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  • 1.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    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.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hösthagen, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simplified methods for crack risk analyses of early age concrete: Part 1: Development of Equivalent Restraint Method2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 46, no 2, p. 17-38Article in journal (Refereed)
    Abstract [en]

    The present study deals with both the compensation plane method, CPM, and local restraint method, LRM, as alternative methods studying crack risks for early age concrete. It is shown that CPM can be used both for cooling and heating, but basic LRM cannot be applied to heating. This paper presents an improved equivalent restraint method, ERM, which easily can be applied both for usage of heating and cooling for general structures. Restraint curves are given for two different infrastructures, one founded on frictional materials and another on rock. Such curves might be directly applied in design using LRM and ERM.

  • 2.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bernander, Stig
    Emborg, Mats
    Gabrielsson, Henrik
    Groth, Patrik
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Nilsson, Martin
    Noghabai, Keivan
    Ronin, Vladimir
    Westman, Gustaf
    Design of high performance concrete structures: a Swedish design handbook1999In: Utilization of high strength/high performance concrete: proceedings : symposium in Sandefjord, Norway 20-24 June 1999 / [ed] Ivar Holand; Erik J. Sellevold, Oslo: Norsk Betongforening , 1999, p. 232-242Conference paper (Refereed)
  • 3. Elfgren, Lennart
    et al.
    Emborg, Mats
    Gabrielsson, Henrik
    Groth, Patrik
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Noghabai, Keivan
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Design of high performance concrete structures in Sweden1998In: International Symposium on High-Performance and Reactive Powder Concretes: organized by Université de Sherbrooke / [ed] Pierre-Claude Aïtcin; Yves Delagrave, Sherbrooke, Que: University of Sherbrooke , 1998, p. 139-156Conference paper (Refereed)
  • 4.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Enochsson, Ola
    Olofsson, Jan
    Skanska Teknik, Göteborg.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Paulsson, Björn
    Banverket, Borlänge.
    Kieksi, Katarina
    Banverket, Borlänge.
    Tillståndsbedömning av betongbroar2006In: Bygg & Teknik, ISSN 0281-658X, Vol. 98, no 7, p. 35-40Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    En vanlig frågeställning för befintliga broar är deras tillstånd: Har bärförmågan minskat med tiden så att bron behöver repareras eller förstärkas? Eller, är det rentav så att man med bättre beräkningsmetoder kan visa att en bro idag klarar att bära en högre last än den som den ursprungligen dimensionerades för?

  • 5. Emborg, Mats
    et al.
    Bernander, Stig
    Ekerfors, Katarina
    Luleå tekniska universitet.
    Groth, Patrik
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Temperatursprickor i betongkonstruktioner: beräkningsmetoder för hydrationsspänningar och diagram för några vanliga typfall. Del A, B och C1997Report (Other academic)
  • 6. Emborg, Mats
    et al.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Groth, Patrik
    Luleå tekniska universitet.
    Temperatursprickor i betong p g a hydratationen för några vanliga typfall1994Report (Other academic)
    Abstract [sv]

    I samråd mellan Vägverket, Div. Väg och Trafik, Sekt. Broteknik (VTb) och Luleå Tekniska Högskola, Avd. för Konstruktionsteknik har ett antal förekommande typfall vid gjutning av betong studerats med avseende på temperaturspänningar på grund av hydratationen. För de studerade typfallen har spänningsanalyser utförtss och diagram framtagits över sprickrisk vid olika förutsättningar t ex gjutförhållanden och dimensioner. Diagrammen ger underlag för mer säkra sprickriskbedömningar än diagraam enbart baserade på temperaturberäkningar. Rapporten är indelad i tre delar. Del A berör hur temperatursprickor kan uppkomma, vilka huvudfaktorer som inverkar på sprickrisken, vilka förhållanden som gäller för aktuella typfall samt hur sprickrisker kan beräknas. I Del B sker en redogörelse för vilka förutsättningar som gäller allmänt vid sprickriskberäkningar och speciellt vid beräkningarna för typfallen. I Del B kommenteras de diagram över sprickrisker som redovisas i Del C. Del B och Del C kan användas separat vid sprickriskbedömningar.

