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  • 1.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bernspång, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering. Norut Northern Research Institute, Narvik.
    Tu, Yongming
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering. College of Civil Engineering, Southeast University, Nanjing.
    Carolin, Anders
    Trafikverket, Trafikverket, Luleå.
    Performance of a prestressed concrete bridge loaded to failure2015In: IABSE Conference Geneva 2015: Structural Engineering: Providing Solutions to Global Challenges, Geneva: International Association for Bridge and Structural Engineering, 2015, p. 1088-1095Conference paper (Other academic)
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  • 2.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Instrumentation and Full-Scale Test of a Post-Tensioned Concrete Bridge2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 51, p. 63-83Article in journal (Refereed)
    Abstract [en]

    To meet new demands, existing bridges might be in need for repair, upgrading or replacement. To assist such efforts a 55-year-old post-tensioned concrete bridge has been comprehensively tested to calibrate methods for assessing bridges more robustly. The programme included strengthening, with two systems based on carbon fibre reinforced polymers (CFRPs), failure loading of the bridge’s girders and slab, and determination of post-tension cables’ condition and the material behaviour. The complete test programme and related instrumentation are summarised, and some general results are presented. The measurements address several current uncertainties, thereby providing foundations for both assessing existing bridges’ condition more accurately and future research.

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  • 3.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sundquist, Håkan
    Royal Institute of Technology.
    Carolin, Anders
    Trafikverket, Luleå.
    Assessment and failure test of a prestressed concrete bridge2017In: Life-Cycle of Engineering Systems: Emphasis on Sustainable Civil Infrastructure / [ed] Jaap Bakker; Dan M Frangopol; Klaas van Breugel, Leiden: CRC Press/Balkema , 2017, p. 1058-1063Conference paper (Refereed)
    Abstract [en]

    Tests have been carried out at service- and ultimate load levels of a 55 year-old prestressed concrete girder bridge. The bridge, located in Kiruna, Sweden, was continuous in five spans with a total length of 121.5 m. The overall aim of the study was to determinate the accuracy of assessment methods for existing structures and to provide procedures for optimized assessment. Before the tests a 2D finite element (FE) analysis was performed to predict the behavior and load-carrying capacity of the bridge. In order to more accurately assess the bridge response a 3D FE model has now been developed. The actual loading history and material properties has been considered in the model. A Life Cycle Cost Assessment of the bridge has also been performed

  • 4.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Evaluation of residual prestress force in a concrete girder bridge2016In: IABSE CONGRESS, STOCKHOLM, 2016: Challenges in Design and Construction of an Innovativeand Sustainable Built Environment / [ed] Lennart Elfgren, Johan Jonsson, Mats Karlsson, Lahja Rydberg-Forssbeck and Britt Sigfrid, CH - 8093 Zürich, Switzerland, 2016, p. 222-229Conference paper (Refereed)
    Abstract [en]

    When assessing the structural behaviour of prestressed concrete bridges, understanding the level of prestressing is crucial. However, for existing structures, this is usually an unknown parameter and the literature only describes a few methods of experimentally determining the residual prestress forces. For this paper, a non-destructive testing approach has been evaluated based on testing of a multi-span continuous girder bridge. The method, consisting of in-situ measurements in combination with finite element (FE) simulations, revealed prestress levels in the range 25 % to 82 % of the reinforcement steel yield strength, depending on the section tested. A comparison with theoretically calculated residual prestress forces, taking into account friction and timedependent losses, indicated values of the same order but with some inconsistencies.

  • 5.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    In-situ methods to determine residual prestress forces in concrete bridges2017In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 135, p. 41-52Article in journal (Refereed)
    Abstract [en]

    Levels of residual prestress forces are key parameters when assessing the structural behaviour of existing prestressed concrete bridges. However, these parameters are often unknown and not easy to determine. To explore them, two existing non-destructive and destructive approaches have been further developed for practical application and demonstrated on a multi-span continuous girder bridge. The evaluation of the prestress forces was part of an extensive experimental programme aimed to calibrate and develop assessment methods. Due to the pursuit of practical applications for existing bridges, the main focus was on non-destructive methodology, combining experimental data and finite element modelling to obtain the residual prestress forces. Assuming that the initial prestress force corresponded to 85% of the characteristic 0.2% proof strength of the reinforcing steel, estimated losses in investigated sections ranged between 5 and 70%. However, determined residual prestress forces were generally higher than theoretically based estimates accounting for friction and time-dependent losses in the prestressing system. In addition to describing in detail the methods for prestress evaluation, this paper presents suggestions for improvements and further studies, based on experiences from the field tests.

  • 6.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Enochsson, Ola
    Sabourova, Natalia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Grip, Niklas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lundmark, Tore
    Ramböll Sverige AB, Luleå.
    Tu, Yongming
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Protecting a five span prestressed bridge against ground deformations2015In: IABSE Conference Geneva 2015: Structural Engineering: Providing Solutions to Global Challenges, Geneva: International Association for Bridge and Structural Engineering, 2015, p. 255-262Conference paper (Other academic)
    Abstract [en]

    A 55 year-old, 121.5 m long, five span prestressed bridge was situated in the deformation zone close to a mine in Kiruna in northern Sweden. There was a risk for uneven ground deformations so the bridge was analyzed and monitored. Results and measures taken to ascertain the robustness of the bridge are presented.The analysis resulted in an estimate that the bridge could sustain 24 mm in uneven horizontal and 83 mm in uneven vertical displacement of the two supports of a span. To be able to sustain larger deformations, the columns of the bridge were provided with joints, where shims could be inserted to counteract the settlements. To accomplish this, each one of the 18 columns of the bridge was unloaded by help of provisional steel supports. The column was then cut and a new foot was mounted to it. This made it possible to lift each individual column with two jacks, when needed, and to adjust its height by inserting or taking away shim plates.The deformations of the bridge and the surrounding ground were monitored. The eigenmodes of the bridge were studied with accelerometers and by analysis with finite elements (FE) models. Comparison indicated good agreement between the model and the actual bridge, with calculated eigenfrequencies of 2.17, 4.15 and 4.67 Hz, for the first transversal, vertical and torsional modes, respectively. Measurements during winter resulted in higher values due to increased stiffness caused by frozen materials.

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  • 7.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Puurula, Arto
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Carolin, Anders
    Trafikverket, Luleå.
    Full-Scale Tests to Failure Compared to Assessments: Three Concrete Bridges2018In: High Tech Concrete: Where Technology and Engineering Meet - Proceedings of the 2017 fib Symposium / [ed] Lukovic M.,Hordijk D.A., Cham: Springer, 2018, p. 1917-1924Conference paper (Refereed)
    Abstract [en]

    Three Swedish concrete bridges have been tested to failure and the results have been compared to assessment using standard code models and advanced numerical methods.

    The three tested and assessed bridges were:

    1. (1)

      Lautajokk, a 29 year old one span (7 m) concrete trough bridge tested in fatigue to check the concrete shear capacity.

       
    2. (2)

      Ӧrnskldsvik, a 50 year old two span trough bridge (12 + 12 m) strengthened to avoid a bending failure.

       
    3. (3)

      Kiruna Mine Bridge, a 55 year old five span prestressed concrete road bridge (18 + 21 + 23 + 24 + 20 m) tested in shear and bending of the beams and punching of the slab.

       

    The main 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. In all three cases the bridges had a considerable hidden capacity.

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  • 8.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. WSP Bridge & Hydraulic Design, Göteborg, Sweden.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sarmiento, Silvia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Puurula, Arto
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Savonia University of Applied Sciences, Kuopio, Finland.
    Gonzalez-Libreros, Jaime
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Carolin, Anders
    Swedish Transport Administration, Luleå, Sweden.
    Häggström, Jens
    Swedish Transport Administration, Luleå, Sweden.
    Enoksson, Ola
    Swedish Transport Administration, Luleå, Sweden.
    Coric, Ibrahim
    Swedish Transport Administration, Luleå, Sweden.
    Full Scale Test of a PC Bridge to Calibrate Assessment Methods2021In: IABSE Congress Ghent 2021: Structural Engineering for Future Societal Needs / [ed] H.H. (Bert) Snijder, Bart De Pauw, Sander van Alphen, Movares, Pierre Mengeot, International Association for Bridge and Structural Engineering (IABSE) , 2021, p. 965-973Conference paper (Refereed)
    Abstract [en]

    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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  • 9.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. WSP, Luleå, Sweden.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Norut Teknik, Norut, Norge.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Bernspång, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Carolin, Anders
    Trafikverket, Luleå.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Assessment of concrete bridges - Structural capacity: Experiences from full-scale testing to failure of a bridge in Kiruna2017In: Proceedings of the 23rd Nordic Concrete Research Symposium, Oslo, Norway: Nordic Concrete Federation, Oslo: Nordic Concrete Federation , 2017, p. 263-266Conference paper (Refereed)
    Abstract [en]

    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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  • 10.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Tu, Yongming
    College of Civil Engineering, Southeast University, Nanjing.
    Carolin, Anders
    Trafikverket.
    Loading to failure of a 55 year old prestressed concrete bridge2015In: IABSE Workshop Helsinki 2015: Safety, Robustness and Condition Assessments of Structures, Zurich: International Association for Bridge and Structural Engineering, 2015, p. 130-137Conference paper (Refereed)
    Abstract [en]

    In order to provide relevant data for calibration and development of methods for assessment ofexisting bridges, a 55 year old posttensioned concrete bridge has been subjected to non-destructiveand destructive tests. The bridge, located in Kiruna, Sweden, was a 121 m long girder bridgecontinuous in five spans. The test programme included failure loading of the girders and slab,respectively, condition assessment of the post-tensioned cables and material tests. Moreover, twostrengthening systems, using carbon fibre reinforcing polymer (CFRP), were evaluated. In this paperthe experimental programme and some preliminary results are presented to give an insight to researchproject.

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  • 11.
    Bagge, Niklas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. WSP, Luleå, Sweden.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Norut Teknik, Norut, Norge.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Carolin, Anders
    Trafikverket, Luleå.
    Paulsson, Björn
    Trafikverket; UIC, Paris, France; Charmec, Chalmers tekn högskola.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Assessment of concrete bridges - Prestress forces: Experiences from full-scale testing to failure of a bridge in Kiruna2017In: Proceedings of the 23rd Nordic Concrete Research Symposium, Oslo, Norway: Nordic Concrete Federation, Oslo: Nordic Concrete Federation , 2017, p. 267-270Conference paper (Refereed)
    Abstract [en]

    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 the residual forces in the prestressed reinforcement.

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  • 12.
    Bennitz, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Schmidt, Jacob W.
    Technical University of Denmark, Division of Structural Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Goltermann, Per
    Technical University of Denmark, Division of Structural Engineering.
    Ravn, Dorthe L.
    COWI A/S.
    Reinforced concrete T-beams externally prestressed with unbonded carbon fiber-reinforced polymer tendons2012In: ACI Structural Journal, ISSN 0889-3241, E-ISSN 1944-7361, Vol. 109, no 4, p. 521-530Article in journal (Refereed)
    Abstract [en]

    This study describes a series of experiments examining the behavior of seven beams prestressed with unbonded external carbon fiber-reinforced polymer (CFRP) tendons anchored using a newly developed anchorage and post-tensioning system. The effects of varying the initial tendon depth, prestressing force, and the presence of a deviator were investigated. The results were compared to those observed with analogous beams prestressed with steel tendons, common beam theory, and predictions made using an analytical model adapted from the literature. It was found that steel and CFRP tendons had very similar effects on the structural behavior of the strengthened beams; the minor differences that were observed are attributed to the difference between the modulus of elasticity of the CFRP and the steel used in the tests. The models predicted the beams’ load-bearing behavior accurately but were less effective at predicting the stress experienced by the tendons.

  • 13.
    Blanksvärd, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Häggström, Jens
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sabourova, Natalia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Grip, Niklas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Carolin, Anders
    Trafikverket, Luleå & Borlänge, Sweden.
    Paulsson, Björn
    Trafikverket, Luleå & Borlänge, Sweden.
    Tu, Yongming
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering. Southeast University, Nanjing, PR China.
    Test to failure of a steel truss bridge – Calibration of assessment methods2014In: Bridge Maintenance, Safety, Management and Life Extension: proceedings of the Seventh International Conference of Bridge Maintenance, Safety and Management, 7-11 July 2014, Shanghai, China / [ed] Airong Chen; Dan M. Frangopol; Xin Ruan, London: CRC Press, Taylor & Francis Group , 2014, p. 1076-1081Conference paper (Refereed)
    Abstract [en]

    The steel truss railway bridge at Åby River was built in 1957 with a span of 32 m (105 feet). In 2012 it was replaced by a new steel beam bridge and the old bridge was placed beside the river. It was tested to failure to study its remaining load-carrying capacity in September 2013. The test was carried out by Luleå University of Technology by commission from Trafikverket as a part of the European Research Project MAINLINE (www.mainline-project.eu). In this paper some preliminary results are given. Two hydraulic jacks, anchored by cables to the bedrock, pulled the bridge downwards. The bridge remained elastic up to about three times the original design load and the load could then be almost doubled with substantial yielding deformations before a buckling failure appeared in the top girders for a load of ca. 11 MN (1000 short tons) for a midpoint deflection of ca. 0, 2 m (8 inches). No brittle or fatigue failure in any of the joints appeared and the bridge proved to behave in a ductile way with a substantial hidden capacity.

