetime to strengthen the network connectivity and improve the system resilience. The results show the detrimental effects of structural deterioration at the network scale and the benefits of infrastructure investments for network upgrading to enable long-term resilient infrastructures
Life-cycle resilience of deteriorating bridge networks under earthquake scenarios
No full textResilience of bridges and infrastructure networks is generally investigated considering damage and disruption caused by sudden extreme events, such as earthquakes. However, damage could also arise continuously in time due to aging and structural deterioration, which can modify over time the structural performance and functionality and, consequently, the system resilience. Therefore, for critical infrastructures exposed to seismic and environmental hazards, resilience depends on the time of occurrence of the seismic event. This paper investigates the life-cycle seismic resilience of aging infrastructures and presents a probabilistic approach to seismic assessment of deteriorating bridges and resilience analysis of road networks under prescribed earthquake scenarios. The time-variant seismic fragilities of the deteriorating bridges in the network are assessed for several limit states, from damage limitation up to collapse. The seismic demand is evaluated for each bridge based on a ground motion prediction equation in terms of earthquake magnitude and epicentral distance. The corresponding levels of seismic damage are derived from the time-variant fragilities and related to vehicle restrictions and traffic limitations. A traffic analysis is carried out over the entire road network to compute both the time-variant system functionality and life-cycle seismic resilience under prescribed post-event recovery processes. The proposed approach is applied to reinforced concrete bridges in a highway network with detour and re-entry link. The bridges are exposed to chloride-induced corrosion and earthquake scenarios considering different magnitude and epicenter location. The results show the detrimental effects of aging and structural deterioration and emphasize the role of the earthquake scenario on the time-variant seismic performance of bridge structures and life-cycle resilience of road networks
Seismic resilience of aging bridges and evolving road networks
No full textThis paper investigates the seismic resilience of aging infrastructures and presents a probabilistic approach to life-cycle seismic assessment of concrete bridges exposed to corrosion and resilience analysis of evolving road networks under prescribed earthquake scenarios. The seismic demand is evaluated for each bridge in the network based on a ground motion prediction equation in terms of earthquake magnitude and epicentral distance. The corresponding levels of seismic damage are derived from the bridge time-variant fragilities and related to vehicle restrictions and traffic limitations. Finally, a traffic analysis of the road network is carried out to compute both the time-variant system functionality and life-cycle seismic resilience under prescribed post-event recovery processes considering the evolution over time of the road network
Simulation-based seismic risk and robustness assessment of ageing bridge networks
No full textCivil infrastructure systems are prone to environmental deterioration processes that gradually reduce their mechanical properties and their capability to sustain severe natural hazards, such as earthquakes. The rate of occurrence of major seismic events, the time-variant seismic vulnerability of single bridges, and the indirect economic losses due to traffic flow redistribution related to the closure of key routes within the highway network are affected by uncertainties to be addressed by modelling their constitutive parameters as random variables and processes. This paper presents an integrated simulation-based methodology to estimate the user cost-based risk and system robustness of spatially distributed bridge networks subjected to prescribed deterioration and regional seismic hazard scenarios. Life-cycle seismic risk metrics are evaluated in terms of bridges failure rates and exceedance rates of indirect monetary losses based on free-flow traffic analysis and user cost assessment. The lifetime system robustness is also evaluated based on appropriate probabilistic performance indicators
Assessment of residual prestress in existing concrete bridges: The Kalix bridge
No full textThe direct socio-economic consequences of the deterioration of aging infrastructure systems have triggered a continuous process of revising and updating current design standards and guidelines for critical network components. Specifically, long-term degradation processes demand the analysis and evaluation of vital structural assets such as prestressed concrete bridges. It is crucial to develop theoretically consistent, user-friendly, and non-destructive methodologies that engineering professionals can employ to prevent and mitigate potential catastrophic outcomes during the service life of these bridges. This study provides a thorough review of the available testing methods employed over the years for prestressed concrete bridges and introduces a comprehensive framework for evaluating existing methods for residual prestress force assessment. Through a multi-criteria selection process, the three most feasible tests were designed and carried out on an existing 66-year-old balanced cantilever box girder bridge exposed to freezing temperatures that affected the instrumentation plan and test execution. Finally, predictive models compliant with standard codes were calibrated based on the experimental results and the life cycle loss of prestress forces was evaluated to assess relevant bounding intervals. Findings reveal limited on-site testing and discrepancies between calculated residual forces and predictions by standard codes. The saw cut method showed a 18% difference from the initial applied prestress according to the prestress protocol, suggesting the use of a cover meter and concrete modulus evaluation for improved accuracy. The strand cutting method resulted in a 14% difference, emphasizing the need for stress redistribution assessment. The second-order deflection method showed a 6% difference, indicating a focus on enhanced boundary conditions and thorough sensitivity analysis for future investigations.Validerad;2024;Nivå 2;2024-05-31 (hanlid);Funder: Interreg Aurora; Full text license: CC BY</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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