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  • 51.
    Björnfot, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sardén, Ylva
    Prefabrication: a lean strategy for value generation in construction2006Ingår i: 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, s. 265-277Konferensbidrag (Refereegranskat)
    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.

  • 52.
    Björnfot, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Stehn, Lars
    A design structural matrix approach displaying structural and assembly requirements in construction: a timber case study2007Ingår i: Journal of engineering design (Print), ISSN 0954-4828, E-ISSN 1466-1837, Vol. 18, nr 2, s. 113-124Artikel i tidskrift (Refereegranskat)
    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.

  • 53.
    Björnfot, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Stehn, Lars
    A systematic framework for long-span timber structures2004Ingår i: Proceedings, The 8th World Conference on Timber Engineering: WCTE 2004, 2004, Vol. 1, s. 93-98Konferensbidrag (Refereegranskat)
  • 54.
    Björnfot, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Stehn, Lars
    Industrialization of construction: a lean modular approach2004Ingår i: 12th Conference of the International Group for Lean Construction: proceedings of IGLC-12 : Helsingør, Denmark, August, 3-5, 2004 / [ed] Sven Bertelsen; Carlos T. Formoso, 2004Konferensbidrag (Refereegranskat)
  • 55.
    Björnfot, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Stehn, Lars
    Product design for improved material flow: a multi-storey timber housing project2005Ingår i: Proceedings: 13th Conference of the International Group for Lean Construction / [ed] Russell Kenely, Sydney: International group for lean construction , 2005, s. 297-306Konferensbidrag (Refereegranskat)
    Abstract [en]

    Understanding of construction has evolved to include a deeper understanding of its mechanics; in addition to traditional on-site work involving the manufacturing of building products - industrial construction. One of the most important aspects of any industrial process is flow of materials and resources. Using empirical data from a unique multi-storey timber housing project, this paper aims at building a better understanding of how product design affects flow of materials in housing construction. Even though a high degree of prefabrication was used in the project, the amount of complementary site work caused delays, complaints, and a slow learning cycle. A standardization process was used to shift product 'know-how' from person to product, resulting in increased flow and a reduction of errors. Prefabrication was not the sole solution to the encountered problems, but the controlled and ordered environment in prefabrication provided solutions at early stages. Instead of working towards solving the main production issues, the management was instead observed working with minor changes (first-aid solutions) to control flow. If industrialized multistorey timber housing construction is to be successful, product design decisions should be thought through, thoroughly, from start to finish using standardization as a guiding star

  • 56.
    Björnfot, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Stehn, Lars
    Value delivery through product offers: a lean leap in multi-storey timber housing construction2007Ingår i: Lean Construction Journal, ISSN 1555-1369, E-ISSN 1555-1369, Vol. 3, nr 1, s. 33-45Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Among large Swedish contractors there is currently a specialization trend towards an increased use of prefabrication and complete systems in housing construction. The Lean Construction development up to date has focused on the management of value delivery for complex construction projects. Typical Swedish housing projects do not experience this broad complexity; instead the main challenge seems to be to better specify and deliver customer value. Currently, the Lean Construction methods available are not by themselves enough for the generation of value in Swedish multi-storey housing construction. The aim of this paper is to examine the potential of the product offer (a well-defined and highly standardized building system developed from the value views of specific customers) as an aid in the generation and delivery of value for multi-storey timber housing construction.From the point of view of manufacturing and customer value, the product offer is considered a Lean strategy for integrated consideration of internal and external value. Case study experiences indicate that the product offer strategy provides stability and continuity for producers that in turn provides with Lean practices in marketing, design and manufacturing. Approaching Lean, small- to medium-sized Swedish producers should focus on improvements through Lean Manufacturing. However, since an emerging demand from the Swedish construction industry forces these producers to take a larger role in the construction process, more construction related Lean improvements must also be considered. In this regard, the product offer is demonstrated to be a promising Lean strategy for the Swedish housing industry.

  • 57.
    Björnfot, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Torjussen, Liv
    Gjövik University College.
    Extent and effect of horizontal supply chain collaboration among construction SME2012Ingår i: Journal of Engineering, Project, and Production Management, ISSN 2221-6529, E-ISSN 2223-8379, Vol. 2, nr 1, s. 47-55Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The majority of companies involved in value delivery in the Swedish housing industry are Small- and Medium-sized Enterprises (SME). An SME is often managed in an informal way with focus on sales and production. Many SME are also financially vulnerable as they are strongly dependent on a few key customers and key products. As variation will always exist, SME should learn to deal with variation instead of try eliminating it. This paper hypothesises that structural flexibility in SME supply chains through horizontal collaboration leads to a regional environment of economical growth from which all active SME will benefit. The hypothesis is examined through two case studies; a Swedish supplier network that has worked together six years and a four year old Norwegian supplier network. A benefit of collaboration is knowledge sharing that lessens the economical strain of keeping up with the “latest”. Other examples of collaboration are shared production resources in case of low capacity. Collaboration within supplier tier networks is considered to mark the emergence of a “collective strength” that improves individual suppliers bargaining position towards their customers. This evolution is considered an indication of the emergence of a “Lean Enterprise” within the house building sector.

