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  • 1.
    Andersson, Jörgen
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Design Guide: Dimensionering av ekonomiska och långsiktigt hållbara samverkansbroar med integrerade landfästen.2011Report (Other academic)
    Abstract [sv]

    Denna dimensioneringshandbok är ett resultat av forskningsprojektet RFS-PR-04120 INTAB “Economic and Durable Design of Composite Bridges with Integreral Abutments” (Feldmann, et al., 2010) och det efterföljande disseminationsprojektet RFS – P2 - 08065 INTAB+ “Economic and Durable Design of Composite Bridges with Integreral Abutments” (Feldmann, et al., 2012), som varit delfinansierat av EU:s forskningsfond ”Research Fund for Coal and Steel” (RFCS) samt Svenska Byggbranschens Utvecklingsfond (SBUF). Inom forskningsprojektet har väsentlig kunskap inhämtats för att skapa möjlighet att öka konkurrenskraften hos samverkansbroar med integrerade landfästen. Denna kunskap har inarbetats i denna dimensioneringshandbok, vars engelska version har presenterats vid ett antal internationella seminarier och workshops.

  • 2.
    Andrade, Pedro
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Monteiro, Safira
    Gervásio, Helena
    University of Coimbra, Faculty of Science and Technology, Coimbra, Portugal.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Assessment and monitoring of a student residential building using an innovative execution solution2013In: Proceedings of SB13 Portugal: Contribution of Sustainable Building to Meet EU 20-20-20 Targets / [ed] Luís Bragança; Ricardo Mateus; Manuel Pinheiro, Guimarães, Portugal, 2013, 403-410 p.Conference paper (Refereed)
    Abstract [en]

    The construction, fit-out, operation and the final demolition of buildings contributes to a large-scale negative impacts on the environment, even at the level of material and energy consumption, or even because the inefficient infrastructure. This document is based on a thorough study that encompasses the design phase, construction, use and, finally,the end of life. This work it is followed by an innovative modular building and execution process, within theFRAMEUP project, which will take place in Lulea, Sweden. The aim of this study is to analyze the sustainability of this future building; first from an energy point of view so as to know the specific energy consumption using specific software, and on the other hand from an environmental stand point by leading a complete life-cycle assessment (cradle-to-grave).

  • 3.
    Andrade, Pedro
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Pavlovic, Marko
    Faculty of Civil Engineering, University of Belgrade.
    Heistermann, Christine
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Heistermann, Tim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Structural Behaviour of a Novel Column-Splice Joint: Finger Connection2015In: The 13th Nordic Steel Construction Conference: NSCC-2015 / [ed] Markku Heinisuo; Jari Mäkinen, Tampere: Tampere University of Technology, Department of Civil Engineering , 2015, 215-216 p.Conference paper (Refereed)
    Abstract [en]

    The novel joint presented in this paper is a friction connection used for column-splice connections of modular buildings as part of the innovative construction method introduced in the research project Optimization of frames for effective assembling - FRAMEUP. This type of joint provides a quick assembly and can deal with misalignments by introducing a connection gap. A filler and finger plate are welded to the upper part of the column to this end.The gap between finger plates and lower column faces is closed during tightening of the bolts and, thus, establishes a slip-resistant connection. The efficiency of the joint resistance based on different connection gaps subjected to uniform compression is assessed.The column-splice is composed of four slip-resistant connections, one at each side of the tube. Each finger plate consists of three long slotted holes and is welded to the upper column face. Long slotted holes are used to accommodate vertical misalignments and, therefore, allow fitting the bolts which are pre-installed in the lower column. Filler plates with different thicknesses (4, 6 and 8 mm) welded between the finger plate and upper column face are used to create a connection gap which allows balancing horizontal misalignments. The lower column faces consist of each nine holes with no clearance in order to pre-fit the bolts in a workshop. Thus, the assembling process on the construction site can be speeded up as once the lowercolumns are in place all bolts can be tightened immediately.

  • 4.
    Andrade, Pedro
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Project: FRAMEUP - Optimization of frames for effective assembling2014Other (Other (popular science, discussion, etc.))
  • 5.
    Andrade, Pedro
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Feldmann, Markus
    Institute for Steel Structures, RWTH Aachen University.
    Pak, Daniel
    Institute for Steel Structures, RWTH Aachen University.
    Pyschny, Dominik
    Institute for Steel Structures, RWTH Aachen University.
    Lundholm, John
    Part Construction AB.
    Design and execution of a 3D modular building2014In: Eurosteel 2014: 7th European Conference on Steel and Composite Structures / [ed] Raffaele Landolfo; Frederico M. Mazzolani, Brussels, Belgium: European Convention for Constructional Steelwork, ECCS , 2014, 103-104 p.Conference paper (Refereed)
  • 6.
    Andrade, Pedro
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lundholm, John
    Part Construction AB.
    Heistermann, Tim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Innovative Construction of Student Residences: Frameup concept2015In: The 13th Nordic Steel Construction Conference: NSCC-2015 / [ed] Markku Heinisuo; Jari Mäkinen, Tampere: Tampere University of Technology, Department of Civil Engineering , 2015, 199-200 p.Conference paper (Refereed)
    Abstract [en]

    Sweden has a strong demand on the construction of student accommodations and therefore significant efforts have been taken towards an affordable and easy solution of the problem. A concept combining these requirements may be based on the use of structural steel frames in combination with prefabricated 3D modules fully equipped and suitable for student accommodations. Therefore, the need to investigate and develop a system suitable for an effective assembly of student residences is considered in this paper, as part of an international project, Optimization of the frames for effective assembling - FRAMEUP. The Fig. 1 reveals an overview of the system within the execution process.The Frameup system introduces a new approach in terms of execution technique which consists of the execution of a building starting from the roof to the 1st floor. The existence of a lifting system constituted of a horizontal rigid frame - grid - in combination with lifting towers - pylons - permits the erection of the building, promoting each time the building is lifted, a clearance of one-floor-height plus tolerances at the ground level. This creates room enough for the assembly of the lower floor from below the previously assembled floor. The procedure is repeated several times according to the number of floors until the 1st floor of the building, the last floor of the execution sequence, is assembled. Moreover the Frameup system introduces an innovation, the Frameup conveyor system, which streamlines the assembly process so to move/slide the elements, as they come, directly from the lorry to their final position in the building.The development of the Frameup system benefits from a stepwise detailed 3D modeling and structural analysis and design tools. However, when it comes to attest the reliability and efficiency of the system, a full scale feasibility test is essential and it is performed on the majority of the sequences of construction.