  • 7. Emborg, Mats
    et al.
    Jonasson, Jan-Erik
    Westman, Gustaf
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Crack risk due to thermal and humidity stresses in high performance concrete (EMC)1996In: Proceedings: Nordic Concrete Research Meeting, Espoo, Finland 1996, Oslo: Norsk Betongforening , 1996, p. 56-57Conference paper (Refereed)
  • 8.
    Fjellström, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    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.
    Heat loss compensation for semi-adiabatic calorimetric tests2013In: Nordic Concrete Research, ISSN 0800-6377, Vol. 47, no 1, p. 39-60Article in journal (Refereed)
    Abstract [en]

    Heat of hydration has long been of importance since it affects the temperature levels within a concrete structure, and thus, potentially affects its durability. The only source of energy is the reaction between cement and water. This energy warms up the concrete sample and all the ambient materials. Therefore, in order to model these energies, the TSA (traditional semi-adiabat) setup is transformed into an associated sphere. By this, the temperature distribution and the energies within each layer of the TSA can be calculated. The sum of all energies gives the total heat of hydration. A refined model using a correction factor is introduced, which accounts for energies lost to the TSA setup materials. Results show that the effect of this factor cannot be disregarded, especially not for TSAs with low cooling factors.

  • 9.
    Fjellström, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    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.
    Model for concrete strength development including strength reduction at elevated temperatures2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 45, no 1, p. 25-44Article in journal (Refereed)
    Abstract [en]

    When casting concrete structures, one of the most important properties is the concrete strength development. The need of actions on site is different at various stages of hardening, from the fresh concrete to the hardened concrete. The paper defines a model analysing maturity and associated strength growth within three important time periods. The model can be applied separately within each of these periods depending on test data available.It is shown in the paper that the temperature plays an important role on the strength development of concrete structures. The hydration rate increases with increased temperatures, which can be described by maturity functions. If the concrete temperature remains high, strength reduction at later ages usually occurs compared to hardening at lower temperature, which may be denoted strength reduction at elevated temperatures or cross over effects. Both these phenomena have been implemented in the model for strength growth presented in the paper. The functionality of the model is demonstrated by evaluation of laboratory tests for five concrete mixes and two types of cement.

  • 10.
    Groth, Patrik
    et al.
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Air cooling of concrete by means of embedded cooling pipes: Part II: Application in design1998In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 31, no 210, p. 387-392Article in journal (Refereed)
    Abstract [en]

    This paper relates the second part of the investigation of air-cooling in concrete; the first part is presented in `Air cooling of concrete by means of embedded cooling pipes Part I: Laboratory tests and heat transfer coefficients'. Embedded cooling pipes are used to reduce the risk of thermal cracking in early age concrete. Traditionally, water has been used as a cooling medium, but air cooling has been shown to be advantageous for many applications. The experimentally-determined heat transfer coefficients of cooling pipes, have been used and verified in comparisons of in situ measurements at the Igelsta Bridge in Sodertalje, Sweden. The close agreement between measured and calculated temperatures of air-cooled sections seems to justify the use of the averaged heat transfer coefficients determined in [1]. Some exemplifying calculations are also shown, and the general behaviour of cooled structures is discussed. The principles of designing a cooling system for a general case are proposed. It is concluded that it is possible to design prismatic structures, such as a columns, by the use of existing models and measured heat transfer coefficients

  • 11.
    Groth, Patrik
    et al.
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Luftkylning av betong med ingjutna kylrör1996Report (Other academic)
    Abstract [sv]