  • 58.
    Björnfot, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Torjussen, Liv
    Gjövik University College.
    Erikshammar, Jarkko
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Horizontal supply chain collaboration in Swedish and Norwegian SME networks2011Ingår i: 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, s. 678-688Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    An SME is often managed in an informal way with focus on sales and production. Many SME are also financially vulnerable as they are strongly dependent on a few key customers and key products. As variation will always exist, SME should learn to deal with variation instead of try eliminating it. This paper hypothesises that structural flexibility in SME supply chains through horizontal collaboration leads to a regional environment of economical growth from which all active SME will benefit The hypothesis is examined through two case studies; a Swedish supplier network that has worked together six year and a freshly started Norwegian supplier network. The Swedish suppliers are cooperating; e.g. in case of low capacity, they are sharing production resources. Another benefit of cooperation, supported by Norwegian findings, is the sharing of knowledge amongst each other that lessens the economical strain of keeping up with the “latest”. Cooperation within supplier tier networks marks the emergence of a “collective strength” improving individual suppliers bargaining position towards their customers, e.g. when obtaining new orders, when lobbying for changes in regulations, or when developing and verifying new products. This evolution indicates the emergence of a “Lean Enterprise” within the house building sector.

  • 59.
    Blandine, Feneuil
    et al.
    Aalto University, Concrete Technology Laboratory, Department of Civil and Structural Engineering, School of Engineering, Aalto University.
    Habermehl-Cwirzen, Karin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Cwircen, Andrzej
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Erratum to: Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste2017Ingår i: Frontiers of Structural and Civil Engineering, ISSN 2095-2430, E-ISSN 2095-2449, Vol. 11, nr 2, s. 255-255Artikel i tidskrift (Refereegranskat)
  • 60.
    Blomberg, Josefin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriellt och hållbart byggande.
    Materialdokumentation vid miljöcertifiering: En kvalitativ studie av utmaningar och förutsättningar för SME att använda BIM som hjälpmedel2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 61.
    Borg, R. P.
    et al.
    University of Malta.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Introduction to Eco-efficency2007Ingår i: Sustainability of Constructions: Integrated Approach to Life-time Structural Engineering. Proceedings of the First Workshop Lisbon 13. 14. 15 September 2007 / [ed] L. Braganca; H. Koukkari; R. Blok; H. Gervasio; M. Veljkovic, Multicomp , 2007Konferensbidrag (Övrigt vetenskapligt)
  • 62.
    Borg, R.P.
    et al.
    University of Malta.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Plewako, Zbigniew
    Eco-efficiency2008Ingår i: Proceedings of Seminar on Sustainability of Constructions - Integrated approach to life-time structural engineering: COST Action C25, Dresden, Germany 6.-7.10.2008, 2008, s. 3.1-3.3Konferensbidrag (Övrigt vetenskapligt)
  • 63.
    Boström, Staffan
    Luleå tekniska universitet.
    Crack location in steel structures using acoustic emission techniques1999Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Denna avhandling utvärderar möjligheten att använda akustisk emission (AE) för att detektera och lokalisera sprickor i stora stålkonstruktioner med ett långt avstånd mellan givarna. De industriella/ekonomiska motivet för projektet är att en noggrannare undersökning av befintliga konstruktioners tillstånd medför att utbyte av dessa konstruktioner kan skjutas på framtiden med bibehållen säkerhet, vilket i sin tur medför besparingar för till exempel broägare. Motiv för långt avstånd mellan givarna är att hålla kostnaden förundersökningen nere. Fältförsöken omfattade mätningar på fyra broar och en kranbana. I korthet var resultaten att det ofta gick att detektera sprickor men att säkerheten i metoden behövde förbättras och att mättiderna behövde reduceras. MAE utvecklades och den baseras på digital signalbehandling samt användandet en ny detektor för att upptäcka AE signaler. Den största fördelen med den nya tekniken är att bruset reduceras, vilket innebär att även svaga signaler går att detektera. Resultat från laboratorieförsök och försök ute i fält visar att MAE kan användas för sprickdetektering och lokalisering med ett avstånd mellan givarna på upp till 20m. Det är dock viktigt att den verkliga våghastigheten för konstruktionen bestäms. I jämförelse med traditionell AE kan mättiderna med MAE kortas, vilket leder till enklare och billigare kontroller/undersökningar av konstruktioners tillstånd.

