Change search
Refine search result
1234567 1 - 50 of 838
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Almblad, Cecilia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Stommaterialets klimatpåverkan: En jämförande studie mellan stommaterialen trä och betong ur ett livscykelperspektiv applicerat på en passivhusförskola2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 2.
    Alniemi, Jamal
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Jämförande studie av lastnedräkningar för hand och med FEM-program2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 3.
    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.

  • 4.
    Andrade, Pedro
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Structural Assessment and Optimization of the Modular System of a Student Residential Building in Luleå and Coimbra: Affordable Houses Project2010Report (Refereed)
    Abstract [en]

    Nowadays there is a main concern that should always be present in our minds; it is important to integrate and reconcile the economic, social and environmental aspects within a holistic and balanced sustainable development framework.Therefore, the construction sector has been facing a profound change in the materials used, new processes and approaches. According to this new aim, a new concept of structures had been born; the Affordable Houses.A concept is more often seen as an abstract idea of something, being it materialization always faced as a challenge. Therefore the challenge of this thesis is to create a system that could be able to erect, literally, a structure and, simultaneously, create conditions for the construction of a building, through the appliance of the concept of Modular Houses and Top Down Construction.For the implementation of these new concepts two case studies were created for the construction of a student residential building in Coimbra and Luleå. These case studies are integrated in different environments and socio-economic conditions, which will allow the assessment of this study to a more global application.This study was developed within the scope of a partnership between the University of Coimbra and Luleå University of Technology and was supervised by Professor Luís Simões da Silva (UC) and Professor Milan Veljkovic( LTU).

  • 5.
    Andrade, Pedro António Pimenta de
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Innovative Construction of Student Residences: Frameup Project2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the majority of university cities in Sweden, a strong demand for student accommodations has initiated various development and research projects focusing on costs reduction and fast execution. The present thesis brings up a solution based on the development of a feasible assembly concept and process, for a Modular Building erection, where prefabricated 3D Modules are assembled into a sway steel frame. The concept has been initiated within FRAMEUP project: Optimization of Frames for Effective Assembling (RFCS contract RFS-PR-10121). One of the main project objectives was to investigate and develop a competitive structural system suitable for fast in-situ execution and dismounting. Thus, in order to streamline the construction process, the use of optimized prefabricated frames and room 3D modules has become a very attractive alternative. The building is designed considering a six-story building, as it has been seen as the suitable choice of industrial partners in the project on market demands for the optimal payoff time. The use of Intensive Use of Steel together with Modular Construction enhances the conditions for industrialization of the construction process towards the cost reduction.The development of the whole concept is described and followed up by a 4D construction sequence. The concept is based on the original structural system for which calculations, drawings and feasibility test at full scale are made to prove the credibility of the system. The 3D Modules are designed by Norrbotten based SME, which has influenced the global concept design. In addition, development of a novel joint, by means of laboratory tests and finite element models, is shown in the thesis. It is believed that its use in the frame, for the column splice connection, may be advantageous for the execution process. The issue of execution tolerances has been addressed by advanced FEA, which has been validated by experiments.

  • 6.
    Andrade, Pedro
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Lagerqvist, Ove
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Simões, Rui
    University of Coimbra, Department of Civil Engineering, Coimbra.
    Veljkovic, Milan
    Delft University of Technology, Department of Structural Engineering.
    Structural assessment of a column splice with opened slotted holes: Finger Connection2017In: ce/papers, E-ISSN 2509-7075, Vol. 1, no 2-3, p. 514-521Article in journal (Refereed)
    Abstract [en]

    This paper introduces a novel joint based on a friction connection designed for column-splices. The jointwas developed within the scope of modular construction to improve the fast assembly of prefabricatedframes and to accommodate eventual misalignments. Gaps at the connection are considered on the jointhorizontal and vertical axis to accommodate misalignments whether they are rotations and/ordisplacements and so to allow for the easy fit of the columns. The efficiency of the joint resistance basedon different connection gaps subjected to uniform compression is assessed.

  • 7.
    Andrade, Pedro
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Lagerqvist, Ove
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Veljkovic, Milan
    Delft University of Technology.
    Simoes, Rui
    University of Coimbra.
    Lundholm, John
    Part Construction AB.
    Innovative system for the construction and management of student resisdences: Frameup system2016In: IABSE CONGRESS, STOCKHOLM, 2016: Challenges in Design and Construction of an Innovativeand Sustainable Built Environment / [ed] Lennart Elfgren, Johan Jonsson, Mats Karlsson, Lahja Rydberg-Forssbeck and Britt Sigfrid, CH - 8093 Zürich, Switzerland: International Association for Bridge and Structural Engineering, 2016, p. 1364-1370Conference paper (Refereed)
    Abstract [en]

    Sweden has a strong demand on the construction of student accommodations and consequently significant efforts have been taken to increase and streamline construction methods. In addition, the fluctuation on the number of students admitted at each year, in each university, lead to periods of house shortage or, in opposition to that, to eventual surplus on the housing market. For these reasons urges finding a fast execution process in construction to fulfil the market needs, together with a housing mechanism of control which balances the students’ needs with the housing availability. In this sense, the Frameup system arises as a solution to solve both problems by combining a modular construction with an innovative execution process.

    The FRAMEUP buildings uses a steel frame in combination with prefabricated 3D modules - fully equipped and suitable for student accommodations – which are assembled by starting from the roof to the 1st floor. The existence of the lifting system permits the erection of the building, promoting each time the building is lifted, a clearance of one-floor-height, at ground level, for the assembly of a new 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.

    Alongside with its advantage on the fast execution, the Frameup system allows to efficiently increase or decrease the number of the floors and consequently its exchangeability with other buildings of same nature. Thus, assuming a net of FRAMEUP buildings at each university, its exchangeability system would create the necessary conditions so that the number of floors at each campus would follow the fluctuations of the students’ population among the different universities on different periods of time, so to suppress the needs for housing or to avoid the surplus on construction.

  • 8.
    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, p. 403-410Conference 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).

  • 9.
    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, p. 215-216Conference 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.

  • 10.
    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.))
  • 11.
    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, p. 103-104Conference paper (Refereed)
  • 12.
    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, p. 199-200Conference 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.

  • 13. Andre, Alann
    Fibres for strengthening of timber structures2006Report (Other academic)
    Abstract [en]

    Wood properties are often inappropriate for high performance structural applications. Major drawbacks like durability and high variability can be reduced by using glued-laminated timber. A further step to decrease this variability is to strengthen the cross-section to prevent tensile failure perpendicular to the grain. This has been widely investigated during the last decades by bonding Fibre Reinforced Polymer (carbon, aramid and glass fibres) to timber or glulam beams, with mostly promising results. However, a great concern about environmental friendly materials showed up a few years ago. Mineral and petrol-based fibres are difficult to recycle, and increase the amount of carbon dioxide in the atmosphere, leading, for instance, to the preoccupant greenhouse effect. Natural fibres such as flax, hemp and wood are on the contrary, recyclable and CO2 neutral. Their low density and high specific mechanical properties provide great advantages for timber construction. This technical report is the state of the art review of timber reinforced FRP (Fibre reinforced polymer) with a large description of the actual research projects in that field, but also of natural fibre reinforced composite. Geographic origins of the fibre, chemical constitution, mechanical properties and treatments are covered.