  • 7.
    Bhalla, Suresh
    et al.
    Indian Institute of Technology, New Delhi.
    Vittal, Panduranga A.
    Indian Institute of Technology, New Delhi.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Piezo-impedance transducers for residual fatigue life assessment of bolted steel joints2012In: Structural Health Monitoring, ISSN 1475-9217, E-ISSN 1741-3168, Vol. 11, no 6, 733-750 p.Article in journal (Refereed)
    Abstract [en]

    This article presents a new approach for fatigue life assessment of bolted steel joints using the equivalent stiffness determined by surface-bonded piezo-impedance transducers. The piezo transducers acquire electromechanical admittance signatures comprising the conductance (real part) and the susceptance (imaginary part), from which the equivalent system parameters of the joint are identified. The equivalent stiffness, one of the identified parameters, is experimentally found to be related to the residual stiffness of the joint and is correlated with the remaining life of the component in terms of the cycles of loading that can be further sustained by the joint. Through tests on three prototype steel joints, empirical equations are derived to relate the residual fatigue life to the loss of equivalent identified stiffness. The most promising feature of the proposed approach is that it employs the admittance signature of the surface-bonded piezo transducers directly, thereby circumventing the determination of the in situ stiffness of the joint.

  • 8.
    Borg, R. P.
    et al.
    University of Malta.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Introduction to Eco-efficency2007In: Sustainability of Constructions: Integrated Approach to Life-time Structural Engineering. Proceedings of the First Workshop Lisbon 13. 14. 15 September 2007 / [ed] L. Braganca; H. Koukkari; R. Blok; H. Gervasio; M. Veljkovic, Multicomp , 2007Conference paper (Other academic)
  • 9.
    Borg, R.P.
    et al.
    University of Malta.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Plewako, Zbigniew
    Eco-efficiency2008In: Proceedings of Seminar on Sustainability of Constructions - Integrated approach to life-time structural engineering: COST Action C25, Dresden, Germany 6.-7.10.2008, 2008, 3.1-3.3 p.Conference paper (Other academic)
  • 10. Bragança, Luís
    et al.
    Koukkari, HeliBlok, RijkGervásio, HelenaVeljkovic, MilanLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.Plewako, ZbigniewLandolfo, RaffaeleUngureanu, ViorelSilva, Luís Simões da
    Sustainability of Constructions - Integrated Approach to Life-time Structural Engineering: Proceedings of the 1st Workshop: Lisbon 13, 14, 15 September 20072007Collection (editor) (Other academic)
  • 11. Bragança, Luís
    et al.
    Koukkari, HeliBlok, RijkGervásio, HelenaVeljkovic, MilanLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.Plewako, ZbigniewLandolfo, RaffaeleUngureanu, ViorelSilva, Luís Simões da
    Sustainability of Constructions - Integrated Approach to Life-time Structural Engineering: Proceedings of the Workshop, Timişoara, 23-24 October 2009. COST Action C252009Collection (editor) (Other academic)
  • 12. Bragança, Luís
    et al.
    Koukkari, HeliBlok, RijkGervásio, HelenaVeljkovic, MilanLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.Plewako, ZbigniewLandolfo, RaffaeleUngureanu, ViorelSilva, Luís Simões daHaller, Peer
    Sustainability of Constructions Integrated Approach to Life-time Structural Engineering: Proceedings of Seminar, Dresden 6. 7 October 20082008Collection (editor) (Other academic)
  • 13. Bragança, Luís
    et al.
    Koukkari, HeliVeljkovic, MilanLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.Borg, Ruben Paul
    Sustainable construction - a life cycle approach in engineering: International Training School, Malta, 26 July - 1 August 20102010Collection (editor) (Other academic)
  • 14. Bragança, Luís
    et al.
    Koukkari, HeliVeljkovic, MilanLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.Borg, Ruben Paul
    Sustainable construction - a life cycle approach in engineering: Proceedings, International Symposium Malta, 23 - 25 July 2010. COST Action C252010Collection (editor) (Other academic)
  • 15. Bragnaca, Luis
    et al.
    Koukkari, HeliBlok, RijkGervasio, HelenaVeljkovic, MilanLuleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.Plewako, ZbigniewBorg, Ruben Paul
    Summary report of the cooperative activities of the Cost Action C25: Sustainability of constructions. Integrated approach towards sustainable constructions2011Collection (editor) (Other academic)
  • 16.
    Byström, Alexandra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Cheng, Xudong
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Full-scale experimental and numerical studies on compartment fire under low ambient temperature2012In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 51, 255-262 p.Article in journal (Refereed)
    Abstract [en]

    A fire experiment with wood crib was conducted in a concrete building under low ambient temperature of −10 °C to explore fire development and temperature distribution. The concrete building consists of a two-storey compartment with the size of 9.0 m by 5.0 m by 4.8 m high and a four-storey stairwell with the size of 5.0 m by 2.4 m by 10.0 m high. The fuel mass loss rate and temperatures at different positions were measured. Two fire cases, with different assumed ambient temperatures of −10 °C and 20 °C respectively, were then simulated by using FDS software to investigate the effect of ambient temperature and compare with the experimental results. The numerical results show that the calculated heat release rate is in reasonably good agreement with the measured full-scale result before water suppression. The calculated temperatures in the hot combustion gas layer at different positions agree also very well with the measured values. However, the measured fresh air temperature at the floor level near the fire source is higher than the calculated value. This discrepancy may partly depend on measuring errors as analyzed in the paper.

