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  • 1.
    Balazs, Peter
    et al.
    Försvarets Forskningsanstalt.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Balkar av höghållfast betong belastade med impulslast: Brottmekanisk provning av RILEM-balkar1996Report (Other academic)
  • 2.
    Balazs, Peter
    et al.
    Försvarets Forskningsanstalt.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Brotmekanisk provning av Ballistocrete-, Densit-, och Finpartikelbetongbalkar med impulslast och statisk last1997Report (Other academic)
  • 3.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Evaluation of Punching Shear Strength of Slabs with Shear reinforcementAccording to Eurocode 2 (EN 1992-1-1)2010In: Codes in Structural Engineering : Developments and Needs for International Practice, Zagreb, Croatia: SECON , 2010, p. 927-934Conference paper (Refereed)
  • 4.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Flexural and Shear Capacity of Reinforced High Strength Concrete Beams without Stirrups1994Licentiate thesis, monograph (Other academic)
  • 5.
    Hallgren, Mikael
    KTH, Superseded Departments, Building Sciences and Engineering.
    Punching Shear Capacity of Reinforced High Strength Concrete Slabs1996Doctoral thesis, monograph (Other academic)
  • 6.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Punching Shear on Steel Egde Columns2011In: Nordic Concrete Research: Research Projects 2011 / [ed] The Nordic Concrete Fedaration, Oslo: Norsk Betongforening , 2011, p. 183-186Conference paper (Refereed)
    Abstract [en]

    In the design of flat slabs supported on steel edge columns, the same design method for punching shear as for slabs on ridged concrete columns is usually adopted. This has been questioned, as a slender steel column cannot transfer the hogging moment of the slab which is normally assumed in punching shear design. An alternative design method based on beam shear analogy has been proposed and also been verified by non-linear finite element analyses.

  • 7.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Sustainable design of concrete slabs supported by steel edge and corner columns2012In: fib Symp.: Concr. Struct. Sustainable Community - Proc., 2012, p. 121-124Conference paper (Refereed)
    Abstract [en]

    In the design of flat slabs supported on steel edge columns, the same design method for punching shear as for slabs on ridged concrete columns is usually adopted. This has been questioned, as a slender steel column cannot transfer the hogging moment of the slab which is normally assumed in punching shear design. With a more realistic design model, material savings and a more sustainable design could be achieved.

  • 8.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Utvärdering av bärförmågan vid genomstansning av betongplattor med skjuvarmering enligt Eurokod 22009In: Bygg & Teknik, ISSN 0281-658X, Vol. 101, no 7, p. 49-53Article in journal (Other (popular science, discussion, etc.))
  • 9.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Balazs, Peter
    Försvarets Forskningsanstalt.
    Armerade balkar av höghållfast betong belastade med luftstötvåg1999Report (Other academic)
  • 10.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Bjerke, Mats
    Scandiaconsult.
    Non-linear finite element analyses of punching shear failure of column footings2002In: Cement & Concrete Composites, ISSN 0958-9465, E-ISSN 1873-393X, Vol. 24, no 6, p. 491-496Article in journal (Refereed)
    Abstract [en]

    Current design methods and code formulas for the assessment of the punching shear strength are normally based on tests on slabs with relatively high slenderness, i.e., with high shear-span to depth ratios. Column footings normally have low shear-span to depth ratios. Previous punching tests on column footings indicate that the failure mechanism for punching of slabs with low shear-span to depth ratios differs from that of slabs with high shear-span to depth ratios. In this investigation, punching tests on two circular column footings of reinforced concrete were simulated numerically. The results show how the failure mechanism differs from that of more slender slabs. A parametric study also confirms that the punching shear strength of the analysed slabs strongly depends on the compressive strength of concrete.

  • 11.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures. Tyréns AB, Sweden.
    Eriksson, I.
    Karlsson, N.
    Numerical simulations of a concrete bridge deck loaded to shear failure2017In: High Tech Concrete: Where Technology and Engineering Meet - Proceedings of the 2017 fib Symposium, Springer, 2017, p. 1898-1906Conference paper (Refereed)
    Abstract [en]

    This paper presents numerical simulations of the shear failure of a bridge slab previously tested in full scale on an existing bridge. Using the non-linear finite element method, a model of the bridge is assembled with the purpose to simulate the test procedure and realistically capture the failure load and behaviour. This in order to conclude what type of shear failure that occurred. Furthermore, the shear capacity of the bridge is calculated according to current design codes. A parametric study is conducted on the FE model with the aim to study the influence of key variables on the outcome of the analyses. From the studied parameters, it is observed that a combined reduction of the tensile strength and fracture energy, together with a low fixed crack coefficient has the largest influence. It is also observed that the location of the failure and the ultimate load is dependent on how the loading was applied to the model, i.e. via load control or deformation control. In the final FE analysis, the model fails at a load which slightly exceeds the experimental ultimate load. The mode of failure obtained in all the analyses are the result of a large shear crack propagating from the edges of the loading plate, through the slab to the slab/girder-intersection. This indicates that the type of failure that occurred in the full scale test was primarily due to a one-way shear mechanism with a secondary punching effect. The design values calculated with current codes results in very conservative values when compared to the obtained failure load from the experiment.