  • 14. Andre, Alann
    Flax fibers for strengthening of timber structures: finite element modelling2008Conference paper (Other academic)
    Abstract [en]

    A Finite Element Analysis (FEA) using the commercial finite element package ABAQUS [1] was carried out to model small prismatic glulam specimens and curved glulam beams reinforced with flax fibers composites. Two- and three-dimensional models were used to study the elastic and the softening response of the specimens. Damage and crack opening was modeled based on the "fictitious crack model". Cohesive elements together with a traction separation law were used. The model of glulam specimen where high tensile stresses perpendicular to grain are expected should consider the cylindrical orthotropy (annual rings) assumption. The tensile stresses perpendicular to grain obtained with FEA can be compared to those from experiments. Cohesive interface elements have been used successfully to model the crack formation and propagation in glulam under tension perpendicular to the grain.

  • 15. Andre, Alann
    Strengthening of timber structures with flax fibres2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The natural defects present in timber are the source of large variations in mechanical properties. This drawback has been partially counteracted with the use of Engineered Wood Products EWP (glulam, composite I-beam, parallel strand lumber, etc.) instead of solid wood. A few decades ago, fiber/polymer composite materials made their entrance in the civil engineering arena. They are used mostly as strengthening devices. The content of this thesis is related to the use of natural composite materials to strengthen glulam. The weak mechanical properties of wood in tension perpendicular to the grain are often the origin of catastrophic brittle failure. In order to enhance the design value of the tension perpendicular to grain strength, decrease the mechanical variation and provide the structure a more ductile failure, flax fibres and glass fibres reinforced polymer (FRP) composites have been used to strengthen glulam timber specimens. Three series of specimen of glued-laminated timber (flax fibre reinforced, glass fibre reinforced and unreinforced), with a grand total of 28 specimens, have been tested in tension perpendicular to the grain. Epoxy resin has been used in the composite and for bonding glulam to composite. For an approximate amount of FRP reinforcement of 1.2 % in volume (thickness ~ 0.7 mm), an increase of the tensile strength was shown by +23% using glass fibre reinforced polymer (GFRP-250 g/m2) , +25% using flax fibre reinforced polymer (FFRP-185 g/m2) and +74% using flax fibre reinforced polymer (FFRP- 230 g/m2). Regarding the modulus of elasticity, the previous reinforcement devices led to an increase by respectively +35%, +32% and +41%. For all specimen reinforced with fibre composites, semi-ductile failures were observed. An analytical model describing the mechanical behaviour of the glulam reinforced FRP was developed. It was found that the theoretical results from the model are comparable to those obtained experimentally for the flax fiber reinforced glulam specimens. However, debonding was observed for the glass fibre reinforced glulam specimen and the model does not include this type of failure. A parametric study was carried out using both the Monte Carlo method (MC) and the First Order Second Moment method (FOSM). It was shown that the mean values obtained during experiments where in agreement with those from the MC simulation. However, the standard deviations from the MC simulation are much higher. From the FOSM analysis, it was demonstrated that the variation within the stiffness perpendicular to grain of the glulam is not the first parameter driving the variation for the reinforced system. The variation within the mechanical properties of the flax fibres appeared to be the driving parameters for the design value of the system. A Finite Element Analysis was carried out to model the small prismatic glulam specimens and curved glulam beams. Two- and three-dimensional models were used to study first the elastic response and then the softening response of the specimen. Damage and crack opening was modeled based on the "fictitious crack model". Cohesive elements together with a traction separation law were used. A glulam model where high tensile stresses perpendicular to grain are expected should take into account the cylindrical orthotropy (annual rings) assumption. For both prismatic glulam specimen and curved glulam beams, the tensile stresses perpendicular to grain obtained with FEA are comparable to those from experiments.

  • 16.
    André, Alann
    et al.
    Swerea SICOMP AB.
    Johnsson, Helena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Flax fibre-reinforced glued-laminated timber in tension perpendicular to the grain: experimental study and probabilistic analysis2010In: Journal of materials in civil engineering, ISSN 0899-1561, E-ISSN 1943-5533, Vol. 22, no 9, p. 827-835Article in journal (Refereed)
    Abstract [en]

    The weak mechanical properties of wood in tension perpendicular to the grain are often the origin of catastrophic brittle failure. In order to enhance the tension strength perpendicular to the grain and achieve a more ductile failure, flax fibre and glass fibre reinforced polymer (FRP) composites were used to strengthen glued-laminated (glulam) timber specimens. Three series of specimen of glulam timber (flax fibre reinforced, glass fibre reinforced and unreinforced), with a grand total of 28 specimens, were tested in tension perpendicular to the grain. For an approximate amount of FRP reinforcement of 1.2- in volume (thickness ~ 0.7 mm), an increase of the tensile strength up to 74- was shown, with a stiffness increase up to 41-. For all reinforced specimens, semi-ductile failures were observed. A parametric study was carried out using both the Monte Carlo method (MC) and the First Order Second Moment method (FOSM). It is shown that the mean values obtained during experiments are in agreement with those from the MC simulation. However, the standard deviations from the MC simulation are larger. From the FOSM analysis, it is demonstrated that the variation in glulam stiffness perpendicular to the grain is not the first parameter driving the variation for the reinforced system. The variation in mechanical properties of the flax fibres appeared to be the driving parameters for the strength of the system.

  • 17.
    Atashipour, Seyed Abdolrahim
    et al.
    Department of Civil, Chemical and Environmental Engineering, Genoa University.
    Sburlati, R.
    Department of Civil, Chemical and Environmental Engineering, Genoa University.
    Atashipour, Seyed Rasoul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Elastic analysis of thick-walled pressurized spherical vessels coated with functionally graded materials2014In: Meccanica (Milano. Print), ISSN 0025-6455, E-ISSN 1572-9648, Vol. 49, no 12, p. 2965-2978Article in journal (Refereed)
    Abstract [en]

    In recent years, functionally graded material (FGM) has been widely explored in coating technology amongst both academic and industry communities. FGM coatings are suitable substitutes for many typical conventional coatings which are susceptible to cracking, debonding and eventual functional failure due to the mismatch of material properties at the coating/substrate interface. In this study, a thick spherical pressure vessel with an inner FGM coating subjected to internal and external hydrostatic pressure is analyzed within the context of three-dimensional elasticity theory. Young’s modulus of the coating is assumed to vary linearly or exponentially through the thickness, while Poisson’s ratio is considered as constant. A comparative numerical study of FGM versus homogeneous coating is conducted for the case of vessel under internal pressure, and the dependence of stress and displacement fields on the type of coating is examined and discussed.