  • 17.
    Byström, Alexandra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Cheng, Xudong
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Measurement and calculation of adiabatic surface temperature in a full-scale compartment fire experiment2013In: Journal of fire sciences, ISSN 0734-9041, E-ISSN 1530-8049, Vol. 31, no 1, 35-50 p.Article in journal (Refereed)
    Abstract [en]

    Adiabatic surface temperature is an efficient way of expressing thermal exposure. It can be used for bridging the gap between fire models and temperature models, as well as between fire testing and temperature models. In this study, a full-scale compartment fire experiment with wood crib fuel was carried out in a concrete building. Temperatures were measured with plate thermometers and ordinary thermocouples. Five plate thermometers and five thermocouples with a diameter of 0.25 mm were installed at different positions. These two different temperature devices recorded different temperatures, especially near the floor surface. The adiabatic surface temperature was derived by a heat balance analysis from the plate thermometer measurements. The thermal inertia of the plate thermometer was taken into account to correct the measured results. In addition, the fire experiment scenario was also simulated with fire dynamics simulator. The fire source was specified as a given heat release rate, which was calculated from the measured mass loss rate of the wood fuel. The adiabatic surface temperatures at these measuring positions were simulated by the fire dynamics simulator model and compared with the experimental adiabatic surface temperatures. The comparative results showed that fire dynamics simulator predicted the adiabatic surface temperature accurately during the steady-state period.

  • 18.
    Byström, Alexandra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sjöström, Johan
    SP Technical Research Institute of Sweden, Borås.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lange, David
    SP Technical Research Institute of Sweden, Borås.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Large scale test on a steel column exposed to localized fire2014In: Journal of Structural Fire Engineering, ISSN 2040-2317, E-ISSN 2040-2325, Vol. 5, no 2, 147-160 p.Article in journal (Refereed)
    Abstract [en]

    A localized fire is a fire which in a compartment is unlikely to reach flash-over and uniform temperature distribution. Designing for localized fires is generally more difficult than for flash-over compartment fires because of the complexity of the problem. There is also a lack of experimental data. We report here on a full scale test series on a steel column exposed to localized fires. The setup is a 6 meters tall hollow circular column, ϕ = 200 mm with a steel thickness of 10 mm. The unloaded column was hanging centrally above different pool fires. Temperatures of gas and steel were measured by thermocouples, and adiabatic surface temperatures at the steel surface were measured by plate thermometers of various designs. The results are compared with estimates based on Eurocode 1991-1-2 which in all cases studied overestimate the thermal impact for this setup. The input from plate thermometers was used to compute the steel temperatures using finite element methods. Excellent agreement was found if the radiation exchange within the column due to asymmetry of the exposure was taken into account.

  • 19.
    Byström, Alexandra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sjöström, Johan
    Technical Research Institute of Sweden, SP.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    A steel column exposed to localized fire2012In: Nordic Steel Construction Conference 2012: September 5-7, 2012 Oslo, Norway : Proceedings, Norwegian Steel Association , 2012, 401-410 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we report on a series of experiments which were conducted in the large fire hall of SP’sThe unprotected steel column with Ø=200 mm and thikness 10 mm was placed with its base in a pan with the fuel and exposed to fires of various liquid fuels and magnitudes. Temperatures were recorded in the gas phase and in the steel. In the gas phase temperatures were measured with traditional thermocouples and Plate Thermometers (PTs). It was observed that measured temperatures were much lower than the correspond temperatures calculated based on the formulas presented in Eurocode 1991-1-2. For a better estimation of the steel temperatures the emissivity of the flame should be taken into account.

  • 20.
    Byström, Alexandra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sjöström, Johan
    Technical Research Institute of Sweden, SP.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Large scale test to explore thermal exposure of column exposed to localized fire2012In: Proceedings of the 7th International Conference on Structures in Fire / [ed] Mario Fontana; Andrea Frangi; Markus Knobloch, Zurich: ETH Zurich, Institute of Structural Engineering , 2012, 185-194 p.Conference paper (Refereed)
    Abstract [en]

    A localized fire is a fire in a compartment which is unlikely to reach flash-over or a uniform temperature distribution. Designing for localized fires are generally more difficult than for a typical room fire both because of the complexity of the problem as well as the lack of experimental data. We reports on a full scale test on a steel column exposed to a localized fire. The setup is a 6 meters hollow circular column, Ø=200 mm with a steel thickness of 10 mm. The unloaded column was hanging centrally above different pool fires. We report temperatures of gas and steel as well as those measured by plate thermometer of the somewhat asymmetric fires. The results are compared with estimates based on Eurocode 1991-1-2 which in all cases studied overestimates the thermal impact for this setup.

  • 21.
    Byström, Alexandra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Use of plate thermometers for better estimate of fire development2011In: Performance, Protection and Strengthening of Structures under Extreme Loading / [ed] Ezio Cadoni; Marco di Prisco, Trans Tech Publications Inc., 2011, 362-367 p.Conference paper (Refereed)
    Abstract [en]

    The concept of Adiabatic Surface Temperature (AST) opens possibilities to calculate heat transfer to a solid surface based on one temperature instead of two as is needed when heat transfer by both radiation and convection must be considered. The Adiabatic Surface Temperature is defined as the temperature of a surface which cannot absorb or lose heat to the environment, i.e. a perfect insulator. Accordingly, the AST is a weighted mean temperature of the radiation temperature and the gas temperature depending on the heat transfer coefficients. A determining factor for introducing the concept of AST is that it can be measured with a cheap and robust method called the plate thermometer (PT), even under harsh fire conditions. Alternative methods for measuring thermal exposure under similar conditions involve water cooled heat flux meters that are in most realistic situations difficult to use and very costly and impractical.This paper presents examples concerning how the concept of AST can be used in practice both in reaction-to-fire tests and in large scale scenarios where structures are exposed to high and inhomogeneous temperature conditions.