    Rapporten inleds med en sammanfattande genomgång av tidigare genomfört arbete inom detta projekt vilket redovisas i kapitel 2. Kapitel 3 innefattar en redovisning av de fältmätningar som utförts inför denna del av projektet på Igelstabrons enkelspårspelare. Som en uppföljning till fältmätningarna har även laboratorieförsök utförts i syfte att finna värmeövergångstal för kylrör, dessa återfinns i kapitel 4. Till sist har ett antal beräkningar avseende temperaturer och temperaturspänningar genomförts vilka visar en jämförelse mellan uppmätta och beräknade resultat och en del exempelfall vilket finns i kapitel 5. Bilaga A och B innehåller samtliga mätresultat från fältundersökningen och bilaga C innehåller en redovisning av de beräkningsverktyg, HETT2D och TEMPSTRE, som använts. Bilaga D innehåller samtliga resultat från laboratorieförsöken och i bilaga E redovisas de parametrar som använts i exempelberäkningarna.

  • 12.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hardening concrete: measurments and evaluation of non-elastic deformation and associated restraint stresses2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    If a structural member of hardening concrete is restrained to some degree against expansion and contraction during the heating phase of the hydration process and the subsequent contraction phase, stresses will be induced. The issue of primary interest is whether or not these induced stresses will lead to cracking. Volume changes in hardening concrete are not only ruled by the thermal movements. High Performance Concrete (HPC) is usually based on high binder content mixed with small amounts of water. The low water-to-binder ratio leads to significant autogenous deformations, which has to be included in stress analyses. For water-to-cement ratios below about 0.40, self-desiccation results in a significant drop in the pore humidity even at early ages. In contrast to the moisture flux, self-desiccation is reflected all over the structure, and at restraint conditions this may be a significant contribution to the risk of early age cracking. Models for descpition of autogenous shrinkage and different evaluation techniques how to split between moisture and thermal deformations are presented in the thesis. Laboratory tests and modelling in early age of the stresses caused by restraint volume changes have been performed and discussed for high performance and normal strenght concrete. Evaluated parameters are presented for a great number of concrete mixes. It has been shown that all material data for stress calculations can be taken from material related tests on each individual property without any correction when comparison is done with measured stresses in the relaxation test-frame.

  • 13.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Stresses in high performance concrete due to temperature and moisture variations at early ages1996Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents results from laboratory tests and numerical analyses of stress states in concrete structures arising from volume changes due to temperature and shrinkage during hydration. The laboratory tests presented here deal with: the determination of heat transfer coefficients for cooling pipes measurements of self-desiccation and shrinkage under sealed conditions deformation measurements under temperature and moisture changes and measurements of stress development during hardening for a fully restrained structural member. The thesis comprises three papers dealing with the following topics:Paper A - Air cooling of concrete by means of embedded cooling pipes. Laboratory tests of heat transfer coefficientsThis paper presents a laboratory method for determining heat transfer coefficients for cooling pipes. The embedded cooling pipes are used in order to reduce the temperature rise in massive structures as a measure against thermal cracking. When air is used as cooling medium, relative large diameters with surface profiles (roughness) causing friction losses along the pipe are preferable. Heat transfer coefficients for two different types of cooling pipes have been determined for varying pipe flows in combination with different temperature levels. Paper (A) constitutes the first part of the thesis dealing with the laboratory tests on heat transfer coefficients.Paper B - Air cooling of concrete by means of embedded cooling pipes. Application in designPaper B constitutes the second report on the subject air cooling of concrete. Embedded cooling pipes are used in order to reduce the risk of thermal cracking in early age concrete. Traditionally, water has been used as the cooling medium, but air cooling has shown to be advantageous in many applications. The experimentally determined heat transfer coefficients of cooling pipes, investigated in Paper A, have been used and verified in comparisons with in situ measurements at the Igelsta Bridge in Södertälje, Sweden. The close agreement between measured and calculated temperatures of air-cooled sections seems to justify the use of average heat transfer coefficients. A few exemplifying calculations are also given, and the general behaviour of cooled structures is discussed. The principles of designing cooling systems for the general case are proposed. It is concluded that it is possible to design prismatic structures, such as a columns, by the use of existing models and the measured heat transfer coefficients evaluated according to the method presented in Paper A.Paper C - Deformation and Stresses in Hardening Concrete due to Simultaneous Changes in Humidity and Temperature. Laboratory tests and evaluation This paper describes test methods and equipments for determination of strength and maturity growth, heat of reaction, and free thermal deformation. Measurements of shrinkage, relative humidity and stress development are carried out under sealed conditions during hardening of the young concrete. Results for both high performance and normal strength concretes are presented and discussed here. Also, methods for describing shrinkage at sealed conditions as a function of maturity and as a decrease in relative humidity are presented. An evaluation is performed of the free thermal deformation during the hardening of concrete where the deformation is separated into pure thermal deformation and shrinkage. In this context some pilot calculations of non-linear modelling of stress development have been performed taking stress-induced deformations and simultaneous changes in humidity and temperature into account. Calculations are made for a structural member which is fully restrained, i.e. to a degree of 100%. A sensibility analysis of the non-linear stress model is performed and presented.

