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  • 51.
    Saback de Freitas Bello, Vanessa
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Popescu, Cosmin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. SINTEF Narvik AS , Narvik , Norway.
    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.
    Asset Management of Existing Concrete Bridges Using Digital Twins and BIM: a State-of-the-Art Literature Review2022In: Nordic Concrete Research, ISSN 0800-6377, Vol. 66, no 1, p. 91-111Article, review/survey (Refereed)
    Abstract [en]

    The need to optimize investments in bridge maintenance has created a demand for improved bridge management systems (BMS). Outdated practices in bridge inspection and constant advances in information technology have also contributed to this demand. The use of Digital Twins (DT), although well established in other industries, is still incipient for asset management and structural analysis of bridges. There is a great deal of research on Building Information Modelling (BIM) for bridge inspection, but its post-construction potential is still under-explored. This study presents a state-of-the-art review of the literature on asset management for bridges using digital models such as BIM and digital twins. The review was conducting using a systematic approach. Despite the rapid increase in research on DT and the amount of existing research on BIM, several gaps remain to be addressed, such as the lack of consensus about the definition of digital twins, which has led to wrongful categorisation of digital models as DT. The complex data flow and software compatibility required to develop a functional DT have hindered the exploitation of their full potential so far. The integration of BIM post-construction to BMS and existing automation technologies can also significantly improve current practices of bridge management.

  • 52.
    Sandström, Thomas
    et al.
    WSP Group.
    Fridh, Katja
    Division of Building Materials, Lund University.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hassanzadeh, Manouchehr
    Vattenfall Research & Development.
    The influence of temperature on water absorption in concrete during freezing2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 45, no 1, p. 45-58Article in journal (Refereed)
  • 53.
    Sas, Gabriel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering. NORUT, N-8504 Narvik, Norway.
    Blanksvärd, Thomas
    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.
    Emborg, Mats
    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.
    Puurula, Arto
    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.
    Flexural-Shear Failure of a Full Scale Tested RC bridge Strengthened with NSM CFRP. Shear capacity analysis2011In: Nordic Concrete Research, ISSN 0800-6377, Vol. 2/2011, no 44, p. 189-206Article in journal (Refereed)
    Abstract [en]

    A test to failure has been carried out on a 50 -year-old RC railway trough bridgestrengthened in flexure with near-surface mounted (NSM) Carbon Fibre ReinforcedPolymers (CFRP) bars. The failure occurred at 11.7 MN load, by a flexural shear failuremechanism. At failure intermediate crack (IC) debonding of the CFRP bars was noticed,and at the same moment the major shear crack opened. The NSM CFRP increased boththe flexural and shear capacity of the bridge. The present codes provided conservativeestimates of shear force capacity; more accurate models are required for detailed capacityassessments of existing concrete through bridges.

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    sammanfattning
  • 54.
    Sayahi, Faez
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Plastic Shrinkage Cracking in Concrete: State of the Art2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 51, p. 95-110Article in journal (Refereed)
    Abstract [en]

    As plastic shrinkage cracking can dramatically reduce the durability of a concrete member and causes considerable repair costs annually, a comprehensive understanding of the mechanism of the phenomenon is essential to prevent these damages in future. In this paper, an overview is given on the mechanism of plastic shrinkage crack formation and the status of present technologies avoiding the cracking are reported through referring to previously conducted research and observations.

  • 55.
    Sayahi, Faez
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Plastic shrinkage cracking: research in Scandinavia2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 351-354Article in journal (Refereed)
    Abstract [en]

    As plastic shrinkage cracking still causes considerable repair costs annually, an understanding of the phenomenon is essential to prevent these damages in the future. In the paper, the status of present technology to avoid cracking is briefly reported through referring to research conducted in Scandinavia. In addition, on-going activities at LTU are described and future plan is demonstrated. Thus, experiments are performed on concrete slabs cast in rectangular moulds and cured at some variations of environmental conditions. The results will be used to find critical evaporation rate at very early age.

  • 56.
    Sayahi, Faez
    et al.
    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.
    Hedlund, Hans
    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.
    Plastic Shrinkage Cracking of Self-compacting Concrete: Influence of Capillary Pressure and Dormant Period2019In: Nordic Concrete Research, ISSN 0800-6377, Vol. 60, no 1, p. 67-88Article in journal (Refereed)
    Abstract [en]

    This research investigates the effect of capillary pressure and the length of the hydration dormant period on the plastic shrinkage cracking tendency of SCC by studying specimens produced with different w/c ratios, cement types and SP dosages.