  • 18.
    Atashipour, Seyed Rasoul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Structural Analysis of Deep Composite Box-Type Components with application to a proprietary stabilising timber wall element2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The stabilising wall element of the Trä8-system is a deep box-type beam/column element which is made of different types of timber composites including framing members of gluedlaminated timber (glulam) and sheathings of laminated veneer lumber (LVL). This element is used as a ―shear wall‖ in multi-storey buildings up to four storeys. To be able to optimise thecomposite stabilising element and use its maximum potential and efficiency, it is necessary to have sufficient fundamental knowledge and information about the structural behaviour and influences of different mechanical properties and geometrical parameters and dimensions of the sub-elements.In this thesis, structural analysis and design principles of the Trä8 stabilising wall element are discussed, including the early stage of erection during assembly to the final usage and residence. A list of required fundamental basic analyses are presented, including accurate deflection analysis for the serviceability limit state, local pre- and post-buckling of the LVL sheathings, global buckling as well as the lateral-torsional buckling of the stabilising element in different design situations. This thesis is then focused on deformations and local instability. For each type of structural problem, accurate, but simple and general methodology is employed to incorporate a large number of effective geometric and property parameters. In this way, a fast evaluation of the influence of different parameters is possible for a wide range of values without needing several time-consuming 3-D finite element (FE) simulations. In several cases, the accuracy and validity of the obtained solutions and formulae are examined and confirmed by comparing their results to those based on the 3-D FE simulations. First, different composite beam theories including shear effects are employed for deflection analysis of the stabilising timber element. Next, an accurate energy-based methodology isdeveloped rendering an explicit formula that gives accurate predictions for the deflection of the stabilising element within a medium range of sheathing or web thicknesses and/or stiffnesses. For weak shear webs, however, this model is not sufficient. Therefore, another new model based on the partial composite interaction theory is developed for accurate deflection predictions of the element having weak shear webs. This model contains simple but accurate formulae for deflection analysis of any similar composite box-type of element with an arbitrary range of geometry and property parameters.Next, shear buckling of the rectangular LVL-panel between the framing members are analysed using differential quadrature (DQ) numerical technique as well as an explicit analytical solution and a formula is established for accurate and fast prediction of the shear pre-buckling of the LVL. This study is extended by considering the effect of each individual lamina of the LVL as well as general orthotropic material properties using a laminated theoryand the DQ solution approach. Further, the post-buckling of the LVL panel is studied based on a simple analytical method with rotating stress fields together with the accurate 3-D FE simulations. A simple formula is then proposed for accurate prediction of the shear post-buckling resistance of the LVL-panel in the stabilising element. As a result of the thesis concerning the two main focus areas, deformations and local instability, explicit analytical formulae are presented for the design of the box-type stabilisingelement with respect to deflections including shear effects in the serviceability limit state and with respect to local shear buckling of the sheathings of the stabilising element including the post-critical area in the ultimate limit state.

  • 19.
    Atashipour, Seyed Rasoul
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Girhammar, Ulf Arne
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    On the Shear Buckling of Clamped Narrow Rectangular Orthotropic Plates2015In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, Vol. 2015, article id 569356Article in journal (Refereed)
    Abstract [en]

    This paper deals with stability analysis of clamped rectangular orthotropic thin plates subjected to uniformly distributed shear load around the edges. Due to the nature of this problem, it is impossible to present mathematically exact analytical solution for the governing differential equations. Consequently, all existing studies in the literature have been performed by means of different numerical approaches. Here, a closed-form approach is presented for simple and fast prediction of the critical buckling load of clamped narrow rectangular orthotropic thin plates. Next, a practical modification factor is proposed to extend the validity of the obtained results for a wide range of plate aspect ratios. To demonstrate the efficiency and reliability of the proposed closed-form formulas, an accurate computational code is developed based on the classical plate theory (CPT) by means of differential quadrature method (DQM) for comparison purposes. Moreover, several finite element (FE) simulations are performed via ANSYS software. It is shown that simplicity, high accuracy, and rapid prediction of the critical load for different values of the plate aspect ratio and for a wide range of effective geometric and mechanical parameters are the main advantages of the proposed closed-form formulas over other existing studies in the literature for the same problem.

  • 20.
    Atashipour, Seyed Rasoul
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Girhammar, Ulf Arne
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Challamel, Noël
    University of Europeenne Bretagne, Laboratory Genie Civil & Genie Mecan, Université Européenne de Bretagne, Mechanics Division, Department of Mathematics, University of Oslo, LIMATB, Université Européenne de Bretagne, University of South Brittany, Lorient.
    The effect of weak shear webs on the deformations of timber box type beams2015In: Proceedings of the Fifteenth International Conference on Civil, Structural and Environmental Engineering Computing / [ed] J. Kruis; Y. Tsompanakis; B.H.V. Topping, Stirlingshire: Civil-Comp Press , 2015, article id 259Conference paper (Refereed)
    Abstract [en]

    This paper deals with deflection analysis of a deep composite box beam due to inplane shear deformations, especially the modelling of the shear deformations in the webs is considered. The beam is composed of three framing members with sheathings on both sides. The sheathings or webs between the framing members are modelled as shear media with equivalent slip moduli corresponding to the partially composite beam model with three separated layers and two interlayer slip areas. The minimum total potential energy principle is employed to obtain the governing equilibrium equations and corresponding boundary conditions. The coupled set of governing equations is recast into an uncoupled form and solved explicitly together with the corresponding boundary conditions. The closed-form solutions obtained are compared to those based on the conventional beam theories. It is shown that the model is capable of predicting accurately the deflections for a wide range of geometry and property parameters, especially for small shear stiffness (slip modulus) values for the webs. The formula for the deflection is reduced to the Timoshenko formula for full composite interaction when the shear slip modulus of the web approaches infinity. Comparative numerical results are presented to show the influence of bending deformations, shear deformations in the framing layers and the in-plane shear deformations in the sheathings