  • 12.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Kaklauskas, Gintaris
    Technical University of Vilnius.
    Curvature Analysis of Experimental High Strength Concrete Beams1999In: Statyba Civil Engineering, ISSN 1392-1525, Vol. V, no 6, p. 357-363Article in journal (Refereed)
  • 13.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Kinnunen, Sven
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Punching Shear Tests on Circular High Strength Concrete Slabs without Shear Reinforcement1991In: Nordic Concrete Research, ISSN 0800-6377, no 10, p. 37-47Article in journal (Refereed)
  • 14.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Kinnunen, Sven
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Nylander, Birgitta
    Vägverket.
    Punching Shear Tests of Column Footings1998In: Nordic Concrete Research, ISSN 0800-6377, no 21, p. 1-22Article in journal (Refereed)
  • 15.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Kjellsen, Knut O.
    Norcem.
    Wallevik, Olafur H.
    Icelandic Building Research Institute.
    Fracture mechanical properties of high-performance concrete - Influence of silica fume2000In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 33, no nov, p. 552-558Article in journal (Refereed)
    Abstract [en]

    High-performance concrete and high-quality ordinary concrete, with or without silica fume, were tested for mechanical and fracture mechanical properties. Testing was performed at 28 days and 2 years. Ten percent silica fume resulted in a 20 to 25% increase in the direct tensile strength and a 10 to 20% increase in flexural and compressive strength, but had little effect on the dynamic modulus of elasticity. The brittleness appeared to increase with the presence of silica fume.

  • 16.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Kjellsen, Knut O.
    Norcem.
    Wallevik, Olafur H.
    Icelandic Building Research Institute.
    On the Compressive Strength Development of High-Performance Concrete and Paste – Effect of Silica Fume1999In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 32, no jan-feb, p. 63-69Article in journal (Refereed)
    Abstract [en]

    The compressive strength development of sealed high-performance concrete and paste specimens, with and without silica fume, have been studied from 1 day and up to 4 years. The paste and concrete specimens were prepared in such a way that segregation was avoided and the silica fume became well dispersed. Under these conditions silica fume increased the strength of paste just as much as it increased the strength of concrete. It appears that the enhancing effect of silica fume on concrete strength is due to an improved strength of the paste phase as a whole, and not due to an improved bond strength between the paste phase and the aggregate particles, as has been suggested earlier. The concretes and the pastes with 10% silica fume appeared to loose strength over a period of time before the strength increased again.

  • 17.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Nilsson, Ulf
    Ramböll Sverige AB.
    Non-Linear Analyses and Optimized Strengthening of Slussen2009In: Concrete: 21st Centruary Superhero: Building a Susatinable Future, London: The Concrete Society , 2009Conference paper (Refereed)
  • 18.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Nilsson, Ulf
    Ramböll Sverige AB.
    Slussen: Analys och förstärkning i väntan på beslut2007In: Väg och Vattenbyggaren, ISSN 0042-2177, no 3, p. 8-12Article in journal (Other (popular science, discussion, etc.))
  • 19.
    Hallgren, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Zhang, H.
    Dahlin, T.
    Fall, N.
    Welchermill, K.
    King, F.
    Severin, P.
    The tubed mega frame - An innovative structural system for tall buildings2015In: Concrete - Innovation and Design: fib Symposium Proceedings, Technical University of Denmark , 2015, p. 473-474Conference paper (Refereed)
    Abstract [en]

    The Tubed Mega Frame is a new structure concept for high-rise buildings which is developed by Tyréns in Sweden. The Tubed Mega Frame consists of large hollow vertical shafts, mega columns, and perimeter walls. In a series of in-depth structural studies, the global response of the system as well as the detailed design of the mega columns and the perimeter walls have been investigated. The studies have been performed on an 800 m high prototype building. Parallel to these studies, the feasibility of the construction process has been the objective in another investigation. The chosen structural material for the Tubed Mega Frame is reinforced high-strength concrete. The conclusions from the studies show that the Tubed Mega Frame is a potentially feasible structural system with high-efficiency for high-rise buildings.

  • 20. King, F.
    et al.
    Hallgren, M.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering. Tyréns AB, Stockholm, Sweden.
    Partovi, A.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Svärd, Jenny
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Tubed mega frame structural systems for tall buildings2016In: IABSE Congress Stockholm, 2016: Challenges in Design and Construction of an Innovative and Sustainable Built Environment, International Association for Bridge and Structural Engineering (IABSE) , 2016, p. 2742-2749Conference paper (Refereed)
    Abstract [en]

    The Tubed Mega Frame is a new structure concept for high-rise buildings which is developed by Tyréns in Sweden. The original design of the Tubed Mega Frame consists of mega columns in the periphery of the building and connecting perimeter walls. Hence, the stabilising central core in traditional high-rise structures has been omitted. Due to the tube action, this creates an efficient structural system and also increases the floor area utilization ratios when compared to traditional structures. In a previous series of structural studies, the global response of the system, the detailed design as well as the construction process was investigated. In an on-going study, the structural system is further developed by replacing the mega columns with façade frames and perimeter walls with internal crossing walls. The central core is still omitted in the modified systems. Various Tubed Mega Frame systems are compared with a traditional structure of a slender 425 m high-rise building recently constructed. The conclusions from the present study show that both the original Tubed Mega Frame and other Tubed Mega Frame systems are potentially feasible structural systems with high-efficiency for high-rise buildings.

