| 1. |
- Elfgren, Lennart, 1942-, et al.
(författare)
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Infrastructure in NW Russia - Potential development : A Pre-feasibility Study with Special Reference to Winter Transportation, Concrete Structures, and Timber Structures
- 2000
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In co-operation with a Finnish Group of researchers a pre-feasibility study was undertaken regarding potential development of the Infrastructure in NW Russia. Special emphasis was given: Winter Transportation and Reinforcement of Load Bearing Ice Covers; Concrete Construction and Strengthening of Concrete Structures; Timber Construction and Mechanical Wood Industry Development; and Energy Conservation and Industrial Energy Development.Based on the study three Russian-Swedish co-operation projects have started:- Load Bearing Ice Covers (Literature Survey)- Forces caused by Ice Crushing against Off-Shore Structures (EC funded Research Project)- Strengthening of a Bridge. Co-operation Stabilator/Skanska - Arkhangelsk Road
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| 2. |
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High performance concrete structures : design examples & properties
- 2000
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- The report presents examples of design calculations for high performance concrete structures. It also summarizes some of the test results and material properties in a Swedish Research Program on High Performance Concrete. The aim is to give a background to and propose characteristic material properties to be used in design of high strength concrete.
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| 3. |
- Paulsson, Björn, 1946-, et al.
(författare)
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Upgrading of infrastructure in order to meet new operation and market demands
- 2017
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Rapport (refereegranskat)abstract
- The European objective of a modal shift of freight transports to railways will require extensive upgrading of existing railway lines since very few dedicated freight railways are currently being built and existing lines were built for traffic demands at the time of construction. A transition to increased and enhanced railway freight operations can therefore be costly and complicated. To minimize negative effects, a guideline for upgrading was developed within the Capacity4Rail project. This handbook presents the major findings. In particular it outlines different upgrading possibilities and their implications, and details structured approaches to upgrading analyses. It discusses possibilities for upgrading of substructures, bridges, tunnels, and the track structure. In these areas, an overview of challenges and possibilities is presented together with examples of experience from operational upgrading. It concludes that freight line upgrading using a more streamlined approach as outlined in the guideline is a necessity if EU objectives on modal shifts in transportation are to be met. Further, it demonstrates why a political drive is necessary to increase efforts to upgrade freight lines.
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| 4. |
- Westerberg, Bo, 1942-, et al.
(författare)
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Hållfasthet
- 2021. - 3
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Ingår i: Betonghandbok Material, Del II, tredje reviderade upplagan. - Stockholm : Svensk Byggtjänst. - 9789179170882 ; , s. 27-187
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Bokkapitel (refereegranskat)abstract
- Kapitlet omfattar följande delar:14.1 Inledning14.2 Begreppet hållfasthet14.3 Faktorer som generellt påverkar hållfastheten14.4 Tryckhållfasthet14.5 Centrisk draghållfasthet14.6 Spräckhållfasthet14.7 Böjdraghållfasthet14.8 Brottmekanik14.9 Skjuvhållfasthet14.10 Slaghållfasthet14.11 Hållfasthet vid stämpellast14.12 Hållfasthetssamband14.13 Hållfasthet i färdig konstruktion14.14 Bedömning av hållfasthet i färdig konstruktion14.15 Hållfasthetens spridning14.16 Litteratur
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| 5. |
- Agredo Chávez, Angélica, et al.
(författare)
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Assessment of residual prestress in existing concrete bridges: The Kalix bridge
- 2024
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Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 311
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Tidskriftsartikel (refereegranskat)abstract
- The 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.
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| 6. |
- Agredo Chavez, Angelica Maria, et al.
(författare)
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Available Tests to evaluate Residual Prestressing Forces in Concrete Bridges
- 2022
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Ingår i: IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures - Report, International Association for Bridge and Structural Engineering. - Zurich, Switzerland : International Association for Bridge and Structural Engineering. ; , s. 1123-1131
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Konferensbidrag (refereegranskat)abstract
- The reduction of the structural capacity and eventual collapse of existing concrete bridges is often related to the loss of the initial prestressing forces. This loss can be associated to immediate or time dependent factors such as elastic shortening, creep, relaxation, loading, and cracking, among others. In addition, environmental factors can lead to corrosion of the strands with the subsequent reduction of their area, loss of bond with the concrete and additional cracking which in turn will influence the value of the residual prestress force and the bridge capacity. Therefore, the evaluation of such losses is critical in the decision-making process of defining a financial and environmental cost optimized intervention strategies (e.g., strengthening or replacement). In this paper, a detailed literature review regarding destructive and non-destructive methods for measuring the residual force in prestressed concrete bridges is carried out and used to develop a database of existing experimental tests.
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| 7. |
- Agredo Chavez, Angelica Maria, et al.