  • 21.
    Axelsson, Kennet B. E.
    et al.
    Högskolan i Luleå, Luleå tekniska universitet, Luleå University of Technology.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Grennberg, Torsten
    Luleå tekniska universitet.
    Horrigmoe, Geir
    Luleå tekniska universitet.
    Johansson, Bernt
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Institutionen för Anläggningsteknik, Verksamhetsberättelse 1988/891989Report (Other (popular science, discussion, etc.))
  • 22.
    Axelsson, Kennet B. E.
    et al.
    Högskolan i Luleå, Luleå tekniska universitet, Luleå University of Technology.
    Elfgren, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Grennberg, Torsten
    Luleå tekniska universitet.
    Horrigmoe, Geir
    Luleå tekniska universitet.
    Johansson, Bernt
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Institutionen för Anläggningsteknik. Verksamhetsberättelse 1989/901990Report (Other (popular science, discussion, etc.))
  • 23.
    Axhag, F.
    et al.
    Luleå tekniska universitet.
    Johansson, Bernt
    Tension flange instability of I-beams1999In: Journal of constructional steel research, ISSN 0143-974X, E-ISSN 1873-5983, Vol. 49, no 1, p. 69-81Article in journal (Refereed)
    Abstract [en]

    The possible lateral-torsional instability of an I-beam with braced compression flange is studied. It is shown that taking the sagging prior to lateral-torsional buckling into account gives a finite critical moment. A solution for a uniform I-beam under uniform bending is presented. It is further shown that this solution can be approximated by a simple geometrical relation for the critical strain. This approximation is a lower bound also where the bending is causing inelastic deformations. For normal structures tension flange instability will not be a problem but it may be necessary to consider it for very high strength shallow beams or if plastic rotations occur in the sagging region.

  • 24.
    Axhag, Frank
    Luleå tekniska universitet.
    Plastic design method for steel-concrete composite bridges allowing for local buckling1995In: Nordic Steel Construction Conference '95: proceedings : [new materials, new codes, new applications] : Malmö, Sweden, June 19-21, 1995, Stockholm: Stålbyggnadsinstitutet , 1995, p. 139-146Conference paper (Refereed)
    Abstract [en]

    This paper focus on three different applications of concentrated forces applied to the flanges of steel girders. Concentrated forces applied at one flange, opposite concentrated forces applied at two flanges and concentrated forces applied at an unstiffened girder end. The first application is recognized as patch loading, the second and third are herein referred to as opposite patch loading and end patch loading, respectively. Results from 43 tests with the high strength steel Weldox 700 are presented, covering all three load applications, with the majority of the tests performed as end patch loading. The tests have been added to test results published elsewhere and used for development of a unified design procedure that is harmonized with those normally used for describing other buckling problems.

  • 25.
    Axhag, Frank
    Luleå tekniska universitet.
    Plastic design of composite bridges allowing for local buckling1995Report (Other academic)
    Abstract [en]

    This report is a documentation of the project "Plastic Design of Composite Bridges Allowing for Local Buckling" aiming at assessing the feasibility of using plastic design method for continuous steel-concrete composite bridges, in ultimate limit states. The method shall allow for local buckling in the steel girders at internal supports. In order to obtain the moment-rotation relationship for the steel girders at the internal supports, fifteen double-symmetric, welded, I-shaped steel girders were tested. Steel with a nominal yield strength of 700 MPa and 220 MPa was used. The 220 MPa steel was used in the web of two of the tested girders (hybrid girders), while flanges were made of 700 MPa. Flange and web slenderness ratios as well as the length of the girders were varied in the tests. The flange slenderness ratio (flange with over thickness) bfl/tf varied from 10 to 15, the web slenderness ration, hw/tw from 36 to 110 and the length of the girders from 2.66 to 6.0 m.The report shows that plastic design of composite bridges, taking into account local buckling in the girders, is feasible. An example using plastic design is outlined in the report. However more work has to be carried out with respect to the moment-rotation relationship and flange induced buckling.The plastic design method presented in this report saves approximately 10% of material in the steel girders compared to an elastic design.

  • 26.
    Axhag, Frank
    Luleå tekniska universitet.
    Plastic design of steel bridge girders1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis assesses the feasibility of a modified plastic design method for continuous steel or composite bridges with slender I-girders. The feasibility evaluation of the design method is closely connected to the moment-rotation relationship of the I-girders at internal supports. Due to local buckling of the slender I-girders, the full plastic moment resistance cannot be sustained as the rotation develops. On the contrary, the girders will reach a moment maximum, which might be less than the full plastic moment, followed by a decline in moment resistance as the rotation increases. Assuming that the moment-rotation relationships are known for all plastic hinges developing in the bridge, a plastic design method can in principle be employed but modified for these relationships. A fundamental condition for a modified plastic design method to be employed is thus that the moment-rotation relationships can be predicted. A simple plate model is developed in this thesis, which predicts the moment-rotation relationship for girders with compact or semi-compact flanges and slender webs. Included in this thesis is also test results in fourteen slender, high- strength steel girders in three point bending tests. A study on the lateral instability of I-girders and also an evaluation of the modified plastic design method with respect to the formal risk of failure, compared to an ordinary elastic design, have also been included.

  • 27.
    Berge, Staffan
    et al.
    Department of Management and Engineering, Linköping University.
    Stehn, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nord, Tomas
    Department of Management and Engineering, Linköping University.
    Business models in industrialized building of multi-storey houses2014In: Construction Management and Economics, ISSN 0144-6193, E-ISSN 1466-433X, Vol. 32, no 1-2, p. 208-226Article in journal (Refereed)
    Abstract [en]

    The business model construct has been widely used during the last decade, partly because of its potential to provide a holistic view of how companies do business. A test of how prefabrication could form the basis of a construction firm’s business model can lead to an understanding of the potential for the competitiveness and profitability of industrialized building. The aim is to adapt a general business model construct and use it to empirically identify the most frequently used and the most viable business model. The theoretical perspective is employed to examine how a company does business and which activities and resources are mobilized through the distinction between strategic and operational effectiveness. The multiple case studies include five major Swedish companies that produce prefabricated timber building systems and the analysis is grounded in pattern-finding. The business model construct includes: market position, offering, and operational platform. The result indicates five business model elements: prefabrication mode, role in the building process, end-user segments, system augmentation and complementary resources. Applying this construct to the five case companies revealed that one out of seven models was found to be viable in terms of both ‘market share’ and decision-makers’ opinions. One important conclusion is to take the prefabrication mode as the starting point for business model design and then adapt the other elements to a good fit

  • 28.
    Bergsten, Susan
    Luleå tekniska universitet.
    Industrialised building systems: vertical extension of existing buildings by use of light gauge steel framing systems and 4D CAD tools2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [sv]