  • 64.
    Boström, Staffan
    Luleå tekniska universitet.
    Förspända skruvar i skjuvförband: förspänningsmetoder och utmattningshållfasthet1990Licentiatavhandling, monografi (Övrigt vetenskapligt)
  • 65.
    Boström, Staffan
    et al.
    Luleå tekniska universitet.
    Johansson, Bernt
    Résistance à la fatigue des boulons précontraints dans les assemblages à recouvrement1994Ingår i: Construction Métallique, ISSN 0045-8198, nr 3, s. 25-34Artikel i tidskrift (Refereegranskat)
  • 66.
    Boström, Staffan
    et al.
    Luleå tekniska universitet.
    Johansson, Bernt
    The fatigue strength of preloaded bolts in lap-joints1993Ingår i: Proceedings, Nordic Steel Colloquium, ECCS Annual Meeting: Odense, Danish Steel Institute, September 1991, Odense: Danish Steel Institute , 1993Konferensbidrag (Övrigt vetenskapligt)
  • 67. Boström, Staffan
    et al.
    Johansson, Bernt
    Kellner, Håkan
    Renässans för järnvägsbroar1993Ingår i: V-byggaren : väg- och vattenbyggaren, ISSN 0283-5363, nr 3, s. 44-47Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 68. Bragança, Luís
    et al.
    Koukkari, HeliBlok, RijkGervásio, HelenaVeljkovic, MilanLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.Plewako, ZbigniewLandolfo, RaffaeleUngureanu, ViorelSilva, Luís Simões da
    Sustainability of Constructions - Integrated Approach to Life-time Structural Engineering: Proceedings of the 1st Workshop: Lisbon 13, 14, 15 September 20072007Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
  • 69. Bragança, Luís
    et al.
    Koukkari, HeliBlok, RijkGervásio, HelenaVeljkovic, MilanLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.Plewako, ZbigniewLandolfo, RaffaeleUngureanu, ViorelSilva, Luís Simões da
    Sustainability of Constructions - Integrated Approach to Life-time Structural Engineering: Proceedings of the Workshop, Timişoara, 23-24 October 2009. COST Action C252009Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
  • 70. Bragança, Luís
    et al.
    Koukkari, HeliBlok, RijkGervásio, HelenaVeljkovic, MilanLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.Plewako, ZbigniewLandolfo, RaffaeleUngureanu, ViorelSilva, Luís Simões daHaller, Peer
    Sustainability of Constructions Integrated Approach to Life-time Structural Engineering: Proceedings of Seminar, Dresden 6. 7 October 20082008Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
  • 71. Bragança, Luís
    et al.
    Koukkari, HeliVeljkovic, MilanLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.Borg, Ruben Paul
    Sustainable construction - a life cycle approach in engineering: International Training School, Malta, 26 July - 1 August 20102010Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
  • 72. Bragança, Luís
    et al.
    Koukkari, HeliVeljkovic, MilanLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.Borg, Ruben Paul
    Sustainable construction - a life cycle approach in engineering: Proceedings, International Symposium Malta, 23 - 25 July 2010. COST Action C252010Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
  • 73. Bragnaca, Luis
    et al.
    Koukkari, HeliBlok, RijkGervasio, HelenaVeljkovic, MilanLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.Plewako, ZbigniewBorg, Ruben Paul
    Summary report of the cooperative activities of the Cost Action C25: Sustainability of constructions. Integrated approach towards sustainable constructions2011Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
  • 74.
    Brege, Staffan
    et al.
    Industrial Marketing, Management and Engineering, Linkping University.
    Nord, Tomas
    Industrial Marketing, Management and Engineering, Linkping University.
    Sjöström, Roland
    Industrial Marketing, Management and Engineering, Linkping University.
    Stehn, Lars
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Value-added strategies and forward integration in the Swedish sawmill industry: positioning and profitability in the high-volume segment2010Ingår i: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 25, nr 5, s. 482-493Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The changing market conditions for the Swedish sawmill industry place a focus on a better understanding of the pros and cons of value-added and forward integration strategies. The purpose of this article is to describe and explain recent value-added strategies in the Swedish sawmill industry. The study includes strategies from 13 of the 15 largest sawmill companies for the period between 2002 and 2005, describing a differentiation between value added in primary sawmill production and forward integration into secondary production. It also aims to relate some basic conditions, such as company size, company growth and corporate strategy, to value added and forward integration to profitability. The results show strong positive and significant correlations between forward integration, value added in primary production (somewhat weaker) and unit revenue, and profitability measured as return on investment. There were no strong or significant correlations between size and profitability, playing down the importance of economies of scale (among these already large companies). An interesting result is the much higher profitability of the buying sawmill companies compared with the forest corporations, stressing the importance of both a long-term strategy when investing in value-added activities and ultimately the priorities of ownership.

  • 75.
    Bröchner, Jan
    et al.
    Organization of Construction, Department of Technology Management and Economics, Chalmers University of Technology.
    Lagerqvist, Ove
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    From ideas to construction innovations: Firms and universities collaborating2016Ingår i: Construction Economics and Building, ISSN 2204-9029, Vol. 16, nr 1, s. 76-89Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose here is to study patterns of project collaboration found in one government supported programme for construction innovation. Preferred types of interaction were identified using data from two questionnaire surveys, one with experienced construction sector respondents and one aimed at construction researchers. All sixteen development projects within the Swedish Bygginnovationen programme were investigated, relying on documents and a survey of project managers. Important types of interaction, according to construction respondents, are informal contacts, joint research projects and staff mobility. For university respondents, informal contacts is also seen as the most important type of interaction, followed by MSc thesis work in firms and industrial PhD candidates. Grant applicants from manufacturing depended more on university laboratories and were less sensitive to firm/university distance. Laboratory use was also more frequent for projects relying on the field of materials engineering. In conclusion, there is a consensus about which types of collaboration are valuable. The broadness of participation in the programme, ranging over many industries, both as to origin of ideas and ultimate applications, reaches beyond narrow interpretations of the construction industry. Policy makers should recognize the innovation importance of university laboratory facilities and field testing, rather than seeing researchers as sources of ideas.

  • 76.
    Buck, Dietrich
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Production and In-Plane Compression Mechanics of Alternatively Angled Layered Cross-Laminated Timber2018Ingår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, nr 2, s. 4029-4045Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increasing awareness of sustainable building materials has led to interest in enhancing the structural performance of engineered wood products. This paper reports mechanical properties of cross-laminated timber (CLT) panels constructed with layers angled in an alternative configuration on a modified industrial CLT production line. Timber lamellae were adhesively bonded together in a single-step press procedure to form CLT panels. Transverse layers were laid at an angle of 45°, instead of the conventional 90° angle with respect to the longitudinal layers’ 0° angle. Tests were carried out on 20 five-layered CLT panels divided into two matched groups with either a 45° or a 90° configuration; an in-plane uniaxial compressive loading was applied in the principal orientation of the panels. These tests showed that the 45°-configured panels had a 30% higher compression stiffness and a 15% higher compression strength than the 90° configuration. The results also revealed that the 45°-configured CLT can be industrially produced without using more material than is required for conventional CLT 90° panels. In addition, the design possibility that the 45°-configured CLT can carry a given load while using less material also suggests that it is possible to use CLT in a wider range of structural applications.