  • 14.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Groth, Patrik
    Luleå tekniska universitet.
    Air cooling of concrete by means of embedded cooling pipes: Part I: Laboratory tests of heat transfer coefficients1998In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 31, no 5, p. 329-334Article in journal (Refereed)
    Abstract [en]

    Embedded cooling pipes can be used to reduce the temperature rise in massive structures as a measure against thermal cracking. When air is used as a cooling medium, relatively large diameters with profiles causing friction losses along the pipe are preferred. In this paper, heat transfer coefficients for two different types of cooling pipes have been determined for different pipe flows in combination with various temperature levels. This paper relates to the first part of the investigation dealing with the laboratory tests of heat transfer coefficients. The second part, dealing with application in design, is presented in "Air cooling of concrete by means of embedded cooling pipes-Part II: Applications in design"

  • 15.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Groth, Patrik
    Luleå tekniska universitet.
    Jonasson, Jan-Erik
    Reduction of thermal stresses in structures with air-cooling1995In: Thermal cracking in concrete at early ages: proceedings of the international symposium held by RILEM at the Technical Univ. of Munich ..., Oct. 10-12, 1994 / [ed] Rupert Springenschmid, London: Spon press, 1995, p. 433-440Conference paper (Refereed)
  • 16.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Hur skiljer man mellan krympning och temperatur-rörelse?2000In: Bygg & Teknik, ISSN 0281-658X, no 7, p. 12-15Article in journal (Other (popular science, discussion, etc.))
  • 17.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Measurements of self-desiccation and shrinkage of hardening concrete1997In: Moisture Measurement in Concrete Constructions Exposed to Temperature and Moisture Variations: Nordic mini-seminar of the Nordic Concrete Federation, Espoo, Finland 22.8.1997 / [ed] Heikki Kukko; Hemming Paroll, Espoo: Valtion teknillinen tutkimuskeskus. Tie- ja liikennelaboratorio , 1997, p. 73-101Conference paper (Refereed)
  • 18.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Värme- och mognadsutveckling för PK-cement1999Report (Other academic)
  • 19.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Ronin, Vladimir
    Concrete of the future with energetically modified cement (EMC)1996In: Proceedings: Nordic Concrete Research Meeting, Espoo, Finland 1996, Oslo: Norsk Betongforening , 1996, p. 23-24Conference paper (Refereed)
  • 20.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Jan
    Luleå tekniska universitet.
    Restraint analyses and simplifications: typical structure ; wall-on-wall2001Report (Other academic)
  • 21.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Ronin, Vladimir
    Jonasson, Jan-Erik
    Elfgren, Lennart
    Grönare betong1999In: Bygg & Teknik, ISSN 0281-658X, Vol. 91, no 7, p. 12-13Article in journal (Other (popular science, discussion, etc.))
  • 22.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Autogenous deformations and stress development in hardening concrete1998In: Autogenous shrinkage of concrete: proceedings of the international workshop, organised by the JCI (Japan Concrete Institute), Hiroshima, June 13-14, 1998 / [ed] Ei-ichi Tazawa, London: Taylor and Francis Group , 1998, p. 315-326Conference paper (Refereed)
  • 23.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Evaluation and comparison of sealed and non-sealed shrinkage deformation measurements of concrete1998In: Autogenous shrinkage of concrete: proceedings of the international workshop, organised by the JCI (Japan Concrete Institute), Hiroshima, June 13-14, 1998 / [ed] Ei-ichi Tazawa, London: Taylor and Francis Group , 1998, p. 121-132Conference paper (Refereed)
