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  • 151.
    Enochsson, Ola
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hejll, Arvid
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Thun, Håkan
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Bro över Luossajokk: beräkning med säkerhetsindexmetod, böjdragkapacitet i överkant i mittsnittet i korta spannet2002Report (Other academic)
    Abstract [sv]

    I samband med projektet "30 ton på Malmbanan", Paulson-Töyrä (1996), konstaterades att bron över Luossajokk i Kiruna inte klarade de nya förhöjda lasterna. Bron har två spann och en utkragande konsol 10,25 + 6,3 + 3,4 m. Överbyggnaden utgörs av ett slakarmerat betongtråg med ett nytt mellanstöd som uppfördes 1965 då en äldre överbyggnad byttes ut. En klassningsberäkning och en utredning av förstärkningsbehov utfördes. Efter en förnyad översyn av brons bärförmåga utfördes töjningsmätningar vintern och sommaren 2001. Töjningsmätningarna indikerade förvånansvärt små påkänningar i bron. En närmare utredning av brons säkerhet att bära uppträdande laster genomförs därför i denna rapport. Detta sker med hjälp av en nyanserad säkerhetsberäkning med säkerhetsindexmetod. Den nya genomgången visar att medelvärdet för bärförmågan för moment är 2,89 MNm med standardavvikelsen 0,19 MNm i det mest utsatta snittet med dragpåkänningar i överkant i korta spannet. Detta kan jämföras med det formella dimensioneringsvärdet 1,99 MNm som erhölls i klassningsberäkningen med beaktande av aktuella partialkoefficienter. I det nya medelvärdet har en lägre uppmätt effektiv höjd beaktats, att ett av tolv armeringsjärn borrats av samt att betong- och armeringshållfastheterna är högre än de nominella dimensioneringsvärdena. På lastsidan gav klassningsberäkningen i motsvarande snitt att det formella dimensioneringsvärdet för momentet är 2,79 MNm. En analys av verkliga uppträdande laster ger att medelvärdet maximalt uppgår till 2,05 MNm. Detta lastfall utgörs av ett lok placerat med tre axlar i längsta spannet och tre axlar placerade på konsolen, om såväl bromslast som ojämn temperaturlast och dynamiskt tillskott uppträder samtidigt. Enligt BV Bärighet (1996) behöver ojämn temperatur inte beaktas, vilket är rimligt med tanke på att detta är ett statiskt obestämt lastfall som försvinner vid uppsprickning i brottstadiet. Det har heller inte medräknats i tidigare klassningsberäkningar. I så fall fås att lasten har medelvärdet 1,66 MNm och att säkerhetsindex β varierar mellan 3,8 och 6,0 beroende på vilka antaganden som görs om lasternas statistiska fördelning. För en rimlig fördelning innehålls kravet i säkerhetsklass 3 att säkerhetsindex β 4,75. Bron visar sig därför, enligt vår bedömning och med beaktande av erhållna mätresultat, ha erforderlig bärförmåga om hastigheten begränsas på bron så att eventuella dynamiska tillskott blir låga och/eller inverkan av ojämn temperatur försummas. Brons fortsatta uppförande bör kontrolleras genom ett mätprogram. Detta bör förutom armeringstöjningar med befintliga givare även inkludera mätningar av nedböjningar för att säkerställa att använda beräkningsmodeller och randvillkor på ett korrekt sätt återger brons beteende. Storleken på den dynamiska förstoringsfaktorn D bör även mätas liksom inverkan av bromskrafter och ojämn temperaturfördelning. På så sätt kan ett säkrare underlag erhållas för bedömning av frekvensfunktionerna för dessa vanliga lasteffekter. Dessa värden borde även vara av intresse vid säkerhetsbedömning av likartade järnvägsbroar.