  • 77.
    Byström, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Fire temperature development in enclosures: Some theoretical and experimental studies2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Den här licentiatavhandlingen behandlar problem kopplade till branddynamik islutna utrymmen med tonvikt på värmeöverföring mellan gaser och utsattakonstruktioner. Avhandlingen består av en huvuddel samt fyra bilagor. Ihuvuddelen sammanfattas och diskuteras först några viktiga grundläggandeteorier och principer inom värmelära och branddynamik. Efter det presenterasett antal specialfall av brandscenarion som baseras på dessa teorier. I deavslutande bilagorna (Artiklar I-IV) finns fyra vetenskapliga artiklar somgrundligare beskriver de ovan nämnda specialfallen.Huvudfokus i avhandlingen ligger på temperaturutveckling vid brand i slutnautrymmen. Först har ett antal experiment genomförts där temperaturen mättsmed några olika typer av temperaturgivare. Sedan har ett antal försökgenomförts där den termiska exponeringen av konstruktioner kvantitativt harbestämts baserat på sådana mätningar.I avhandlingen har ett par olika brandscenarion studerats experimentellt.Framförallt behandlas den så kallade tvåzonsmodellen, där brandrummet delasin i en övre zon med höga temperaturer och en nedre med låga temperaturer.Dessutom har så kallad lokal brand studerats. I tillägg presenteras ett nytt sättatt analysera fullt utvecklade ventilationskontrollerade bränder med enenzonsmodell, där hela brandrummet antas ha en jämnt fördelad temperatur.I ett fullskale-experiment av lokal brand samlades temperaturdata in med olikatyper av plattermometrar (PT), små termoelement (TC, Ø=0.25 mm) samttermoelement fästa vid en stålbalk. Temperaturerna i stålbalken jämfördes senmed beräknade baserade på mätningar med plattermometrar och konceptetadiabatiska yttemperaturer. God överenstämmelse mellan de beräknade värdena (från finit-elementanalys med mjukvaran TASEF) och de uppmättaståltemperaturerna observerades.I tillägg har en fullskalig brand i ett slutet utrymme studerats experimentellt.Experimentet genomfördes i ett betonghus med två våningar. Under dettaexperiment uppmättes temperatur med plattermometrar och små termoelementplacerade på olika positioner i huset.Slutligen så har en ny modell för att beräkna brandtemperatur i övertändautrymmen analyserats. Både analytiska och numeriska lösningar (med hjälp avtemperaturberäkningsprogrammet TASEF) presenteras tillsammans medanalyser av bränder i slutna utrymmen med olika typer av omslutningsytor.

  • 78.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Cheng, Xudong
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Full-scale experimental and numerical studies on compartment fire under low ambient temperature2012Ingår i: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 51, s. 255-262Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 79.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Cheng, Xudong
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Measurement and calculation of adiabatic surface temperature in a full-scale compartment fire experiment2013Ingår i: Journal of fire sciences, ISSN 0734-9041, E-ISSN 1530-8049, Vol. 31, nr 1, s. 35-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 80.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Lind, Oskar
    Luleå tekniska universitet.
    Palmklint, Erika
    Luleå tekniska universitet.
    Jönsson, Petter
    Luleå tekniska universitet.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Analysis of a new plate thermometer: the copper disc plate thermometer2015Ingår i: Proceedings of the International Fire Safety Symposium 2015: Coimbra, Portugal, 20th-22nd April 2015 / [ed] João Paulo C Rodrigues, International Fire Safety Symposium , 2015, s. 453-460Konferensbidrag (Refereegranskat)
    Abstract [en]

    Two temperatures govern heat transfer to a surface of a solid body. One is the gas temperature which can be measured with thermocouples (TC) and the other the black body radiation temperature. The latter can also be expressed as the incident radiant heat flux. It is difficult to measure as radiometers cannot be used under hot fire conditions. Indirectly the radiation temperature can be obtained by measuring the Adiabatic Surface Temperature (AST) with plate thermometers (PT) for example as defined in the fire resistance furnace standards EN 1363-1 and ISO-834-1 combined with measurements of gas temperature with thin TC. In the test reported here a smaller gauge is used to measure adiabatic surface temperature at surfaces. It has been named copper disc Plate Thermometer (cdPT). Then a thin copper disc with an attached TC is mounted flush at the surface to obtain the AST in e.g. cone calorimeters according to ISO 5660. A main advantage of the cdPT is that it can record the AST before as well after a material has ignited. It can thereby be used to indicate ignition as well as continue recording the thermal exposure thereafter when ignition occurs the cdPT reacts immediately by displaying a quick temperature rise.

  • 81.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sjöström, Johan
    SP Technical Research Institute of Sweden, Borås.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Lange, David
    SP Technical Research Institute of Sweden, Borås.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Large scale test on a steel column exposed to localized fire2014Ingår i: Journal of Structural Fire Engineering, ISSN 2040-2317, E-ISSN 2040-2325, Vol. 5, nr 2, s. 147-160Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 82.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sjöström, Johan
    Technical Research Institute of Sweden, SP.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    A steel column exposed to localized fire2012Ingår i: Nordic Steel Construction Conference 2012: September 5-7, 2012 Oslo, Norway : Proceedings, Norwegian Steel Association , 2012, s. 401-410Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 83.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sjöström, Johan
    Technical Research Institute of Sweden, SP.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Large scale test to explore thermal exposure of column exposed to localized fire2012Ingår i: Proceedings of the 7th International Conference on Structures in Fire / [ed] Mario Fontana; Andrea Frangi; Markus Knobloch, Zurich: ETH Zurich, Institute of Structural Engineering , 2012, s. 185-194Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 84.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Influence of surrounding boundaries on fire compartment temperature2015Ingår i: International Conference ‘’Applications of Structural Fire Engineering" / [ed] Wald F.,Bjegovic D.,Horova K.,Burgess I.,Jelcic Rukavina M., Prague: Czech Technical University , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper shows and demonstrates how an analysis of the energy and mass balance of a fully developed (ventilation controlled) compartment fire can be used as a basis for simple and accurate predictions of fire temperatures. The model has been applied on compartments of light weight concrete structures. A finite element FE analysis has been used to solve the heat transfer equation. Effects of moisture were considered for material properties of the surrounding structure. The results were validated with experiments. The model then accurately predicted the fire temperatures and among other things it showed the influence of moisture in the surrounding structure on the fire temperature. Parametric temperature curves according to EN 1991-1-2, 2002 were shown to overestimate the fire temperature.