  • 24.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Laboratory tests of self-desiccation and shrinkage under sealed conditions1996In: Proceedings of an International Seminar on Self-desiccation and its Importance in Concrete Technology: Trondheim, 28-29 November 1996, Trondheim: NTNU/SINTEF , 1996, p. 85-140Conference paper (Refereed)
  • 25.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Measurements and modelling of volume change and reactions in hardening concrete1997In: Self-desiccation and its importance in concrete technology: proceedings of an International research seminar in Lund, June 10, 1997 / [ed] Bertil Persson; Göran Fagerlund, 1997, p. 174-192Conference paper (Refereed)
  • 26.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Emborg, Mats
    Jonasson, Jan-Erik
    Bernander, Stig
    Hardening technology for concrete structures1997In: Advanced design of concrete structures: [papers presented at the Symposium on Advanced Design of Concrete Structures, held in Chalmers University of Technology in Göteborg, Sweden on June 12 - 14, 1997] / [ed] Kent Gylltoft, Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 1997, p. 313-318Conference paper (Refereed)
  • 27.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Emborg, Mats
    Jonasson, Jan-Erik
    Bernander, Stig
    Härdningsstyrning av betongkonstruktioner1996In: Byggforskning : Byggforskningsrådets tidning för en bättre byggd miljö, ISSN 1102-3686, no 3, p. 38-39Article in journal (Other (popular science, discussion, etc.))
  • 28.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Jonasson, Jan-Erik
    Analysis of early age cracking in HPC structures1999In: Utilization of high strength/high performance concrete : proceedings: symposium in Sandefjord, Norway 20-24 June 1999 / [ed] Ivar Holand; Erik J. Sellevold, Oslo: Norsk Betongforening , 1999, p. 1134-1143Conference paper (Refereed)
  • 29.
    Hösthagen, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    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.
    Equivalent Restraint Method Correlated to Empirical Measurements2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 505-508Article in journal (Refereed)
    Abstract [en]

    The present study deals with the correlation between numerical models and empirical observations in newly cast concrete specimens. The model used is the equivalent restraint method, ERM, which is established from several local restraint method calculations, LRM. The csating of walls in a tunnel construction is investigated. Correlation between models and empirical measurements is established in three steps.

  • 30.
    Hösthagen, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    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.
    Wallin, Kjell
    Projektengagemang i Stockholm AB.
    Stelmarcik, Marcin
    Thermal crack risk estimations for tunnel: equivalent restraint method correlated to empirical observations2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 49, p. 127-143Article in journal (Refereed)
    Abstract [en]

    The present study deals with the correlation between numerical models and empirical observations in newly cast concrete structures. The model used is the equivalent restraint method, ERM, which is established from several local restraint method calculations, LRM. The casting of walls and roof in a tunnel construction is investigated. Correlation between models and empirical measurements is established in three steps: 1) the restraint situation is analyzed; 2) the calculated temperature developments are compared to empirical temperature measurements to calibrate the models; and 3) calculated strain ratios are compared with observed crack patterns, and in general a good correlation is achieved

