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  • 751.
    Uppfeldt, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Outinen, T. Ala
    VTT.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    A design model for stainless steel box columns in fire2008In: Journal of constructional steel research, ISSN 0143-974X, E-ISSN 1873-5983, Vol. 64, no 11, p. 1294-1301Article in journal (Refereed)
    Abstract [en]

    A study of stainless steel cold-rolled box columns at elevated temperatures is presented, which is a part of an on-going RFCS project "Stainless Steel in Fire", 2004-2007. Experimental results of six, class 4, stub columns at elevated temperature, tested by Ala-Outinen [Members with Class 4 cross-sections in fire: Work package 3, ECSC project stainless steel in fire. Contract no. RFS-CR-04048, Espoo, Finland; 2005], were used to evaluate the finite element (FE) model. The FE analysis obtained using the commercially available software, ABAQUS, shows that the critical temperature was closely predicted. Further, a parametric study was performed using the same numerical model. This was a basis to check the quality of prediction of a newly proposed improvement for design rules of class 4 cross-sections in fire according to EN 1993-1-4 [Eurocode 3 - Design of steel structures - Part 1-4: General rules - Supplementary rules for stainless steels, CEN; 2006] and EN 1993-1-2 [Eurocode 3: Design of steel structures - Part 1.2: General rules - Structural fire design, CEN; 2005].

  • 752.
    Uppfeldt, Björn
    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.
    Class 4 stainless steel box columns in fire2007In: Urban habitat constructions under catastrophic events: proceedings of workshop, Prague, 30. - 31.3.2007 / [ed] Frantisek Wald; F. Mazzolani; M. Byfield; D. Dubina; M. Faber, Prague: Czech Techn. Univ., , 2007, p. 87-92Conference paper (Refereed)
    Abstract [en]

    A study of stainless steel cold-rolled box columns at elevated temperatures is presented, which is a part of an on-going RFCS project "Stainless Steel in Fire". Experimental results of six, class 4, stub columns at elevated temperature, tested by Ala-Outinen (2005), were used to evaluate the FE model. The FE analysis obtained using the commercially available software, ABAQUS, shows that the critical temperature was closely predicted. Further, a parametric study was performed using the same numerical model. This was a basis to check the quality of prediction of a newly proposed improvement for design rules of class 4 crosssections in fire according to EN 1993-1-4 (2006) and EN 1993-1-2 (2005).

  • 753.
    Uusitalo, Petri
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Engström, Susanne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Detecting and understanding bottlenecks in production using multiple methods2017In: ICCREM 2016: BIM Application and Offsite Construction - Proceedings of the 2016 International Conference on Construction and Real Estate Management 2016 / [ed] Wang Y.,Al-Hussein M.,Shen G.Q.P.,Zhu Y., Reston, VA: American Society of Civil Engineers (ASCE), 2017, p. 307-315Conference paper (Refereed)
    Abstract [en]

    In a competitive situation where clients demand for high responsiveness to order-specific requirements, suppliers of volumetric preassemblies are struggling to maintain efficiency in production. In operation management literature, bottleneck detection has been suggested as key to continuous improvement processes in manufacturing. Yet, there is no consensus on definition and detection of bottlenecks. In an ongoing study, aiming to better understand manufacturing implications of high responsiveness to unique clients' specifications, a volumetric preassembly company providing prefabricated bathroom pods was addressed. Bottlenecks were explored based on three methods suggested in the literature i.e. by asking knowledgeable employees, by observing WIP inventory, and by analyzing process data in a field experiment. By juxtaposing the results, a mixed and somewhat contradictory view was displayed of bottlenecks and their potential root causes. Thus, a more complex view emerges of how to understand and address bottlenecks to improve production efficiency, highlighting the need to potentially extend shop-floor assessments to include supplier and client interfaces.

  • 754.
    Uusitalo, Petri
    et al.
    Stora Enso Plc, FI-94800, Kemi.
    Lidelöw, Helena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    The Struggle of Multiple Supply Chain Structures: Theoretical Overview2015In: Procedia Economics and Finance, E-ISSN 2212-5671, Vol. 21, p. 185-192Article in journal (Refereed)
    Abstract [en]

    Supplier firms are integrating downstream closer to the construction client. Sawmills have tried for decades to start producing timber buildings in order to capitalise on their core product; sawn timber. Their efforts have often failed, which is attributed to the different business logics between sawing timber and constructing buildings. This research identifies the supply chain structure as an important classification of production and business logic. Many firms operate make-to-stock, make-to-order and even engineer-to-order within the same firm, thus utilising the same or overlapping resources. From a theoretical viewpoint, this paper explores the problem of multiplicity in supply chains within construction and construction supplier firms. Literature on operations strategies, operations management, and supply chain structures is covered and put into perspective. It is an important capability to handle diversity in supply chain structures, not only when expanding business, but also in balancing different product categories internally e.g. to handle variations in market demand. The effect on internal resource utilisation can be vast. Operations management must take the differences in supply chain structures into account when developing key performance indicators and operations management strategies.

  • 755.
    Vallion, Simon
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Identifiering och Klassificering av Osäkerheter i Förvärvsprocessen vid Bostadsutvecklingsprojekt2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Early stages of construction projects are usually very complex, and many project conditions are uncertain. Uncertainties can be seen as lack of information and knowledge, which implies that many uncertainties are involved in early stages.  These can result in both positive and negative outcomes. Hence it is important to identify and manage uncertainties in order to make decisions and create proper project conditions.

    The purpose of this study is to increase the understanding of uncertainties and uncertainty management in the acquisition process in real estate development, by answering the research question: How can a framework be designed to create a secure basis for decisions by business- and project development during the acquisition process for real estate development in terms of uncertainties? To manage this a case study of a Swedish real estate developer has been conducted, where observations and interviews were conducted at the case company.

    The result from this study is increased understanding about uncertainty identification but also knowledge about which uncertainties to take in to consideration when making decisions on acquisitions. The identified uncertainties were divided into six major areas: Time, Economy, Project, Organization, Government and Market. This study has also resulted in a framework for analyzing and evaluating uncertainties, which also visualize the uncertainties in relation to each other. The result from this study contributes to theory by studying the acquisition process in real estate development projects and presents a structured approach to classifying and analyzing uncertainties. The framework is mainly relevant for decision-makers within the acquisition process and can be used as the basis for decisions on acquisition of new projects.