  • 85.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Temperature of post-flashover compartment fires: calculations and validation2018Ingår i: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 42, nr 3, s. 255-265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes and validates by comparisons with tests a one-zone model for computing temperature of fully developed compartment fires. The model is based on an analysis of the energy and mass balance assuming combustion being limited by the availability of oxygen, i.e. ventilation controlled fire. It is demonstrated that the model can be used to predict fire temperatures in compartments with semi-infinitely thick boundaries as well as with boundaries of insulated and uninsulated steel sheets where the entire heat capacity of the surrounding structure is assumed to be concentrated to the steel core. That is so called lumped heat capacity is assumed.

    When developing the fire model a maximum fire temperature was defined depending on combustion efficiency and opening heights only. This temperature was then used as a thermal boundary condition to calculate the temperature of the surrounding structure. The fire temperature was then derived to be a weighted average between the maximum fire temperature and the current calculated surrounding structure surface temperature.

    A general finite element solid temperature calculation code (TASEF) was used to calculate the temperature in the boundary structure. With this code it is possible to analyze surrounding structures of various kinds comprising materials with properties varying with temperature as well as assemblies of various materials.

    The experiments referred to were accurately defined and surveyed. In all the tests a propane diffusion burner was used as the only fire source. Temperatures were measured with thermocouples and plate thermometers at several positions [1].

  • 86.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Sjöström, Johan
    SP Technical Research Institute of Sweden, Sverige.
    Anderson, Johan
    Sverige.
    Project: Validation of a one-zone room fire model with well-defined experiments2016Övrigt (Övrig (populärvetenskap, debatt, mm))
  • 87.
    Byström, Alexandra
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Use of plate thermometers for better estimate of fire development2011Ingår i: Performance, Protection and Strengthening of Structures under Extreme Loading / [ed] Ezio Cadoni; Marco di Prisco, Trans Tech Publications Inc., 2011, s. 362-367Konferensbidrag (Refereegranskat)
    Abstract [en]

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

  • 88.
    Bäckman, Ellen
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Visuell planering inom projektering2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 89.
    Caprolu, Giuseppe
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Evaluation of Splitting Capacity of Bottom Rails in Partially Anchored Timber Frame Shear Walls2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The horizontal stabilization of timber frame buildings is oftenprovided by shear walls. Plastic design methods can be used todetermine the load-carrying capacity of fully and partially anchoredshear walls. In order to use these methods, a ductile behaviour of thesheathing-to-framing joint must be ensured. If hold-downs are notprovided, the vertical uplifting forces are transferred to the substrate bythe fasteners of the sheathing-to-framing joints. Since the forces in theanchor bolts and the sheathing-to-framing joints do not act in the samevertical plane, the bottom rail will be subjected to bending in thecrosswise direction, and splitting of the bottom rail may occur. If thebottom rail splits the applicability of the plastic design method forpartially anchored shear walls is questionable. This doctoral thesisaddresses the problem of brittle failure of the bottom rail in partiallyanchored timber frame shear walls.The first part of the study comprised of two basic experimentalprograms, for single-sided and double-sided sheathed shear walls. Theaim was to evaluate the different failure modes and the correspondingsplitting capacity of the bottom rail. Two brittle failure modes wereobserved: (1) a crack opening from the bottom surface of the bottomrail; and (2) a crack opening from the side surface of the bottom railalong the line of the fasteners of the sheathing-to-framing joints. It wasfound that the distance between the washer edge and the loaded edgeof the bottom rail has a decisive influence on the type of failure modeand the maximum failure load of the bottom rail.Two theoretical models for the load-carrying capacity for each typeof failure mode based on a fracture mechanics approach are studied andvalidated. The two analytical closed-form solutions are in goodagreement with the test results. The fracture mechanics models seem tocapture the essential behaviour and to include the decisive parametersof the bottom rail. These parameters can easily be determined and thefracture mechanics models can be used in design equations for bottomrails in partially anchored shear walls. Also, an extended fracturemechanics model for the load-carrying capacity for each type of failuremode is presented and evaluated.The present study discusses the splitting behaviour of the bottom railand provides methods to determine the splitting capacity for two brittlefailure modes, splitting of the bottom surface (mode 1) and of the sidesurface of the rail (mode 2). By these means brittle failure of thebottom rail can be avoided and the full plastic load-carrying capacity ofthe sheathing-to-framing joints can be utilized.