    Genom införandet av den nya lagen om tre dimensionell fastighetsbildning i januari 2004 har möjligheterna för påbyggnad av befintliga byggnader ökat. Behovet av centralt belägna bostäder är idag stort i storstadsområdena. För att möta den efterfrågan och bibehålla en hållbar stadsutveckling kan lokaler med attraktiva lägen utnyttjas mer effektivt genom om-, till- eller påbyggnader. I detta forskningsprojekt har byggsystemet lättbyggnad med stål med särskild fokus på påbyggnader i kombination med industriellt byggande och 4D modellering studerats. Vidare har lättbyggnad med avseende på stålets utförbarhet för industriella produktionsmetoder utforskats. I två projekt, där lättbyggnadssystemet använts, har de använda industriella produktionsmetoderna studerats. Forskningsprojektet har också undersökt fem påbyggnadsprojekt. Problem uppkomna under produktionen relaterade till påbyggnadsprocessen har beaktas och de industriella byggmetoder som har använts i påbyggnadsprojekten har studerats. För att öka nyttan för inblandade parter har forskningsprojektet vidare haft syftet att utvärdera moderna projekteringshjälpmedel för informationshantering, såsom 3D CAD och 4D CAD. Inom ramen för projektet har 4D CADs möjligheter för att förenkla och förbättra denna process iakttagits. De industriella byggsystemen och produktionsmetoderna i de undersökta projekten var koncentrerade till fältfabrikproduktion snarare än helhetslösningar för hela leverantörskedjan och värdekedjan för byggprocessen. Många uppkomna problem under produktionstiden hade inte sin grund i själva byggsystemet och dess möjligheter för industriell produktion utan till hur man implementerade de förändrade krav som ett industriellt byggande medför. Lättbyggnad med stål har med sin lätta egenvikt samt smala toleranser stora möjligheter för industriella produktionsmetoder. Många av de upptäckta problemen i fallstudierna är relaterade till avsaknad av kunskap för planering och utförande av industriella produktionsmetoder samt bristande koordination mellan projektering och produktion på byggarbetsplatsen. Här har 4D CAD stora möjligheter att förenkla integreringen av projektering och produktion men också byggarbetsplaneringen. Med tanke på att vid påbyggnader är byggarbetsplatsen en av de viktigaste restriktionerna, måste byggarbetsplatsens aktiviteter beaktas. Logistikplaneringen på, till och från byggarbetsplatsen i alla de undersökta projekten kunde ha utförts mer koordinerat och därmed hade materialhanteringen till och från arbetsplatsen men även på byggarbetsplatsen effektiviserats mer.

  • 29. Bergström, Max
    Industrialised timber frame housing: managing customisation, change, and information2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The overall aim of this thesis is to develop an increased understanding of industrialised timber frame housing (timber frame housing construction fully or partially conducted in a controlled environment utilising industrial processes and machinery). Of specific interest is how industrialised timber frame housing companies manage customisation, change, and information. Three single case studies (at a medium-sized industrialised timber frame housing company), one multiple-case study, and one survey were conducted. The first single case study investigates how production can benefit from integrating a customer-oriented design and production. The second single case study illustrates the shift towards an enterprise resource planning (ERP) approach through a change process. The third single case study describes the ERP system implementation. The multiple-case study investigates the prospects and pitfalls among four small and medium-sized industrialised timber frame housing companies that manufacture complex products utilising advanced prefabrication. The survey, conducted among the vast majority of industrialised timber frame housing companies in Sweden, presents the industry structure and investigates the benefits and disadvantages of ERP. The results demonstrate that matching customer requirements and an industrialised building system is facilitated through product and process development. Other findings suggest that ERP can meet the needs of industrialised timber frame housing, promote an organisation to be re- engineered through comprehensive change, and act as a driver for a more efficient internal and external supply chain. However, a lack of history regarding information technology (IT) systems for production processes and the timing of the system selection in the overall ERP adoption are both critical for the ERP system implementation outcome. With no previous history of IT systems for production processes, an ERP system implementation is a big step even if it is carefully conducted. Industrialised timber frame housing has increased in popularity on the market over the last years. An important reason for this is the increased customer focus. However, blind customer focus leads to poor utilisation of resources. By balancing customer orientation with internal efficiency, achieving an effective construction process seems possible. Communication between different actors in the construction process, finding a reasonable level of customer focus, and capacity limitations are current problem areas with the potential for improvement. Possible ways of improving the construction process are an increased integration between actors, a gradual increase in IT support, and finding the balance between project and process orientation. The survey demonstrates low ERP usage in industrialised timber frame housing with a low degree of strategic importance, while there are operational and managerial benefits. The results also show the potential of the ERP approach for industrialised timber frame housing, while its use is favoured by an increased maturity in IT. The overall results show that customer orientation, change, and information management are important ingredients in industrialised timber frame housing. Customer orientation can act as a driver for change and for improved information management. Changes in business processes are needed to facilitate customisation and information management. Information management has a key role in the entire construction process to facilitate customisation, while the need of efficient information management can act as a driver for change.

  • 30. Bergström, Max
    et al.
    Stehn, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Benefits and disadvantages of ERP in industrialised timber frame housing in Sweden2005In: Construction Management and Economics, ISSN 0144-6193, E-ISSN 1466-433X, Vol. 23, no 8, p. 831-838Article in journal (Refereed)
    Abstract [en]

    Industrialised timber frame housing is successful in the Swedish market for one-family housing. In the manufacturing industry, methods and software systems such as enterprise resource planning (ERP) are widespread, demonstrating significant benefits. A survey of the majority of industrialised timber frame housing companies in Sweden demonstrates low ERP use with a low degree of strategic importance, but with operational and managerial benefits. The ERP approach has potential for industrialised housing and its use is favoured by an increased maturity in IT.

  • 31. Bergström, Max
    et al.
    Stehn, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Ett effektivt stombyggande i trä2005In: Bygg & Teknik, ISSN 0281-658X, no 5, p. 42-44, 46Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Industriellt trähusbyggande i Sverige.

  • 32. Bergström, Max
    et al.
    Stehn, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Integrated design and production of multi-storey timber frame houses: production effects caused by customer-oriented design2002In: International Journal of Production Economics, ISSN 0925-5273, E-ISSN 1873-7579, Vol. 77, no 3, p. 259-269Article in journal (Refereed)
    Abstract [en]

    This paper presents the results from an ongoing R and D project aiming for an industrialised development of a multi-storey timber frame house system. The development was conducted systematically using methods from concurrent engineering (CE) focusing on the customer satisfaction and production-design problems/possibilities. A Swedish SME building company was investigated from the viewpoint of customer orientation, production and design of multi-storey timber frame houses. The company uses industrial fabrication of volumes. The aim was to analyse how the production can benefit from an integration of a customer-oriented design and production. First, a model based on the QFD method is proposed on how requirements from customers, i.e., tenants, can be taken into account in the design process and how CE can be adapted to a SME design process. Second, a preliminary model is proposed considering disturbances and relative cost effects on the production due to changes in the design solutions. The presented model aims to predict the total cost for a customer affected design on the used building system to forecast the costs for the main contractor and building owner for a similar integrated design in the future. All observations are based on case studies of the design process and the industrialised production of a three-storey timber frame house with three different floor designs.