  • 756.
    Vehmas, Tapio
    et al.
    VTT Technical Research Centre of Finland, Espoo .
    Anna, Krönlof
    VTT Technical Research Centre of Finland, Espoo.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Calcium chloride acceleration in ordinary Portland cement2018In: Magazine of Concrete Research, ISSN 0024-9831, E-ISSN 1751-763X, Vol. 70, no 16, p. 856-863Article in journal (Refereed)
    Abstract [en]

    Early-age hydration of ordinary Portland cement is now acknowledged to originate from nucleation and crystal growth of calcium–silicate–hydrates. The acceleration mechanism of water-soluble inorganic substances, such as calcium chloride, is still unclear. In the present study, the acceleration mechanism was approached in two independent ways. First, the acceleration effect of filler materials (limestone and quartz powder) and calcium chloride (CaCl2) were studied experimentally with a conduction calorimeter. Second, the calcium chloride effect was studied with thermodynamic modelling. The experimental test results showed that the filler materials accelerated the acceleration period of ordinary Portland cement hydration, whereas calcium chloride accelerated hydration throughout the 24 h measuring period. A synergistic effect was observed with fillers and calcium chloride. Thermodynamic modelling indicated that calcium chloride provides a supersaturation with respect to pure calcium–silicate–hydrate. It was concluded that the supersaturation provides a qualitative explanation for both calcium chloride-induced acceleration and the synergistic effect observed with fillers

  • 757.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Behaviour and design of shallow composite slab2000In: Proceedings of the Conference Composite Construction in Steel and Concrete IV, American Society of Civil Engineers (ASCE), 2000, p. 310-321Conference paper (Refereed)
    Abstract [en]

    The aim of this paper is to present a design method based on small scale tests and a finite element analysis called 3P PCSM (three parameters partial connection strength method) for composite slabs with shallow sheeting. A short review of the current design methods in Eurocode 4 (1) are given just to accentuate a new contribution. Distribution of forces within composite slabs for various loading is discussed. A well established definition of the shear length is redefined in the context of the new findings, in Veljkovic (2) and for implementation in the new design method. Finally, an example is given where a design according to 3P PCSM is compared with two methods given in Eurocode 4, the m-k method and the partial connection strength method.

  • 758.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Behaviour and resistance of composite slabs: experiments and finite element analysis1996Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Composite slab flooring systems are used in steel framed buildings as well as in conjunction with concrete, prestressed concrete and timber structures. Composite slabs consist of a thin-walled profiled steel sheet, reinforcement and in-situ cast concrete. The profiled sheeting acts as permanent formwork and once the concrete has hardened as an outer reinforcement. Unlike a bar reinforcement, the sheeting does not benefit from being totally embedded in concrete. Partial connection between the sheeting and concrete takes place after the adhesion is broken. Composite slab design is usually based on parameters of partial connection obtained from full scale bending test. The objective of this thesis is to analyse composite slabs which fail in longitudinal shear and flexural failure. An analytical approach based on FE simulations and data from small scale tests (detail tests) has been used. A new test rig has been designed and a procedure developed to evaluate the characteristics of the interaction. Mechanical interlocking resistance, reduction of mechanical interlocking due to high strains in the sheeting, and friction between sheeting and concrete has been assessed. Cracking of concrete in composite slabs has a major influence on the distribution of horizontal shear forces between the sheeting and concrete, and consequently on the behaviour of the composite slab. An intensive FE nonlinear study has therefore been performed to examine various concepts of concrete cracking. FE predictions have been validated with the full scale tests and the good agreement obtained shows that modeling and input data were correct. Results of small scale tests and FE calculations have increased the knowledge of composite slab behaviour. A parametric study of the influence of load arrangements and various characteristic of partial connection have created the basis for an improved design method. A design method based on small scale tests and FE calculation is proposed. It uses a simple structural model and a new concept of transfer length to properly define a parth of slab length mobilized for longitudinal shear connection. The design method is an improved version of existing partial connection strength method described in Eurocode 4. The method is applicable for ductile and non ductile slabs and accounts for various loading arrangements in a consistent manner. Design recommendations for a general load arrangement are given.

  • 759.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Design of composite slabs based on small scale test1998In: Proceedings / Nordic Steel Construction Conference 98: Bergen, Norway, September 14th - 16th, 1998 ; new materials, new codes, new applications, Oslo: Norwegian Steel Association , 1998, p. 415-426Conference paper (Refereed)
    Abstract [en]

    An obvious tendency from recent research in the area of composite slabs is to substitute design rules based on so called parametric tests and m-k method by design rules that are established on structural principles. The aim of this paper is to show advantages of partial connection strength method based on three interface characteristics evaluated from the small scale tests: mechanical interlocking resistance, friction at the support, and reduction of the mechanical interlocking due to high strains in the profiled sheeting. The design method, so called 3P PCSM, is proposed for a possible inclusion as an alternative method for design of composite slabs with shallow profiled sheeting in Eurocode 4. The proposal is an improved version of the existing partial connection strength method because it uses a similar structural model to calculate design bending resistance but it covers even a slab with brittle behaviour. A design example is given to illustrate the proposed procedure and to compare results obtained by various design methods

  • 760.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Development of a new sheeting profile for composite floors: experimental study and interpretation1993Report (Other academic)
  • 761.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Improved partial connection method for composite slab design1997In: Proceedings of the 1996 Engineering Foundation Conference on Composite Construction in Steel and Concrete III, American Society of Civil Engineers (ASCE), 1997, p. 644-659Conference paper (Refereed)
    Abstract [en]

    This paper discusses deficiencies in the design methods presented in Eurocode 4 and the method proposed for possible application in Australian codes. An attempt has been made to formulate a new design method which is consistent with Eurocode's safety concept and as close as possible to the existing design model for partial connection used in Eurocode 4. The new procedure has three corner stones. An experimental program is used to establish material and interface characteristics. So called small scale tests (push test, tension-push test, and friction test) are used as the basis for the interface models used in FE calculations and to provide statistical characteristics of basic variables. A finite element parametric study of a simply supported slab is used to predict the distribution of resistance. The procedure presented in Annex Z of Eurocode 3 is used to evaluate the partial safety factor for resistance. A simple to use design formula has been derived for the longitudinal shear failure and the flexural failure of simply supported slabs.

  • 762.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Influence of load arrangement on composite slab behaviour and recommendations for design1998In: Journal of constructional steel research, ISSN 0143-974X, E-ISSN 1873-5983, Vol. 45, no 2, p. 149-178Article in journal (Refereed)
    Abstract [en]

    A parametric study of the behaviour of composite slabs consisting of profiled steel sheeting and concrete is presented. The FEM program DIANA was used to model the slab as a two-dimensional structure. Non-linear material and interface properties are considered as well as discrete cracking of the concrete. The main parameter is the horizontal shear transfer between the sheeting and the concrete; this is varied with respect to strength, ductility and influence of strain level in the sheeting. The FEM simulations have been validated by comparison with full-scale tests. It is clear from these comparisons that the full-scale behaviour can be described accurately using interface properties determined with small-scale push tests. The results of the simulations show clearly the importance of cracking of the concrete, which has a strong influence on the distribution of horizontal shear between the sheeting and the concrete. The largest slip will be at the so-called governing crack; at such a location the strains in the sheeting are high. For sheeting where the shear transfer relies on indentations, the strains in the sheeting reduce the shear transfer. The partial interaction method for design described in Eurocode 4 part 1 requires a very ductile connection between sheeting and concrete. The purpose of this study was to investigate the distribution of horizontal shear when the connection is less ductile, and to compare results for different load arrangements in order to develop a more general design method. The new method is based on detailed test results and FE analysis. Background information of the proposed method is given.