  • 90.
    Caprolu, Giuseppe
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Experimental testing of anchoring devices for bottom rail in partially anchored timber frame shear walls with two-sided sheathing2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Källsner and Girhammar [1] have presented a new plastic design method for wood-framed shear walls at ultimate limit state. This method allows the designer to calculate the load-carrying capacity of shear walls partially anchored, where the leading stud is not fully anchored against uplift. The anchorage system of shear walls is provided from anchor bolts and hold downs. Anchor bolts provide horizontal shear continuity between the bottom rail and the foundation. Hold downs are directly connected from the vertical end stud to the foundation. When hold downs are not provided, the bottom row of nails transmits the vertical forces in the sheathing to the bottom rail (instead of the vertical stud) where the anchor bolts will further transmit the forces into the foundation. Because of the eccentric load transfer, due to forces acting in the same vertical plane, transverse bending is created in the bottom rail and splitting often occurs. It is important to evaluate this cross-wise bending and to ensure that no brittle failure occur in the bottom rail. The bottom rail is experimentally studied with respect to two primary failure modes, splitting along the bottom of the bottom rail due to cross-wise bending and splitting along the edge side of the bottom rail due forces perpendicular to the grain from the sheathing-to-framing connections. The parameters varied are the size of the washer and the orientation of the pith. The bottom rail was subjected to loading perpendicular to grain through two-sided sheathing. In this report the different set of series are presented. Five sets were conducted depending on the size of the washer and in each set the pith was placed upwards and downwards. The tests showed three different failure modes. In addition to the failure modes that the testing program was aimed at, splitting along the bottom or side of the bottom rail, the final failure was also due to plastic bending and withdrawal of the sheathing-to-framing nails. The results show that the size of the washer has a significant influence on the maximum load and the failure modes. The results show also that the orientation of the pith have a significant influence on the maximum load.

  • 91.
    Caprolu, Giuseppe
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Experimental testing of hold down devices for timber frame shear walls2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Källsner and Girhammar [1] have presented a new plastic design method for wood-framed shear walls at ultimate limit state. This method allows the designer to calculate the load-carrying capacity of partially anchored shear walls, where the leading stud is not anchored against uplift. The anchorage system of shear walls is provided by anchor bolts in the bottom rail and hold downs at the leading stud. Anchor bolts provide horizontal shear continuity between the bottom rail and the foundation. Hold downs are directly connecting the vertical leading stud to the foundation. Sometimes hold downs are not provided and only the bottom rail is anchored to the substrate. In this case the bottom row of nails transmits the vertical forces in the sheathing to the bottom rail (instead of the stud) where the anchor bolts will further transmit the forces into the foundation. In this report hold downs have been experimentally studied with respect to the strength and stiffness of the connection. Four different types of hold downs have been tested. The specimen was subjected to tension load applied to the stud. Four tests series are presented. Each series was divided into different sets according to the type of fastener used with the hold down device. The results show that the failure load is higher when hold downs with anchor bolts are used, up to ten times higher than the anchorage that uses only screws or nails. The failure mode vary with the type of hold down and the type of fasteners used. The tests showed three primary failure modes: failure of the stud when a bolt is used as the fastener between hold down device and stud, failure due to pull-out of the screws or nails from the rail and failure due to failure or pull-out of screws or nails from stud. Also, failure of the stud itself occurred in some tests caused by some defect of the timber

  • 92.
    Caprolu, Giuseppe
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Matching tests of brittle failure of bottom rail versus tensile strength perpendicular to the grain and fracture energy in RT and TR plane.2014Rapport (Övrigt vetenskapligt)
  • 93.
    Caprolu, Giuseppe
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Girhammar, Ulf Arne
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Källsner, Bo
    School of Engineering, Linnæus University, Växjö, Linnéuniversitetet, Linnaeus University, Växjö.
    Analytical models for splitting capacity of bottom rails in partially anchored timber frame shear walls based on fracture mechanics2017Ingår i: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, nr 3, s. 165-188Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plastic design methods can be used for determining the load-carrying capacity of partially anchored shear walls. For such walls, the leading stud is not fully anchored against uplift and tying down forces are developed in the sheathing-to-framing joints and the bottom rail will be subjected to crosswise bending, leading to possible splitting failure of the rail. In order to use these plastic design methods, a ductile behaviour of the sheathing-to-framing joints must be ensured. In two earlier experimental programmes, the splitting failure capacity of the bottom rail has been studied. Two brittle failure modes occurred during testing: (1) a crack opening from the bottom surface of the bottom rail and (2) a crack opening from the side surface of the bottom rail. In this article, a fracture mechanics approach for the two failure modes is used to evaluate the experimental results. The comparison shows a good agreement between the experimental and analytical results. The failure mode is largely dependent on the distance between the edge of the washer and the loaded edge of the bottom rail. The fracture mechanics models seem to capture the essential behaviour of the splitting modes and to include the decisive parameters. 

  • 94.
    Caprolu, Giuseppe
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Girhammar, Ulf Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Källsner, Bo
    School of Engineering, Linnæus University, Växjö, Linnéuniversitetet, Linnaeus University, Växjö.
    Comparison of models and tests on bottom rails in timber frame shear walls experiencing uplift2015Ingår i: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 94, s. 148-163Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The authors present two different studies: one experimental study and one where analytical models developed to calculate the splitting failure capacity of bottom rails in partially anchored timber frame shear walls are evaluated and validated. The experimental study was divided into three parts with specimens matched to each other: (1) first the splitting capacity and failure mode of bottom rails subjected to uplift were studied; (2) then material properties such as tensile strength perpendicular to the grain; and (3) fracture energy were determined by testing specimens cut from the specimens belonging to study (1). The experimental results were compared with models based on a linear fracture mechanics approach presented earlier, using as input values results from (2) and (3). Almost all tested models show good agreement with the test results. The models showing the best agreement have been selected and proposed to be used as basis for calculation of the splitting failure capacity of bottom rails in partially anchored timber frame shear walls.