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  • 14.
    Carolin, Anders
    et al.
    Trafikverket, Luleå.
    Anderson, Robert
    Network Rail, London, United Kingdom.
    Heissenberger, Roman
    ÖBB, Wien, Austria.
    Hermosilla Carrasco, Carlos
    Acciona Technology, Madrid, Spain.
    Schewe, Britta
    Deutsche Bahn, Berlin, Germany.
    Nilimaa, jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwircen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Innovative Intelligent Management of Railway Bridges, In2Rail: A European Horizon 2020 Project2016In: IABSE CONGRESS, STOCKHOLM, 2016: Challenges in Design and Construction of an Innovativeand Sustainable Built Environment / [ed] Lennart Elfgren, Johan Jonsson, Mats Karlsson, Lahja Rydberg-Forssbeck and Britt Sigfrid, CH - 8093 Zürich, Switzerland, 2016, p. 2552-2561Conference paper (Refereed)
    Abstract [en]

    Innovative Intelligent Railways, In2Rail, is a European Horizon 2020 Project with the objective to enhance capacity, increase reliability and reduce Life Cycle Costs of European Railways. Bridges and Tunnels is the main focus in Work Package 4. The aim is to study, benchmark and further develop new Inspection Technologies in order to create more proactive maintenance procedures. In this paper some preliminary results are presented.

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  • 15.
    Chen, Shiwei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Lu, Weizhuo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Dehghanimohammadabadi, Mohammad
    Northeastern University, Boston.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Wang, Yaowu
    Harbin Institute of Technology.
    Kailun, Feng
    Harbin Institute of Technology.
    Concrete Construction: How to Explore Environmental and Economic Sustainability in Cold Climates2020In: Sustainability, E-ISSN 2071-1050, Vol. 12, no 9, article id 3809Article in journal (Refereed)
    Abstract [en]

    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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  • 16.
    Duvnjak, Ivan
    et al.
    University of Zagreb, Croatia.
    Bartolak, Marko
    University of Croatia.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Lessons Learnt from Full-Scale Tests of Bridges in Croatia and Sweden2018In: IABSE Symposium, Nantes 2018: Tomorrow's Megastructures, International Association for Bridge and Structural Engineering , 2018, p. S23-127-S23-134Conference paper (Refereed)
    Abstract [en]

    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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  • 17.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bagge, Niklas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Shu, Jiangpeng
    Chalmers University of Technology.
    Plos, Mario
    Chalmers University of Technology, Department of Civil and Environmental Engineering , Chalmers University of Technology.
    Larsson, Oskar
    Faculty of Engineering, LTH, Department of Constructional Sciences, Lund University.
    Sundquist, Håkan
    Kungliga tekniska högskolan, KTH, KTH, Structural Engineering & Bridges.
    Brottbelastning av en 55 år gammal spännbetongbro i Kiruna - Kalibrering av modeller för tillståndsbedömning: Slutrapport till BBT2015Report (Refereed)
    Abstract [sv]

    En 55 år gammal spännbetongbro med fem spann med längden 121,5 m har provats till brott för att studera och kalibrera metoder för tillståndsbedömning av befintliga broar. Projektet harbidragit till att ge svar på flera av de frågor som ställs beträffande hållbart byggande och uppföljning av befintliga konstruktioner inom BBT - Branschprogram för forskning och innovation avseende byggnadsverk inom transportsektorn. Framför allt adresseras följande områden:A.2.1 Säkerhet, robusthet och sårbarhet – En betydande robusthet finns i den studerade typen av broar och säkerheten mot brott är större än den som erhålls med modellerna i de europeiska betongnormerna.A.2.4 Metodik för individuell bärighetsklassning av broar – En kombination av FE-modellering och analytiska studier baserade på verklig geometri och aktuella materialdata har goda förutsättningar att kunna ge betydligt mer kvalificerade bedömningar av kvarvarande bärförmåga än nu tillämpade metoder.A.2.5 Beständighet och livslängd hos nya byggnadsverk – Projektet ger underlag för förbättrade metoder att bestämma beständighet och livslängd hos spännbetongbroar.A.3.1 Mätmetoder – I projektet har en ny metod för fotografisk töjningsmätning provats. Resultaten har ännu inte hunnit helt utvärderas men de ser lovande ut.A.3.2 Bedömning av tillstånd och livslängd – Projektet ger underlag för förbättrade metoder för bedömning av tillstånd och livslängd.Projektet har hittills redovisats i en doktors- och en licentiatavhandling och i tio tidskrifts- och konferensartiklar.

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  • 18.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bell, Brian
    UIC, Network Rail, London.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Häggström, Jens
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Tu, Yongming
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering. College of Civil Engineering, Southeast University, Nanjing.
    Lundgren, Karin
    Chalmers University of Technology, Department of Civil and Environmental Engineering.
    Plos, Mario
    Chalmers University of Technology, Department of Civil and Environmental Engineering.
    Larsson, Oskar
    Faculty of Engineering, LTH, Department of Constructional Sciences, Lund University.
    Casas, Joan Ramon
    Universitat Politècnica de Catalunya.
    New technologies to extend the life of elderly rail infrastructure: Deliverable 1.3 in MAINLINE - a project within the EC 7th Framework Programme2015Report (Refereed)
    Abstract [en]

    There are many traditional technologies available to extend the life of elderly rail infrastructure, some of which are being improved or developed, whilst new technologies continue to emerge.In two earlier reports a benchmark of new technologies was given and assessment methods were presented, ML-D1.1 (2013) and ML-D1.2 (2013). In this report, ML-D1.3, an overview is given of some of the most promising new or updated technologies. Based on the findings, work in the Mainline project has focused on the following two areas for bridges, tunnels and track:- Assessment methods- Repair and Strengthening methodsSome of the methods are still under development and may not yet be available commercially. Hence these are presented on a “for information” basis and as something that may be introduced on a broader scale in a near future.In the report assessment and strengthening of bridges are treated in Chapter 4 and Chapter 5.Tunnels are treated in Chapter 6 and track and earthwork in Chapter 7.The report also includes with five appendices with details of important work that has been donein the MAINLINE project. Appendix A presents results from the assessment and full scale testing to failure of a 50 year old metallic truss bridge. Appendix B presents results from the strengthening by post-tensioning of a concrete trough bridge. Appendix C presents methods to extend life for tunnels. Appendix D proposes methods for the assessment of fatigue andAppendix E, finally, gives a fairly comprehensive list of references on how to extend the life of structures.A Guideline for application of the new technologies is given in ML-D1.4 (2014).

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  • 19.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Project: Mainline-MAINtenance, renewaL and Improvement of rail transport iNfrastructure to reduce Economic and environmental impacts2012Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    - Apply new technologies to extend the life of elderly infrastructure - Improve degradation and structural models to develop more realistic life cycle cost and safety models - Investigate new construction methods for the replacement of obsolete infrastructure- Investigate monitoring techniques to complement or replace existing examination techniques -Develop management tools to assess whole life environmental and economic impact.

  • 20.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Enochsson, Ola
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Puurula, Arto
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Töyrä, Björn
    Trafikverket.
    Preliminary Assessment of Finnish Railway Bridges: Railway Infrastructure Upgrading with Increase of Axle loads from 25 to 30 tonnes on the Line Tornio - Kolari, A Comparison with Swedish Railway Bridges on the Lines Luleå - Narvik and Haparanda - Boden2009Report (Other academic)
    Abstract [en]

    Some 60 bridges on the Finnish Railway Line between Tornio and Kolari have been assessed in a preliminary way. The study is based on experiences on the two neighbouring Swedish Railway Lines Malmbanan and Haparandabanan.

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  • 21.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Bagge, Niklas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. WSP, Luleå, Sweden.
    Tu, Yongming
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Puurula, Arto
    Savonia University of Applied Sciences, Kuopio.
    Häggström, Jens
    Trafikverket, Luleå, Sweden.
    Paulsson, Björn
    Charmec, Chalmers University of Technology.
    Load-testing used for quality control of bridges2018In: Quality Specifications for Roadway Bridges: Workshop of COST TU 1406 / [ed] José Matos, 2018, p. 1-6Conference paper (Refereed)
    Abstract [en]

    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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  • 22.
    Gamil, Yaser
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    The Impact of Different Parameters on the Formwork Pressure Exerted by Self-Compacting Concrete2023In: Materials, E-ISSN 1996-1944, Vol. 16, no 2, article id 759Article in journal (Refereed)
    Abstract [en]

    Despite the advantageous benefits offered by self-compacting concrete, its uses are still limited due to the high pressure exerted on the formwork. Different parameters, such as those related to concrete mix design, the properties of newly poured concrete, and placement method, have an impact on form pressure. The question remains unanswered on the degree of the impact for each parameter. Therefore, this study aims to study the level of impact of these parameters, including slump flow, T500 time, fresh concrete density, air content, static yield stress, concrete setting time, and concrete temperature. To mimic the casting scenario, 2 m columns were cast at various casting rates and a laboratory setup was developed. A pressure system that can wirelessly and continuously record pressure was used to monitor the pressure. Each parameter’s impact on the level of pressure was examined separately. Casting rate and slump flow were shown to have a greater influence on pressure. The results also demonstrated that, while higher thixotropy causes form pressure to rapidly decrease, a high casting rate and high slump flow lead to high pressure. This study suggests that more thorough analysis should be conducted of additional factors that may have an impact, such as the placement method, which was not included in this publication.

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  • 23.
    Gamil, Yaser
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Experimental based assessment of formwork pressure theoretical design models for self-compacting concrete2023In: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 68, article id 106085Article in journal (Refereed)
    Abstract [en]

    Self-Compacting Concrete (SCC) offers favourable properties which help accelerate the casting time, especially in congested reinforced structures but when casting with SCC uncertainty remains a challenge on the behaviour of its formwork pressure. Researchers have introduced several design models to predict pressure and its behaviour. This research aims to assess the design models that have been reported in the literature. The assessment was carried out through a series of rigorous laboratory tests and the results from the tests served as input for the mathematical model evaluation. Twelve concrete columns with 2 m height were cast in the laboratory to study the effect of varying the input parameters in the existing design models. The formwork pressure was documented by a pressure monitoring system, with the capacity to produce instant results for real-time remote monitoring of the pressure development during and after concrete casting. The formwork pressures were calculated according to the current design models and were compared with pressure data acquitted from the laboratory tests. The results showed that the pressure predicted by the design models was typically greater than the pressure observed during the laboratory tests. The DIN18218 design model showed a relatively close approximation of the pressure distribution over the formwork height and casting time. The limitation of the models is observed when the casting rate varies, and models are sensitive to the input parameters. Thus, additional development of the current design models is needed to enable reliable estimations of the pressure, for example, in the case of low and high casting rates. The laboratory tests also showed that high casting rates and high slump flows generate higher pressures whereas higher thixotropy results in faster pressure reduction during construction.

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  • 24.
    Gamil, Yaser
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Lateral Formwork Pressure for Self-Compacting Concrete—A Review of Prediction Models and Monitoring Technologies2021In: Materials, E-ISSN 1996-1944, Vol. 14, no 16, article id 4767Article, review/survey (Refereed)
    Abstract [en]

    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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  • 25.
    Gamil, Yaser
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Najeh, Taufik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Formwork pressure prediction in cast-in-place self-compacting concrete using deep learning2023In: Automation in Construction, ISSN 0926-5805, E-ISSN 1872-7891, Vol. 151, article id 104869Article in journal (Refereed)
    Abstract [en]

    The prediction of formwork pressure exerted by self-compacting concrete (SCC) remains a challenge not only to researchers but also to engineers and contractors on the construction site. This article aims to utilize shallow neural networks (SNN) and deep neural networks (DNN) using Long Short-Term Memory (LSTM) approach to develop a prediction model based on real-time data acquitted from controllable laboratory testing series. A test setup consisting of a two-meter-high column, ø160 mm, was prepared and tested in the laboratory. A digital pressure monitoring system was used to collect and transfer the data to the cloud on a real-time basis. The pressure was monitored during- and after casting, following the pressure build-up and reduction, respectively. The two main parameters affecting the form pressure, i.e., casting rate and slump flow, were varied to collect a wide range of input data for the analysis. The proposed model by DNN was able to accurately predict the pressure behavior based on the input data from the laboratory tests with high-performance indicators and multiple hidden layers. The results showed that the pressure is significantly affected by the casting rate, while the slump flow had rather lower impact. The proposed model can be a useful and reliable tool at the construction site to closely predict the pressure development and the effects of variations in casting rate and slump flow. The model provides the opportunity to increase safety and speeding up construction while avoiding costly and time-consuming effects of oversized formwork.

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  • 26.
    Huang, Zheng
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. School of Civil Engineering, Southeast University, Nanjing, China.
    Tu, Yongming
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. School of Civil Engineering, Southeast University, Nanjing, China.
    Meng, Shaoping
    School of Civil Engineering, Southeast University, Nanjing, China.
    Bagge, Niklas
    Department of Bridge & Hydraulic Design, WSP Sverige AB, Gothenburg, Sweden.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Validation of a numerical method for predicting shear deformation of reinforced concrete beams2019In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 197, article id 109367Article in journal (Refereed)
    Abstract [en]

    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.

  • 27.
    Häggström, Jens
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Bagge, Niklas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Puurula, Arto
    Savonia University of applied Sciences, Kuopia, Finland.
    Rydberg-Forssbeck, Lahja
    Trafikverket, Stockholm.
    Carolin, Anders
    Trafikverket, Luleå.
    Testing Bridges to Failure: Experiences2017In: IABSE Symposium, Vancouver, 2017: Engineering the Future, Zürich, Switzerland: IABSE - International Association for Bridges and Structural Engineering , 2017, p. 2832-2839Conference paper (Refereed)
    Abstract [en]

    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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  • 28.
    Najeh, Taoufik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Gamil, Yaser
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Department of Civil Engineering, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, 47500 Bandar Sunway, Selangor, Malaysia.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Forecasting maximum formwork pressure for self-compacting concrete using ARX-Laguerre machine learning model2024In: Developments in the Built Environment, ISSN 2666-1659, Vol. 18, article id 100409Article in journal (Refereed)
    Abstract [en]

    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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  • 29.
    Nilforoush, Rasoul
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Bagge, Niklas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Wsp Bridges and Tunnels, Göteborg, Sweden.
    Puurula, A
    Savonia University of Applied Sciences, Kuopio, Finland.
    Ohlsson, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Fracture energy of concrete for bridge assessment2020In: 1st IABSE Online Symposium 2020: Synergy of Culture and Civil Engineering - History and Challenges / [ed] Jan Bien; Jan Biliszczuk; Pawel Hawryszkow; Maciej Hildebrand; Marta Knawa-Hawryszkow; Krzysztof Sadowski, International Association for Bridge and Structural Engineering (IABSE) , 2020, p. 692-699Conference paper (Refereed)
    Abstract [en]

    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.

  • 30.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Concrete Bridges: Improved Load Capacity2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There are many beautiful old structures around the world, some of which were designed for completely different purposes than their current applications. For example, Swedish railway bridges were only designed to carry axle loads up to 200 kN in the beginning of the 20th century, while modern loads can be twice as high. The traffic intensities have also increased dramatically and the velocities are now higher than ever before. In order to maintain old structures while the loads increase, upgrading of their load carryingcapacity may be needed. Administrative upgrading refers to increasing their nominal capacity to withstand stresses beyond original limits by refined calculations, using real material data, geometry and loads. This sometimes allows bridges to be upgraded with little or no physical modification. Upgrading by strengthening refers to physical alteration of the structure.The objective of the studies this thesis is based upon (reported in detail in five appended papers, designated Papers I-V) was to evaluate several strengthening systems by assessing their in-situ effects on existing bridges.First, a novel strengthening method involving internal post-tensioning of bridge slabs was developed and examined in a laboratory test (Paper I). The material used in the test consisted of two 1:3 scale trough bridge specimens, and the purpose was to study effects of the method in a controlled (laboratory) environment. The results were encouragingand the method was subsequently applied to a real railway bridge in Haparanda, Sweden. To assess the method’s ability to increase load capacities, the bridge’s response to a train load were monitored before and after strengthening (Paper II). The results showed how the bridge’s tensile strains from the train load were completely counteracted by the posttensioning.Next, an assessment procedure, consisting of curvature monitoring wasproposed for double-trough bridges. The proposal was based on results of the field test in Haparanda (Paper III).In addition, the effects of two systems for strengthening post-tensioned concrete bridges were investigated in tests using a highway bridge in Kiruna, Sweden, which was taken out of service due to increasing ground movements. Near-surface mounted carbon fiber reinforced polymer (CFRP) bars (Paper IV) and prestressed CFRP laminates (Paper V)were installed on different girders of the bridge, then loaded to failure while the structure was monitored by a battery of sensors. The results showed that both systems can reduce tensile strains in the steel reinforcement and improve post-tensioned bridge’s load capacity.In summary, the research has provided insights into the effects of several strategies for upgrading bridges that may prolong their service life, simplify their health monitoring and enhance the cost-effectiveness of maintaining a bridge stock.

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  • 31.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Lateral form pressure induced by SCC2022In: 24th NCR Symposium Proceedings / [ed] Johan Silfwerbrand, Nordic Concrete Federation , 2022Conference paper (Refereed)
    Abstract [en]

    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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  • 32.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    New Examination Approach for Real-World Creativity and Problem-Solving Skills in Mathematics2023In: Trends in Higher Education, E-ISSN 2813-4346, Vol. 2, no 3, p. 477-495Article in journal (Refereed)
    Abstract [en]

    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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  • 33.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Post-tensioning of reinforced concrete trough bridge decks: laboratory test2012Report (Other academic)
    Abstract [en]

    The Swedish Transport Administration (Trafikverket) is the owner of a large number of railway concrete trough bridges, which were designed according to standard codes in the 1950’s. The traffic loads are today higher than the design loads and the level of ballast is also much higher today. The degree of utilization of the bottom slab is very high, which can be confirmed by calculations and visual inspections (flexural cracks are visible). This report presents the results from a laboratory test of a trough bridge, strengthened by transversal post-tensioning of the slab, at Luleå University of Technology.Calculations according to three design codes, gives a theoretical increase of the shear capacity with 5 – 100%, and the test confirmed a large increase of shear capacity. The main objective for the strengthening was to increase the shear capacity, but also the theoretical flexural capacity was increased by 21%.

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  • 34.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Smart materials and technologies for sustainable concrete construction2023In: Developments in the Built Environment, E-ISSN 2666-1659, Vol. 15, article id 100177Article, review/survey (Refereed)
    Abstract [en]

    This paper presents a comprehensive review of current trends and opportunities for sustainable concrete construction, emphasizing the importance of adopting eco-friendly practices to mitigate the industry's environmental impact. Green concrete, supplementary cementitious materials, permeable concrete, cool concrete, and the use of local materials are explored as sustainable materials and technologies. Innovations like self-healing concrete, 3D-printed concrete, photocatalytic concrete, electrified machineries, and carbon capture, utilization, and storage principles are also discussed, highlighting their potential to improve the sustainability of construction practices. Challenges faced in implementing sustainable concrete construction practices, such as technical, economic, and social barriers, are also addressed. The roles of governments, industry, and academia in promoting sustainable concrete construction are examined, stressing the need for interdisciplinary collaboration and research. Lastly, emerging trends and technologies, including digitalization, data-driven approaches, and circular economy principles, are identified as critical factors in driving the transition towards sustainable concrete construction.

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  • 35.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Upgrading concrete bridges: post-tensioning for higher loads2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    There are a great number of old structures around the world, some of which were designed for completely different purposes than in their current application. Swedish railway bridges were for example only designed for maximum axle loads of 200 kN in the beginning of the 20th century, while the highest axle loads of today are twice as high. The traffic intensities have also increased dramatically and the velocities are now higher than ever before. Reinforced concrete trough bridges were typically designed and built in the mid-20th century and it is still one of the most frequent railway bridge types in Sweden. The trough bridges were normally designed for traffic loads which were smaller than the loads today and in order to maintain an old structure as the loads increases, structural upgrading of the load bearing capacity might be necessary. Upgrading the load carrying capacity can be performed in two ways, namely administrative upgrading or strengthening. Administrative upgrading refers to refined design calculations, using real material data, geometry and loads, which provides a higher capacity than the original design and the bridge can thereby be upgrading with minor physical impact. Upgrading by strengthening on the other hand, refers to, often, larger physical alteration of the structure in order to enhance the original load carrying capacity.Upgrading methods for increased flexural resistance of concrete trough bridges has been developed and tested previously, but strengthening methods for increased shear resistance in the bridge deck are still absent. The objective of this thesis is therefore to find an existing- or develop a new strengthening method which can be applied in order to enhance the shear resistance of concrete trough bridge decks. The difficulties associated to strengthening of existing railway bridges include traffic during the strengthening work and concrete surfaces concealed by the ballast.The State-of-the-Art indicated that none of the existing strengthening techniques were sufficient for this application and internal unbonded post-tensioning in the transverse direction was nominated as the most promising method. The research was thereafter focused on testing the possibilities and strengthening effects of post-tensioning. Two laboratory investigations were performed during the research project and the method was finally tested in a field test on a 50 years old trough bridge in Haparanda, Sweden. The strengthening procedure of internal unbonded post-tensioning consists of four consecutive steps:1.Transverse drilling of the horizontal holes through the bottom slab.2.Installation of the prestressing system.3.Post-tensioning of the system.4.Sealing of the prestressing system.The laboratory and field tests were successful and the results proved that the internal steel reinforcement within the concrete was compressed when the trough bridge was post-tensioned. Due to the compression, a higher load could be carried by the bridge deck before the tensile reinforcement yields and the bridge fails. In other words, the flexural capacity of the bridge deck was increased. The field test actually showed that eight steel bars, post-tensioned with 430 kN per bar on the Haparanda Bridge, completely counteracted the tensile stresses caused by a train with 215 kN axle loads. The effect on the shear resistance was however not as easy to measure, but the laboratory test recorded a significant strain reduction in the tensile reinforcement which was bent up at the transition zone between the bridge deck and the main girders. The reduced strain might be interpreted as lower shear stresses and post-tensioning can thereby be considered to have a positive effect on the shear resistance of the bridge deck. Shear design according to the protocol of Eurocode 2 or BBK was however found to be restrictive in predicting the post-tensionings effect on the shear capacity and further research is proposed in chapter 8.

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  • 36.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Upgrading the Haparanda Bridge: A case study2012Report (Other academic)
    Abstract [en]

    This report presents the design and results of the strengthening of a double trough concrete railway bridge in Haparanda, Sweden. The objective was to find a strengthening solution, which provides a sufficient shear capacity in the transversal direction for the bridge slab when the allowed axle loads on the railway are increased from 25 to 30 ton.Unbonded post-tensioning was chosen as the strengthening method and the design was performed according to the design criteria of Eurocode. The results indicate increased interaction between the two troughs, as well as an increased capacity. All reinforcement strains caused by a train with 21.5 ton axle loads were counteracted by the compressive action obtained by eight prestressing bars, stressed with 430 kN/bar.The main conclusion was that the load carrying capacity increased significantly and the effect is probably higher than what is shown in the design calculations.

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  • 37.
    Nilimaa, Jonny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Upgrading the Haparanda Bridge: Unbonded Posttensioning2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 425-428Article in journal (Refereed)
    Abstract [en]

    The Haparanda Railway Bridge was upgraded for a higher load resistance in the summer of 2012. The slab of the 50 year old bridge was subjected to horizontal posttensioning and the railway administrators could thereby permit higher axle loads, 300 kN instead of the original 250 kN. The strengthening procedure was first examined in a laboratory pilot study and since the results were good, the method was applied on a real bridge. The posttensioning of the Haparanda Bridge reduced the strain in the tensile reinforcement substantially; all strains from a 215 kN/axle train were in fact counteracted.

  • 38.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bagge, Niklas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    NSM CFRP Strengthening and Failure Loading of a Posttensioned Concrete Bridge2016In: Journal of composites for construction, ISSN 1090-0268, E-ISSN 1943-5614, Vol. 20, no 3, article id 04015076.Article in journal (Refereed)
    Abstract [en]

    Two carbon-fiber-reinforced polymer (CFRP) systems developed as possible means to strengthen existing concrete structures have been applied to a bridge at Kiruna (Sweden). The bridge was no longer in service and was thus used in extensive tests to failure. It was a posttensioned five-span bridge consisting of three longitudinal main girders topped with a concrete slab. The program reported here consisted of a series of three tests of the girders in the second span: loading each girder up to 2.0 MN before strengthening, loading each girder up to 2.0 MN after strengthening, and loading to failure after strengthening. One of the girders was strengthened by installing three 10×10  mm 2 near-surface mounted (NSM) CFRP bars on the soffits, and another by installing three prestressed 1.4×80  mm 2 CFRP laminates. This paper focuses on the NSM-strengthened girder, which failed at a maximum load of 6.1 MN, with a corresponding midspan deflection of 159 mm. The failure was a combination of flexure and shear, and the strain in the NSM bars at the ULS was 1.2%.

  • 39.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Bagge, Niklas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Häggström, Jens
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    More Realistic Codes for Existing Bridges2016In: IABSE CONGRESS, STOCKHOLM, 2016: Challenges in Design and Construction of an Innovativeand Sustainable Built Environment / [ed] Elfgren, Lennart; Jonsson, Johan; Karlsson, Mats; Rydberg-Forssbeck, Laja; Sigfrid, Britt, CH - 8093 Zürich, Switzerland, 2016, p. 399-407Conference paper (Refereed)
    Abstract [en]

    Examples are given from comparisons of analyses based on (1) code models, (2) finite element models and (3) full scale tests to failure of three bridges. The analyses based on the code models gave very conservative results, while the finite element models could better predict the real behaviour.

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  • 40.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Al-Emrani, Mohammad
    Chalmers University of Technology.
    Haghani, Reza
    Chalmers University of Technology.
    Kliger, Robert
    Chalmers University of Technology.
    Innovativa metoder för förstärkning av befintliga konstruktioner med förspänt kompositmaterial: Förstärkning och brottbelastning av bro i full skala - SBUF 12849 Slutrapport2015Report (Refereed)
    Abstract [sv]

    Rapporten redovisar resultat och erfarenheter från ett forskningsprojekt delfinansierat av SBUF. Projektet omfattade ett fältförsök där en förspänd betongbro, Gruvvägsbron, i Kiruna belastades till brott och där två olika förstärkningsmetoder undersöktes. Bron var uppförd i fem spann över121,5 m och bestod av tre efterspända T-balkar. Mittenbalken förstärktes med tre 10 x 10 mm2 täckskiktsmonterade (NSM) kolfiberstavar och den södra balken förstärktes med tre 1,4 x 80 mm2 kolfiberlaminat som förspänts upp till 100 kN med en nyutvecklad metod för gradvis förspänning. Båda örstärkningssystemen monterades på balkarnas underkant för att öka derasmomentkapacitet. Belastningsförsöket gjordes i spann 2-3 och bestod av tre delar: (1) Belastning av den oförstärkta bron upp till totalt 6,0 MN, (2) Belastning av den förstärkta bron upp till 6,0 MN och (3) Brottbelastning av den de två förstärkta balkarna.Syftet med laminatförstärkningen var att i fält utvärdera det förspända laminatsystemet som utvecklats vid Chalmers Tekniska Högskola. Utvärderingen omfattade dels en analys av systemets tillämpbarhet med belysning av eventuella problem och förbättringsmöjligheter, dels en undersökning av eventuella förstärkningseffekter på en förspänd betongbro. Syftet med NSM-förstärkningen var att utvärdera eventuella förstärkningseffekter. Slutligen gav de två förstärkningsåtgärderna en möjlighet att kunna jämföra kostnader och resultat för ett aktivt- (förspänt) och ett passivt (ospänt) förstärkningssystem på samma bro.Undersidan på balkarna hade fått en krökning uppåt, överhöjning, på grund av den ursprungliga förspänning som gjordes vid uppförandet av bron 1959. Det resulterade i att laminaten förlorade kontakten med betongbalken över en sträcka av 14 m när de förspändes och glipan mellan betong och laminat uppgick till maximalt 31 mm. Ett ospänt laminat har förmågan att anpassa sig efter underlaget, men när det förspänns förlorar det sin anpassningsförmåga. Det betyder att metoden inte kan användas effektivt på konkava konstruktioner och såvida underlaget inte är helt jämnt kommer det att uppstå skillnader i limfogens tjocklek, vilket kan leda till förankringsproblem. För att undvika krökningen, på grund av överhöjningen från förspänningen, hade en pågjutning på balkarnas underkant kunnat genomföras för att skapa en plan yta, en sådan åtgärd hade väldigt besvärlig samt kostsam att genomföra.Ett annat problemområde som identifierades var förankringen av örspänningssystemet. 12 stycken 210 mm långa ankarbultar användes för att förankra förspänningsanordningarna i balken för varje laminat. Det betyder att ett stort antal Ø22 mm hål måste borras i balken och eftersom det i underkant ofta förekommer mycket armering är det en ytterst svår uppgift att undvikaarmeringsskador vid borrningen. För att undvika att armeringen skadas föreslås att utformning på förankringen av förspänningssystemet förändras.Resultaten från belastningsförsöken visade att båda metoderna kan användas för att öka förspända betongbroars lastkapacitet. De tydligaste effekterna av förstärkning var framförallt reducerade töjningsnivåer i balkens dragarmering. För NSM-systemet visade resultaten en ökande förstärkningseffekt för högre lastnivåer medan laminatsystemet tvärtom visade en minskande effekt för högre lastnivåer. Effekten av laminatförstärkningen påverkades dock av förankringsproblemen som gjorde att laminattöjningen i mittspannet var mindre än töjningen i balkens underkant. Laminaten lossnade från betongbalken vid en last på 9,0 MN och förankringsbrottet var en följd av att det oförankrade området i mittspannet växte utåt. Den maximala utnyttjandegraden för laminaten var 37 % (inkl förspänningskraft, 12 % exkl. förspänningskraft), i laborativ miljö uppvisar förspänningssystemet avsevärd högre utnyttjadegradi vissa fall upp till nästan 100 % (brott i laminat). Förstärkningssystemet med NSM-stavar uppvisade en nyttjandegrad på 85 % vid maxlasten då den förstärka balken gick till brott i kombinerad böjning och skjuvning.

  • 41.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Kunskapsåterföring av erfarenheter från MAINLINE: Verktyg och metoder för att förbättra den svenska järnvägsinfrastrukturen - SBUF 13139 Slutrapport2016Report (Refereed)
    Abstract [sv]

    Rapporten redovisar resultat och erfarenheter från ett EU-finansierat forskningsprojekt MAINLINE. Tanken med rapporten är att samla och analysera den kunskap som tagits fram inom MAINLINE och anpassa den för den svenska byggindustrin.Tillväxten och efterfrågan av säkra och effektiva järnvägstransporter spås fortsätta att öka över hela Europa under de kommande decennierna. En stor del av denna transportökning måste fördelas ut på de järnvägslinjer som finns idag och består av en stor del gammal infrastruktur. Den ökade belastningen kommer att leda till ett ökat slitage på infrastrukturen och ett växande behov av snabbare underhållsarbeten som orsakar mindre trafikstörningar och framför allt kortare totalstopp. Vid planeringen av nya åtgärder bör hänsyn tas till att minimera störningarna och samtidigt reducera de ekonomiska behoven, samt de miljömässiga konsekvenserna. Nya metoder och tekniker kommer att behövas för att stödja och informera beslutsfattare om de långsiktiga ekonomiska och miljömässiga konsekvenserna av de åtgärder som planeras för järnvägen.Projektet MAINLINE, som står för MAINtenance, renewaL and Improvement of rail transport iNfrastructure to reduce Economic and environmental impacts, var en del i EUs 7e ramverksprogram. Finansieringen utgjordes av kontraktet SST.2011.5.2-6 mellan Europakommissionen och den internationella järnvägsunionen, UIC. UIC var även koordinator för MAINLINE.Tanken med MAINLINE var att utreda möjligheterna för ökad användning av den Europeiska järnvägen genom att öka nyttjandegraden och livslängden på befintliga konstruktioner och andra tillgångar. Projektet genomfördes i en serie av sammanhängande arbetspaket. Målsättningen var att resultaten ska leda till årliga kostnadsbesparingar på minst 300 miljoner Euro för den Europeiska järnvägen, och samtidigt minimera klimatpåverkan. Projektet MAINLINE har arbetat för att:a) tillämpa nya teknologier för att öka livslängden hos befintlig infrastrukturb) förbättra modeller för nedbrytning och strukturanalys för skapa mer realistiska livscykelkostnader och tillförlitlighetsmodellerc) undersöka nya konstruktionsmetoder för att ersätta/byta ut föråldrad infrastrukturd) undersöka mättekniker (tillståndsbedömning) som antingen kompletterar eller ersätter existerande undersökningsmetodere) utveckla förvaltningsverktyg som tar hänsyn till livscykelberäkningar för både miljö- och ekonomipåverkan (LCA och LCC analyser).

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  • 42.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Transversal post tensioning of RC trough bridges: laboratory tests2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 46, no 2, p. 57-74Article in journal (Refereed)
  • 43.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Assessment of concrete double-trough bridges2015In: Journal of Civil Structural Health Monitoring, ISSN 2190-5479, Vol. 5, no 1, p. 29-36Article in journal (Refereed)
    Abstract [en]

    The behaviour of reinforced concrete double-trough bridges has been assessed regarding the stress distribution in the transverse direction of the slab. Two bridges were studied and the curvature, as well as the tensile steel reinforcement strain, was monitored. One bridge was loaded with a reference train, producing a distributed load of 17.1 kN/m on a theoretical 1-m-wide slab strip, while the load on the other bridge was not specified. Each bridge consisted of two parallel troughs, presumably cast on different occasions, and connected by continuous reinforcement and a concrete shear stud. Previous assessment calculations regarded these two troughs acting as two separate structures, with the slab simply supported by the main beams. This paper, however, shows that there is a composite action between the troughs, and the bridge deck should instead be regarded as continuous in the transverse direction. By using this approach, the load capacity of the bridge can be increased without strengthening. Structural health monitoring using curvature- or tensile strain monitoring, is finally recommended for double-trough bridges and an assessment chart is proposed for the Haparanda Bridge.