  • 763.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Longitudinal shear capacity of composite slabs1995In: Nordic Steel Construction Conference '95: proceedings : [new materials, new codes, new applications] : Malmö, Sweden, June 19-21, 1995, Stockholm: Stålbyggnadsinstitutet , 1995, p. 547-554Conference paper (Refereed)
    Abstract [en]

    Two parameters, mechanical interlocking and friction factors, are considered as sufficient for the prediction of longitudinal shear failure when strain levels in the sheeting are relatively low or when strong longitudinal slip resistance is considered. The mentioned parameters and reduction of mechanical interlocking caused by additional tensile strains in the thin-walled steel sheeting are measured on a segment of the composite slab by using the small scale test

  • 764.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Partial interaction in composite slabs1993In: Proceedings: Nordic Concrete Research Meeting : Göteborg 1993, Oslo: Norsk Betongforening , 1993, p. 293-296Conference paper (Refereed)
  • 765.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Project: Economic and Durable Design of Composite Bridges with Integral Abutments2007Other (Other (popular science, discussion, etc.))
  • 766.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Project: High-strength steel tower for wind turbines2007Other (Other (popular science, discussion, etc.))
  • 767.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Varför rasade World Trade Center?2003In: Årsbok / Bergshandteringens vänner, ISSN 0522-9243, p. 105-110Article in journal (Other (popular science, discussion, etc.))
  • 768.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Feldmann, Markus
    Institut für Stahlbau, Institute for Steel Construction, RWTH Aachen, University.
    Nuames, Johannes
    Institut für Stahlbau, Institute for Steel Construction, RWTH Aachen, University.
    Pak, Daniel
    Institut für Stahlbau, Institute for Steel Construction, RWTH Aachen, University.
    Rebelo, Carlos
    University of Coimbra.
    Silva, Luis Simoes da
    University of Coimbra.
    Friction connection in tubular towers for a wind turbine2010In: Stahlbau, ISSN 0038-9145, E-ISSN 1437-1049, Vol. 79, no 9, p. 660-668Article in journal (Refereed)
    Abstract [en]

    Innovative solution for assembling joints of a tubular tower for wind turbines has been studied by a European consortium since 2005 and the HISTWIN (High-Strength Steel Tower for Wind Turbine) project provides background for design of the friction connection considered. This solution is simpler to produce and 80% less expensive than traditional flange connection. A feasibility study at the production plant indicates that the towers would be easy to assemble in-situ. In addition to the direct costs savings due to technical simplicity of the solution, the higher fatigue endurance than the flange connection is experimentally established. The loss of pretension forces in the friction connection with long opened slotted holes is studied using segment short-term and long-term static tests, fatigue tests, down-scaled bending tests and by a specimen used in a feasibility study. The total reduction of the costs for tower is estimated to about 10% to 15% compared to the traditional tower with the flange connection.

  • 769.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Filipsson, Tomas
    Luleå tekniska universitet.
    Experimental and finite element study of gypsum plaster board shear walls2002Report (Other academic)
    Abstract [en]

    A part of the ECSC-project Development of dry composite construction systems based on steel in residential application focus on design recommendations for stabilizing buildings by using shear resistance in the walls. The existing design method suggested and used by the Swedish plasterboard manufacturer Gyproc AB is considered as too conservative. Therefore a number of tests concerning the behaviour of plasterboards, steel studs and fasteners have been carried out in order to investigate the possibilities for improvements and to obtain necessary input as well as comparative data for detailed FE-analyses. The experimental investigation covered - various cases of connections between one or two layers of plasterboards and a steel stud using one single fastener - various cases of small scale walls (900x900 mm) built up by one or two layers of plasterboards applied with fasteners to both sides of a steel stud frame - full scale test of two story wall with openings, 2*2700mm height and 4500mm width. A new design method is evaluated on an example of wall with double boards and without openings.

  • 770.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Gozzi, Jonas
    Towards economic design of a pressure vessel made of duplex stainless steel2005In: Super-High Strength Steels: 1st international conference, 2 - 4 November 2005, Rome, Italy, [proceedings], Milano: Associazione Italiana di Metallurgia , 2005Conference paper (Refereed)
    Abstract [en]

    The feasibility of manufacturing pressure vessels from duplex stainless steel (grade EN 1.4462, duplex 2205: 0.02%C, 22%Cr, 5.7%Ni, 3.1%Mo, 0.17%N) was evaluated by measurements of the mechanical properties of the parent metal and welds, and by finite element modelling. The tensile stress-strain properties of 4 mm sheet, and of the weld metal and the HAZ were measured in the transverse and rolling directions. Behaviour under biaxial stress was studied by pressurising circular sheet specimens from one side only, and measuring the strain as a function of applied pressure. The specimens included parent metal, and sheet with welds and a nozzle attached by welding. These specimens, and a cylindrical pressure vessel with hemispherical ends and a central nozzle, were modelled by finite element analysis. The results are discussed in relation to the current requirement for duplex stainless steel to be classified as a ferritic steel for design purposes.

  • 771.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Gozzi, Jonas
    Use of duplex stainless steel in economic design of a pressure vessel2007In: Journal of Pressure Vessel Technology-Transactions of the ASME, ISSN 0094-9930, E-ISSN 1528-8978, Vol. 129, no 1, p. 155-161Article in journal (Refereed)
    Abstract [en]

    Pressure vessels have been used for a long time in various applications in oil, chemical, nuclear, and power industries. Although high-strength steels have been available in the last three decades, there are still some provisions in design codes that preclude a full exploitation of its properties. This was recognized by the European Equipment Industry and an initiative to improve economy and safe use of high-strength steels in the pressure vessel design was expressed in the evaluation report (Szusdziara, S., and McAllista, S., EPERC Report No. (97)005, Nov. 11, 1997). Duplex stainless steel (DSS) has a mixed structure which consists of ferrite and austenite stainless steels, with austenite between 40% and 60%. The current version of the European standard for unfired pressure vessels EN 13445:2002 contains an innovative design procedure based on Finite Element Analysis (FEA), called Design by Analysis-Direct Route (DBA-DR). According to EN 13445:2002 duplex stainless steels should be designed as a ferritic stainless steels. Such statement seems to penalize the DSS grades for the use in unfired pressure vessels (Bocquet, P., and Hukelmann, F., 2001, EPERC Bulletin, No. 5). The aim of this paper is to present an investigation performed by Luleå University of Technology within the ECOPRESS project (2000-2003) (http://www.ecopress.org), indicating possibilities towards economic design of pressure vessels made of the EN 1.4462, designation according to the European standard EN 10088-1 Stainless steels. The results show that FEA with von Mises yield criterion and isotropic hardening describe the material behaviour with a good agreement compared to tests and that 5% principal strain limit is too low and 12% is more appropriate.

  • 772.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Gozzi, Jonas
    Lagerqvist, Ove
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Rudolfsson, J.
    Duplex stainless steel for pressure vessel design: experimental and finite element study performed within ECOPRESS, subtask 4.3,5.1,5.4 and 6.22002Report (Other academic)
    Abstract [en]

    The main objectives of the work presented in this report are to gain knowledge and collect characteristics for the application of duplex stainless steel (EN 1.4462) in economical pressure vessel design. The work covers ECOPRESS subtasks 4.3, 5.1, 5.4 and 6.2 and have included a total of 30 uniaxial tensile tests on base material, weld material and material from HAZ, redesign of an existing test set-up for membrane tests, a total of 12 membrane tests on plain and butt welded specimens and specimens with nozzles welded to them, 3 biaxial tests, design according to the Swedish Pressure vessel code of a typical pressure vessel in duplex stainless steel and a non-linear finite element analysis of the previously designed pressure vessel using material characteristics and other necessary inputs obtained from the evaluation of the uniaxial and membrane tests.