    The results show, that the cracking tendency of SCC was the lowest in case of w/c ratio between 0.45 and 0.55, finer rapid hardening cement and lower dosage of SP. The dormant period was prolonged by increasing the w/c ratio, using coarser cement and higher SP dosage. It was concluded that the cracking tendency of concrete is a function of the capillary pressure build-up rate and the length of the dormant period.

    Download full text (pdf)
    fulltext
  • 57.
    Simonsson, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    R&D, Betongindustri AB, 100 74 Stockholm.
    Increasing productivity through utilization of new construction techniques and lean construction philosophies in civil engineering projects2009In: Nordic Concrete Research, ISSN 0800-6377, Vol. 39, no 1, p. 53-74Article in journal (Refereed)
    Abstract [en]

    The implementation of Self Compacting Concrete (SCC) together with two types of reinforcement and form techniques makes it possible to increase the degree of industrialization at construction sites markedly. To be able to realize this, Lean Construction principles prove to be important utensils during the planning and design phase. Also, the working environment is improved vastly when using SCC and different prefabricated reinforcement solutions. At the construction of the first full scale project "The Industrialized Concrete Bridge", which was built during 2006 in Sweden, the new techniques were applied. It was concluded that the working environment was improved by three fold, production time at site could be reduced with up to 20 % and that the number of workers could be reduced by virtually 25 %.

    Download full text (pdf)
    fulltext
  • 58.
    Simonsson, Peter
    et al.
    Luleå University of Technology.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering. R&D, Betongindustri AB, Stockholm, Sweden.
    Industrialized construction: Benefits using SCC in cast in-situ construction2009In: Nordic Concrete Research, ISSN 0800-6377, Vol. 39, no 1, p. 33-52Article in journal (Refereed)
    Abstract [en]

    As known the product SCC comprises many advantages compared with traditional concrete, but yet it has not changed the market of cast in place concrete as expected. This relates to some robustness problems of the concrete and to a general opinion that the product is considered to be expensive. However, manufacturers have improved their quality vastly and SCC has become more robust over the last few years.

    To increase the use of SCC, the actors of the building trade need to be informed and convinced how to benefit from all the advantages of SCC: i.e. the working environment the health and safety of the workers, the productivity etc.

    This paper deals with full-scale examples on the use and the realization of SCC obtaining several benefits during a projects whole construction time. Specially, the economics and the working environment are treated.

    Download full text (pdf)
    fulltext
  • 59.
    Simonsson, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Robust self compacting concrete for bridge construction2011In: Nordic Concrete Research, ISSN 0800-6377, Vol. 2011, no 44Article in journal (Refereed)
    Download full text (pdf)
    FULLTEXT01
  • 60. Thun, Håkan
    et al.
    Ohlsson, Ulf
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Concrete strength in old Swedish concrete bridges2006In: Nordic Concrete Research, ISSN 0800-6377, Vol. 35, no 1-2, p. 47-60Article in journal (Refereed)
    Abstract [en]

    In this paper the development and variation of compressive and tensile strength of concrete are presented for old reinforced concrete bridges in Sweden. The mean increase in concrete compressive strength was about 70% for twenty bridges built during 1931-1962 (a rather high dispersion must be taken into consideration). The increase is related to the original 28-day concrete compressive strength which varied between 18 and 51 MPa. The compressive strength within a typical reinforced railway concrete trough bridge was approximately 15% higher in the longitudinal beams than in the bottom slab (measured on drilled cores). The tensile strength showed a similar variation as the compressive strength, but the difference could not be statistically verified. Different equations to convert compressive strength into tensile strength have also been studied. The investigation shows that it is important which conversion equation that is used in an assessment situation.

    Download full text (pdf)
    FULLTEXT01
  • 61. Thun, Håkan
    et al.
    Ohlsson, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Tensile fatigue capacity of concrete2007In: Nordic Concrete Research, ISSN 0800-6377, Vol. 36, no 1-2, p. 48-64Article in journal (Refereed)
    Abstract [en]

    Results and analyses are presented from cyclic uniaxial tensile tests on plain cylindrical concrete cores. The influence of the load amplitude and the mean load level were studied with so called factorial design. It was found that both factors were important but that neither of them could be established to be more important than the other. Further, the deformation rate was studied. It appears that a certain fatigue limit exists below which a clearly greater number of load cycles is required for failure. From this research the exact limit cannot be predicted, but for tests with a mean load level of 40% of fpeak and an amplitude of 40% of fpeak, a very low deformation rate has been obtained. Finally, the test results have been compared with other Wöhler curves proposed for cyclic load in tension.