  • 22. Carolin, Anders
    et al.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Vill vi betala mer för ökad dammsäkerhet?2007In: Norrbottens-Kuriren, 3- p.Article in journal (Other (popular science, discussion, etc.))
  • 23.
    Cheng, Xudong
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Byström, Alexandra
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Thermal analysis of a pool fire test in a steel container2012In: Journal of fire sciences, ISSN 0734-9041, E-ISSN 1530-8049, Vol. 30, no 2, 170-184 p.Article in journal (Refereed)
    Abstract [en]

    A pool fire test was conducted in an uninsulated steel container under low ambient temperature condition, at −20°C. The heat balance of the enclosure fire was analyzed. The size of the container was 12 m × 2.4 m and 2.4 m high, and it was made of 3-mm-thick steel. During the fire test, the fuel mass loss rate was recorded and the temperatures at different positions were measured with high-temperature thermocouples and plate thermometers. The fire scenario was simulated by using fire dynamics simulator software, and the simulated and measured results were compared. The coarse high-temperature thermocouple responded slower, and therefore, temperature measured by the high-temperature thermocouple was corrected to eliminate the effect of the thermal inertia. Furthermore, a simple two-zone model was proposed for estimating gas temperature in the enclosure of the highly conductive steel walls assuming a constant combustion rate. The convective and radiative heat transfer resistances at the inside and outside surfaces of the enclosure were analyzed.

  • 24.
    Cheng, Xudong
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Byström, Alexandra
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Iqbal, Naveed
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sandström, Joakim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Prediction of temperature variation in an experimental building2011In: Proceedings of International Conference Applications of Structural Fire Engineering: Prague, 29 April 2011, 2011, 387-392 p.Conference paper (Refereed)
  • 25.
    Ditrani, Marco
    et al.
    Politecnico di Milano.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Eriksen, Jörgen
    Enochsson, Ola
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Andersson, P.
    Vägverket.
    Eriksson, Per
    Vägverket.
    Improving transportation investment decision through life-cycle cost analysis: case study on some bridges in the north of Sweden2009In: Sustainability of Constructions - Integrated Approach to Life-time Structural Engineering: Proceedings of the Workshop Timişoara, 23-24 October 2009. COST Action C25, 2009, 266-275 p.Conference paper (Refereed)
    Abstract [en]

    The scope of this project is to perform Life Cycle Cost Analysis (LCCA) on different types of bridges, in order to learn which is most cost-efficient in a particular situation. A second scope is to study the impact of different cost items on the whole Life Cycle Cost. The work is performed to enable optimal strategic decisions regarding future investments.Beam and Slab Bridges, Slab Bridges and Slab Frame Bridges are analyzed. The bridges are located in the north of Sweden, in the regions of Norrbotten and Västerbotten. All bridges have a total length of around 20 m, which is the most common length in Sweden and in Europe. Furthermore, the analysis includes Timber and Soil-Steel bridges in order to understand the prospects for this types of bridges in Sweden. The analysis does not focus on a particular bridge but, based on information from some Swedish producers, it studies different scenarios.The data collection covers initial investments, maintenance, repair and rehabilitation (MR&R) costs, user and demolition costs.

  • 26.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Projekt: Centrum för riskanalys och riskhantering, CRR2012Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    En centrumbildning vid LTU i samarbete med näringsliv och samhälle för studier av riskanalys och riskhantering

  • 27. Eriksen, Jörgen
    et al.
    Gervasio, Helena
    University of Coimbra.
    Rebelo, Carlos
    University of Coimbra.
    Silva, Luis Simoes da
    University of Coimbra.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Vesikari, Erkki
    VTT.
    Guidelines to perform life cycle analysis of bridges2008In: Proceedings of Seminar on Sustainability of Constructions - Integrated approach to life-time structural engineering: COST Action C25, Dresden, Germany 6.-7.10.2008, 2008, 5.27-5.51 p.Conference paper (Other academic)
  • 28. Eriksen, Jörgen
    et al.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Monitoring of a bridge with integral abutments2009In: Proceedings of Workshop: COST Action C25 : Sustainability of Constructions - Integrated Approach to Life-time Structural Engineering, 2009, 176-183 p.Conference paper (Refereed)
    Abstract [en]

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

  • 29.
    Feldmann, M.
    et al.
    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH).
    Naumes, J.
    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH).
    Pak, D.
    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH).
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Eriksen, J.
    Luleå tekniska universitet.
    Popa, N.
    ArcelorMittal Belval & Differdange (AM R & D).
    Hechler, O.
    ArcelorMittal Belval & Differdange (AM R & D).
    Seidl, G.
    SSF-Ingenieure AG (SSF).
    Economic and durable design of composite bridges with integral abutments (INTAB+)2012Report (Refereed)
    Abstract [en]

    In the design and construction of bridges, questions of sustainability, maintenance and durability become more and more important for European road administrations in addition to safety and serviceability issues. Therefore integral abutment bridges become highly attractive to designers, constructors and road administrations as they tend to be less expensive to build, easier to maintain and more economical to own over their lifetime. However in Europe less experience in building integral bridges has been gained so far. Therefore in 2005 the European RFCS-projects INTAB has been launched. Within the scope of the project, universities, consulting engineering companies as well as steel producers worked together to develop economic and safe solutions for composite bridges with integral abutments. Significant knowledge has been gained and cost-effective, environmentally friendly and sustainable bridge structures have been developed. Furthermore their durability has been proven to obtain competitive composite bridges for small and medium spans. The outcome of that project was reworked within the scope of the current project to make it available to a larger number of practitioners. To disseminate the knowledge, two workshops have been organised. A design guide was written and translated into German and French. It was completed by a design example as well as CEN-recommendations regarding actual Eurocodes. A software tool was written to help designers to perform some calculations regarding the design of integral abutment bridges.

  • 30.
    Feldmann, M.
    et al.
    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH).
    Naumes, J.
    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH).
    Pak, D.
    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH).
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Eriksen, J.
    Luleå tekniska universitet.
    Collin, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Kerokoski, O.
    Ramböll Sverige AB (Ramböll).
    Pétursson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Verstraete, M.
    Université de Liège.
    Vroomen, C.
    Université de Liège.
    Haller, M.
    ArcelorMittal Belval & Differdange (AM R & D).
    Hechler, O.
    ArcelorMittal Belval & Differdange (AM R & D).
    Popa, N.
    ArcelorMittal Belval & Differdange (AM R & D).
    Economic and durable design of composite bridges with integral abutments2010Report (Refereed)
    Abstract [en]

    In the design and construction of bridges, questions of sustainability, maintenance and durability are becoming more and more important for European road administrations, in addition to safety and serviceability issues. Therefore integral abutment bridges are becoming highly attractive to designers, constructors and road administrations, as they tend to be less expensive to build, easier to maintain and more economical to own over their life time. Bearings and joints are main sources of maintenance costs during a lifetime. These costs vanish because the bridges are joint- and bearing-free. However, this very advantage complicates the design compared to conventional bridges in some crucial respects. Combined with the fact that most European countries have only limited experience with integral bridges to date, this leads to a reluctance of road administrations to use this bridge type. Thus the main objective of the project is to experimentally and theoretically investigate the behaviour of critical points of integral abutment bridges. Regarding the soil-structure interaction, recommendations are elaborated based on monitoring results as well as previous research and monitoring campaigns. Conventional HP piles and sheet piles are investigated as a foundation. Furthermore a hinged HP connection is developed to decrease the stresses in the pile system. An investigation of the design and construction of the slab to pavement approach is also carried out to avoid major damages to the structure. Finally the most important information is condensed into the essential features in form of a 'Design guide for composite bridges with integral abutments'

  • 31. Fontoura, B.
    et al.
    Matos, R.
    Abílio, M.P. Jesus
    Rebelo, C.
    Silva, L. Simões da
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Avaliação da Resistência à Fadiga de Ligações por Atrito em Aço Estrutural de Alta Resistência S6902011In: Construção Metálica e Mista VIII / [ed] L. Simões da Silva; P. Cruz; N. Lopes; J. Almeida Fernandes; A. Batista, Lissabon: CMM Press , 2011, 191-200 p.Conference paper (Refereed)
  • 32.
    Garzon, Olga
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Heistermann, Tim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    A study of an axially compressed cold-formed folded plate2011In: Proceedings of the 6th International Conference on Thin-Walled Structures: Recent Research Advances and Trends, Timisoara, 2011, 297-304 p.Conference paper (Refereed)
    Abstract [en]

    Cold formed steel members are new compared to hot rolled material in building construction. Mostly all cold formed elements have open cross sections and the thicknesses of its members are normally small related to their widths. Therefore, local buckling may occur before the section yields. The work presented is based on experiments of axially compressed cold formed folded plates with two different plate thicknesses of 6 mm and 8 mm; for thickness of 6 mm with two different lengths, 400 mm and 900 mm and for 8 mm plate thickness with a length of 400 mm. A nominal steel grade of S355 is used in experiments. The results, carried out in experiments, are compared to Finite Element Analyses (FEA), taking into consideration different yield strength in the cold-formed areas. The commercial software ABAQUS is used and the validity of rules of EN 1993 part 1-3 is checked.

  • 33.
    Gervasio, Helena
    et al.
    University of Coimbra.
    Eriksen, Jörgen
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Silva, Luis Simoes da
    University of Coimbra.
    Comparative analysis of an integral abutment composite bridge and a concrete bridge with expansion joints2008In: Steel bridges : advanced solutions & technologies: 7th International Conference on Steel Bridges ; conference proceedings ; Guimarães, Portugal, 4 - 6 June, 2008 ; [ICSB '08] / [ed] Paulo J. S. Cruz, Brussels: European Convention for Constructional Steelwork, ECCS , 2008Conference paper (Refereed)
    Abstract [en]

    Bridge engineers very often face economic restrictions on their designs in addition to technical requirements. Those requirements are related not only to initial construction costs but also the cost to maintain the bridge condition at the level required by the bridge administration. In standard bridge structures, expansion joints are one of the most expensive components to maintain. In this regard, jointless bridges have major advantages. Integral bridges are built without joints, they span from one abutment to the other abutment, possibly over intermediate piers, without any joints in the deck. The absence of joints and bearings results in savings in initial costs and reduce maintenance efforts. Apart from economical benefits, the reduction of maintenance leads to less disturbance of the traffic over the bridge and thus to smaller environmental and social impacts. In this paper a case study is presented with the purpose of making a comparative life cycle analysis between an integral composite bridge and a concrete bridge with expansion joints. The result of this life cycle analysis will enhance the advantages of the former solution in regard of economical and environmental aspects.

  • 34.
    Gervásio, Helena
    et al.
    ISISE, Department of Civil Engineering, University of Coimbra.
    Rebelo, Carlos
    ISISE, Department of Civil Engineering, University of Coimbra.
    Moura, André
    ISISE, Department of Civil Engineering, University of Coimbra.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Silva, Luis Simões da
    ISISE, Department of Civil Engineering, University of Coimbra.
    Comparative life cycle assessment of tubular wind towers and foundations: Part 2: Life cycle analysis2014In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 74, 292-299 p.Article in journal (Refereed)
    Abstract [en]

    In the first part of the paper the design of tubular towers and respective onshore foundations was addressed. The considered solutions were based on steel, concrete and hybrid steel-concrete tubular towers supporting multi-megawatt turbines of 2, 3.6 and 5 MW power with hub heights of 80, 100 and 150 m respectively. In this second part of the paper, the life cycle analysis of the designed case studies is performed and conclusions about their environmental impact are drawn. Two different scenarios concerning the lifetime of the towers were established. The first scenario considers 20 years lifetime and two different construction methods for the connection of the steel segments, the first based in current technology using flange connections and the second using newly developed friction connections. Assuming equal importance for all environmental categories in this scenario, it may be concluded that for heights up to 100 m hybrid towers with friction connections are the most efficient solution. For higher heights, the concrete tower becomes more efficient. The second scenario considers an increased total lifetime of 40 years, assuming the reuse of the tower after 20 years of operation. In this case, the use of friction connections in steel towers enhances the possibility of dismantling and reusing the tower potentiating much better performance in relation to the environmental category of global warming.

  • 35.
    Heistermann, Christine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Heistermann, Tim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Limam, Marouene
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Finite element analysis of a single lap joint2012In: Nordic Steel Construction Conference 2012: September 5-7, 2012 Oslo, Norway : Proceedings, Oslo: Norwegian Steel Association , 2012, 673-682 p.Conference paper (Refereed)
    Abstract [en]

    A single shear lap joint of steel grade S355 is modelled with finite elements to investigate the influence of externally applied tensile loading on the loss of pretension in the engaged bolts. Additionally, a parameter study is performed to understand the effect of various steel grades on the loss of pretension. It is found that the slip resistance of the specimen depends on the steel grade of the clamped plates. Besides, the final resistance of the single shear lap joint has been found to increase after a slip of 0,15 mm has occurred due to a secondary bending moment. However, the final resistance of the specimen has been found to depend on the size of assembling tolerances; the bigger the distance between the clamped plates, the lower the resistance.

  • 36. Heistermann, Christine
    et al.
    Heistermann, Tim
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Remaining pretension force in friction connections2010In: Proceedings of the 4th International Conference on Steel and Composite Structures: 21 - 23 July 2010, Sydney, Australia / [ed] Brian Uy, Singapore: Research Publishing Services, 2010, 275-278 p.Conference paper (Refereed)
  • 37. Heistermann, Christine
    et al.
    Husson, Wylliam
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Flange connection vs. friction connection in towers for wind turbines2009In: Nordic Steel Construction Conference: Proceedings : September 2.-4., 2009, Malmö, Sweden, Stockholm: Stålbyggnadsinstitutet , 2009, 296-303 p.Conference paper (Refereed)
    Abstract [en]

    The paper deals with connections used to assemble sections of tubular steel towers supporting wind turbines. The design of current ring flange connections is briefly presented. An alternative option for the assembling connection is to use single overlapping friction connection. This is introduced in on-going research project "HISTWIN- High-Strength Steel Tower for Wind Turbine, 2006-2009". The main characteristic of the friction connection is long open slotted holes. Design example for equivalent design load at ultimate load of the friction connection is compared to the flange solution on a particular example of REpower Tower MM92. The benefits of the new connection in terms of design simplicity, fatigue strength and material costs are discussed.

  • 38.
    Heistermann, Christine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Pavlovic, Marko
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Andrade, Pedro
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Rebelo, Carlos
    ISISE, Department of Civil Engineering, University of Coimbra.
    Silva, Luís Simões da
    ISISE, Department of Civil Engineering, University of Coimbra.
    Finite Element Analysis of Lap Joints in Steel Tubular Towers2014In: Eurosteel 2014: 7th European Conference on Steel and Composite Structures / [ed] Raffaele Landolfo; Frederico M. Mazzolani, Brussels, Belgium: European Convention for Constructional Steelwork, ECCS , 2014, 291-292 p.Conference paper (Refereed)
  • 39.
    Heistermann, Christine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Tran, Anh Tuan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Rebelo, Carlos
    ISISE, Department of Civil Engineering, University of Coimbra.
    Flangeless Connections in Steel Tubular Wind Towers2014In: Proceedings of the METNET Seminar 2013 in Luleå: Metnet Annual Seminar in Luleå, Sweden, on 22 - 23 October 2013 / [ed] Kuldeep Virdi; Lauri Tenhunen, Hämeenlinna: HAMK University of Applied Science , 2014, 157-168 p.Conference paper (Other academic)
    Abstract [en]

    Extensive research is conducted on the improvement of renewable energies. One field is the use of wind energy, where the tower construction is one of the main issues. This paper deals with new ideas and ongoing research in this area. To raise the height of steel tubular towers, fatigue as the design limit and constraints due to transportation issues have to be overcome. Changes in the cross-section are considered as one of possible solutions. This work presents an extensive finite element study dealing with different ways to improve shell stability, which become the limiting criteria if a friction connection substitutes the common flange connection between two tower segments. The use of circular and polygonal cross-sections is briefly described and will be investigated in an experimental program.

  • 40.
    Heistermann, Christine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bolts for slip resistant joints in towers for wind turbines2012In: Proceedings of the METNET Seminar 2012 in Izmir: Metnet Annual Seminar in Izmir, Turkey, on 10 - 11 October 2012 / [ed] Kuldeep Virdi; Lauri Tenhunen, Hämeenlinna, Finland: HAMK University of Applied Science , 2012, 31-39 p.Conference paper (Other academic)
    Abstract [en]

    This paper deals with a new solution to connect various segments in a tubular steel tower for wind power plants. Tests are performed to determine appropriate bolts for such connections. They focus on checking the development of pretension forces in the bolts during a period of one week. The behaviour of four different types of bolts is described and evaluated. For one type of bolt the force reduction is monitored for two different clamping lengths. Finally, recommendations for further tests are given.

  • 41.
    Heistermann, Christine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Loss of pretension in bolted connections: influence of loading2011In: Proceedings of the 6th European Conference on Steel and Composite Structures: Eurosteel 2011, August 31 - September 2, 2011, Budapest, Hungary, Budapest: European Convention for Constructional Steelwork, ECCS , 2011, 399-404 p.Conference paper (Refereed)
    Abstract [en]

    A common problem in bolted connections is the self-loosening effect of bolts over time. Therefore the remaining strength in a slip resistant connection can only roughly be estimated for a certain point of time. A possible solution ot avoid self-loosening is the use of lockbolts, which have been studied in order to achieve recommendations for connections which are "free from maintenance". The pretension force in the bolt unavoidably reduces over time due to creep of primer, forces in bolts and in plates. These effects are experimentally studied. For all types of connections this effect is very important and in this paper the focus is brought on lap joints, where the influence of various types of loading is examined.

  • 42.
    Heistermann, Christine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simões, R.
    ISISE, Department of Civil Engineering, University of Coimbra.
    Rebelo, C.
    ISISE, Department of Civil Engineering, University of Coimbra.
    Silva, L. Simões da
    ISISE, Department of Civil Engineering, University of Coimbra.
    Design of slip resistant lap joints with long open slotted holes2013In: Journal of constructional steel research, ISSN 0143-974X, E-ISSN 1873-5983, Vol. 82, 223-233 p.Article in journal (Refereed)
    Abstract [en]

    Current design procedures for slip resistant connections according to Eurocodes and American specifications are reviewed. Although failure of a slip resistant connection is defined at different levels of slip, 0.15 mm and 0.5 mm respectively, the calculation of the resistance is similar. Most of the research is performed on bolts in normal clearance holes. A testing program was conceived to evaluate the influence of long open slotted holes on the behavior of slip resistant lap joints with tension control bolts because of possible use of such connections in towers for wind turbines. In comparison to specimens with normal clearance holes it is found that the friction coefficient is about 4% lower. This reduction is lower than suggested by the current correction factors. Since none of the design procedures takes the reduction in bolt forces by time into account, the loss of pretension force is experimentally studied and an approximation is proposed. A second testing program was carried out with friction standard specimens in order to determine the slip factor for different surface treatments and steel grades in range between S275 and S690. The achieved slip factors for different surface preparations are in accordance with the classification of friction surfaces in EN 1090-2:2008 and differences obtained are addressed to variations in exposure to weather conditions. The steel grade does not have a significant influence.

  • 43.
    Heistermann, Tim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Iqbal, Naveed
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lopes, Fernanda
    University of Coimbra, Department of Civil Engineering.
    Santiago, Aldina
    University of Coimbra, Department of Civil Engineering.
    Silva, Luís Simões da
    University of Coimbra, Department of Civil Engineering.
    Reverse channel connections at elevated temperature: finite element modelling2011In: Proceedings of the 6th European Conference on Steel and Composite Structures: Eurosteel 2011, August 31 - September 2, 2011, Budapest, Hungary, Budapest: European Convention for Constructional Steelwork, ECCS , 2011, 1587-1592 p.Conference paper (Refereed)
  • 44.
    Heistermann, Tim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Koltsakis, Efthymios
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lopes, Fernanda
    University of Coimbra, Department of Civil Engineering.
    Santiago, Aldina
    ISISE, Department of Civil Engineering, University of Coimbra.
    Silva, Luís Simões da
    Virginia Polytechnic Institute and State University, Universidade de Coimbra , ISISE, Department of Civil Engineering, University of Coimbra.
    Initial stiffness evaluation of reverse channel connections in tension and compression2015In: Journal of constructional steel research, ISSN 0143-974X, E-ISSN 1873-5983, Vol. 114, 119-128 p., 4268Article in journal (Refereed)
    Abstract [en]

    The so-called Reverse Channel connection has been conceived for the purpose of accommodating the thermal expansion of beams so that premature failure due to thermal buckling is avoided. The connection is made of a channel-shaped element, welded along the tips of its flanges onto the face of a hollow section column; an endplate welded on the beam is bolted onto the web of the channel. In a fire situation, the thermal expansion of a reverse-channel supported beam causes extensive bending deformation of the connection, therefore preventing the development of significant axial stress in the beam. Furthermore, this connection offers a high rotational capacity, if designed properly, which is beneficial in a fire situation where excessive deflections of beams can be expected. This paper aims to provide analytical stiffness assessment tools for reverse channel connections in compression and tension under uniform temperatures. The proposed analytical models are compared to results of Finite Element simulations, which in turn have been benchmarked with experiments. In addition, a comprehensive parametric study is conducted in order to identify all influencing factors on the initial stiffness response: reverse channel geometry and thickness, plate thickness, bolt position, and bolt diameter. Correction factors that account for 3D effects and bolt size are presented and discussed. The obtained expressions for the reverse channel stiffness are found to provide an accuracy that is acceptable for structural applications and can, therefore, be used as a design tool

  • 45.
    Heistermann, Tim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Koltsakis, Efthymios
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lopes, Fernanda
    University of Coimbra, Department of Civil Engineering.
    Santiago, Aldina
    ISISE, Department of Civil Engineering, University of Coimbra.
    Silva, Luís Simões da
    Universidade de Coimbra , ISISE, Department of Civil Engineering, University of Coimbra.
    Initial Stiffness of Reverse Channel Connections2014In: Eurosteel 2014: 7th European Conference on Steel and Composite Structures, September 10-12, 2014, Naples, Italy / [ed] Raffaele Landolfo; Federico M. Mazzolani, Brussels: European Convention for Constructional Steelwork, ECCS , 2014Conference paper (Refereed)
    Abstract [en]