  • 31. Jonasson, Jan-Erik
    et al.
    Ekerfors, Katarina
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Modelling of temperature, moisture and stresses in young concrete1996In: Proceedings: Nordic Concrete Research Meeting, Espoo, Finland 1996, Oslo: Norsk Betongforening , 1996, p. 239-240Conference paper (Refereed)
  • 32.
    Jonasson, Jan-Erik
    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.
    Measurement and modelling of strength and heat of hydration for young concrete2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 501-504Article in journal (Refereed)
    Abstract [en]

    Strength development and heat evolution at hydration are two of the most important properties when analysing concrete structures concerning young concrete. The present model for strength development is shown to properly predict the strength development for high early temperatures during hardening stage. The detemination of heat of hydration based on semi-adiabatic test has been refined with respect to the warming up the test equipment.

  • 33. Jonasson, Jan-Erik
    et al.
    Groth, Patrik
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Modelling of temperature and moisture field in concrete to study early age movements as a basis for stress analysis1995In: Thermal cracking in concrete at early ages: proceedings of the international symposium held by RILEM at the Technical Univ. of Munich ..., Oct. 10-12, 1994 / [ed] Rupert Springenschmid, London: Spon press, 1995, p. 45-52Conference paper (Refereed)
  • 34. Jonasson, Jan-Erik
    et al.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Framework for restraint factors: typical cases 1 - 5 in IPACS expert system2001Report (Other academic)
  • 35. Jonasson, Jan-Erik
    et al.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Förbättrade materialbeskrivningar av den unga betongen2001In: Bygg & Teknik, ISSN 0281-658X, Vol. 93, no 7, p. 45-50Article in journal (Other (popular science, discussion, etc.))
  • 36. Jonasson, Jan-Erik
    et al.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Instructions and users guide for ConTeSt12001Report (Other academic)
  • 37.
    Jonasson, Jan-Erik
    et al.
    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.
    Utsi, Sofia
    Creep and shrinkage for structures using dense concrete2006In: Creep, Shrinkage And Durability of Concrete And Concrete Structures: Concreep 7 / [ed] Gilles Pijaudier-Cabot; Bruno Gerard; Paul Acker, ISTE Ltd , 2006, p. 621-626Conference paper (Refereed)
  • 38. Jonasson, Jan-Erik
    et al.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    High performance concrete at severe conditions: creep and shrinkage deformations1998In: Concrete under severe conditions 2: Environment and loading : proceedings of the Second International Conference on Concrete Under Severe Conditions CONSEC '98, Tromsø, Norway, June 21-24, 1998 / [ed] Odd E. Gjørv, London: Taylor and Francis Group , 1998, Vol. 2Conference paper (Refereed)
  • 39.
    Jonasson, Jan-Erik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Lars-Olof
    Lunds tekniska högskola, LTH.
    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.
    Moisture and mechanical properties aimed for crack risk analyses if early age concrete2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 409-412Article in journal (Refereed)
    Abstract [en]

    Within the project Crack-Free-Con - Nordic coordination for sustainable construction by novel shrinkage modelling and user friendly Expert System - a collaborative project between research area of Building Material at LTH and Structural Engineering at LTU a comprehensive test program has been performed. The tests at LTH are concentrated on moisture related properties while the tests at LTU cover mechanical properties and stress development. At present the interesting work to combine the test results from the laboratories are in progress