  • 21.
    Magnusson, Johan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    High performance concrete beams subjected to shock waves from air blast, part 22003Report (Other academic)
  • 22.
    Magnusson, Johan
    et al.
    Försvarets Forskningsanstalt.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    High Performance Concrete Beams Subjekted to Shock Waves from Air Blast2000Report (Other academic)
  • 23. Magnusson, Johan
    et al.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    High strength concrete beams subjected to shock waves from air blast2002In: Proceedings of the 6th International Symposium on Utilization of high strength/high Performance Concrete, p. 355-368Article in journal (Refereed)
  • 24.
    Magnusson, Johan
    et al.
    Swedish Defence Research Agency, FOI.
    Hallgren, Mikael
    Scandiaconsult.
    Reinforced high strength concrete beams subjected to air blast loading2004In: STRUCTURES UNDER SHOCK AND IMPACT VIII, ASHURST, ENGLAND: WIT PRESS , 2004, p. 53-62Conference paper (Refereed)
    Abstract [en]

    A total of 49 reinforced concrete beams of both high strength concrete (HSC) and, for reference, normal strength concrete (NSC) were tested. 38 beams were subjected to air blast loading in a shock tube and the remaining eleven beams were tested statically for reference. Concrete with nominal compressive cube strengths 40, 100, 140, 150 and 200 MPa were used and a few beams also contained steel fibres. Furthermore, beams with two concrete layers of different strength were tested. The purpose of this investigation was to study the structural behaviour of the concrete beams subjected to air blast loading.

    All beams subjected to static loading failed in flexure. In the dynamic tests, beams without fibres and with high ratios of reinforcement exhibited shear failure. It was observed that the inclusion of steel fibres in the matrix increased the shear strength and the ductility of the beams. This investigation indicates that beams subjected to air blast loading obtained an increased load capacity when compared to the corresponding beams subjected to static loading.

  • 25.
    Magnusson, Johan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Hallgren, Mikael
    Tyréns AB.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Air-blast-loaded, high-strength concrete beams. Part I: Experimental investigation2010In: Magazine of Concrete Research, ISSN 0024-9831, E-ISSN 1751-763X, Vol. 62, no 2, p. 127-136Article in journal (Refereed)
    Abstract [en]

    The structural behaviour of concrete beams subjected to air blast loading was investigated. Beams of both high-strength concrete (HSC) and normal-strength concrete (NSC) were subjected to air blasts from explosives in a shock tube and for reference were also loaded statically. Concrete with nominal compressive strengths of 40, 100, 140, 150 and 200 MPa were used and a few beams also contained steel fibres. Furthermore, beams with two concrete layers of different strength were tested. All beams subjected to static loading failed in flexure. For some beam types, the failure mode in the dynamic tests differed from the failure mode in the corresponding static tests. In these cases, the failure mode changed from a ductile flexural failure in the static tests to a brittle shear failure in the dynamic tests. Beams without fibres and with high ratio of reinforcement exhibited shear failures in the dynamic tests. It was observed that the inclusion of steel fibres increased the shear strength and the ductility of the beams. The investigation indicates that beams subjected to air blast loading obtain an increased load capacity when compared with the corresponding beams subjected to static loading.

  • 26. Magnusson, Johan
    et al.
    Hallgren, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Shear in concrete structures subjected to dynamic loads2014In: Structural Concrete, ISSN 1464-4177, E-ISSN 1751-7648, Vol. 15, no 1, p. 55-65Article in journal (Refereed)
    Abstract [en]

    Shear failures in reinforced concrete structures under intense dynamic loads are brittle and limit the structure's energy-absorbing capabilities. This paper comprises a review of the literature dealing with the problem of dynamic shear of reinforced concrete elements, with a focus on parameters that control flexural shear and direct shear. In this context, dynamic loads refer to intense events due to explosions and impacts. For this reason, the initial response is also highlighted. Experimental investigations and calculations show that shear force and bending moment distributions in dynamic events are initially significantly different from the distributions under slowly applied loads. Therefore, structural wave propagation, geometrical properties of elements, strain rate effects and dynamic load characteristics need to be considered when analysing shear. The review also indicates that arch action in the shear span soon after the load has been applied has a large influence on the shear capacity of an element. This action is of particular importance in intense loading events. Finally, suggestions for further research are identified.

1 - 26 of 26
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