    The robustness of a structure in a fire situation greatly depends on the rotational capacity of the connection region. High rotational capacity is required at elevated temperatures since the steel beams lose their bending stiffness and exhibit increasingly large deflections under constant load. Beam deflections result in increasing rotations at the supports and may lead to collapse due to connection failure. The reverse channel has been proposed as a practical alternative to assemble beams to tubular columns. In a simple implementation, the bending moment generated in the joint due to rotation of the beam may be neglected; however, research efforts are being attempted to quantify the level of constraint. The typical arrangement of the connection type consists of a reverse channel with its flanges welded onto the face of concrete-filled tubular columns and the web bolted to the endplate of a beam. Thicknesses and depths of the reverse channel determine the level of rotational restraint at high temperature. The reverse channel has the ability to undergo catenary deformation in the tensile zone due to the applied rotation at the support and similarly it is relatively ductile in the compression zone. Overall, the reverse channel connection response is rather ductile in terms of its ability to undergo large rotational deformation as long as bolt failure is avoided through proper design.Various tests have been performed to study the behaviour of this type of connection such as full scale buildings, sub-frames, isolated joints and individual sections. The aim of these tests was to capture the connection behaviour in relation to other structural components in fire. This paper, however, focuses on the derivation and verification of analytical models to assess the initial stiffness of reverse channel/partial-depth endplate connections. The results from finite element analyses have been utilized to validate analytical models that describe the behaviour of this type of connection at ambient and elevated temperature. Insight into the analytical models provides proper background to a structural designer to estimate the initial stiffness and understand the behaviour of the reverse channel in the connection.

  • 46. Husson, Wylliam
    et al.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Behaviour of a friction connection using TCB in long slotted holes2007In: Proceedings of the 9th International Conference on Steel, Space and Composite Structures, Singapore: CI-Premier Pte Ltd, 2007Conference paper (Refereed)
    Abstract [en]

    With constantly increasing demand for renewable energies the cost optimization of steel towers supporting multi-mega-watt wind turbines becomes important. Luleå University of Technology currently coordinate European research project (RFCS), including partners from 5 countries, which aim is to ensure the high competitiveness of the next generation of steel towers produced in Europe. One innovation investigated within this project is the use of friction grip connection with long slotted holes to connect the steel tower sections. This paper presents a part of ongoing experimental program and result of three segment tests performed with weathering steel plates and M20 Tension Control Bolts. Experimental results are compared to the prediction according to European structural code EN 1993-1-8 Furthermore a three dimensional numerical model was used to describe behaviour of the connection with a long slotted hole together and a thick cover plate FE-analysis of the preliminary experiments was used to endorse conclusions from the experiments.

  • 47. Husson, Wylliam
    et al.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Innovative connections in tubular steel towers: experiments on segment specimens under static loading2008In: Proceedings / Eurosteel 2008: 5th European Conference on Steel and Composite Structures - Research, Eurocodes, Practice - Graz, Austria, September 3 - 5, 2008 / [ed] Robert Ofner; Darko Beg; Josef Fink; Richard Greiner; Harald Unterweger, European Convention for Constructional Steelwork, ECCS , 2008, Vol. A, 651-656 p.Conference paper (Refereed)
  • 48. Husson, Wylliam
    et al.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Performance of a high-strength friction grip connection with open slotted hole2008In: Connections in Steel Structures VI: Proceedings of the 6th international workshop, 2008, 585-596 p.Conference paper (Refereed)
  • 49.
    Iqbal, Naveed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Gervasio, H.
    Universidade de Coimbra.
    Eriksen, J.
    Luleå tekniska universitet.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Silva, L. Simoes da
    Universidade de Coimbra.
    Inflation adjusted LCCA of a comparative study of an Integral abutment bridge and a Concrete bridge with expansion joints2010In: Sustainable construction - a life cycle approach in engineering: Proceedings, International Symposium Malta, 23 - 25 July 2010. COST Action C25, 2010, 151-161 p.Conference paper (Refereed)
    Abstract [en]

    Gervasio H. et al [1]in there comparative life cycle analysis of an integral abutment composite bridge and concrete bridge have established the advantages of integral bridge due to its limited initial construction cost and maintenance and repair costs during its life cycle. This paper is based on the same data with a modification to the life cycle cost analysis of the bridge by using an inflation adjusted discount rate. In standard bridge structures, expansion joints are one of the most expensive components to maintain. In this regard, joint less bridge have major advantages. Integral bridges are built without joints, they span from one abutment to the other abutment, possibly over intermediate piers, without any joints in the deck. The absence of joints and bearings results in savings in initial costs and reduce maintenance efforts. Apart from economic benefits, the reduction of maintenance leads to less disturbance of the traffic over the bridge and thus to smaller environmental and social impacts. In this paper a case study is presented with the purpose of making a comparative life cycle analysis between an integral composite bridge and a concrete bridge with expansion joints. The result of this life cycle analysis will enhance the advantages of the former solution in regards to the economic and environmental aspects.

  • 50.
    Iqbal, Naveed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Heistermann, Tim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Lopes, Fernanda
    University of Coimbra, Department of Civil Engineering.
    Santiago, Aldina
    ISISE, Department of Civil Engineering, University of Coimbra.
    Silva, Luís Simões da
    ISISE, Department of Civil Engineering, University of Coimbra.
    Axial Force And Deformation Of A Restrained Steel Beam In Fire: Description and validation of a simplified analytical procedure2016In: Advanced steel construction, ISSN 1816-112X, Vol. 12, no 2, 174-193 p., 6Article in journal (Refereed)
    Abstract [en]

    Structural fire design is exceedingly adopting the performance based approach. There are evidentadvantages of this approach compared to the prescriptive methods from codes. An analytical procedure, based on thereal performance, must accurately predict the beam behaviour in fire. The study presented here proposes one suchsimplified analytical procedure aim to predict the real behaviour of a restrained steel beam. The proposed analyticalprocedure is validated through FE Analysis using FE models validated through test results. The study also attempts toestablish the importance of using semi-rigid connection strength with respect to accurately predicting the behaviorof the restrained beam at catenary stage.

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