  • 33. Bergström, Max
    et al.
    Stehn, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Manufacturing resource planning in industrialized timber frame house construction in Sweden2003In: Construction economics and organization: proceedings of the 3rd Nordic Conference on Construction Economics and Organization, 24-24 April 2003, Lund, Sweden / [ed] Bengt Hansson; Anne Landin, Lund: Lund Institute of Technology , 2003, p. 81-90Conference paper (Refereed)
  • 34. Bergström, Max
    et al.
    Stehn, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Matching industrialised timber frame housing needs and enterprise resource planning: a change process2005In: International Journal of Production Economics, ISSN 0925-5273, E-ISSN 1873-7579, Vol. 97, no 2, p. 172-184Article in journal (Refereed)
    Abstract [en]

    The potential for improvements in industrialised housing through the adoption of concepts like enterprise resource planning (ERP) from the manufacturing industry, as applied to small and medium-sized enterprises, is evaluated in this paper. Four single, consecutive case studies were performed at a Swedish medium-sized industrialised housing company. The findings suggest that ERP can meet industrialised housing needs as well as promote an organisation to be re-engineered through comprehensive change and act as a driver for a more efficient internal and external supply chain.

  • 35.
    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, p. 733-750Article 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.

  • 36.
    Bhattacharjee, Shimantika
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Lidelöw, Sofia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Schade, Jutta
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Performance evaluation of a passive house in sub-arctic climate2018In: 9th International Cold Climate Conference, Kiruna, Sweden. March 12-15, 2018: Sustainable New and Renovated Buildings in Cold Climate, 2018Conference paper (Refereed)
    Abstract [en]

    As the operational energy use in buildings contributes highly to the total energy used and greenhouse gases emitted in the cold climate regions of Europe, buildings which are more energy-efficient and less carbon-intensive during operation are key to meet sustainability objectives in these regions. Yet, research shows that the practice of passive or low-energy buildings in the sub-arctic climate of northern Sweden is comparatively less than in the southern region. Moreover, previous studies did not explicitly examine the performance of low energy buildings in sub-arctic climate in relation to established building energy efficiency standards. Consequently, knowledge regarding the energy performance of low-energy buildings in such climate is limited. Therefore, the aim is to evaluate the performance, in terms of indoor temperature and energy use for heating, domestic hot water and electricity of a new-built passive house titled “Sjunde Huset” in the sub-arctic town of Kiruna. It is Sweden’s northernmost house designed to fulfil the Swedish passive-house criteria of a maximum heat loss factor of 17 W/m2 and a maximum annual energy use of 63 kWh/m2. The implemented passive design strategies include a highly insulated, compact and airtight building envelope with a vestibule, mechanical ventilation with heat recovery and renewable energy production through photovoltaic solar cells. The house is connected to district heating and is equipped with energy-efficient appliances to allow low occupant energy use. Ongoing performance evaluation is based on building simulation and measurements of energy and temperature in different zones of the building. Energy performance deviations between occupied and non-occupied zones are explored through internal heat gain evaluations. The indoor temperature is also evaluated to assess the temperature variations throughout the year. The ongoing research further evaluate a comparative simulated and measured energy analysis of heating, hot water and electricity based on both the international passive house standard and the Swedish passive house criteria “Feby 12”.

  • 37.
    Bildsten, Louise
    et al.
    Industrial Marketing, Department of Management and Engineering, Linköping Institute of Technology.
    Björnfot, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sandberg, Erik
    Logistics Management, Department of Management and Engineering, Linköping Institute of Technology.
    Value-driven purshasing of kitchen cabinets in industrialized housing2011In: Journal of Financial Management of Property and Construction, ISSN 1363-2175, Vol. 16, no 1, p. 73-83Article in journal (Refereed)
    Abstract [en]

    Purpose – The purpose of this paper is to hypothesize that value-driven purchasing of customized kitchen cabinets is more profitable than market-driven purchasing in industrialised housing construction. The hypothesis is examined through a case study of kitchen carpentry at one of the Sweden's largest producers of industrialised prefabricated multi-storey housing. By comparing characteristics of market- vs value-driven purchasing, this paper aims to further clarify the benefits and drawbacks of these two strategies. Design/methodology/approach – By comparing characteristics of market- vs value-driven purchasing, a theoretical framework is proposed that clarifies the benefits and drawbacks of the two strategies. An explorative case study of kitchen carpentry at a house manufacturer illustrates purchasing of kitchen cabinets in the industrialised housing industry in relation to the proposed framework. Findings – The case study results indicate that, from a value perspective, a long-term relationship with a dedicated local smaller supplier is a preferable choice over a short-term relationship with a low-price mass producer. Research limitations/implications – This is a single case study that should be verified by further empirical work of a test delivery from the local sub-system manufacturer. Such a study would provide more insights into this area of work and make it possible to thoroughly evaluate potential risks. The indicative results in this paper can be made conclusive through quantification of the proposed lean purchasing characteristics. Originality/value – A comparison of value- and market-driven purchasing is carried out in theory and applied to a real case study that brings new perspectives to purchasing. In this way, the paper proposes alternative purchasing strategies to the construction industry

  • 38.
    Bildsten, Louise
    et al.
    Linköping University.
    Björnfot, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sandberg, Erik
    Linköping University.
    Value-driven vs. market-driven purchasing of kitchen cabinets2010In: Proceedings IGLC-18: 18th Conference of the International Group for Lean Construction / [ed] Ken Walsh; Thais Alves, Haifa: Technion-Israel Institute of Technology , 2010, p. 202-211Conference paper (Refereed)
    Abstract [en]

    In economic and management literature, the relationship between supplier and buyer can be more or less intimate. It can vary from market-driven with a constant change of suppliers to a value-driven relationship with one sole supplier. Purchasing strategies of construction companies have often been described as short-sighted, where price is the most considered aspect. Recent lean management literature promote value-driven purchasing, since it provides benefits such as just-in-time delivery, zero defects and customized products through close technical collaboration. This article hypothesises that value-driven purchasing of customized kitchen cabinets is more profitable than market-driven purchasing in industrialized housing construction. The hypothesis is examined through a case study of kitchen carpentry at one of Sweden‘s largest producers of industrialized prefabricated multi-storey housing. By comparing characteristics of market-driven vs. value-driven purchasing, this article aims to further clarify the benefits and drawbacks of these two strategies. At the case company, kitchens are ordered cabinet-by-cabinet and then installed inside the factory. The company is considering the possibility of a long-term relationship with a smaller local supplier that can deliver a new kind of innovative kitchen cabinet solution that is prefabricated. If the local supplier can meet the expectations of just-in-time delivery, zero defects and a product -tailor-made‖ for the housing company, there is much to gain.