(författare)
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Cracking and Fatigue of Heavy Loaded Prestressed Concrete Bridge in Sweden
- 2022
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Ingår i: IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures - Report, International Association for Bridge and Structural Engineering. - Zürich : International Association for Bridge and Structural Engineering. ; , s. 792-799
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Konferensbidrag (refereegranskat)abstract
- A prestressed concrete bridge was built in 1963 with BBRV cables. It has three spans and a total length of 134.8 m. Due to mining activities the bridge was loaded with trucks with a total weight of 90 ton during 2012-2014 and from 2019. Crack development has been monitored manually and from 2020 with strain gauges and LVDTs.Cracks normally vary between 0.1 to 0.3 mm in width and grow in length with time. In November 2020 some of the strain gauges on the concrete showed alarming growth and the bridge was closed for traffic. Additional strain gauges were installed on vertical reinforcement bars and an assessment was carried out of the fatigue capacity of the bridge. It was found that the new strain gauges did not indicate any growth in strain and that the fatigue capacity was sufficient. The bridge could be opened again for traffic after being closed for five weeks. Monitoring drift in the strain gauges and fatigue are discussed.
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| 8. |
- Agredo Chavez, Angelica Maria, et al.
(författare)
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Data Validation of Strain-Based Monitoring Systems in Low Temperature Conditions, Case Study : The Kalix Bridge
- 2023
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Ingår i: Building for the Future: Durable, Sustainable, Resilient - Proceedings of the fib Symposium 2023 - Volume 2. - : Springer. - 9783031325106 - 9783031325113 ; , s. 986-995
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Konferensbidrag (refereegranskat)abstract
- Over the last decades, economic growth and sustained development have enforced the need to ensure reliable and long-lasting infrastructure network to guarantee serviceability and safety. Nevertheless, detrimental effects can lead over time to insufficient structural performance under increasing service loadings and extreme events. Hence, Structural Health Monitoring (SHM) arises as a solution to cope with the need of having timely and continuous data to assess the state of crucial structural assets, such as prestressed concrete bridges. On this matter, the validation of the retrieved data becomes essential for the risk-based decision making in the assessment of bridges, where selecting the most suitable monitoring system could allow to addressed main causes to the right phenomena of deterioration during the service life of the bridge. Consistently with these efforts, this paper deals with a comparative study between the data acquired by different strain-based sensors such as Fiber optic systems (FOS) and strain gauges that were installed to monitor a proof loading test developed on a 65-year-old balanced cantilever prestressed concrete bridge located in Northern Sweden. The monitored data led to establish main differences between emerging types of monitoring systems such as FOS to the well-based strain gauges when exposed to low temperature conditions. Conclusions regarding the influencing parameters between both retrieved data are drawn when evaluating the structural response under serviceability loading conditions is performed, supporting decision makers when different levels of structural assessment are required.
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| 9. |
- Agredo Chavez, Angelica Maria, et al.
(författare)
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Structural model updating of an existing concrete bridge based on load testing and monitoring data
- 2023
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Ingår i: Life-Cycle of Structures and Infrastructure Systems. - : Taylor & Francis Group. - 9781003323020 ; , s. 3999-4006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The backbone of European infrastructure was built after the end of the second World War and has reached, or is near to, the end of its nominal design life. This issue urges the development of structural assessment procedures that can provide infrastructure managers the information to make decisions for repairing, upgrading, or replacement. In this paper, a methodology based on load testing and Structural Health Monitoring (SHM) for the assessment of a 65- year-old prestressed concrete bridge located in Northern Sweden is presented. The retrieved data is used to develop and calibrate structural models with different levels of data completeness. The SHM procedure includes the evaluation of material properties by diagnostics, definition of the layout and installation of the instrumentation, test execution, and data analysis. A preliminary structural model is developed based only on the original design parameters, and it is sequentially updated with monitoring data retrieved during a performed proof loading test of the bridge.
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| 10. |
- Andersson, Emelie, et al.
(författare)
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Biogeochemical and mechanical characterization of the landfill fraction generated by mechanical waste sorting
- 2021
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Ingår i: Detritus. - : CISA Publisher. - 2611-4127 .- 2611-4135. ; 15, s. 120-135
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Tidskriftsartikel (refereegranskat)abstract
- As the resource recovery from mixed waste streams are performed, new mixed waste streams are generated. Some of these waste streams does not fit well to existing waste management options, for example, they may hold a to low heating value to sustain combustion and they may have a too high carbon content to be accepted at non-hazardous landfills. Also various health and pollution risks may arise as well as practical handling issues due to the physical properties of such wastes. One such waste is the under sieve fraction generated when recovering metals and fuel from mixed waste streams using mechanical and magnetic separation tools. Such mechanical sorting is typically used for mixed wastes of different properties and particle sizes, such as houshold bulky wastes, construction and demolition waste, and at landfill mining materials. In this work, we examine the properties of one case of mechanical sorting of bulky wastes, including construction and demolition wastes. We analyse a broad spectrum of chemical, physical, and mechanical properties as well as some biological. Based on the data we develop recommendations for landfilling, what potential problems might arise and how to counteract them.
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