  • 40. Jonasson, Jan-Erik
    et al.
    Ronin, Vladimir
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    High strength concretes with energetically modified cement and modelling of shrinkage caused by self-desiccation1996In: Fourth International Symposium on Utilization of High Strength/High Performance Concrete: 29 - 31 May 1996, Paris, France; proceedings / [ed] F. de Larrard, Paris: Presses Ponts et Chaussées , 1996, Vol. 2, p. 245-254Conference paper (Refereed)
  • 41. Jonasson, Jan-Erik
    et al.
    Wallin, Kjell
    Emborg, Mats
    Gram, Annika
    Saleh, Iad
    Nilsson, Martin
    Larsson, Mårten
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Handbok med sprickriskbedömning inklusive åtgärder för betongkonstruktioner2001In: Bygg & Teknik, ISSN 0281-658X, Vol. 93, no 7, p. 16-20Article in journal (Other (popular science, discussion, etc.))
  • 42. Jonasson, Jan-Erik
    et al.
    Wallin, Kjell
    Emborg, Mats
    Gram, Annika
    Saleh, Iad
    Nilsson, Martin
    Larsson, Mårten
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Temperatursprickor i betongkonstruktioner: handbok med diagram för sprickriskbedömning inklusive åtgärder för några vanliga typfall. Del D och E2001Report (Other academic)
    Abstract [sv]

    Föreliggande handbok är framtagen i ett SBUF-projekt med Kjell Wallin, Peab som projektledare. Projektet har genomförts i nära samarbete mellan Peab Sverige AB och Luleå tekniska universitet. Arbetet har inneburit att ett stort antal datorberäkningar har genomförts, och de redovisas i diagramform i denna handbok. Resultaten avses att användas att fylla i en blankett i ett Excel-ark. Syftet är att för typfallet vägg-på-platta ska handboken ge underlag för sprickriskbedömning och i förekommande fall ange vilka typåtgärder som ska sättas in. Avsikten är därvid att man inte ska behöva göra några externa beräkningar, men användaren har full frihet att själv ta fram temperaturen eller tvångssituationen på godtyckligt annat sätt. Handboksmetodiken avser en fortsättning på det som i Bronormen (Bro 94, bilaga 9-5) kallas metod 2, och den redovisade kompletteringen innefattar främst att erforderliga åtgärder (kylning och/eller värmning) för det valda typfallet inkluderas.

  • 43. Jonasson, Jan-Erik
    et al.
    Westman, Gustaf
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Creep and shrinkage in high performance concrete: an engineering approach1999In: Utilization of high strength/high performance concrete : proceedings: symposium in Sandefjord, Norway 20-24 June 1999 / [ed] Ivar Holand; Erik Sellevold, Oslo: Norsk Betongforening , 1999, Vol. 1, p. 378-387Conference paper (Refereed)
  • 44.
    Olofsson, Jan
    et al.
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Uhlán, Mathias
    Luleå tekniska universitet.
    Concrete cast on rock: restraint evalutaion2001Report (Other academic)
  • 45.
    Olofsson, Jan
    et al.
    Luleå tekniska universitet.
    Uhlán, Mathias
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    2D and 3D restraint analyses: typical structure : wall-on-slab2001Report (Other academic)
  • 46.
    Olofsson, Jan
    et al.
    Luleå tekniska universitet.
    Uhlán, Mathias
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Slab cast on rock ground: model for restraint estimation2001Report (Other academic)
  • 47.
    Orosz, Katalin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Fjellström, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    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.
    Evaluation of the Linear Logarithmic Creep Model2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 417-420Article in journal (Refereed)
    Abstract [en]

    In order to make reliable predictions of thermal cracking risks in young concrete, modelling of the creep behaviour is important. The linear logarithmic creep model (LLM) has only been used to describe the creep behaviour of moisture-sealed concrete samples (basic creep). The aim of the present research is to check whether LLM could be also applied to drying creep. The results indicate that the LLM delivers good results for sealed but not for drying samples. Thus, refinement of the existing model (e.g., tri-linear instead of bi-linear in logarithmic time scale), or a new model is needed to account for the increase of creep due to on-going drying.