  • 773.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Heistermann, Christine
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Husson, Wylliam
    Limam, Marouene
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Feldmann, M.
    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH).
    Naumes, J.
    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH).
    Pak, D.
    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH).
    Faber, T.
    Germanischer Lloyd Industrial Services GmbH.
    Klose, M.
    Germanischer Lloyd Industrial Services GmbH.
    Fruhner, K-U
    Germanischer Lloyd Industrial Services GmbH.
    Krutschinna, L.
    Germanischer Lloyd Industrial Services GmbH.
    Baniotopoulos, C.
    Aristotle University of Thessaloniki.
    Lavasas, I.
    Aristotle University of Thessaloniki.
    Pontes, A.
    Martifer Energia — Equipamentos para energia, S.A..
    Ribeiro, E.
    Martifer Energia — Equipamentos para energia, S.A..
    Hadden, M.
    Martifer Energia — Equipamentos para energia, S.A..
    Sousa, R.
    Martifer Energia — Equipamentos para energia, S.A..
    Silva, L. da
    Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
    Rebelo, C.
    Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
    Simoes, R.
    Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
    Henriques, J.
    Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
    Matos, R.
    Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
    Nuutinen, J.
    Rautaruukki Oy.
    Kinnunen, H.
    Rautaruukki Oy.
    High-strength tower in steel for wind turbines (Histwin): Final report2012Report (Refereed)
    Abstract [en]

    Innovative solutions for assembling joints of a tubular tower for wind turbines were studied and the project provides a background for design. This solution is simpler to produce and 80 % less expensive than traditional flange connection. Our feasibility study at the production plant indicates that the towers would be easy to assemble in situ. In addition to the direct cost savings due to the technical simplicity of the solution, the higher fatigue endurance than that of the flange connection is experimentally established. Further reduction of costs due to optimal use of higher-strength steel grades, especially in the bottom segments of the tower where the stiffening of the door opening is costly, is shown in the report. The total reduction of the costs for tower is estimated at about 10–15 % compared to the traditional tower. The project objectives are achieved in following sequences. • Experimental activities of the friction connection: small-scale tests to establish resistance of the friction connection for a variety of faying surfaces and bolt types, accompanying testing to ensure realistic input data for FEA, long-term testing to establish loss of pretension forces during the lifetime and fatigue tests.• Bending test of the friction and flange connection in a down-scaled tower. • Feasibility of production of the tower segments in the laboratory and at the production plant. • Monitoring of the existing tower to access a stress variation during the operation. • FEA analysis of experimental results and a complete case study of the monitored tower. Numerical examples for design of the friction connection are given for the sake of illustration and to encourage use of the new connection

  • 774.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Bernt
    Design for buckling of plates due to direct stress2001In: NSCC 2001 Proceedings: Helsinki, Finland, 18 - 20 June 2001, organized by Helsinki University of Technology ... / [ed] P. Mäkeläinen; J. Kesti; A. Jutila; O. Kaitila, Helsinki: Helsinki University of Technology , 2001, p. 729-736Conference paper (Refereed)
  • 775.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Bernt
    Design of hybrid steel girders2004In: Journal of constructional steel research, ISSN 0143-974X, E-ISSN 1873-5983, Vol. 60, no 3-5, p. 535-547Article in journal (Refereed)
    Abstract [en]

    A hybrid steel girder is a welded girder with different steel grades in flanges and web. Usually, the flanges are made of high strength steel (HSS) like S690 and the web of a lower grade say S355 but combinations like S460 and S355 are also used. Such girders are more economical than homogenous girders. Hybrid girders have been used in the US since long but they are not commonly used in Europe. Some examples of the use of hybrid girders in Sweden are presented together with economic comparisons. Design rules for hybrid girders are presented together with justifications. Typically, hybrid girders are of cross-section class 4 according to Eurocode 3. The resistance in bending in ultimate limit state is influenced by the local yielding of the web, which limits the stresses in the web and affects the effective width of the web as well. Simplified formulae for the bending resistance are presented. For serviceability limit states, the local yielding of the web has to be accepted but the requirement of reversible behaviour will still be fulfilled. For the limit state of fatigue, Eurocode 3 states a restriction that the stress range should not exceed 1.5 times the yield strength. For hybrid girders, it is shown that this restriction applies to the yield strength of the flanges and that yielding of the web does not influence the fatigue strength.

  • 776.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Bernt
    Design of thin-walled steel column with partially closed cross-section2006In: Proceedings of SDSS 2006: International Colloquium on Stability and Ductility of Steel Structures : [Lisbon, Instituto Superior Técnico, 06 - 08 September 2006] / [ed] Dinar Camotim, Lisboa: Instituto Superior Técnico , 2006, p. 639-647Conference paper (Refereed)
    Abstract [en]

    Cold formed sections can be optimized for different purposes and they are fairly inexpensive to produce in small series. They have an inherent weakness in their small torsional stiffness, which is unfavourable for columns. The solution presented here is to make closed section by adding a thin cover plate connected with self-tapping screws. It is here called a partially closed cross-section because it is not continuously and rigidly connected. The aim of this paper is to evaluate the efficiency of this solution by comparing the behaviour of partially closed and open cross-section. Four columns were tested within the project, two of them with centric axial load and two with eccentricities. Numerical analysis was performed using ABAQUS for establishing the influence of the cover plate on the critical load and the resistance. A good agreement between non-linear FEM and experiments were found. After this verification of the FE model a parametric study was carried out. Results of experiments and numerical analysis were compared with the predicted resistance by Eurocode 3, Part 1-3, and the Direct Strength Method.

  • 777.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Bernt
    Design of uniformly compressed stiffened plates: a review of Eurocode 3-1-52000In: Coupled Instabilities In Metal Structures: Proceedings of the Third International Conference Held in Lisbon / [ed] Dinar Camotim; Dan Dubina; Jacques Rondal, Singapore: World Scientific and Engineering Academy and Society, 2000, p. 305-314Conference paper (Refereed)
  • 778.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Bernt
    Light steel framing for residential buildings2006In: Thin-walled structures, ISSN 0263-8231, E-ISSN 1879-3223, Vol. 44, no 12, p. 1272-1279Article in journal (Refereed)
    Abstract [en]

    Building systems with light steel members, gypsum plasterboards and mineral wool have a wide spread use in the US, Australia and Japan and are gaining market in some European countries. The systems have often load-bearing walls and the floors may be of lightweight steel profiles or concrete. Such systems are suited for industrial production and can contribute to a more efficient building process. Examples of components and systems are given in the paper. For low and medium rise buildings it is natural to use the walls as stabilising for horizontal loads from wind and imperfections. In Sweden and Finland this has been common practice for single-family timber houses since the 1970s. The paper describes the traditional design model for walls with single-layer gypsum plasterboards and an extension to double layers, which are needed for fire protection in multi-storey buildings.

  • 779.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Bernt
    Residual static resistance of welded stud shear connectors2006In: Composite Construction in Steel and Concrete V: Proceedings of the 5th International Conference / [ed] Roberto T. Leon; Jorg Lange, American Society of Civil Engineers (ASCE), 2006, p. 524-533Conference paper (Refereed)
    Abstract [en]

    Headed studs are widely used in composite bridges to provide longitudinal shear force transfer in the interface between concrete deck and steel beam. There is still no theoretical model available to describe the local failure mechanism and the resistance under the monotonic loading of the stud. The standard design of shear studs assumes that the static resistance is independent of fatigue. A test series on 12.5mm studs published by Oehlers however indicates a linear reduction of the static resistance with the number of cycles. In order to shed more light on this question a test series on 22mm studs was performed, which is the common size in bridges. The residual static resistance of shear studs after cyclic loading was measured using push tests according to Eurocode 4-1-1. The test program consisted of two series of tests. Five static tests were performed for establishing a reference static resistance and five residual strength tests were used to measure residual static resistance after cyclic preloading. In order to give an insight into the local failure mechanism under the monotonic loading a realistic 3D FE analysis of a single stud embedded in the concrete is presented. Results obtained from the FE model are compared with experiments and rather good agreement is obtained.

  • 780.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Bernt
    Stabilizing light weight steel buildings with shear walls2005In: EUROSTEEL 2005: 4th European Conference on Steel and Composite Structures / [ed] B. Hoffmeister; O. Hechler, Aachen: Verlag Mainz , 2005, p. 1.8/25-1.8/33Conference paper (Refereed)
  • 781.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Johansson, Bernt
    Thin-walled steel columns with partially closed cross-section: tests and computer simulations2008In: Journal of constructional steel research, ISSN 0143-974X, E-ISSN 1873-5983, Vol. 64, no 7-8, p. 816-821Article in journal (Refereed)
    Abstract [en]

    Cold formed sections can be optimized for different purposes and they are fairly inexpensive to produce in small series. They have an inherent weakness in their small torsional stiffness, which is unfavourable for columns. One solution presented here is to make a closed section by adding a thin cover plate connected discretely with self-tapping screws. It is here called a partially closed cross-section because it is not continuously and rigidly connected. The aim of this paper is to evaluate the efficiency of this solution by comparing the behaviour of partially closed and open cross-section. Four columns were tested within the project, two of them with centric axial load and two with eccentricities. Numerical analysis was performed using ABAQUS for establishing the influence of the cover plate on the critical load and the resistance. A good agreement between non-linear FEM and experiments were found. After this verification of the FE model a parametric study was carried out. Results of experiments and numerical analysis were compared with the predicted resistance by Eurocode 3, Part 1-3, and the Direct Strength Method. Both design methods give good predictions of the resistance.

  • 782.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Koukkari, H.
    Borg, R.P.
    Stoian, V.
    Plewako, Z.
    Overview on eco-efficiency of constructions2011In: Summary report of the Cooperative Activities of the Cost Action C25: Sustainability of Constructions. Integrated Approach Towards Sustainable Constructions, 2011, p. 177-187Chapter in book (Other academic)
  • 783.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Koukkari, Heli
    VTT Technical Research Centre of Finland, Espoo.
    Braganca, Luis
    University of Minho, Guimarães.
    Survey on educational material on sustainable constructions2008In: Proceedings of Seminar on Sustainability of Constructions - Integrated approach to life-time structural engineering: COST Action C25, Dresden, Germany 6.-7.10.2008, 2008, p. 1.59-1.67Conference paper (Other academic)
    Abstract [en]

    Higher education of professionals in the construction and real estate sector is in the process of "Greening curricula". Pressures to educate environmentally literate workforce are increasing. The literature survey shows that technical universities worldwide have incorporated modules, courses and programmes of sustainable construction. In general, new teaching methods and approaches are regarded as necessary due to the complexity of the triple bottom-line issues of the sustainable construction. In addition to traditional lecturing and exercises, life-cycle and overall performance matters are taught by methods of team-work, problem-solving and learning-by-doing. The material for this study was gathered from literature and virtual site visits of universities as well as a questionnaire among the participants of the COST C25. First remarks concerning all the material is that there are still few technical universities with a cross-cutting strategy about sustainability.

  • 784.
    Veljkovic, Milan
    et al.
    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.
    Heistermann, Christine
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Rebelo, Carlos
    University of Coimbra.
    Silva, Luis Simoes da
    University of Coimbra.
    Feasibility study of friction connection in tubular towers for wind turbines2010In: Steel structures: culture & sustainability 2010: international symposium, Istanbul, 21 - 23 September 2010, Istanbul: Turkish Constructional Steelwork Association , 2010Conference paper (Refereed)
    Abstract [en]

    In steel tubular towers flange connections are used to assemble two segments of the tower. As an alternative for these fatigue-sensitive joints a new type of friction connection has been investigated both in laboratory and at a production plant where the feasibility study was performed. The specimen used in the feasibility test consists of two tower segments, each about 3m high and 2 m in diameter. The segments are connected by 222 M30 high-strength bolts. The production process and tolerances achieved are briefly explained. The assembling process is modeled using a realistic FEA model to predict the stress in the segments during pretensioning. A simplified FE analysis was performed to assess the influence of the compressive strength of the specimens. This paper presents results of a short parametric study on the influence of the gap between two tower segments exploring possibilities to use higher-strength steel in the towers. Keywords: Finite Element Model, Gap, High Strength Friction Grip Connection, Tubular Steel Tower, Wind Energy Converter

  • 785.
    Veljkovic, Milan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lopez, Nuno
    University of Naples.
    Real, Paulo Vila
    University of Naples.
    Uppfeldt, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Silva, Luis Simoes da
    University of Coimbra.
    Franssen, Jean-Marc
    University of Liège.
    Bouchaïr, Hamid
    Polytech' Clermont-Ferrand.
    Muzeau, Jean-Pierre
    Polytech' Clermont-Ferrand.
    Vassart, O
    Bacinskas, Darius
    Vilnius Gediminas Technical University.
    Kaklaskaus, Gintaris
    Vilnius Gediminas Technical University.
    Gribniak, Viktor
    Vilnius Gediminas Technical University.
    Nigro, Emido
    University of Naples.
    Cvetkovska, M
    Lazarov, L
    Cefarelli, G
    Structural member behaviour and analysis in case of fire2008In: Urban Habitat Constructions under Catastrophic Events: COST Action C26 / [ed] Federico M Mazzolani, Valetta: Editura Universitatii de Vest din Timisoara / University of the West Timisoara Publishing House, 2008, p. 45-50Conference paper (Other academic)
  • 786.
    Vessby, Johan
    et al.
    Linnaeus University, Växjö, Linnéuniversitetet.
    Källsner, Bo
    School of Engineering, Linnæus University, Växjö, Linnéuniversitetet, Linnaeus University, Växjö.
    Girhammar, Ulf Arne
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olsson, Anders
    Faculty of Technology, Linnaeus University.
    Evaluation of softening behaviour of timber light-frame walls subjected to in-plane forces using simple FE models2014In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 81, p. 464-479Article in journal (Refereed)
    Abstract [en]

    The present investigation focuses on evaluating the entire load–displacement relationship, especially the softening part, of light-frame wall segments subjected to in-plane monotonic forces when the load-slip curves of the individual sheathing-to-framing fasteners are considered. Different sheathing-to-framing joint characteristics, including unloading behaviour, and stud-to-rail joint characteristics are incorporated in the analyses. Two loading cases are investigated: Horizontal loading resulting in uplift of the leading stud and diagonal loading representing a fully anchored wall.Two common types of finite element (FE) models for the sheathing-to-framing joints are used for the analyses: A single spring model and a spring pair model, where the joint characteristics valid for the timber properties perpendicular and parallel to the grain are used. The maximum capacity of the wall segments is somewhat overestimated when using the spring pair model compared to that of the single spring model. The softening parts of the load–displacement curves are significantly affected, regardless of whether the perpendicular or parallel characteristics of the joints are used.The results from FE simulations using models with perpendicular and parallel characteristics are compared with full scale test results for walls with a single segment loaded horizontally and diagonally. The behaviour of the wall segments subjected to horizontal loading is dominated by fastener displacements perpendicular to the bottom rail. Hence, FE models including perpendicular characteristics should be used. For diagonal loading the behaviour of the wall segments is dominated by displacements parallel to the framing members, and FE models including parallel characteristics should therefore be used.The analyses were extended to multiple segment walls resulting in the same type of behaviour as single segment walls.

  • 787.
    Vicente, Guiomar
    et al.
    ISISE, Department of Civil Engineering, University of Coimbra.
    Andrade, Pedro
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simões, Rui
    ISISE, Department of Civil Engineering, University of Coimbra.
    Rebelo, Carlos
    ISISE, Department of Civil Engineering, University of Coimbra.
    Silva, Luís Simões da
    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.
    Sistema Inovador de Construção Metálica: FRAMEUP2015Conference paper (Refereed)
    Abstract [en]

    The methodology developed under the project FRAMEUP includes the construction of residential buildings from the top to the base, whose compartments are prefabricated modules. The construction begins with the execution of the roof, on the ground level, which is later on lifted, allowing from beneath the construction of the lower floors, while it protects them from the weather. The construction ends with the execution of the ground floor. It is adopted a framed structure with tubular sections for which the beam-to-column connections are developed and the columns-splices designed to facilitate and the use of this constructive methodology.

  • 788.
    Viking, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Byggkravsutredningen missar målet: Industriella byggares syn på särkrav2014In: Samhällsbyggaren, ISSN 2000-2408, Vol. 2014, no 6, p. 38-39Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Vi menar att den definition av termen kommunala särkrav som används av Byggkravsutredningen är för snäv för att vara riktigt meningsfull för det industriella byggandet. De förbättrade förutsättningarna för industriellt byggande som utlovats till följd av de lagändringar som träder i kraft vid årsskiftet riskerar därför till stor del att utebli.

  • 789.
    Viking, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Föreslagna ändringar i plan- och byggprocessen: En workshopdokumentation2014Report (Other academic)
    Abstract [sv]

    Denna rapport är en delrapportering inom ramen för forsknings- och utvecklingsprojektet ATTRACT (Attractive and Sustainable Cities in Cold Climate). Rapporten presenterar resultaten från en workshop som genomfördes 25/2 2014 i Malmberget med temat: Föreslagna ändringar i plan- och byggprocessen. Bakgrunden till workshopen var det större antal statliga utredningar, promemorior, lagrådsremisser och riksdagspropositioner som det senaste året lagt fram förslag på förändringar av den svenska plan- och byggprocessen. Workshopdeltagarna fick möjlighet att diskutera hur dessa förslag skulle påverka plan- och byggprocessen med särskilt fokus på effektivitet och kvalitet, två viktiga aspekter vid samhällsomvandlingarna i Malmfälten.Ett antal återkommande teman dök upp i de diskussioner som hölls och sammanfattningsvis kan sägas att förslagen möttes med blandad entusiasm. Framför allt tyckte deltagarna att det är viktigt att hitta en balans mellan effektivitet och kvalitet. Allt arbete måste göras ordentligt, annars riskerar processen att dras ut av långsamma överklagandeprocesser. Samtidigt är det svårt att utvärdera förslagen eftersom ett större antal intressenter är involverade i plan- och byggprocessen och alla dessa påverkas på olika sätt.Deltagarna menade också att det är viktigt att åstadkomma en röd tråd genom planeringen för hållbarhetsfrågor för att konsekvent och med hjälp av stringent uppföljning och dokumentering kan arbeta strukturerat med att konkretisera hållbarhetsdimensionerna allteftersom processen fortskrider.

  • 790.
    Viking, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Industriella byggföretags syn på kommunalt kravställande2014Report (Other academic)
    Abstract [sv]

    Efter mer än två decennier av otillräckliga produktionsvolymer på bostadsmarknaden lider Sverige nu i allt ökad utsträckning av en brist av bostäder i allmänhet och av små, billiga bostäder i synnerhet. Industriella byggare symboliserar ett sätt att, genom användning av standardiserade processer och byggsystem, bygga bostäder mer kostnadseffektivt än med traditionella metoder men för att uppnå full effekt krävs förutsägbara villkor. Rätten för svenska kommuner att ställa krav på lokala byggprojekt ärcentralt i svensk byggrätt. Sentida samhällsförändringar har dock ökat kommuners behov av att profilera sig själva i en allt hårdare kamp om invånare, företagsetableringar och resurser. Detta har gjort dem mer benägna att tillämpa rätten till kravställning på byggprojekt i en högre utsträckning än tidigare.Bakgrunden till förstudien som presenteras i den här rapporten är att många industriella byggare uttrycker att det finns problem i gränssnittet mellan industriellt byggande och den kommunala planeringen. Denna rapport är en delrapportering inom ramen för projektet och presenterar preliminära resultat och analys av empiriskt material insamlat under en förstudie som genomförts mellan augusti 2013 och januari 2014. Rapporten syftar till att presentera den empiri och de resultat som hittills genererats. Materialet består av intervjuer med representanter från fem industriella byggföretag. Resultaten visar att förekomsten av kommunalt särkravsställande i Sverige idag är tämligen utbredd. Mycket pekar på att byggprojekt situerade i resursstarka centralt belägna kommuner drabbas hårdast av denna företeelse. Industriella byggkoncept bygger på upprepning och stordriftsfördelar och alla individuella krav som tvingar till avsteg från det industriella byggsystemet vara sig i form av tekniska lösningar eller måttsättningar leder till ökade omkostnader som i slutändan återspeglas i boendekostnaderna. Byggarna tillämpar ett antal olika strategier för att hantera kommunal kravställning. En strategi är att försöka förebygga särkravsproblematik genom att ta sig in tidigt i processen, en annan att på förhand försöka inventera vilka särkrav som kan tänkas ställas och på så sätt undvika projekt som väntas bli för krångliga. En tredje strategi verkar vara att identifiera kommuner som är särskilt viktiga och att anpassa sig efter deras särkrav. Gemensamt verkar dock vara en önskan om att föra dialog imening att skapa förståelse och samverkan för att navigera runt de mest snåriga kraven. Det förefaller dock inte som att någon av dessa strategier ger fullständigt tillfredsställande resultat. I detta läge kan man bara spekulera kring orsakerna till kommuners agerande, dock framgår tydligt att faktorer på både individ- och organisationsnivå spelar in. Kommunalt särkravsställande grundar sig i de bästa intentioner men resulterar inte alltid i de bästa utfallen. De industriella byggarna har teorier om varför kommuner agerar som de gör, men har inte en full förståelse för deras situation. De teman som identifierats i intervjumaterialet ger en generell förklaring av grundproblematiken mellan industriellt byggande och kommunal planering men det finns fortfarande en diskrepans mellan dessa och den utförliga intervjudatan. Därför krävs fortsatta analyser för att åstadkomma en ökad förståelse för de bakomliggande orsaker som finns och inte minst de konsekvenser som uppstår till följd av kommunalt särkravsställande. Fortsatta studier bör dessutom belysa det kommunala perspektivet.

  • 791.
    Viking, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lidelöw, Sofia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Exploring industrialised housebuilders' interpretations of local requirement setting using institutional logics2015In: Construction Management and Economics, ISSN 0144-6193, E-ISSN 1466-433X, Vol. 33, no 5-6, p. 484-494Article in journal (Refereed)
    Abstract [en]

    Industrialized housebuilding contractors use standardized processes and building systems to improve time and cost efficiency. Recent governmental investigations argue that Swedish local planning authorities’ requirement setting practices stifle the potential for increased industrialization. Yet, no previous research has accounted for the industrialized housebuilders’ perspective. We aim to explore industrialized housebuilders’ interpretationsof local requirement setting, using institutional logics to increase the understanding of how structure and human agency influence the emergence of local requirements. Interviews were conducted with representatives of fiveindustrialized housebuilders who together span the Swedish multi-family housing market. Findings indicate that industrialized housebuilders do not perceive intentional local requirement setting as problematic, yet struggle tocope with interpretive local requirement setting. Findings also necessitate distinguishing local requirement setting in the exercise of public authority from local requirement setting in public procurement. The agency structure dualism contributes an understanding of interpretive local requirement setting in the exercise of public authority as an expression of agency and of local requirement setting in public procurement as one of structure. Furthermore, using an institutional logics approach is found to provide an accentuation of human agency and the individual level of analysis that is often absent from construction management research.

  • 792.
    Viking, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lidelöw, Sofia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Exploring industrialised house-builders' perceptions of local requirement setting: An institutional logics perspective2014In: Procs 30th Annual ARCOM Conference: 1-3 September 2014, Portsmouth, UK / [ed] Ani Raiden; Emmanuel Aboagye-Nimo, Reading: Association of Researchers in Construction Management , 2014, Vol. 2, p. 1133-1142Conference paper (Refereed)
    Abstract [en]

    Industrialised house-builders (IHBs) are housing contractors who use standardised processes and building systems as a means to time and cost efficiently address the current housing shortage in Sweden. Recent governmental investigations argue that the mandate for local planning authorities (LPAs) to intentionally set stricter requirements than those prescribed in the national building code can stifle the potential for increased industrialisation. The aim of this paper is to explore IHBs’ perceptions of local requirement setting (LRS). It seeks to use the concept of institutional logic to advance the understanding of how LRS affects IHBs. Data was collected through in-depth interviews with representatives of five IHBs encompassing a mix of building systems spanning the Swedish multi-family housing market. From the data we identify three distinct categories of LRS: intentional, interpretive and public procurement-related. The respondents' perceived issues with LRS are found to relate more closely to the process of setting requirements than to the requirements themselves. The political debate about LRS has entirely neglected interpretive LRS, LRS in public procurement as well as the entire process perspective. Institutional logics is shown to offer new and interesting perspectives on the agency/structure dominated cognitive and intra-organisational processes that shape the emergence of local requirements in interpretative LRS and LRS in public procurement respectively. Since LRS is affected both by individual planning officers (agency) and the LPA organisation (structure) further studies will explore their perceptions of LRS.

  • 793.
    Viking, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Stehn, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Exploring Swedish local planning authorities' perceptions of standardized housing construction2015In: Procs 31st Annual ARCOM Conference: 7-9 September 2015, Lincoln, UK / [ed] Ani Raidén; Emmanuel Aboagye-Nimo, Reading: Association of Researchers in Construction Management , 2015, Vol. 2, p. 1053-1062Conference paper (Refereed)
    Abstract [en]

    We explore how Swedish Local Planning Authorities perceive standardized housing construction and attempt to use an ideal type typology of institutional logics to describe how Local Planning Authorities make use of the multiple institutional logics available to them. Increased standardization in Swedish housing construction has been suggested as a means to meet the growing need for housing with reasonable rent levels. However, housing contractors that use standardization and repetition of processes and components claim that the variation of requirements set by Local Planning Authorities prevents them from taking full advantage of their standardization. A recent empirical study of standardized housing contractors’ perceptions suggests that Local Requirement Setting, the requirement setting practices of Local Planning Authorities, are interpretational responses to a lack of familiarity with standardized housing construction. Yet, Local Planning Authorities’ perceptions of standardized housing construction have never previously been explored. Empirical material for this on-going study was collected through in-depth exploratory interviews with local planning officers from three municipalities situated in Swedish population growth regions. Findings suggest that Local Planning Authorities perceive potential benefits with standardization, but ultimately expect standardized housing concepts to adapt to local standards for processes and products. In projects with high ambitions for architectural quality standardized housing concepts need to be highly flexible. Conversely, highly standardized housing concepts benefit from project ambitions that favour reasonable rent levels. Therefore, Local Requirement Setting is indicative of a mismatch between the Local Planning Authority’s project ambitions and the standardized housing contractor’s degree of product standardization.

  • 794.
    Viklund, Emma
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Design approaches in industrialized house building: A creativity perspective2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Industrialized house builders strive towards structure and control of their processes, including design. Such structure is seldom sought for in architectural design practice, where individuality and autonomy are considered essential. This is causing a tension in the construction industry as industrialized house builders and architects strive to improve their collaboration. In this licentiate thesis, a first step towards better understanding this tension is taken by exploring different design approaches from a creativity perspective. The analytical framework builds on a theoretical conceptualization of design approach features, including design task, design process, design organization, and knowledge sharing. A creativity perspective is added using heuristic or algorithmic design tasks; divergent or convergent design processes; autonomy or imposed structure from the design organization; and sole designer or teamwork as the basis for knowledge sharing. This framework is used to analyze four empirically explored design approaches, two focusing on platform development and two focusing on project specific design. Three of these are explored using a case study approach, while the fourth is explored through interviews with multiple architects.

    The architectural design approach’s features seem likely to facilitate creativity: the design task is mainly heuristic; the design process enables divergence; and the architects have autonomy in how to go about the design process. However, they experience a lack of knowledge sharing, which could further facilitate creativity. The studied standardized design development approach has the opposite features: the design task is mainly algorithmic; the design process facilitates convergence; and there is a clear structure with instructions of how each subtask should be executed. Hence, this design approach is not likely to facilitate creativity (which was also not its intention). The structure has however improved the design team’s knowledge sharing, which is likely to facilitate creativity.

    The two platform development approaches have a mix of features. Both design tasks are more algorithmic than heuristic and creativity was not expected of the design results. The design processes are clearly convergent. While the house platform development team is multi-functional and work in close collaboration, the design automation platform developers’ knowledge sharing is based on communication with the client’s organization, thus not enabling as many perspectives on the designed product. The design automation platform developers use a support structure with process descriptions and methods to ensure quality, motivated by the variety of platforms that they develop on a regular basis. The house product platform developers on the other hand, were expected to develop only this one platform. Hence, they worked autonomously, using the teamwork setting to progress and converge in the process.

    In summary, the creative intention seems related to how design is approached. If creativity is sought for, the design task is heuristic, and divergence and autonomy is promoted. If creativity is not sought for, structure seem to facilitate other benefits such as reliability and quality control. Knowledge sharing could however be potentially beneficial in most design approaches. By understanding that different design approaches will influence creativity in different ways, a first step has been taken towards understanding why architects and industrialized house builders approach design differently.