  • 95.
    Caprolu, Giuseppe
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Girhammar, Ulf Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Källsner, Bo
    Linnaeus University, Växjö.
    Splitting capacity of bottom rails in partially anchored timber frame shear walls with double-sided sheathing2015Ingår i: The IES Journal Part A: Civil & Structural Engineering, ISSN 1937-3260, E-ISSN 1937-3279, Vol. 8, nr 1, s. 1-23Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In partially anchored shear walls, the leading stud is not fully anchored against the uplift; hence the uplifting force is resisted by the sheathing-to-framing joint along the bottom rail. These joint forces will introduce crosswise bending and shear in the bottom rail leading to possible splitting failures. To design partially anchored shear walls, plastic design methods can be used and, therefore, the bottom rails must not fail in a brittle manner. In this paper, results of two experimental programmes with respect to the splitting capacity of bottom rails with double-sided sheathing due to uplift in partially anchored shear walls are presented. This was evaluated varying the distance between the washer edge and the edge of the bottom rail, and the pith orientation of the bottom rail. The experimental results show two brittle failure modes for the bottom rail: (1) a crack opening from the bottom surface of the bottom rail and (2) a crack opening from the edge surface of the bottom rail. The results indicate that the distance from the edge of the washer to the edges of the bottom rail has a decisive influence on the load-carrying capacity and failure modes of the bottom rail.

  • 96.
    Caprolu, Giuseppe
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Girhammar, Ulf Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Källsner, Bo
    Linnaeus University, Växjö.
    Johnsson, Helena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Test on the splitting failure capacity of the bottom rail due to uplift in partially anchored shear walls2012Ingår i: World Conference on Timber Engineering: Final Papers - Architecture and Engineering Case Studies / [ed] Pierre Quenneville, New Zealand Timber Design Society , 2012, s. 189-194Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Källsner and Girhammar have developed a new plastic design method for wood-frame shear walls at ultimate limit state. The method is capable of calculating the load-carrying capacity of partially anchored shear walls, where the leading stud is not necessarily anchored against uplift. In fully anchored shear walls, the leading stud needs to be anchored using some kind of hold-downs to resist uplift and the bottom rail needs to be fixed by anchor bolts to resist horizontal shear forces. In partially anchored shear walls, where hold-downs are not provided, the uplifting force is resisted by the sheathing-to-framing joints along the bottom rail. Hence, it is important that the bottom rail is anchored to the floor structure or foundation by anchor bolts and, therefore, able to transmit the forces to the structure below. Because of the eccentric load transfer, transverse bending is developed in the bottom rail and splitting of the bottom rail can occur. In order to use the plastic design method, a ductile behaviour of the sheathing-to-framing joints must be ensured. In this paper, results of tests on the splitting capacity of the bottom rail due to uplift in partially anchored shear walls are presented. Specimens with single-sided sheathing were tested, varying the size of washer, pith orientation of the bottom rails and anchor bolt position along the width of the bottom rail. The aim of the tests was to evaluate the influence of these parameters in order to avoid splitting failure of the bottom rail. Two types of brittle failure modes occurred during testing: (1) a crack opening from the bottom surface of the bottom rail and (2) a crack opening from the edge surface of the bottom rail along the line of sheathing-to-framing joints. These failure modes were mainly dependent on the washer size and the location of the anchor bolt. The results show that the distance between the edge of the washer and the loaded edge of the bottom rail has a decisive influence on the maximum load and the failure modes of the bottom rail.

  • 97.
    Caprolu, Giuseppe
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Girhammar, Ulf Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Källsner, Bo
    School of Engineering, Linnæus University, Växjö.
    Lidelöw, Helena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Splitting Capacity of Bottom Rail in Partially Anchored Timber Frame Shear Walls with Single-Sided Sheathing2014Ingår i: The IES Journal Part A: Civil & Structural Engineering, ISSN 1937-3260, E-ISSN 1937-3279, Vol. 7, nr 2, s. 83-105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Plastic design methods can be used for determining the load-carrying capacity of partially anchored shear walls, where hold-downs are not provided. In order to use these methods, a ductile behaviour of the sheathing-to-framing joints must be ensured. Since the forces in the anchor bolts and the sheathing-to-framing joints do not act in the same vertical plane, the bottom rail will be subjected to bending and shear in the cross-wise direction, and splitting of the bottom rail may occur. In this article, results of two experimental programmes on the splitting capacity of the bottom rail due to uplift in partially anchored shear walls are presented. Two brittle failure modes occurred during testing: (1) a crack opening from the bottom surface of the bottom rail and (2) a crack opening from the edge surface of the bottom rail along the line of the sheathing-to-framing joints. The results show that the distance between the edge of the washer and the loaded edge of the bottom rail has a decisive influence on the maximum load and the failure modes of the bottom rail.

  • 98.
    Caprolu, Giuseppe
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Källsner, Bo
    Linnaeus University, Växjö.
    Girhammar, Ulf Arne
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Vessby, Johan
    Linnaeus University, Växjö.
    Analytical and experimental evaluation of the capacity of the bottom rail in partially anchored timber shear walls2012Ingår i: World Conference on Timber Engineering: Final Papers - Architecture and Engineering Case Studies / [ed] Pierre Quenneville, New Zealand Timber Design Society , 2012, s. 157-166Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Källsner and Girhammar have developed plastic design methods for light-frame timber shear walls that can be used for determining the load-carrying capacity when the shear walls are partially anchored. For such walls, the leading stud is not fully anchored against uplift and tying down forces are developed in the sheathing-to-framing joints. Since the forces in the anchor bolts and the sheathing-to-framing joints do not act in the same vertical plane, the bottom rail will be subjected to cross-wise bending, leading to possible splitting along the bottom side of the rail. Another possible brittle failure mode is splitting along the edge of the bottom rail in line with the sheathing-to-framing fasteners. An experimental program has been conducted using different anchor bolt locations, washer sizes and pith orientations. A fracture mechanics approach for the two failure modes is used to evaluate the experimental results. The comparison shows a good agreement between the experimental and analytical results. The failure mode is largely dependent on the distance between the edge of the washer and the edge of the bottom rail. The size of the washer seems also to have some influence on the failure load. The fracture mechanics models seem to capture the essential behaviour of the splitting modes and to include the decisive parameters. These parameters can easily be adjusted to experimental results and be used in design equations for bottom rails in partially anchored shear walls.

  • 99.
    Carlsson, Elin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Sörebö, Victoria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Utveckling av konventionella småhus till passivhus: En studie med analys av livscykelkostnader, förändring av boendekvaliteter och ett förslag till en alternativ utformning2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Klimatförändringarna blir allt mer omfattande i takt med att jordens befolkning ökar. Den negativa miljöpåverkan bottnar till stor del i användandet av råvaror och energiförbrukning vid skapandet av materiella ting. Enligt energimyndigheten (2015) står byggsektorn för ca 40 % av Sveriges totala energianvändning. För att minska energianvändningen har mål både på nationell och internationell nivå skapats. Målen är tänkta att skapa större förståelse av ett mer energieffektivt byggt samhälle för samtliga aktörer inom byggbranschen. En hållbar utveckling av husbyggandet kräver förutom att värna om miljön en beaktning av de ekonomiska och sociala aspekterna.

     

    I det här examensarbetet har det undersökts om två specifika standardhus från en småhusleverantör kan utvecklas till passivhus med bevarad arkitektonisk karaktär. Studien syftar delvis till att undersöka om begreppet passivhus kan fungera som ett hållbart koncept för byggandet av enfamiljshus. Begreppet hållbar utveckling har begränsats och en förenkling har applicerats i arbetet. Den ekologiska aspekten representeras av energiberäkningar och eventuella åtgärder för att standardhusen ska uppnå kraven för passivhus. Den ekonomiska aspekten representeras av en livscykelkostnadsanalys med hjälp av nuvärdesmetoden och återbetalningsmetoden. Den sociala aspekten representeras av en utvärdering av förändring i boendekvaliteter vid utveckling från ett standardhus till passivhus. Studien presenterar även en alternativ utformning av ett passivhus med avsikt att främja positiva boendekvaliteterna.

     

    Standardhusen tillhör en småhusproducent, Intressanta hus, som har sitt huvudsäte i Västerås. Husen utgörs av en villa på 147 m2 i ett plan med pulpettak samt en villa på 151 m2 i två plan med sadeltak. Med anledning av Intressanta hus geografiska läge har Västerås klimat använts som utgångspunkt vid energiberäkningarna. För att addera ytterligare en utmaning har även möjligheter för utveckling till passivhus undersökts för standardhusen i ett subarktiskt klimat i Kiruna. Västerås representerar därmed klimatzon III och Kiruna klimatzon I.

     

    Resultaten avslöjade att det är möjligt att utveckla standardhuset i två plan med sadeltak till passivhus och samtidigt bevara den arkitektoniska karaktären i de båda klimatzonerna. Standardhuset med ett plan och pulpettak är endast möjligt att anpassa till passivhus i klimatzon III med bevarad arkitektonisk karaktär. Livscykelkostnadsanalysen visar med hjälp av nuvärdesmetoden att det är ekonomiskt fördelaktigt att investera i passivhus som ett koncept för en kalkylperiod på 50 år. Den boendekvalitet som främst förändras är bostadens ljusinsläpp och för passivhuset i ett plan är skillnaden av ljusinsläpp markant i klimatzon I.

     

    Studiens slutsats är att konceptet passivhus är en metod av husbyggnation som främjar den hållarbara utvecklingen i förenklad form. Resultaten är framförallt positiva för klimatzon III men om byggnaden har låg formfaktor kan konceptet fungera bra även i kallare klimat som återfinns i klimatzon I.

  • 100.
    Cederwall, Linnea
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Glasfasader för trämoduler2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Sammanfattning

    Modulbyggnader har utvecklats mycket under de senaste decennierna. Metoden föredras på grund av de snabba monteringstiderna och enkla installationerna. I Sverige föredras trä som bärande material för modulerna. Modulbyggnader kan många gånger upplevas som repetitiv på grund av dess återkommande fasad.

    Glasfasader kan användas för att säkerställa en arkitektonisk uppfattning och bryta det repetitiva mönstret. Syftet med examensarbetet är att undersöka hur en glasfasad med en struktur av glas och trä kan användas med en modul. Fasaden är konstruerad för att produceras industriellt och enkelt monteras ihop med andra fasadelement. Värmeförhållanden och vindbelastning antogs efter en placering i Luleå. Tjockleken på det yttre glasskiktet har utformats efter lastkombinationer, där vindtrycket var den dominerande kvasistatiska belastningen. De påfrestningar som glasskiktet utsätts för har beräknats både analytiskt och med Finita elementmetoden.

    Fasadelementet består av tre glasskivor och en träram. Den yttre glasskivan är laminerad och är 14,8 mm tjock. De andra två är härdade glasskivor med en tjocklek av 4 mm vardera och två luftspalter på 18,5 mm mellan glasskikten. De härdade glasen är behandlade med ett lågemissionsskikt. Fasadens U-värde beräknades till 0,68 W / m2K med hjälp av programmet Spectrum.

    Laminerat trä används för träramen och löper runt glasskivans fyra kanter. Varje del av ramen är utformad som en U-balk med en längd på 3 meter. Fasadelementen är anslutna till trämodulen med 8x300 mm skruvar genom U-balken. Livets tjocklek på U-sektionen dimensionerades för att undvika sprickbildning på grund av borrning och fick dimensionen 88 mm. U-balkens övre och undre fläns är 100 mm bred och har en tjocklek av 20 mm. Deras syfte är att hålla glasplattorna på plats. Mellan glaset och flänsen appliceras ett akrylatlim som förbinder materialen.

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