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  • 51.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Test of wall cast on slab: typical cases 1 - 5 in IPACS expert system2001Report (Other academic)
  • 52.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Thermal cracking of young concrete: partial coefficients, restraint effects and influence of casting joints2000Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Cracks can occur due to temperature induced movements during the hardening phase of concrete. Thermal cracks are not decisive for the load-bearing capacity but cause costs for repair and may reduce the life of the structure. The risk of cracking can be judged through safety values, (partial coefficients) given in building codes. In the thesis, partial coefficients for thermal cracking problems are determined with a probabilistic model. One crucial parameter influencing the risk of cracking is the restraint. In the report, methods are derived and presented for the determination of the restraint. Rotational boundary restraint from elastic foundations is treated as well as the restraint in internal points in the structures. For the determination of the rotational boundary restraint coefficient, applicable and simple graphical tools are presented. The restraint in internal points is based on a so-called plane-section restraint coefficient, a resilience factor for structures with length to height ratios smaller than seven, and a factor for slip failures in joints between the young and old parts. Four experiments of walls cast on slabs are presented in the thesis. On a precast slab, concrete walls are cast and loaded by restraint stresses induced by the temperature during the hydration. Different boundary restraint situations are used for the structure as well as different amount of reinforcement in the joint between the walls and the slab. The restraint and the amount of reinforcement are investigated regarding the risk of through cracking of the wall. The phenomenon of slip failure in joints has been shown in the tests.

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  • 53.
    Nilsson, Martin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Edelbro, Catrin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Edström, Kristina
    Kungliga tekniska högskolan, KTH.
    Adapting Cdio To Civil Engineering: Investigate – Plan – Design – Construct – Operate And Maintain2016In: The 12th International CDIO Conference: Proceedings – Full papers / [ed] Jerker Björkqvist; Kristina Edström; Ronald J. Hugo; Juha Kontio; Janne Roslöf; Rick Sellens; Seppo Virtanen, Turku, 2016, p. 164-172Conference paper (Refereed)
    Abstract [en]

    The aim of this paper is to propose an alternative expression for engineering practice in the context of the civil engineering and built environment sector. Our first objective is to demonstrate that the CDIO approach can, with these modifications, be applied in developing civil engineering and built environment programs. Our second objective is to showcase the adaptability of the CDIO approach, thereby encouraging other thoughtful modifications and transformations. We outline the ideas underpinning the original expression, and identify the role it plays in the CDIO methodology for curriculum development. Taking these factors into account, a modified expression is proposed to describe the engineering process in civil engineering and built environment. We divide the process into ‘investigation – planning – design – construction – operation and management’. Further, to ‘products, processes and systems’, we propose the addition of ‘environments’.

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  • 54. Nilsson, Martin
    et al.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Partial coefficient for thermal cracking problems determined by a probabilistic method2003In: Nordic Concrete Research, ISSN 0800-6377, Vol. 27, p. 107-125Article in journal (Refereed)
    Abstract [en]

    The aim of this work is to calculate partial coefficients for thermal cracking problems of young concrete and to compare the results with the values stated in the Swedish building code for bridges, [1]. The code values are only based on experiences and logical reasoning, whereas the calculated values form a more theoretical base for their determination. The coefficients are calculated with a probabilistic method. Various different possible variations of the used variables have been studied showing the wide range of possible results depending on the input. However, with use of material properties and reasonable assumptions related to thermal cracking problems, fairly good agreement has been found between the stated values in the Swedish code [1] and the values obtained through the probabilistic method. The calculated values are based on many assumptions and assumed values and should therefor not be seen as what is right but rather more as an indication on the reasonableness of the values stated in the Swedish code. Further investigations, calculations and judgements should be performed before wider conclusions can be drawn.