  • 152. Utsi, Sofia
    et al.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Täljsten, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Health monitoring of a CFRP strengthened bridge2001In: Composites in construction: proceedings of the International Conference Composites in Construction - CCC2001 / [ed] J. Figueiras, Lisse: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 2001, p. 745-749Conference paper (Refereed)
  • 153.
    Täljsten, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Liljenfeldt, Lars
    Luleå tekniska universitet.
    Horrigmoe, Geir
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    INTERREG: Uppgradering och övervakning av bygg- och anläggningskonstruktioner2001Report (Other academic)
    Abstract [sv]

    Föreliggande rapport är en sammanställning av ett samnordiskt projekt där de ingående medlemmarna är från Sverige och Norge. Den Norska representanten är Norut teknologi as från Narvik och de Svenska SICOMP AB från Piteå, Luleå Tekniska Universitet, Avdelningen för Konstruktionsteknik samt Skanska AB. Projektet har fokuserat på uppgradering och övervakning av bygg- och anläggningskonstruktioner. Syftet med projektet har varit att närmare studera en förstärkingsmetod där kolfiberväv eller kolfiberlaminat limmas till ytan av en konstruktion för att öka dess bärförmåga och styvhet. Dessutom har ett webb-baserat mät- och registreringssystem utvecklats. Målsättningen har varit att man skall kunna klassificera en konstruktion efter verkligt uppförande. En aktiv övervakning ska kunna ge förslag när en insats behövs. Här kan då förstärkning med kolfiberkomposit var ett alternativ. Rapporten redovisar även kortfattat två fälttillämpningar. En förstärkning med distansmätning på en järnvägsbro i Luleå samt distansmätnng och utvärdering av påkänningar i en siloanläggning belägen i Lidköping. Erfarenheterna från projektet är positiva och såväl en förbättrad förstärkningsmetod som ett system för att mäta på konstruktioner har tagits fram.

  • 154.
    Groth, Patrik
    et al.
    Luleå tekniska universitet.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Brottmekanisk modellering av sprickbildning i ung betong2000In: Bygg & Teknik, ISSN 0281-658X, no 7, p. 27-28Article in journal (Other (popular science, discussion, etc.))
  • 155.
    Godonou, Patrice
    et al.
    Luleå tekniska universitet.
    Liljenfeldt, Lars
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Development and conceptual design of a pedestrian bridge using fibre reinforced composites2000In: Advanced composite materials in bridges and structures / [ed] J. L. Humar, Montréal: Canadian Society for Civil Engineering , 2000, p. 339-345Conference paper (Refereed)
  • 156.
    Godonou, Patrice
    et al.
    Luleå tekniska universitet.
    Liljenfeldt, Lars
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Preliminary design analysis of a pedestrian FRP bridge deck using sandwich construction2000In: Proceedings of the 3rd Nordic Meeting on Materials and Mechanics: 8-11 May 2000 / [ed] Ryszard Pyrz; Nikolaj Vejen; Jan Schjødt-Thomsen, Aalborg: Inst of mechanical engineering, Aalborg university , 2000, p. 175-180Conference paper (Refereed)
  • 157.
    Noghabai, Keivan
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Gustafsson, Jonas
    Luleå tekniska universitet.
    Fibre reinforced high strength concrete beams in shear1999In: High strength concrete : first international conference: proceedings ; July 13 - 18, 1997, Kona, Hawaii / [ed] Atorod Azizinamini; David Darwin; Catherine French, American Society of Civil Engineers (ASCE), 1999, p. 480-193Conference paper (Refereed)
  • 158. 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)
  • 159.
    Noghabai, Keivan
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Effect of tension softening of concrete on the tension stiffening of rebars in plain and fibrous concrete1998In: Fracture mechanics of concrete structures / [ed] Keitetsu Rokugo; Hirozo Mihashi, AEDIFICATIO Publishers , 1998, Vol. Vol. 3, Structural applications and size effect, p. 1547-1556Conference paper (Refereed)
    Abstract [en]

    Tension stiffening effect on rebars embedded in concrete prisms are investigated through computational as well as analytical methods and compared with experimental results. Both metallic (steel) and non-metallic (polyolefin and carbon) fibres of different dimensions are used in high-strength concrete. The softening behaviour of concrete determined by a uniaxial tensile procedure, was used in FEM and analytical models. The tension stiffening effect may be more dependent on the tensile behaviour of the concrete than on a relative slip between rebar and concrete