  • 44.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Post-tensioning of reinforced concrete trough bridge decks2012In: Concrete Structures for Sustainable Community: proceedings of the International FIB Symposium 2012, Stockholm, Sweden, 11 - 14 June 2012 / [ed] Dirch H. Bager; Johan Silfwerbrand, Stockholm: Swedish Concrete Association , 2012, p. 415-418Conference paper (Refereed)
    Abstract [en]

    All aging structures are affected by different deterioration processes, which might cause a performance decrease, and eventually lack of safety, in the structures. In addition to this the changing infrastructural demands pose the Swedish Transport Administration to increase the load capacity of the railway system which then also includes the bridges. This might be carried out by many different methods where strengthening is one. A particular interesting bridge type to strengthen is the concrete trough bridge and in particular in shear between the transition of the beam and the slab. Methods for flexural strengthening of trough bridges have been tested and documented, but there is a lack of methods for strengthening the bottom slab in shear. This paper presents promising laboratory test results for transversal post tensioning of the bottom slab of a concrete trough bridge specimen, and measurements reveal a vast decrease in reinforcement strains.

  • 45.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Unbonded Transverse Posttensioning of a Railway Bridge in Haparanda, Sweden2014In: Journal of Bridge Engineering, ISSN 1084-0702, E-ISSN 1943-5592, Vol. 19, no 3, article id 4013001Article in journal (Refereed)
    Abstract [en]

    The majority of railway lines in Sweden are designed to support axle loads of up to 250 kN. Because of increased transport needs on some lines, an axle load limit of at least 300 kN would be beneficial. To upgrade the Haparanda line in northern Sweden to 300 kN, the slabs in existing concrete trough bridges require a higher transverse shear resistance. Methods for in situ strengthening of bridge slabs in this way have not been fully developed, and this paper discusses the possibility of increasing the load capacity by horizontal prestressing. Internal, unbonded posttensioning was performed on one bridge on the Haparanda line, and the strengthening effects were investigated. The strengthening was designed according to the European Eurocode design regulations, and testing was conducted before and after the implementation. Strains in the main transverse reinforcement, caused by a train with an axle load of 215 kN, were completely counteracted by eight prestressing bars, stressed with 430 kN/bar. The results indicate that the actual strengthening effect is larger than what is predicted by the design equations. The Haparanda project showed that unbonded posttensioning can be implemented relatively fast and does not obstruct the ongoing railway traffic during installation

  • 46.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Carolin, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Paulsson, Björn
    Trafikverket.
    Extended Life of Railway Bridges. Results from EC-FP7-project MAINLINE2013In: Assessment, Upgrading and Refurbishment of Infrastructures: IABSE Conference Rotterdan 2013 / [ed] Philippe Van Bogaert, Zürich: International Association for Bridge and Structural Engineering, 2013, p. 314-315Conference paper (Refereed)
    Abstract [en]

    There is a need to extend the life of many existing railway bridges. To facilitate this is one of the objects of the EC-FP7-Project MAINLINE, covering a period from 2011 to 2014. Three case studies are presented in which existing bridges are being studied in order to extend their life length: First a concrete trough bridge strengthened with post stressed bars in drilled holes through the slab is considered; followed by another concrete trough bridge strengthened with sawn in Near Surface Mounted Reinforcement (NSMR) of Carbon Fibre Reinforce Polymers (CFRP); and finally a steel truss bridge which will be loaded to failure to calibrate the assessment methods.

  • 47.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Carolin, Anders
    Paulsson, Björn
    UIC, Trafikverket.
    Extending the life of elderly rail bridges by strengthening2014In: Bridge Maintenance, Safety, Management and Life Extension: proceedings of the Seventh International Conference of Bridge Maintenance, Safety and Management, 7-11 July 2014, Shanghai, China / [ed] Airong Chen; Dan M. Frangopol; Xin Ruan, London: CRC Press, Taylor & Francis Group , 2014, p. 1082-1088Conference paper (Refereed)
    Abstract [en]

    There is a need to extend the life of many existing railway bridges. To facilitate this is one of the objects of the EC-FP7-Project MAINLINE, covering a period from 2011 to 2014. New or improved technologies are investigated to help with this. For bridges, the most promising techniques are enhanced inspection, assessment and strengthening methods. Case studies are presented where three different strengthening techniques have been applied to existing concrete trough bridges. First, sawn in Near Surface Mounted Reinforcement (NSMR) of Carbon Fibre Reinforce Polymers (CFRP) are used; followed by a bridge where carbon fibre cables were drilled through the bridge and finally a bridge was strengthened with post tensioned bars in drilled holes through the slab in the transverse direction. All three methods proved to be very successful.

  • 48.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Gamil, Yaser
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Zhaka, Vasiola
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Formwork Engineering for Sustainable Concrete Construction2023In: CivilEng, E-ISSN 2673-4109, Vol. 4, no 4, p. 1098-1120Article in journal (Refereed)
    Abstract [en]

    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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  • 49.
    Nilimaa, Jonny
    et al.
    Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, SE-97187 Luleå, Sweden.
    Gamil, Yaser
    Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, SE-97187 Luleå, Sweden.
    Zhaka, Vasiola
    Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, SE-97187 Luleå, Sweden.
    Formwork Engineering for Sustainable Concrete Construction2023In: CivilEng, E-ISSN 2673-4109, Vol. 4, no 4, p. 1098-1120Article in journal (Refereed)
  • 50.
    Nilimaa, Jonny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Häggström, Jens
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bagge, Niklas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Ohlsson, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bernspång, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Carolin, Anders
    Trafikverket, Borlänge, Sweden.
    Paulsson, Björn
    Trafikverket, Borlänge, Sweden.
    Maintenance and Renewal of Concrete Rail Bridges - Results from EC project MAINLINE2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 25-28Article in journal (Refereed)
    Abstract [en]

    There is a need to extend the life and capacity of many existing railway bridges. One of the objects of the EC-FP7-Project MAINLINE, 2011-2014, is to facilitate this. Guidelines for assessment and strengthening methods are presented as well as case studies in which existing bridges are being studied in order to extend their life length. Case studies on bridges tested to failure in order to calibrate assessment methods are also presented. Fatigue is often a vital question. A Life Cycle Assessment Tool (LCAT) is being prepared to enable Infrastructure Managers to choose optimal maintenance strategies.

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