  • 39.
    Bildsten, Louise
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Erikshammar, Jarkko
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Haller, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Värdeflödesanalys hjälper företag att korta ledtider, minska lager och ta bort slöseri2010Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Forskning vid Luleå tekniska universitet har visat på att Värdeflödesanalys (VFA) kan hjälpa företag att korta ledtider, minska lager och reducera slöseri genom att hitta en gemensam bild över företagets processer och fokusera mer på kundbehovet. En utvecklad arbetsmodell lyfter fram vikten av planering, ha rätt team och följa upp resultatet.

  • 40.
    Björnfot, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    An engineering perspective on lean construction theory2008In: IGLC 16 Proceedings: 16th Annual Conference of the International Group for Lean Construction / [ed] Patricia Tzortzopoulos; Mike Kagioglou, University of Salford, U.K. , 2008, p. 15-26Conference paper (Refereed)
    Abstract [en]

    The diversity of Lean Construction research and applications is extensive. Due to this diversity, it can be argued that Lean Construction theory has been overextended and lost some of its fundamental ideas. Even though much theoretical progress has been achieved, theoretical development shows inadequate relation to practical construction. Therefore, theory development is of limited interest for the construction community. The aim of this paper is to make Lean Construction more accessible for construction participants who are interested in learning more about the advances of Lean Construction theory, but are unable to do so due to the vast availability of associated theories. The view of the engineer, representing such a construction participant, is used to revivify and organise Lean Construction theory  through a classic structural engineering problem, the column-buckling case. Similar to the engineering case, the delivery team should consider four dimensions when designing a stable production system; these dimensions are product standardisation, process standardisation, workload reduction, and organisation strength. Application of these aspects in a systematic manner has potential to reduce variation while improving system stability and control.

  • 41.
    Björnfot, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    An exploration of lean thinking for multi-storey timber housing construction: contemporary Swedish practices and future opportunities2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Construction is affected by a large amount of waste (up to 35% of production costs in Sweden) and adverse relationships which lead to low quality and profitability. In Sweden, industrialized construction is viewed as one solution to the issues of construction which has led to a number of development efforts. Based on the success of Lean Production in manufacturing and the development of Lean Construction in countries such as Denmark, England and USA, the application of Lean Construction is currently debated in Sweden. However, Lean Construction theory seems unable to explain the development of industrialization in Swedish construction. Consequently, there is need of further research on how to better match industrialized construction with Lean Construction theory. The aim of this research is twofold; 1) explore how Lean Construction theory can be used to gain a deeper understanding of Swedish multi-storey timber housing construction and 2) explore how an understanding of contemporary practices can help extend the theory of Lean Construction to better facilitate research on industrialized construction. Currently, there is a Swedish governmental investment campaign supporting development of timber housing construction. Consequently, this is a good opportunity to explore the applicability of Lean Construction. Based on an understanding of the Lean philosophy, contemporary Swedish timber construction practices are analysed through three case studies; element prefabrication, volume prefabrication, and an initiative combining volumes and elements. The driving force in the development of applications for Lean Construction is production system design for increased control over construction events - stability (reliability) and better control (predictability) are sought through the reduction of variety in working practices, supply chains, etc. Consequently, improving work flow is the primary target of Lean Construction. An analysis of the contemporary timber element prefabrication reveals three main issues; 1) complicated design decisions, 2) poor design documentation, and 3) deficient production planning which, from a Lean Construction perspective, obstruct work flow. However, the root cause of work flow issues is identified as a lack of value management which causes ripples all through the production system resulting in variety and poor control. Results from volume and volume/element prefabrication indicate that value management greatly improves production system design. These well-defined technical platforms, so called ‘product offers', represent a new way of thinking in the delivery of value for multi-storey housing construction. The Lean characteristics of the ‘product offer' are product specifications based on customer value, value stream management through specific resources and activities, management of value-adding activities for flow, flexibility to customer demands enabling pull, and transparency for continuous improvements (perfection). Based on these characteristics, the ‘product offer' is viewed as one possible change-agent in the adoption of Lean Construction for Swedish multi-storey housing construction.

  • 42.
    Björnfot, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Industrialiserat byggande möter Leant byggande2007In: V-byggaren : väg- och vattenbyggaren, ISSN 0283-5363, no 2, p. 12-16Article in journal (Other academic)
  • 43.
    Björnfot, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    LWE goes Japan: En resa i hållbarhetens tecken2011In: Samhällsbyggaren, ISSN 2000-2408, no 2, p. 22-25Article in journal (Other (popular science, discussion, etc.))
  • 44.
    Björnfot, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Modular long-span timber structures: a systematic framework for buildable construction2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    One of the identified reasons for the low amount of timber construction in Sweden is a general lack of knowledge about timber engineering and how timber can be used to its full advantage. One way for increased timber construction is the development of a cost-efficient and easy to comprehend building system. Efficiency in construction has recently been under hot debate following the success of lean production in the manufacturing industry. Therefore, the attention of construction has been directed towards the manufacturing industry in an attempt to learn successful methods. Three main principles, modularity, lean construction, and buildability, emerge as potentially useful in order to streamline construction. The aim of this research project is to create a knowledge- based framework for long-span timber construction. This framework should be able to store knowledge and experience about timber construction as well as aid in the design and production of buildable timber structures. A buildable structure is here defined as a structure constructed in competition with all other materials and sub-system choices, i.e., by this definition a constructed structure is buildable and therefore competitive. The research is based on a case study of the design and production of long- span timber structures performed at a Swedish design company. The case study includes interviews, and a survey of 60 constructed long-span timber structures. A literature review of the industrialisation principles reveals that modularity has been a key concept in the evolution of the manufacturing industry. Therefore, the long-span timber construction industry should emit a bottom-up view where product modularity guides the construction processes. A systematic framework, Experience Feedback System (EFS), is created to store buildable construction knowledge based on modularity. The EFS is based on two distinct systems; Experience Based System (EBS), and Construction Knowledge Database (CKD), connected by a feedback loop for buildable construction feedback. The EBS utilises neural network theory containing competitive knowledge and experience of long-span timber structures, providing aid in early design. The CKS is based on the Design Structure Matrix (DSM), providing management of innovative construction and aid in detailed design. Due to the adaptability of neural networks and the developed 3-D DSM hierarchy representing the structural system, the systematic framework is potentially useful for the design and development of other types of structures and materials choices in the future.