  • 48.
    Orosz, Katalin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Fjellström, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    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.
    Evaluation of Thermal Dilation and Autogenous Shrinkage at Sealed Conditions2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 299-302Article in journal (Refereed)
    Abstract [en]

    As known, load independent deformations are of large importance in structural analysis, e. g. when estimating elongations, restraint stresses, or pre-stressing forces. Two models to describe thermal dilation (TD) and autogenous shrinkage (AS) have been evaluated, for a broader range of w/C ratios and cements types than before. In Model I, AS is determined solely based on the maturity model and TD incorporates two TD coefficients (TDC). In Model II, AS is dependent on both the maturity model and a separate temperature adjustment factor, while TDC is constant. For the more rapid-hardening cement, Model I did not give satisfactory results, whereas the usefulness of Model II to describe both AS and TD has shown to be limited, suggesting that a new model is needed.

  • 49.
    Paulsson, Björn
    et al.
    UIC.
    Olofsson, Jan
    Skanska.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bell, Brian
    Network Rail.
    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.
    Sustainable bridges: results from a European integrated project2010In: Large structures and infrastructures for environmentally constrained and urbanised areas: 34th International Symposium on Bridge and Structural Engineering, Venice, Italy, September 22 - 24, 2010, Zurich: International Association for Bridge and Structural Engineering, 2010Conference paper (Refereed)
    Abstract [en]

    In Europe there are more than 1 million bridges, many of  them older than 50 years and quite a few of the railway bridges even have an age of more than100 years. These bridges represent a large value. Often there is a wish to increase speed and loads on existing bridges and then the question is if a bridge can be strengthened to fulfil the demands, or if it has to be replaced with a new one? This was the background for a European integrated research project within the 6th Framework Programme named "Sustainable Bridges". The project  was carried out between 2003 and 2007 with 32 partners from 12 countries and with a gross budget of more than 10 million Euros.  The aim of the project was to help to increase the use of the European railway network. For bridges, this can only be achieved by allowing higher axle loads on freight vehicles and by increasing the maximum permissible speed of passenger trains. In turn, any strengthening or maintenance work on the existing bridge stock to help in meeting this challenge must be undertaken without causing unnecessary disruption to the carriage of passengers and goods, and without compromising the safety and economy of the working railway. The project has developed many background documents and the following four major guidelines:(a) Inspection and Condition Assessment of Railway Bridges (b) Load and Resistance Assessment of Railway Bridges (c) Monitoring of Railway Bridges (d) Repair and Strengthening of Railway Bridges The results have been tested and demonstrated on several bridges in order to promote better engineering solutions which may produce savings throughout Europe. In the paper reflections on the efficiency and dissemination of the project will be given as well as examples of results and how they now are implemented.  All major results from the project are available at the website http://www.sustainablebridges.net/.

  • 50.
    Rajczakowska, Magdalena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Habermehl-Cwirzen, Karin
    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. Concrete Specialist, Skanska AB, Göteborg.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Autogenous Self-Healing: A Better Solution for Concrete2019In: Journal of materials in civil engineering, ISSN 0899-1561, E-ISSN 1943-5533, Vol. 31, no 9, article id 3119001Article in journal (Refereed)
    Abstract [en]

    Self-healing can be defined as the ability of a material to repair inner damage without any external intervention. In the case of concrete, the process can be autogenous, based on optimized mix composition, or autonomous, when using additionally incorporated capsules containing a healing agent and/or bacteria spores. The first process uses unhydrated cement particles as the healing material while the other utilizes a synthetic material or bacteria released into the crack from a broken capsule or activated through access of water and oxygen. The critical reviewing of both methods indicates that the autogenous self-healing is more efficient, more cost effective, safer, and easier to implement in full-scale applications. Nevertheless, a better understanding of the mechanism and factors affecting the effectiveness of the process is needed. The main weaknesses of the autonomous method were identified as loss of workability, worsened mechanical properties, low efficiency and low probability of the healing to occur, low survivability of the capsules and bacteria in harsh concrete environment, very high price, and lack of full-scale evaluation.

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