    Download full text (pdf)
    FULLTEXT01
  • 62.
    Täljsten, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering. Sto Scandinavia AB, Linköping, Sweden.
    Sas, Gabriel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering. Norut Narvi AS, Norway.
    Blanksvärd, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering. Skanska Sverige AB, Göteborg, Sweden.
    Strengthening of concrete structures using FRP – a guideline2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 49, p. 113-126Article in journal (Refereed)
    Abstract [en]

    There is a need to retrofit existing concrete structures. There are many different ways to increase the performance of a concrete structure, FRP (Fiber Reinforced Polymer) strengthening being one. This method is commonly used across the world to improve the load carrying capacity of concrete structures. In this paper, an overview of a Swedish guideline for the FRP strengthening of concrete structures is presented. The guideline covers designing for bending and shear as well as for confinement, and there is also a discussion of the need to proper workmanship and the choice of the right material for strengthening.

  • 63.
    Täljsten, Björn
    et al.
    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.
    Strengthening of concrete structures with FRP: a guideline2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 289-292Article in journal (Refereed)
  • 64. Utsi, Sofia
    et al.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Influence of different amount of fly ash for early age concrete containing Swedish cement: Part I: Tendency model for heat and strength development for variable fly ash content2010In: Nordic Concrete Research, ISSN 0800-6377, no 41, p. 77-91Article in journal (Refereed)
    Abstract [en]

    This paper presents a numerical tendency model for evaluation of heat and strength development for concrete containing fly ash in different amounts. With the presented model, parameters for heat and strength development calculations in early age can be calculated. It facilitates the possibility to evaluate e.g. form removal times and estimations of need for protection against early freezing for concrete mixes containing fly ash in different amounts

  • 65. Utsi, Sofia
    et al.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Influence of different amount of fly ash for early age concrete containing Swedish cement: Part II: Calculation of form stripping times and the risk for early freezing for different amounts of fly ash2010In: Nordic Concrete Research, ISSN 0800-6377, no 41, p. 93-108Article in journal (Refereed)
    Abstract [en]

    A recently presented numerical tendency model has been applied on an assumed civil engineering structure. With the model parameters for heat and strength development calculations in early age period can be calculated. This paper shows the possibility to evaluate e.g. form removal times and estimations of need for protection against early freezing for concrete mixes containing fly ash in different amounts, with different water-to-cement ratios and at different outer conditions. The tendency model has shown to be a useful tool for production planning for concrete containing fly ash. According to the performed calculations, any replacement of cement with fly ash will significantly influence the young concrete properties. The effect on delayed strength growth increases with the increased amount of fly ash and will also increase for lower temperatures. In addition, the effect from fly ash increases at higher water-to-cement ratios

  • 66.
    Westman, Gustaf
    et al.
    Luleå University of Technology.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Development of a relaxations test-frame1994In: Nordic Concrete Research, ISSN 0800-6377, Vol. 15, p. 89-96Article in journal (Refereed)
    Abstract [en]

    This paper describes how relaxation tests on young concrete are performed at the Division of Structural Engineering at Luleá University of Technology. The development of a new test machine is presented and some results from pilot tests are given. The presented test method can be used to simulate different thermal stress conditions in the casting of massive concrete structures. This means that it may reduce the need for complicated and expensive full scale tests to ensure that no cracking takes place in newly cast concrete structures. A one meter long concrete beam is poured directly into a form in a steel frame. Temperated air is blown into a box containing the specimen and is circulated around it. In this way the specimen can be given a temperature development which is representative for a specific concrete structure. One of the short ends of the specimen is fixed in the steel frame and the other end is free to move in the longitudinal direction. The position of the free end of the specimen is kept within 0.2 µm from the initial position by a servo-hydraulic cylinder. In this way, nearly 100% restraint is obtained. The force acting on the cylinder is directly proportional to the stresses occurring in the concrete specimen.

12 51 - 66 of 66
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