  • 160.
    Ohlsson, Ulf
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nyström, Mikael
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Waagaard, Knut
    Influence of hydraulic pressure in fracture mechanics modelling of crack propagation in concrete1998In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 31, no 3, p. 203-208Article in journal (Refereed)
    Abstract [en]

    This paper presents a nonlinear fracture mechanics analysis of a part of an offshore concrete structure. The analysis focuses on the risk of cracking between the prestressing ducts in the shaft of the submerged platform. The influences of water and grout pressure in prestressing ducts have been taken into consideration. The analysis has been performed using both discrete and smeared crack analysis.

  • 161.
    Noghabai, Keivan
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Load carrying capacity of beams using fibres as shear reinforcement1998In: Fracture mechanics of concrete structures / [ed] Keitetsu Rokugo; Hirozo Mihashi, AEDIFICATIO Publishers , 1998, Vol. Vol. 3, Structural applications and size effect, p. 1491-1500Conference paper (Refereed)
    Abstract [en]

    The load bearing capacity of reinforced beams of fibrous high- strength concrete is investigated, experimentally and computationally. Both metallic (steel) and non-metallic (polyolefin and carbon) fibres are used, keeping the volume fraction to 1%. A nonlinear truss model is outlined which incorporates most of the pertinent mechanisms in the experiments, including the rebar-to-concrete bond and crack widths. The law for evolution of stable growth of local cracks in the structure is based on the response of uniaxial tensile tes

  • 162.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Tano, Robert
    Luleå tekniska universitet.
    Klisinski, Marek
    Luleå tekniska universitet.
    Stress locking in the inner softening band method: a study of the origin and how to reduce the effects1998In: Computational modelling of concrete structures: proceedings of the Euro-C 1998 conference on Computational modelling of concrete structures, Badgastein, Austria, 31 March - 3 April 1998 / [ed] René de Borst, Taylor and Francis Group , 1998, Vol. 1, p. 329-335Conference paper (Refereed)
  • 163. Noghabai, Keivan
    et al.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Fracture mechanics applied to bond1997In: 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. 57-64Conference paper (Refereed)
  • 164.
    Ohlsson, Ulf
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Mixed-mode fracture and anchor bolts in concrete analysis with inner softening bands1997In: Journal of engineering mechanics, ISSN 0733-9399, E-ISSN 1943-7889, Vol. 123, no 10, p. 1027-1033Article in journal (Refereed)
    Abstract [en]

    The paper presents a nonlinear fracture mechanics analysis of mixed-mode fracture and anchor pullout in concrete. The analysis is based on elements with inner softening bands (ISB). A major advantage of the ISB approach is that discrete cracks can be introduced anywhere and in any direction within the finite-element mesh. Calculated loads, deformations, and crack patterns are compared to experimental results. A good correspondence is achieved.