  • 795.
    Viklund, Emma
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Sandberg, Marcus
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Lidelöw, Helena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Jansson, Gustav
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Modularization based on commonalities in house-building requirements2017In: ICCREM 2016: BIM Application and Offsite Construction - Proceedings of the 2016 International Conference on Construction and Real Estate Management 2016 / [ed] Wang Y.,Al-Hussein M.,Shen G.Q.P.,Zhu Y., Reston, VA: American Society of Civil Engineers (ASCE), 2017, p. 126-134Conference paper (Refereed)
    Abstract [en]

    Some of the requirements governing the design of houses are common between projects. This opens up for using modularization based on product commonalities. Though modularization is well known in the manufacturing industry, its use in house-building contexts is less studied. Even more scarce is research focusing on how requirement commonalities between one-of-a-kind products are found and managed in a modularization process. In this research, modularization from a requirements management perspective is empirically explored using a case study approach. Though the studied modularization process can be described as sequential, the process steps are highly interrelated, with overlaps and iterations. Commonalities are found by functional decomposition of the customer's portfolio projects, tracing technical solutions back to their initial requirements. These are balanced with the customer's requirements on the product and on the design automation tool. The requirement list is continuously updated based on portfolio analysis and communication of modularization results to the customer

  • 796.
    Vikström, Matilda
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Edlund, Desirée
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Byggnadstekniska lösningar för brandskydd på radhusvindar2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
  • 797.
    Völling, Boris
    et al.
    Lehrstuhl für Stahlbau und Leichtmetallbau, RWTH Aachen.
    Sedlacek, Gerhard
    Lehrstuhl für Stahlbau und Leichtmetallbau, RWTH Aachen.
    Pak, Daniel
    Lehrstuhl für Stahlbau und Leichtmetallbau, RWTH Aachen.
    Clarin, Mattias
    Zum Beulverhalten kaltgeformter und geschweisster Rechteckhohlprofile aus hochfestem Stahl2006In: Stahlbau, ISSN 0038-9145, E-ISSN 1437-1049, Vol. 75, no 11, p. 889-896Article in journal (Refereed)
    Abstract [en]

    New structural steels, such as (liquid) quenched and tempered (QT) steels, with extra high strength, good toughness and weldability have been developed in Europe in recent years and are included in Eurocode 3 Part 1-12 for strengths up to S 700. However, extra high strength steels (EHSS) with a yield strength of 1100 N/mm2 so far have not been taken into account in the present version of Eurocode 3 due to insufficient knowledge on their buckling behaviour and fatigue strength and lack of associated experimental data. In this article results of experimental and numerical investigations concerning the local buckling behaviour of cold-formed and welded hollow sections made of EHSS are summarised. The investigations have been carried out within the scope of an European research project. Results have been used to check the applicability of existing design rules for local buckling to EHSS. As a consequence the scope of Eurocode 3, Part 1.12 could be expanded to cover stability rules also for such steels.

  • 798.
    Wahl, Emma
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Buildings in Arid Desert Climate: Improving Energy Efficiency with Measures on the Building Envelope2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Because of the harsh climate of Saudi Arabia, residential buildings on average, consume more than half of the total consumed energy. A substantial share of energy goes to the air-conditioning of buildings. Cooling buildings during summer is a major environmental problem in many Middle Eastern countries, especially since the electricity is highly dependent on fossil fuels. The aim of this study is to obtain a clearer picture of how various measures on the building envelope affects the buildings energy consumption, which can be used as a tool to save energy for buildings in the Middle East.

    In this study, different energy efficiency measures are evaluated using energy simulations in IDA ICE 4.7 to investigate how much energy can be saved by modifying the building envelope. A two-storey residential building with 247 m2 floor area is used for the simulations. The measures considered are; modifications of the external walls, modification of the roof, window type, window area/distribution, modification of the foundation, shading, exterior surface colour, infiltration rate and thermal bridges. All measures are compared against a base case where the building envelope is set to resemble a typical Saudi Arabian residential. First, all measures are investigated one by one. Thereafter, combinations of the measures are investigated, based on the results from single measure simulations. All simulations are carried out for two cities in Saudi Arabia, both with arid desert climate. Riyadh (midlands) with moderately cold winters and Jeddah (west coast) with mild winter.

    The results from simulations of single measures show the highest energy savings when changing the window type from single clear glass to double glass with reflective surface saving 27 % energy (heating & cooling) in Riyadh and 21 % in Jeddah. Adding insulation to an uninsulated roof saved up to 23 % and 21 % energy for Riyadh respectively Jeddah. Improvements of the thermal resistance of the exterior walls show 21 % energy savings in Riyadh and only 11 % in Jeddah. Lowering the window to wall ratio from 28 % to 10 % and changing the window distribution results in 19 % (Riyadh) and 17 % (Jeddah) energy savings. Adding fixed shades saves up to 8 % (Riyadh) and 13 % energy (Jeddah) when dimensioned for the peak cooling load. Using bright/reflective surface colour on the roof saves up to 9% (Riyadh) and 17 % (Jeddah) when the roof is uninsulated. For the exterior walls, bright/reflective surface saves up to 5 % (Riyadh) and 10 % (Jeddah) when the walls are uninsulated. The other single measures investigated show less than 7 % energy savings.

    The results for combined measures show the highest energy savings for two combined measures when improving the thermal resistance of the exterior walls and changing window area/distribution saving up to 52 % (Riyadh) and 39 % (Jeddah). When performing three measures the addition of improved thermal resistance and reflectance of the windows resulted in the highest energy savings, saving up to 62 % (Riyadh) and 48 % (Jeddah). When adding a fourth measure, improving the thermal resistance of the slab shows the highest energy savings, 71 % (Riyadh) and 54 % (Jeddah). Applying all measures on the building envelope results in 78 % (Riyadh) and 62 % (Jeddah) energy savings.

    Significant energy savings can be achieved with measures on the building envelope. Major savings can be made by adding only 50-100 mm of insulation to the exterior walls and roof. Decreased window area and improvements on the thermal resistance and reflectance on the windows result in significant energy savings. Energy savings achieved with shadings and reflective surface colours decrease significantly when the thermal resistance of the roof and external walls are improved. All measures concerning thermal resistance have a higher impact in Riyadh than in Jeddah due to that a large part of the total heating and cooling is air handling unit (AHU) cooling in Jeddah. AHU cooling is not affected significantly by measures on the building envelope. To optimise energy savings, measures on the building envelope should be considered in combination with measures concerning the AHU.  

  • 799. Wald, F.
    et al.
    Moore, D.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Eliášová, M.
    Continuing education in structural connection2004In: Innovative Steel Connections: June 3-5, 2004, Radison SAS H., Amsterdam, Netherlands, Amsterdam: American Institute of Steel structures , 2004, p. 37-44Conference paper (Other academic)
    Abstract [en]

    The European project Continuing Education in Structural Connections (CeStruCo) under Leonardo da Vinci initiative No. CZ/00/B/F/PP-134049 was prepared by partners from seven European countries to disseminate the latest results in research and standardization during the period of transferring the European Pre-Standard into the European Standard. The project has started by a collection of questions from the European practice. The answers to those questions have been prepared in the form of textbooks in the project partners national languages. The material is available as an easily accessible Internet/CD (www.fsv.cvut.cz/cestruco) media, and includes video and audio files, slides and worked examples.

  • 800.
    Wargsjö, Agneta
    Luleå tekniska universitet.
    Plastisk rotationskapacitet hos svetsade stålbalkar1991Licentiate thesis, monograph (Other academic)
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