  • 45.
    Björnfot, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bildsten, Louise
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Erikshammar, Jarkko
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Haller, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simonsson, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Lessons learned from successful value stream mapping (VSM)2011In: Proceedings of IGLC-19: 19th Conference of the International Group for Lean Construction / [ed] John Rooke; Dave Bhargav, Lima: Fondo Ed. Pontificia Universidad Católica del Peru , 2011, p. 163-173Conference paper (Other academic)
    Abstract [en]

    To improve, it’s crucial to see! Vital characteristics of Lean are visualisation and transparency, i.e. allowing everyone to see all what occurs in production. A common tool for this purpose is Value Stream Mapping (VSM). Due to varying flows, performing a successful VSM in construction confers additional challenges. In this paper, lessons learned from successful VSM studies in construction are provided.Three VSM case studies were performed at different companies ranging from patio door manufacturing to kitchen cabinet assembly. Lessons learned can be structured into three phases; preparing the VSM (selecting “value stream leaders” and VSM team, clarifying values, etc.), performing the VSM (use of mapping tools, approximation of key indicators, waste identification, etc.), and following-up the VSM (Plan-Do-Check-Act, evaluating customer values, etc.).For the involved companies, the lessons learned imply the start of a “Lean journey” even though the involved companies found it difficult to relate VSM improvements to business strategies. Consequently, there are opportunities to further improve the application of VSM. However, it’s important to remember that VSM is about the straight-forward visualisation of flows and that these flows are made transparent for the whole organisation.

  • 46.
    Björnfot, Anders
    et al.
    Faculty of Technology, Economy and Management, Gjøvik University College.
    Johnsson, Helena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simonsson, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    'Find-think-write-publish': Lean thinking in scientific paper writing2012Conference paper (Refereed)
    Abstract [en]

    Construction research supports long-term development of the construction industry and the society. Thus it is important to evaluate research against existing knowledge and to constantly develop new knowledge. The main mechanism for doing so is publishing scientific papers. In Sweden, praxis has developed that a Ph.D. consists of a handful of scientific papers. The average time period for a Ph.D. is five years after which the funding situation changes drastically. Previously, the duration of Ph.D. studies at Luleå University of Technology, Sweden often exceeded the planned five years, disrupting the flow of Ph.D. examinations. To increase awareness and interest in paper writing, a method was sought to visualise and manage the writing process. This paper investigates how an Oobeya room can be implemented in construction research to support paper writing. Experiences of working with the Oobeya room in three separate research divisions prove that it is possible and fruitful to better manage knowledge in academic institutions. Even though research is creative, it can be properly managed without hampering scientific freedom. Evidence from managing scientific paper writing using the Oobeya room shows that proper management of research will actually create better research that is more publishable with shorter lead times!.

  • 47.
    Björnfot, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jongeling, Rogier
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Application of line-of-balance and 4D CAD for lean planning2007In: Construction Innovation, ISSN 1471-4175, E-ISSN 1477-0857, Vol. 7, no 2, p. 200-211Article in journal (Refereed)
    Abstract [en]

    Purpose - The purpose of this paper is to suggest the application of the line-of-balance (LoB) scheduling technique in combination with a 4D CAD workspace model as a method to improve the management of the flow of resources through locations in construction projects, defined as work flow. Current scheduling methods fail to consistently manage work flow, which can disrupt the construction process, leading to waste such as conflicts in time and space by construction crews. Design/methodology/approach - LoB and 4D CAD are applied to a case study of multi-story timber housing project involving the construction of 95 apartments in five six-storey buildings. Based on the case study results, the benefits and limitations of the combined use of both methods are discussed. Findings - The majority of the problems experienced during the actual construction process quickly become evident from an analysis of a relatively simple LoB diagram. Furthermore, the 4D CAD workspace model provides additional insights in the scheduling of construction activities, such as workspace availability, the spatial context of workspaces and partial overlap of workspaces. Practical implications - Virtual design and construction methods based on principles from lean construction can contribute significantly to the value of the product and the elimination of waste in any construction project. Originality/value - The paper refers to the guiding principles from lean construction in relation to virtual design and construction methods, such as simulations with 4D CAD. Additional research and studies of practical applications are suggested to facilitate the combination of principles from lean construction with virtual design and construction methods.

  • 48. Björnfot, Anders
    et al.
    Lennartsson, Martin
    Stehn, Lars
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Industrilized and sustainable construction.
    Lindbäck, Hans
    Lindbäcks Bygg, Sverige.
    Projekt: Installationssamordning2010Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Projektet syftar till att arbeta fram en modell för hur modularisering kan utnyttjas praktiskt i byggsammanhang. Specifikt handlar det om att definiera och avgränsa moduler samt att redogöra för hur en teknisk plattform kan skapas som stöds av en individuell utveckling av moduler för tekniska installationer. Medverkande parter Universitet: Luleå tekniska universitet (LTU) Företag: Lindbäcks Bygg AB Norvag Byggsystem AB Moelven ByggModul AB Setra Group AB Martinsons Byggsystem AB

  • 49.
    Björnfot, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sardén, Ylva
    Prefabrication: a lean strategy for value generation in construction2006In: Understanding and Managing the Construction Process: Theory and Practice: Proceedings of the 14th Conference of the International Group for Lean Construction / [ed] R. Sacks; S. Bertelsen, Catholic University of Chile, School of Engineering , 2006, p. 265-277Conference paper (Refereed)
    Abstract [en]

    Despite a number of attempts to establish prefabrication as a Lean Construction method, there is still confusion of what prefabrication provides to the management of the construction process. It seems as if prefabrication can provide a means of dealing with value stream fluctuations in highly complex situations, such as a traditional construction project where it is difficult to define client value accurately. The prefabrication decision and the strategies for meeting customer demands have been studied for three Swedish producers of prefabricated timber components for multi-storey housing construction.The case study results indicate that the Swedish construction industry is slowly changing from a traditional project based generation of customer value to offering specific products, adaptable by the customer to suit their own view on value. A prefabrication strategy where a well defined and tested product is offered to customers has the effect of redistributing resources from the design process to the value stream. Such redistribution enables companies with a well developed prefabrication strategy to better control the value stream and to implement new and better ways of meeting customer requirements while continuously improving their work and eliminating waste.

  • 50.
    Björnfot, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Stehn, Lars
    A design structural matrix approach displaying structural and assembly requirements in construction: a timber case study2007In: Journal of engineering design (Print), ISSN 0954-4828, E-ISSN 1466-1837, Vol. 18, no 2, p. 113-124Article in journal (Refereed)
    Abstract [en]

    A fundamental demand of construction design is human safety from structural failure. As a consequence, buildings generally tend to be structurally optimized with cost as the main target parameter. However, a cost-suboptimized structural design often leads to poor constructability decisions with subsequent waste. This paper presents initial research in the development of a design structural matrix (DSM) method able to identify constructability obstacles between structural design and assembly and thus eliminate waste. Empirical data based on a case study of long-span timber structures is used in the development and analysis of the method. The DSM was found to be a holistic tool for systematic consideration of structural design and constructability requirements by providing a standardized system view, a detailed element view, and physical and functional interactions among elements and modules. The DSM was also shown to aid in detailed design and production management through the use of simple matrix tools.

1234567 1 - 50 of 838
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf