| 1. |
- Bagge, Niklas, 1987-, et al.
(författare)
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Assessment of concrete bridges - Structural capacity : Experiences from full-scale testing to failure of a bridge in Kiruna
- 2017
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Ingår i: Proceedings of the 23rd Nordic Concrete Research Symposium, Oslo, Norway: Nordic Concrete Federation. - Oslo : Nordic Concrete Federation. ; , s. 263-266
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Konferensbidrag (refereegranskat)abstract
- To calibrate methods for condition assessment of prestressed concrete (PC) bridges, tests were carried out on a 55 year old five-span bridge with a length of 121 m in Kiruna in northern Sweden. Both non-destructive and destructive full-scale tests were performed. This paper presents results regarding methods for assessment of the structural capacity of concrete bridges.
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| 2. |
- Bagge, Niklas, 1987-, et al.
(författare)
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Full Scale Test of a PC Bridge to Calibrate Assessment Methods
- 2021
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Ingår i: IABSE Congress Ghent 2021. - Zurich, Switzerland : International Association for Bridge and Structural Engineering (IABSE). ; , s. 965-973
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Konferensbidrag (refereegranskat)abstract
- In this paper, experiences on the development of an assessment method for existing bridges are presented. The method is calibrated using the results of full-scale testing to failure of a prestressed bridge in Sweden. To evaluate the key parameters for the structural response, measured by deflections, strains in tendons and stirrups and crack openings, a sensitivity study based on the concept of fractional factorial design is incorporated to the assessment. Results showed that the most significant parameters are related to the tensile properties of the concrete (tensile strength and fracture energy) and the boundary conditions. A finite element (FE) model in which the results of the sensitivity analysis were applied, was able to predict accurately the load-carrying capacity of the bridge and its failure mode. Two additional existing prestressed concrete bridges, that will be used to improve further the method, are also described, and discussed.
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| 3. |
- Chen, Shiwei, et al.
(författare)
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Concrete Construction : How to Explore Environmental and Economic Sustainability in Cold Climates
- 2020
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Ingår i: Sustainability. - : MDPI. - 2071-1050. ; 12:9
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Tidskriftsartikel (refereegranskat)abstract
- In many cold regions around the world, such as northern China and the Nordic countries,on‐site concrete is often cured in cold weather conditions. To protect the concrete from freezing or excessively long maturation during the hardening process, contractors use curing measures. Different types of curing measures have different effects on construction duration, cost, and greenhouse gas emissions. Thus, to maximize their sustainability and financial benefits, contractors need to select the appropriate curing measures against different weather conditions. However, there is still a lack of efficient decision support tools for selecting the optimal curing measures, considering the temperature conditions and effects on construction performance. Therefore, the aim of this study was to develop a Modeling‐Automation‐Decision Support (MADS) framework and tool to help contractors select curing measures to optimize performance in terms of duration, cost, and CO2 emissions under prevailing temperatures. The developed framework combines a concrete maturity analysis (CMA) tool, a discrete event simulation (DES), and a decision support module to select the best curing measures. The CMA tool calculates the duration of concrete curing needed to reach the required strength, based on the chosen curing measures and anticipated weather conditions. The DES simulates all construction activities to provide input for the CMA and uses the CMA results to evaluate construction performance. To analyze the effectiveness of the proposed framework, a software prototype was developed and tested on a case study in Sweden. The results show that the developed framework can efficiently propose solutions that significantlyreduce curing duration and CO2 emissions.
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| 4. |
- Duvnjak, Ivan, et al.
(författare)
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Lessons Learnt from Full-Scale Tests of Bridges in Croatia and Sweden
- 2018
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Ingår i: IABSE Symposium, Nantes 2018. - : International Association for Bridge and Structural Engineering. - 9783857481611 ; , s. S23-127-S23-134
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Konferensbidrag (refereegranskat)abstract
- Load testing is a way to control the capacity and function of a bridge. Methods and recommendations for load testing are described and examples are given form tests carried out in Croatia and Sweden. In order not to damage the bridge being tested, the load must be limited, often to be within the serviceability limit state (SLS). Numerical models can be calibrated by load tests and then be used to check the carrying capacity for higher loads than what has been tested. Need for further work and recommendations are discussed. By effective planning, costs can be saved and a more sustainable use of bridges can be obtained.
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| 5. |
- Elfgren, Lennart, 1942-, et al.
(författare)
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Load-testing used for quality control of bridges
- 2018
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Ingår i: Quality Specifications for Roadway Bridges. ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Load testing is a way to control the capacity and function of a bridge. Methods and recommendations for load testing are described and examples are given form tests carried out. In order not to damage the bridge being tested, the load must be limited, often to be within the serviceability limit state (SLS). Numerical models can be calibrated by load tests and then be used to check the carrying capacity for higher loads than what has been tested. Need for further work and recommendations are discussed. By effective planning costs can be saved and a more sustainable use of bridges can be obtained.
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| 6. |
- Gamil, Yaser, et al.
(författare)
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Lateral Formwork Pressure for Self-Compacting Concrete—A Review of Prediction Models and Monitoring Technologies
- 2021
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 14:16
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Forskningsöversikt (refereegranskat)abstract
- The maximum amount of lateral formwork pressure exerted by self-compacting concrete is essential to design a technically correct, cost-effective, safe, and robust formwork. A common practice of designing formwork is primarily based on using the hydrostatic pressure. However, several studies have proven that the maximum pressure is lower, thus potentially enabling a reduction in the cost of formwork by, for example, optimizing the casting rate. This article reviews the current knowledge regarding formwork pressure, parameters affecting the maximum pressure, prediction models, monitoring technologies and test setups. The currently used pressure predicting models require further improvement to consider several pressures influencing parameters, including parameters related to fresh and mature material properties, mix design and casting methods. This study found that the maximum pressure is significantly affected by the concretes’ structural build-up at rest, which depends on concrete rheology, temperature, hydration rate and setting time. The review indicates a need for more in-depth studies.
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| 7. |
- Huang, Zheng, et al.
(författare)
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Validation of a numerical method for predicting shear deformation of reinforced concrete beams
- 2019
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Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 197
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper is to validate a 2D nonlinear finite element (FE) model for estimating the post-cracking shear deformation of reinforced concrete (RC) beams. The proposed FE model treated the cracked concrete as an orthotropic material in the framework of the fixed-crack approach. The experimental data for both the overall response (including the total and shear-induced deflection) and the detailed response (including the mean shear strain, mean vertical strain and principal compressive strain angle) of five I-section RC beams, monitored by the main authors of this paper with the Digital Image Correlation technique, were used to verify the proposed model. In addition, 27 further test beams evaluated in independent research programs were collected to assemble a database. The proposed FE model was further verified against the database. Two additional FE models (the rotating-crack model developed in this work and Response-2000 developed by Bentz (2000)) were also evaluated by simulating the detailed responses of the beams in the database. The results obtained validate the proposed FE model for predicting the post-cracking shear deformation of RC beams and indicate that the proposed FE model is more suitable for simulating the shear behaviour of RC beams than the rotating-crack model or Response-2000.
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| 8. |
- Häggström, Jens, et al.
(författare)
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Testing Bridges to Failure : Experiences
- 2017
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Ingår i: IABSE Symposium, Vancouver, 2017. - Zürich, Switzerland : IABSE - International Association for Bridges and Structural Engineering. - 9783857481536 ; , s. 2832-2839
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Konferensbidrag (refereegranskat)abstract
- Four bridges of different types have been tested to failure and the results have been compared to the load-carrying capacity calculated using standard code models and advanced numerical methods. The results may help to make accurate assessments of similar existing bridges. Here it is necessary to know the real behaviour, weak points, and to be able to model the load-carrying capacity in a correct way.The four bridges were: (1) a one span steel truss railway bridge; (2) a two span strengthened concrete trough railway bridge; (3) a one span concrete trough bridge tested in fatigue; and (4) a five span prestressed concrete road bridge.The unique results in the paper are the experiences of the real failure types, the robustness/weakness of the bridges, and the accuracy of different codes and models.
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| 9. |
- Najeh, Taoufik, et al.
(författare)
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Forecasting maximum formwork pressure for self-compacting concrete using ARX-Laguerre machine learning model
- 2024
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Ingår i: Developments in the Built Environment. - : Elsevier. - 2666-1659. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Forecasting the maximum pressure exerted by cast-in-place self-compacting concrete (SCC) is a major concern for formwork designers, researchers, and site engineers to accurately design the bearing capacity of the formwork and control the casting rate for safe and fast construction. This article aims to utilize the ARX-Laguerre model, which is a data-driven model to forecast the maximum form pressure. A laboratory instrumented setup was used to cast a 2-m column using SCC made with two different types of cement. A pressure system consisting of four sensors was used to document the pressure during casting. The data were sent to the cloud at every 1-min interval for real-time monitoring. The data were used to develop the model. The results demonstrated that forecasting with the ARX-Laguerre model is highly accurate. The model can forecast the maximum pressure exerted by SCC with less complexity. The model performance was also found to be consistent with insignificant differences between actual experimental results and predicted results. With a recursive and straightforward representation, the resulting model, known as the ARX-Laguerre model, ensures the parameter number reduction. Providing fast prediction of the maximum pressure. The model enables formwork designers to forecast the form pressure to design safe formwork and also helps to control the casting rate when SCC is used.
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| 10. |
- Nilforoush, Rasoul, et al.
(författare)
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Fracture energy of concrete for bridge assessment
- 2020
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Ingår i: 1st IABSE Online Symposium 2020. - : International Association for Bridge and Structural Engineering (IABSE). ; , s. 692-699
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Konferensbidrag (refereegranskat)abstract
- In numerical assessments of concrete bridges, the value of the concrete fracture energy GF plays an important role. However, mostly the fracture energy is only estimated based on the concrete compressive strength using empirical formulae. In order to study methods to determine the concrete fracture energy for existing bridges, tests were carried out on 55-year-old concrete from a bridge tested to failure in Kiruna in northern Sweden. Uniaxial tensile tests are performed on notched cylindrical concrete cores drilled out from this and other bridges. In the paper, different methods to determine the concrete fracture energy are discussed and recommendations are given for assessment procedures.
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| 11. |
- Nilimaa, Jonny, 1986-, et al.
(författare)
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An Overview of Smart Materials and Technologies for Concrete Construction in Cold Weather
- 2023
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Ingår i: Eng. - : MDPI. - 2673-4117. ; 4:2, s. 1550-1580
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Forskningsöversikt (refereegranskat)abstract
- Cold weather conditions pose significant challenges to the performance and durability of concrete materials, construction processes, and structures. This paper aims to provide a comprehensive overview of the material-related challenges in cold weather concrete construction, including slow setting, reduced curing rate, and slower strength development, as well as frost damage, early freezing, and freeze–thaw actions. Various innovative materials and technologies may be implemented to address these challenges, such as optimizing the concrete mix proportions, chemical admixtures, supplementary cementitious materials, and advanced construction techniques. The paper also examines the impact of weather-related challenges for personnel, equipment, and machinery in cold environments and highlights the importance of effective planning, communication, and management strategies. Results indicate that the successful implementation of appropriate strategies can mitigate the challenges, reduce construction time, and enhance the performance, durability, and sustainability of concrete structures in cold and freezing temperatures. The paper emphasizes the importance of staying updated about the latest advancements and best practices in the field. Future trends include the development of smart and functional concrete materials, advanced manufacturing and construction techniques, integrated design, and optimization of tools, all with a strong focus on sustainability and resilience.
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| 12. |
- Nilimaa, Jonny, 1986-, et al.
(författare)
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Assessment and Loading to Failure of Three Swedish RC Bridges
- 2018
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Ingår i: Evaluation of Concrete Bridge Behavior through Load Testing. - Faarmington Hills, MI : American Concrete Institute. - 9781641950077 ; , s. 8.1-8.18
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Bokkapitel (refereegranskat)abstract
- Current codes often underestimate the capacity of existing bridges. The purpose of the tests presented here has been to assess the real behaviour and capacity of three types of bridges in order to be able to utilize them in a more efficient way.The three studied bridges are: (1) Lautajokk – A one-span trough bridge tested in fatigue to check the shear capacity of the section between the slab and the girders; (2) Övik – A two span trough bridge strengthened with Near Surface Mounted Reinforcement (NSMR) of Carbon Fibre Reinforced Polymers (CFRP) tested in bending, shear and torsion; and (3) Kiruna – A five-span prestressed three girder bridge tested to shear-bending failures in the girders and in the slab.The failure capacities were considerably higher than what the code methods indicated. With calibrated and stepwise refined finite element models, it was possible to capture the real behaviour of the bridges. The experiences and methods may be useful in assessment and better use of other bridges.
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| 13. |
- Nilimaa, Jonny, 1986-, et al.
(författare)
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Formwork Engineering for Sustainable Concrete Construction
- 2023
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Ingår i: CivilEng. - : MDPI. - 2673-4109. ; 4:4, s. 1098-1120
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Tidskriftsartikel (refereegranskat)abstract
- This study provides a comprehensive review of the engineering challenges of formwork in concrete construction. The paper investigates different formwork systems, their design based on form pressure, and the difficulties of form stripping. Alternative binders are gaining more and more interest by opening new opportunities for sustainable concrete materials and their impact on form pressure and concrete setting is also investigated in this paper. The discussion involves several engineering challenges such as sustainability, safety, and economy, while it also explores previous case studies, and discusses future trends in formwork design. The findings pinpoint that choosing an appropriate formwork system depends significantly on project-specific constraints and that the development of innovative materials and technologies presents significant benefits but also new challenges, including the need for training and regulation. Current trends in formwork design and use show promising possibilities for the integration of digital technologies and the development of sustainable and ‘smart’ formwork systems. Continued research within the field has the possibility to explore new formwork materials and technologies, which will contribute to the implementation of more effective and sustainable practices in concrete construction.
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| 14. |
- Nilimaa, Jonny, 1986-
(författare)
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Lateral form pressure induced by SCC
- 2022
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Ingår i: 24th NCR Symposium Proceedings. - : Nordic Concrete Federation.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the results from a pilot study regarding lateral form pressure induced by self-compacting concrete (SCC). Three forms were filled with different types of SCC and the form pressure was monitored by pressure sensors, installed in holes through the plywood form. The study showed that the lateral pressure directly after filling is close to the hydrostatic pressure and that the pressure reduces at a faster rate for SCCs with lower initial slump flow.
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| 15. |
- Nilimaa, Jonny, 1986-, et al.
(författare)
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Material and Environmental Aspects of Concrete Flooring in Cold Climate
- 2023
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Ingår i: Construction Materials. - : MDPI. - 2673-7108. ; 3:2, s. 180-201
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Tidskriftsartikel (refereegranskat)abstract
- Dehydration of concrete floor slabs is a critical step to ensure that the flooring material adheres properly and that there is no moisture-related damage to the floor after installation. Dehydration in a cold climate is often a slow process, which can have a big impact on the overall duration of the construction project, and corresponding measures are often taken to accelerate the drying process, especially in constructions exposed to a cold climate. One common method, typically used to accelerate dehydration in cold weather, is to introduce internal heating cables into the slab. This method reduces the dehydration time, but may not be the best solution from a sustainability perspective. This paper presents a concept study of concrete flooring in a cold climate from a cradle to practical completion perspective. The study focused on the environmental and material aspects of the dehydration of concrete floors in a cast-in-place house. This paper showed that concretes with high water-cement ratios, which are typically preferred due to their low CO2 emissions, may require measures for accelerated dehydration, which ultimately results in a higher environmental impact. The importance of environmental studies is also highlighted to fully understand the environmental aspects of construction.
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| 16. |
- Nilimaa, Jonny, 1986-
(författare)
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New Examination Approach for Real-World Creativity and Problem-Solving Skills in Mathematics
- 2023
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Ingår i: Trends in Higher Education. - : MDPI. - 2813-4346. ; 2:3, s. 477-495
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new and innovative examination method designed to foster creativity, problem-solving, and collaboration in mathematics education. Traditional assessment practices often focus on rote memorization and fail to engage students in the exploration of mathematical concepts and connect the content to real-world problems. In contrast, the proposed examination approach requires students to invent and solve their own mathematical tasks based on their personal interests and experiences. By actively engaging with mathematical concepts and relationships, students deepen their understanding while developing essential skills such as communication, self-assessment, and peer feedback. Anonymized peer correction is also introduced as a means of minimizing bias and promoting objectivity and a wider understanding. The study investigates student perceptions of the examination based on their experiences regarding its effects on creativity and problem-solving skills. The findings suggest that the new way of examining may not only enhance students’ mathematical understanding and problem-solving abilities but also foster a collaborative learning environment that encourages communication and peer support. The paper concludes that the adoption of this new method has the potential to transform traditional assessment practices and promote more engaged, creative, and collaborative learning experiences for students in a wide range of subjects.
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| 17. |
- Nilimaa, Jonny, 1986-, et al.
(författare)
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Testing to Failure of a 55-year-old Prestressed Concrete Bridge in Kiruna : Bending, Shear and Punching of Girders and Slab. Fracture Properties of Materials. Test Results, Modelling and Assessment. Final Report BBT 2017-030
- 2020
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Rapport (refereegranskat)abstract
- Results are presented from the testing to failure of a 55-year-old prestressed concrete bridge with five continuous spans and a total length of 121.5 m. The bridge was situated in Kiruna in northern Sweden. Results are given from load, deflection and strain measurements during bending-shear tests of the girders and from a punching test of the slab. The testing was carried out in June 2014.Extensive assessment and modelling of the bridge with finite element methods have taken place and is summarized. The strength of the bridge was much higher than what could be found with ordinary code methods. The advanced non-linear models were, after calibration, able to predict the behaviour in a good way.In numerical assessments of concrete bridges, the value of the concrete tensile strength fct and the fracture energy GF plays an important role. However, mostly these properties are only estimated based on the concrete compressive strength using empirical formulae. In order to study methods to determine the concrete tensile strength and fracture energy for existing bridges, tests were carried out in 2019 on notched cylindrical concrete cores drilled out from the Kiruna Bridge. Different methods to determine the concrete fracture energy are discussed and recommendations are given for assessment procedures.
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| 18. |
- Nilimaa, Jonny, 1986-, et al.
(författare)
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Uniaxial tensile test method for cylindrical concrete cores from existing structures
- 2022
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Ingår i: 24th NCR Symposium Proceedings. - : Nordic Concrete Federation.
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Konferensbidrag (refereegranskat)abstract
- A method for direct tensile tests on cylindrical concrete cores from existing structures was developed at Luleå University of Technology and the method was tested on concrete from a 55 year old bridge from northern Sweden. The tests showed that the tensile strength of the concrete could be upgraded to a higher value.
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| 19. |
- Nilimaa, Jonny, 1986-, et al.
(författare)
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Validation of the Swedish Crack Risk Estimation Models
- 2017
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Ingår i: Proceedings of the 23rd Nordic Concrete Research Symposium. - Oslo : Nordic Concrete Federation. - 9788282080569 ; , s. 321-324
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Konferensbidrag (refereegranskat)abstract
- Thermal cracking may occur during the early hardening process of concrete as a result of the exothermic reactions between water and cement. An approach for thermal crack risk estimation and prevention was introduced in the Swedish design guidelines BRO 94. This paper studies and validates the current safety levels existing concrete structures. Three slab-frame structures were analysed and the preliminary crack risk estimations were compared to the actual cracking and post-estimations were carried out, using actual parameters. This paper shows that all the studied walls with a strain ratio over 70% were affected by thermal cracks.
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| 20. |
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| 21. |
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| 22. |
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| 23. |
- Shu, Jiangpeng, 1987, et al.
(författare)
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Field Destructive Testing of a Reinforced Concrete Bridge Deck Slab
- 2020
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Ingår i: Journal of Bridge Engineering. - : American Society of Civil Engineers (ASCE). - 1084-0702 .- 1943-5592. ; 25:9
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Tidskriftsartikel (refereegranskat)abstract
- Many bridge deck slabs in Europe are rated insufficient load-carrying capacity in shear and punching according to the Eurocodes. In the past, assessment models have mainly been developed from laboratory studies that simplified real-world conditions. Large-scale or full-scale field experiments are needed to validate more recent improved models. The goal of this study is to calibrate improved models using data obtained from a full-scale bridge deck slab shear test; the objective is to exploit and share our findings and to make recommendations for the planning, design, and implementation of such a complex experiment. Full-scale destructive tests of a 55-year-old reinforced concrete bridge deck slab on prestressed concrete girders were conducted to calibrate a model used to assess existing bridges. Concrete properties were also tested to evaluate the condition of the bridge. Results show that both the load-carrying capacity of the bridge deck slab and the strength of the concrete were much greater than were assumed in design. Finite-element analysis of the parameters governing loading positions and prestress in the girders showed that arch action and boundary condition simplification had important effects on shear distribution.
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| 24. |
- Täljsten, Björn, 1961-, et al.
(författare)
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Bridges tested to failure in Sweden
- 2018
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Ingår i: IABSE Conference Copenhagen 2018. - : International Association for Bridge and Structural Engineering (IABSE). ; , s. 64-70
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Konferensbidrag (refereegranskat)abstract
- Five bridges of different types have been tested to failure and the results have been compared to analyses of the load-carrying capacity using standard code models and advanced numerical methods. The results may help to make accurate assessments of similar existing bridges. There it is necessary to know the real behaviour, weak points, and to be able to model the load-carrying capacity in a correct way.The five bridges were: (1) a strengthened one span concrete road bridge - Stora Höga ; (2) a one span concrete rail trough bridge loaded in fatigue – Lautajokk; (3) a two span strengthened concrete trough railway bridge - Övik; (4) a one span railway steel truss bridge -Åby; and (5) a five span prestressed concrete road bridge - Kiruna. The unique results in the paper are the experiences of the real failure types, the robustness/weakness of the bridges, and the accuracy and shortcomings/potentials of different codes and models for safety assessment of existing structures
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| 25. |
- Zhaka, Vasiola, et al.
(författare)
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Observations of Snow–Slush–Snow Ice Transformation and Properties of Brash Ice in Ship Channels
- 2023
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Ingår i: Water. - : MDPI. - 2073-4441. ; 15:13
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Tidskriftsartikel (refereegranskat)abstract
- The thickness and properties of brash ice are usually compared with the properties of the surrounding level ice. The differences between these ice types are important to understand since the consolidated brash ice layer is typically assumed to have the same properties as level ice. Therefore, significant effort in the measurement campaign during the winters of 2020–2021, 2021–2022, and 2023 was made to develop a better understanding of the full-scale brash ice channel development. The channels were located near the shore in the Bay of Bothnia, Luleå, Sweden. The main parameters investigated were the snow, slush, and total ice thicknesses, including ice formed from freezing water and from freezing slush as well as the ice microstructure and strength. To our knowledge, this is the first paper to report the influence of snow in brash ice channels. It was observed that a significant amount of snow covered the brash ice channels between the ship passages. After each ship passage, the snow was submerged and formed slush-filled voids, which thereafter transformed into snow ice (SI) clusters frozen together with columnar ice. The SI content in the brash ice and side ridges was estimated from image analyses. The analyses showed that the snow ice content was 73% in level ice in the vicinity of the ship channel, 58% in the side ridges of the channel, and 21% in the middle of the test channel, whereas in the main channel, the SI contents were 54%, 43%, and 41% in each location, respectively.
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| 26. |
- Zhaka, Vasiola, et al.
(författare)
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Physical and mechanical properties of brash ice in Luleå Harbour
- 2023
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Ingår i: Proceedings of the 27th International Conference on Port and Ocean Engineering under Arctic Conditions. - : Port and Ocean Engineering under Arctic Conditions.
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Konferensbidrag (refereegranskat)abstract
- Brash ice forms when vessels navigate in level ice breaking it, and subsequently along the same track breaking the partly or fully consolidated broken ice field. The formation and growth of brash ice can be rapid and present a hazard for shipping operations, often requiring icebreaker assistance. Compared to other deformed ice structures such as pressure ridges, the physical and mechanical properties of the brash ice formed in heavily navigated harbours or ship channels have not been studied much. In the current study, individual brash ice pieces were sampled from two different harbours in Luleå, Sweden, in March 2020 and March 2021. The brash ice piece size distribution, the compressive strength of individual ice pieces, density, microporosity, and microstructure were measured. The brash ice piece size followed a three-parameter log-normal distribution. The brash ice samples collected in the first year (2020) hada microstructure similar to level ice while the ice pieces collected in the second year (2021) had a mixed microstructure (columnar and granular) similar to deformed ice. For an increase in strain rates from 10-5 s-1 to 10-3 s-1, the maximum strength increased when the brash ice samples were exposed to cyclic loading. The maximum strength was not significantly different between the different locations.
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| 27. |
- Zhaka, Vasiola, 1992-, et al.
(författare)
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Snow effects on brash ice and level ice growth
- 2024
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Ingår i: Journal of Glaciology. - : Cambridge University Press. - 0022-1430 .- 1727-5652.
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Tidskriftsartikel (refereegranskat)abstract
- Brash ice formation and accumulation occur at a faster rate in ship channels, harbours and turning areas compared to the surrounding level ice. Accurate prediction of brash ice thickness plays an important role in addressing operational challenges and optimisation of ice management strategies. This study enhances existing brash ice growth models by considering the effects of snow and accounting for brash ice expulsion towards the sides of ship channels at each passage. To validate the influence of these critical factors on brash ice thickness, three distinct ship channels located in the Bay of Bothnia, Luleå, Sweden, were investigated. For two test channels formed for study purposes, the slower growth rate of brash ice caused by snow insulation was more prominent than the brash ice growth acceleration caused by the snow–slush–snow ice transformation. In the third channel characterised by frequent navigation, the transformation of slush into snow ice played a more substantial role than snow insulation. In both test channels, the brash ice growth model performed optimally, assuming a 10% expulsion of brash ice sideways at each vessel passage. In the third, wider and more frequently navigated channel, a 1.2% brash ice expelling coefficient predicted well the measured brash ice thicknesses.
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