  • 165.
    Groth, Patrik
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Size effects on flexural toughness of steel fibre reinforced concrete1997In: 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. 271-278Conference paper (Refereed)
  • 166.
    Noghabai, Keivan
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Computational modelling of bond using the inner softening band approach1996In: Proceedings: Nordic Concrete Research Meeting, Espoo, Finland 1996, Oslo: Norsk Betongforening , 1996, p. 190-191Conference paper (Refereed)
  • 167.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Emborg, Mats
    Jonasson, Jan-Erik
    High performance concrete structures: a Swedish research program1996In: Concrete in the service of mankind. 4, Radical concrete technology: proceedings of the international conference held at the University of Dundee, Scotland, UK on 24-26 June 1996 / [ed] Ravindra K. Dhir; Peter C. Hewlett, London: Taylor and Francis Group , 1996, Vol. 4, p. 141-150Conference paper (Refereed)
  • 168.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Noghabai, Keivan
    Luleå tekniska universitet.
    Modelling of concrete using fracture mechanics in finite element1996In: Proceedings: Nordic Concrete Research Meeting, Espoo, Finland 1996, Oslo: Norsk Betongforening , 1996, p. 188-189Conference paper (Refereed)
  • 169.
    Gabrielsson, Henrik
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Seghet i högpresterande betongkonstruktion1996In: Byggforskning : Byggforskningsrådets tidning för en bättre byggd miljö, ISSN 1102-3686, no 3, p. 42-Article in journal (Other (popular science, discussion, etc.))
  • 170.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Ohlsson, Ulf
    A simple fracture mechanics model for mixed-mode failure in concrete1995In: Fracture mechanics of concrete structures: proceedings of the Second International Conference on Fracture Mechanics of Concrete Structures (FRAMCOS 2) held at ETH Zurich, Switzerland, July 25 - 28, 1995 / [ed] Folker H. Wittmann, AEDIFICATIO Publishers , 1995, Vol. 1, p. 473-482Conference paper (Refereed)
  • 171. Ohlsson, Ulf
    et al.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Anchor bolts in concrete structures: finite element calculations based on inner softening bands1995In: Fracture mechanics of concrete structures: proceedings of the Second International Conference on Fracture Mechanics of Concrete Structures (FRAMCOS 2) held at ETH Zurich, Switzerland, July 25 - 28, 1995 / [ed] Folker H. Wittmann, AEDIFICATIO Publishers , 1995, Vol. 2, p. 1545-1554Conference paper (Refereed)
  • 172.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Noghabai, Keivan
    Ohlsson, Ulf
    Elfgren, Lennart
    Anchorage and bond properties in concrete1995In: Fracture of brittle, disordered materials: concrete, rock and ceramics : proceedings of the International Union of Theoretical and Applied Mechanics (IUTAM) Symposium on Fracture of Brittle, Disordered Materials: Concrete, Rock and Ceramics / [ed] G. Baker; B.L. Karihaloo, London: Taylor and Francis Group , 1995, p. 525-543Conference paper (Refereed)
  • 173.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Noghabai, Keivan
    Ohlsson, Ulf
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Applications of fracture mechanics to anchors and bond1995In: Fracture mechanics of concrete structures: proceedings / [ed] Folker H. Wittmann, AEDIFICATIO Publishers , 1995, p. 1685-1694Conference paper (Refereed)
  • 174.
    Noghabai, Keivan
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elfgren, Lennart
    Bond between concrete and reinforcement modelled by fracture mechanics1995In: Proceedings of Nordic Symposium on Modern Design of Concrete Structures / [ed] Kirsten Aakjaer, Aalborg: Department of Building Technology and Structural Enginering, Aalborg University , 1995, p. 85-96Conference paper (Refereed)
  • 175.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Klisinski, Marek
    Tano, Robert
    Mixed mode cracking of concrete modeled by inner softening band1995In: Computational plasticity : fundamentals and applications: proceedings of the fourth international conference held in Barcelona, Spain, 3th - 6th April, 1995 / [ed] D. R. J. Owen, Pineridge Press , 1995, p. 1595-1606Conference paper (Refereed)
  • 176.
    Klisinski, Marek
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Tano, Robert
    Luleå tekniska universitet.
    Modelling of cracking of concrete with mixed mode inner softening band1995In: Engineering mechanics: proceedings of the 10th conference / [ed] Sture Stein, American Society of Civil Engineers (ASCE), 1995, p. 1095-1098Conference paper (Refereed)
    Abstract [en]

    The inner softening band approach is used to model the mixed mode (mode I and II) cracking of concrete. The softening behaviour is attributed to a displacement discontinuity within an element. The constitutive relation between tractions and relative displacements is based on the Mohr-Coulomb criterion with tension cut-off. Softening affects both the tensile strength and the cohesion of the material. The cracking pattern is controlled by an energy criterion leading to fairly unique results. Some numerical examples show that the results are objective and independent, to a certain degree, on finite element mesh