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  • 55. Nilsson, Martin
    et al.
    Emborg, Mats
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wallin, Kjell
    Sprickrisker i gjutfogar belastade med tvångsspänningar1998In: Bygg och Teknik, ISSN 0281-658X, E-ISSN 2002-8350, no 7, p. 24-26Article in journal (Other (popular science, discussion, etc.))
  • 56.
    Nilsson, Martin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Eriksen, Jörgen
    Luleå University of Technology.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Towards a better understanding of behaviour of bridges with integral abutments2008In: Composite construction in steel and concrete VI: proceedings of the 2008 conference, July 20 - 24, 2008, Devil's Thumb Ranch, Tabernash, Colorado / [ed] Roberto T. Leon, Reston: American Society of Civil Engineers (ASCE), 2008, p. 717-727Conference paper (Refereed)
    Abstract [en]

    One of the issues that has not been completely resolved in bridges built without expansion joints is the influence of seasonal temperature variations and soil characteristics on the maximum bridge length. To study this problem, a 40 meter long road composite bridge over the river Leduân in the north of Sweden was built in 2005. The bridge superstructure was cast integrally with the substructure. One row of piles on each side of the bridge was constructed to support the abutment. The bridge was continuously monitored for 18 months in order to provide information on the strain level at the top of the pile as a function of the air temperature variations. The results from the measurements were compared to results obtained from 2D Finite Element Analysis. Soil characteristics were varied in the FEA to investigate its influence on the overall bridge behaviour as well as on the level of strain variations at the top of the piles. The bridge monitoring was a part of a research project, INTAB, Economic and Durable Design of Composite Bridges with Integral Abutments, 2005-2008. The main objective of the project was to propose recommendations for rational analysis and design of bridges with integral abutments. The total environmental impact and the life cycle costs of the integral abutment bridge were compared with a concrete bridge alternative for the same crossing

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  • 57. Nilsson, Martin
    et al.
    Husson, Wylliam
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Petursson, Hans
    Monitoring of a bridge with integral abutment2007In: Improving Infrastructure Worldwide: IABSE symposium, Weimar 2007, [September 19 - 21, 2007] ; report / [ed] Ulrike Kuhlmann, Zürich: International Association for Bridge and Structural Engineering, 2007Conference paper (Refereed)
    Abstract [en]

    Preliminary results obtained from short term test-loading are used to illustrate possibilities of FEM used to calibrate complex interaction characteristics between a pile and soil in a bridge with integral abutments. The measurements are obtained during the winter season on the bridge over Ledån, Northern Sweden. The bridge is built in 2006 and used for long term monitoring within the international project supported by RFCS. The main objective of the on-going research project is to proposed recommendations for rational analysis and design of bridges with integral abutments.

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  • 58.
    Nilsson, Martin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Wallin, Kjell
    Emborg, Mats
    Bernander, Stig
    Elfgren, Lennart
    Crack prevention in walls and slabs: the influence of restraint1999In: Innovation in concrete structures: design and construction: design and construction ; proceedings of the international conference held at the University of Dundee, Scotland, UK on 8-10 September 1999 / [ed] Ravindra K. Dhir; M. Roderick Jones, London: Thomas Telford Ltd , 1999, p. 461-471Conference paper (Refereed)
  • 59.
    Nilsson, Martin
    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. Heidelberg Materials Cement Sverige, Sweden.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Heidelberg Materials Cement Sverige, Sweden.
    Hösthagen, Anders
    Betong & Stålteknik, Sweden.
    Westerholm, Mikael
    Heidelberg Materials Cement Sverige, Sweden.
    Materialdata för beräkning av temperatur, hållfasthet och spänningar – betong med AnlFA-cement, flygaska och slagg2024Report (Other academic)
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  • 60.
    Nilsson, Martin
    et al.
    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.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Effects of surface reinforcement on bearing capacity of concrete with anchor bolts2011In: Nordic Concrete Research, ISSN 0800-6377, Vol. 2011, no 44, p. 161-174Article in journal (Refereed)
    Abstract [en]

    66 tests of the influence of surface reinforcement on the tensile load capacity of cast-in fasteners have been carried through. In the tests threaded rods ∅30 mm with a ∅45 mm nut at the end were cast-in centrically in concrete slabs (1.2 m × 1.2 m × 0.3 m up to 2.2 m × 2.2 m × 0.6 m). The amount of surface reinforcement was varied from 0% up to about 1.2%. There is a considerable increase in the load capacity with surface reinforcement present. The increase depends on the geometry and the amount and placement of the reinforcement.

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  • 61. Nilsson, Martin
    et al.
    Ohlsson, Ulf
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Partialkoefficienter för hållfasthet i betongbroar längs Malmbanan1999Report (Other academic)
    Abstract [sv]

    Denna rapport redovisar två metoder att bestämma nyanserade värden på betonghållfasthetens partialkoefficienter för befintliga betongbroar längs Malmbanan. Rapporten presenterar därefter dimensionerande drag- och tryck-hållfasthetsvärden för sju broar mellan Luleå och Boden. Hållfasthetsvärden är baserade dels på de nya partialkoefficienterna, dels på provresultat, Thun et al (1999). Provresultaten ligger till grund för karakteristiska hållfasthetsvärden som bestämts enligt BBK94 (1995). Partialkoefficienter för hållfasthetsvärdena har bestämts med vad som i rapporten benämns tabellmetoden och sannolikhetsteoretisk metod. Tabellmetoden är hämtad från NKB (1978) och NKB (1987). Metoden bygger, som namnet indikerar, på tabeller varur fyra delfaktorer till partialkoefficienten bestäms. Faktorerna behandlar (1) osäkerheter i karakteristiska värden och i förhållandet mellan hållfasthet i konstruktion och i provkropp etc.; (2) osäkerheter i beräk-ningsmodeller; (3) brottkaraktär (segt eller sprött) och (4) omfattningen av kontroll vid uppförandet av broarna. Den sannolikhetsteoretiska metoden för att bestämma partialkoefficienter tar i sin tur också hänsyn till osäkerheter i karakteristiska värden, i förhållandet mellan hållfasthet i konstruktion och i provkropp och osäkerheter i beräkningsmodeller. Metoden tar även med partialkoefficienter för laster, vilka här har satts till normenliga värden förutom tåglastens partialkoefficient som satts till 1,1 enligt en utredning av Östlund (1997) i bilaga A och används här endast vid statistiska beräkningar och godtas därför inte av Banverket. Inverkan av tåglast och last av betong och ballast ingår. Även broarnas individuella längder beaktas då tåglasternas dynamiska förstoringsfaktorer bestäms. Resultaten av bestämning av partialkoefficienten med tabellmetoden och den sannolikhetsteoretiska metoden ger för de sju broarna mellan Luleå och Boden något skilda resultat. Tabellmetoden ger generellt högre värden än den sannolikhetsteoretiska metoden. Tabellmetodens värden varierar mellan 1,44 och 1,95 för draghållfastheten och mellan 1,44 och 1,48 för tryckhållfastheten. Värdena från den sannolikhetsteoretiska metoden ligger ca 15% lägre. Vi förordar i första hand, på grund av sin enkelhet, att tabellmetoden används vid bestämning av partialkoefficienten. Den sannolikhetsteoretiska metoden är något mer komplicerad och måste ofta kompletteras med kvalificerade bedömningar. De dimensionerande hållfasthetsvärdena som bestäms i rapporten är betydligt högre än de värden som föreskrivna hållfasthetsklasser ger. Den största inverkan på detta har de provade hållfasthetsvärdena, som ligger väsentligt över de föreskrivna värdena. Partialkoefficienternas inverkan är mindre. Rapporten avslutas med en diskussion om inverkan av hållfasthetens variation inom konstruktionsdelar, vilken kan ha stor inverkan på bärförmågan. Likaså har läget för uttagna provkroppar i förhållande till aktuellt beräkningssnitt betydelse. Båda dessa faktorer bör ingå vid en bestämning av hållfastheters partialkoefficienter i befintliga konstruktioner.

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  • 62.
    Nilsson, Martin
    et al.
    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.
    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.
    Fastenings (anchor bolts) in concrete structures: influence of surface reinforcement2012In: 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. 419-422Conference paper (Refereed)
    Abstract [en]

    Tests have been carried out to study the influence of surface reinforcement on the load bearing capacity of cast-in headed bars. In 66 tests, rods with a diameter of Φ30 mm and a Φ45 mm nut at the end, were cast-in place centrically in concrete slabs. Width, length and thickness of the slabs varied from 1.2 m × 1.2 m × 0.3 m up to 2.2 m × 2.2 m × 0.6 m. The top reinforcement varied from 0% to about 1.2% (Φ 16 #100). A considerable increase in the load-bearing capacity was noted. The increase depends on the geometry and the amount and placement of the reinforcement. A numerical model to evaluate the influence is proposed.

  • 63.
    Sabourova, Natalia
    et al.
    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.
    Puurula, Arto
    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.
    Tu, Yongming
    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.
    Nilsson, Martin
    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.
    Thun, Håkan
    The railway concrete arch bridge over Kalix river: dynamic properties and load carrying capacity2012In: 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. 609-612Conference paper (Refereed)
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  • 64.
    Sabourova, Natalia
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Grip, Niklas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Tu, Yongming
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Southeast University, Nanjing, China.
    Wang, Chao
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Southeast University, Nanjing, China.
    Enochsson, Ola
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. Boden Kommun.
    Blanksvärd, Thomas
    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.
    Ohlsson, Ulf
    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.
    Railway Concrete Arch Bridge over Kalix River at Långforsen: Dynamic Properties and Load-Carrying Capacity2019Report (Refereed)
    Abstract [en]

    The concrete arch bridge over Kalix River at Långforsen was built in 1960 and has a mid-span of 89,5 m and a height of 13,7 m. The bridge owner, Trafikverket, wanted to increase its allowable axle load from 225 to 300 kN. Field tests were carried out under service condition and with ambient vibrations. The test results were used to update and validate Finite Element Models. At last, the refined models were used to check the possibility to increase the axle load.

    According to earlier assessments, most parts of the bridge is capable of carrying an axle load of 330 kN. The only critical sections are located in the beams carrying the rail on top of the arch in the section where the beams are united with the arch. Here the stresses in the longitudinal bottom reinforcement are slightly too high.

    These sections have been studied in a FEM model for different loads and results show maximum strains of about 50·10-6 corresponding to stresses of only about 10 MPa in the reinforcement in the critical sections. Live load vertical deflections of the crown of the arch is of the order of only ± 6 mm. Dynamic studies have also been made showing that fatigue is no issue. Altogether the studies show that the bridge is able to carry an increased axle load of 300 kN without problems.

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    App A Drawings
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    App B Design calculations
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    App C Photos construction
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    App D Assessment 2002-04
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    App E Measurements
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    App F FEM
  • 65.
    Stenlund, Anders
    et al.
    Luleå University of Technology.
    Nilsson, Martin
    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.
    D1.4 Railway Bridge Research: A Survey 2005 Sustainable Bridges SB-D1.42005Report (Refereed)
    Abstract [en]

    An overview is reported of current research regarding railway bridges. Research themes and active institutes and organisations are listed.

    The work has been carried out during 2004/2005 in the project “Sustainable Bridges –Assessment for Future Traffic Demands and Longer Lives”, an Integrated Research Projectwithin the Sixth Framework Programme of the European Commission.

    Most of the material has been obtained from the web but personal knowledge and direct communication with some of the institutes/organisations has also been used. An overview like this can never be complete and we apologize for all unintended omissions.

    Research is going on all over the world. The most studied subjects are:

    •  Assessment
    •  Structural behaviour and monitoring
    •  Repair and strengthening
    •  Dynamic effects and vibration
    •  Life cycle analysis
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    Railway Bridge Research
12 51 - 65 of 65
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