  • 177.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Noghabai, Keivan
    Luleå tekniska universitet.
    Veljkovic, Milan
    Computational modelling of interaction between concrete and steel1994In: Diana World, no 1, p. 8-10Article in journal (Other academic)
  • 178.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Klisinski, Marek
    Luleå tekniska universitet.
    Nedar, Patrik
    Inner softening bands: a new approach to localization in finite elements1994In: Computer modelling of concrete structures: proceedings of EURO-C 1994 International Conference held in Innsbruck, Austria, 22nd - 25th March, 1994 / [ed] Herbert Mang, Pineridge Press , 1994, p. 373-382Conference paper (Refereed)
  • 179.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Noghabai, Keivan
    Luleå tekniska universitet.
    Bond properties of high strength concrete1993In: Proceedings: Nordic Concrete Research Meeting : Göteborg 1993, Oslo: Norsk Betongforening , 1993, p. 263-265Conference paper (Refereed)
  • 180.
    Noghabai, Keivan
    et al.
    Luleå tekniska universitet.
    Ohlsson, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bond properties of high-strength concrete1993In: Utilization of High Strength Concrete : Proceedings: Symposium in Lillehammer, Norway / [ed] Ivar Holand, Oslo: Norsk Betongforening , 1993, p. 1169-1176Conference paper (Refereed)
  • 181.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Fatigue tension crack growth in plain concrete a creep problem?1992In: Utmattning av betongkonstruktioner: Nordiskt seminarium, 1992Conference paper (Refereed)
  • 182.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sandkvist, Jim
    Luleå tekniska universitet.
    Ice crushing: failure mechanisms1991Report (Other academic)
    Abstract [en]

    From observations and recorded data it is concluded that the contact consist of a narrow line where the melting is attained at high indentation rates. The theoretical analysis and simulation of experiments indicates that the ratio of shear strength to contact pressure controls the fractal behaviour of ice crushing. The contact pressure and shear strength are related to the indentation velocity. As the indentation rate increases the ratio of shear strength to contact pressure decreases causing finer fragmentation of the crushed ice. At present the 2-D model predicts an upper limit of the ice load similar to the Morgan-Nuttall formula for shear failure of an ice sheet with a friction-less indentor.

  • 183.
    Fransson, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sandkvist, Jim
    Luleå tekniska universitet.
    Observations of the failure process in ice blocks crushed by a flat indentor1991In: POAC '91: 11th International conference on port and ocean engineering under arctic conditions : Papers / [ed] D B Muggeridge; D B Colbourne; H M Muggeridge, St. John's, N.L: St Johns University , 1991, Vol. 1, p. 501-514Conference paper (Refereed)
  • 184.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    A non-linear model for the mechanical behaviour of continuous rock joints1985In: Fundamentals of rock joints: proceedings of the International Symposium on Fundamentals of Rock Joints, Björkliden, 15-20 September 1985 / [ed] Ove Stephansson, Luleå: CENTEK , 1985, p. 395-404Conference paper (Refereed)
  • 185.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Mathematical modelling of jointed rock masses1985Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, a theoretical model of the mechanical behaviour of jointed rock masses is developed. An equivalent material approach is used to formulate the constitutive equations, where the structural components, intact rock and joints are assigned continuous material properties. The elastic and inelastic properties of the joints are modelled by an elasto-viscoplastic formulation. The model can be used to study general stress and strain paths for both two- and three-dimensional structures based on constitutive equations, i.e. stress-strain relations or in finite element codes. The rock mass model using the equivalent material approach can be applied to hard rock masses with several sets of intersecting continuous joints. The theoretical model developed for a single joint can also be used for discrete formulation of joint elements in finite element codes, cf. chapter 3. The intact rock is treated as a linearly elastic material. The elastic behaviour of the joint is modelled with a constant stiffness matrix. The onset of plastic flow is initiated when the normal stress exceeds the normal compressive strength of the joint asperities or the tensile normal strength of the joint. the shear stress exceeds the cohesive strength and frictional resistance of the joint surface. The normal tensile strength and the cohesion of the joints are assumed to be constant material properties. The frictional parameters the dilation rate, and the shear asperity angle, and the compressive normal strength are functions of the the compressive normal strength are functions of the applied stress field and joint displacement. Simple relations based on Barton's constants joint roughness coefficient, JRC, joint compressive strength, JCS, and the residual friction angle, 0r, simple relations are fitted to these parameters. This implies that input data to the model can be extracted from the Rock Mechanics literature for a wide variety of joints. Results from laboratory shear box test and numerical calculations has been made for a number of different joints. Good agreement was obtained. It shows, that peak shear strength behaviour of joint in principal is a function of dilation rate. Further, the calculations indicated that the elastic off-diagonal behaviour of joints, reported in the rock mechanics literature, is related to the dilation angle at the asperities in contact. By means of finite element technique the model is applied to a circular opening in a jointed rock mass. It is concluded that the model offers several advantages over a discrete formulation.

  • 186.
    Larsson, H.
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Stephansson, Ove
    Luleå tekniska universitet.
    Reinforcement of jointed rock mass: a non-linear continuum approach1985In: Fundamentals of rock joints: proceedings of the International Symposium on Fundamentals of Rock Joints, Björkliden, 15-20 September 1985 / [ed] Ove Stephansson, Luleå: CENTEK , 1985, p. 567-577Conference paper (Refereed)
  • 187.
    Larsson, Hans
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bolt action in jointed rock1984In: Rock bolting : theory and application in mining and underground construction: proceedings of the International symposium on rock bolting, Abisko, 28 August - 2 September 1983 / [ed] Ove Stephansson, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1984, p. 33-46Conference paper (Refereed)
    Abstract [en]

    A constitutive elasto-viscoplastic model is presented which combines the properties of the jointed rock mass and the rock bolt system. Different mechanisms of single joint-bolt systems are analyzed. Mechanisms like axial straining, tension-stiffening (due to bonding between grouted bolts and rock) and dowel action are included in the model. Stiffness properties are derived from pull-out tests on single bolts. The various stiffnesses and compliances from multi-directional joint sets and bolt sets are superimposed with intact rock properties in a model of the rock mass.

  • 188.
    Swan, Graham
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    A multi-purpose rock core testing device1983In: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 6, no 1, p. 18-23Article in journal (Refereed)
    Abstract [en]

    The need for a multi-purpose rock tester that incorporates a microcomputer for logging and evaluation purposes is identified. A number of semistandard test methods adaptable to such a tester are examined and found suitable from the point of view of simplicity, cheapness, and accuracy of determination. Some design aspects of this tester in its present state of development are considered

  • 189.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sandwichelement av betong med ofullständig samverkan1983Report (Other academic)
  • 190.
    Alm, Ove
    et al.
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Attempt to make accurate measurements of deformations of compressible soilds at high pressure and different states of stress1982In: High pressure in research and industry: 8th AIRAPT Conference, 19th EHPRG Conference, 17 - 22 August 1981, Institte of Physical Chemistry, University of Uppsala, Sweden ; proceedings / [ed] C.-M. Backman, Uppsala: Fysikalisk-kemiska inst., Univ , 1982, p. 619-622Conference paper (Refereed)
  • 191.
    Alm, Ove
    et al.
    Luleå tekniska universitet.
    Norin, Jonas
    Luleå tekniska universitet.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Experimentella bestämningar av mekaniska egenskaper för hårdmetallpulver: slutrapport över pilotstudie1982Report (Other academic)
  • 192.
    Fransson, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Holm, Ingvar
    Istryck mot en bropelare i Lule älv, vintern 1981/821982Report (Other academic)
  • 193.
    Olofsson, Thomas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Liljenfeldt, Hans
    Luleå tekniska universitet.
    Kraftöverförande svetsförband mellan armering och ståldetaljer: undersökning av vanligt förekommande förbandstyper inom betongelementindustrin1982Report (Other academic)
  • 194.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elastic properties of composite cracked bodies: a theoretical study with application to rock analysis1980Report (Other academic)
  • 195. Hehenberger, Michael
    et al.
    Samuelsson, Peter
    Nilsson, Larsgunnar
    Högskolan i Luleå.
    Alm, Ove
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    On the compaction of hard metal powders: preliminary experimental and theoretical studies1980Report (Other academic)
1234 151 - 195 of 195
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