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  • 301.
    Wennberg, Filip
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Förekomst och hantering av psykisk ohälsa och stress inom räddningstjänsten i Norrbotten: En enkät- och intervjustudie2018Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 302.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Boundary Conditions in Fire Protection Engineering2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 45-64Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    A summary of the three kinds of boundary conditions as outlined in Sect. 1.​1.​3 is shown in Table 4.1. The third kind of BC sometimes called natural BC is by far the most important and common boundary condition in fire protection engineering, while the first and second kinds of BCs can rarely be specified. The third kind of BC may be divided into three subgroups, (a), (b) and (c). The subgroup (b) and (c) are particularly suitable for fire engineering applications. Subgroup (a) is applied when the heat transfer coefficient may be assumed constant as assumed in Chaps. 2 and 3. T g is then the surrounding gas temperature. In fire protection engineering it is, however, generally not accurate enough to assume a constant heat transfer coefficient as in particular heat transfer by radiation is highly non-linear, i.e. the heat transfer coefficient varies with the surface temperature. Therefore the subgroups (3b) and (3c) are the most commonly applied. They consist of a radiation term and a convection term with the corresponding emissivity ε and convection heat transfer coefficient h, respectively. The subgroup (3b) presupposes a uniform temperature T f , i.e. the radiation temperature and the gas temperature are equal. This is assumed, for example, when applying time–temperature design curves according to standards such as ISO 834 or EN 1363-1 for evaluating the fire resistance of structures, see Chap. 12. The subgroup (3c) is a more general version of (3b) as it allows for different gas T g and radiation T r temperatures, so-called mixed boundary conditions. Alternatively σ⋅T 4 r σ⋅Tr4 may be replaced by an equivalent specified incident radiation q . ′′ inc q.inc′′ according to the identity q . ′′ inc ≡σ⋅T 4 r q.inc′′≡σ⋅Tr4 (Eq. 1.​17). As shown in Sect. 4.4 all boundary conditions of subgroup 3 may be written as type 3a. That means momentarily a single effective temperature named the adiabatic surface temperature (AST) with a value between the radiation and gas temperatures as well as a corresponding total heat transfer coefficient can always be defined, see Sect. 4.4.

  • 303.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Fire Exposure of Structures According to Standards2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 185-193Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    When exposed to fire structures deform and lose load-bearing capacity which must be considered in design processes. It is then exposures to the more severe fires which are of interest such as post-flashover compartment fires and large flames for longer times. Pre-flashover fires do in general not create thermal conditions that can jeopardize the function of structural elements in a building. For design purposes it is therefore in general exposures relevant for post-flashover compartment fires that are specified in various standards and guidelines in the form of time–temperature curves. These curves are then used for controlling fire resistance test furnaces, see Fig. 12.1.

  • 304.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Heat Transfer by Convection2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 89-105Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    In previous chapters heat transfer by convection or just convection was treated only to the extent that it provides a linear boundary condition of the 3rd kind for conduction problems when the heat transfer coefficient is assumed constant. In this chapter the physical phenomenon of convection is described in more detail.

  • 305.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Heat Transfer by Radiation2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 65-87Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Heat transfer by thermal radiation is transfer of heat by electromagnetic waves. It is different from conduction and convection as it requires no matter or medium to be present. The radiative energy will pass perfectly through vacuum as well as clear air. While the conduction and convection depend on temperature differences to approximately the first power, the heat transfer by radiation depends on the differences of the individual body surface temperatures to the fourth power. Therefore the radiation mode of heat transfer dominates over convection at high temperature levels as in fires. Numerical applications of radiation heat transfer in FSE are outlined in Sect. 4.​1.

  • 306.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Introduction2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 1-16Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Temperature is the dominating factor in determining the rate and extent of chemical reactions including breakdown of organic compounds and deteriorations of strength and stiffness of structural materials such as steel and concrete. Phase change phenomena including ignition as well as severe loss of strength of materials are often related to specific elevated temperature levels. Temperatures of fire gases are also of crucial importance as they initiate gas movements thereby spread of smoke and toxic fire gases. Fire temperatures vary typically over several hundred degrees. Therefore a number of thermal phenomena need special attention such as phase changes of materials and heat transfer by radiation when calculating temperature of fire-exposed materials.

  • 307.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Measurements of Temperature and Heat Flux2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 133-151Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    In FSE temperature is nearly always measured with thermocouples as described in Sect. 9.1. Heat flux measured in different ways is most commonly measured as the sum of the net heat flux by radiation and convection to a cooled surface. The principles are briefly outlined in Sect. 9.2. Alternative methods incident radiation heat flux as well AST using so-called plate thermometers has also been developed as a practical alternative to heat flux meters as outlined in Sect. 9.3

  • 308.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Numerical Methods2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 107-124Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The analytical methods outlined in Chaps. 2 and 3 presume that the material properties and heat transfer coefficients are constant. That is, however, not possible in most cases in fire protection engineering as the temperature then varies within a wide range and therefore both material properties and boundary conditions vary considerably. Phase changes or latent heat due to water vaporization or chemical reactions of materials (see Sect. 14.​1 on concrete) must in many cases be considered to achieve adequate results. Furthermore in particular radiation heat transfer coefficients vary considerably with temperature. As shown in Sect. 4.​1 it increases with the third power of the temperature level. In addition geometries being considered are not as simple as assumed above. Often they are in two or three dimensions, and then analytical methods can seldom be used for practical temperature analyses. Therefore numerical methods involving computer codes are frequently used in fire protection engineering. In some cases in particular for 0-dimension problems (lumped-heat-capacity) relatively simple so-called spreadsheet codes such as Excel may be used. For problems with more complex geometries and boundary conditions computer codes based on finite difference or finite elements methods are needed. Several computer codes based on these methods are commercially available, see Sect. 7.3.2. The superposition technique as presented in Sect. 7.2 may be seen as a combination of a numerical and an analytical method.

  • 309.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Post-Flashover Compartment Fires: One-Zone Models2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 153-174Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    FSE and design of structures and structural elements are in most cases made with a procedure including tests and classification systems. Fire resistance or endurance tests are specified in standards such as ISO 834, EN 1363-1 or ASTM E-119. In these standards time–temperature curves are specified representing fully developed compartment fires to be simulated in fire resistance furnaces for prescribed durations.

  • 310.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Pre-flashover Compartment Fires: Two-Zone Models2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 175-183Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Two-zone models are applied to pre-flashover fires, i.e. compartment fires which have not reached ventilation controlled combustion conditions as defined in Chap. 10. Several more or less advanced computer codes have been developed to calculate temperature under such assumptions. The most fundamental principles of the theory are outlined below.

  • 311.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Steady-State Conduction2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 17-24Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    In one dimension in the x-direction the rate of heat transfer or heat flux is expressed according to Fourier’s law as outlined in Sect. 1.​1.q . ′′ x =−k⋅dTdx q.x′′=−k⋅dTdxwhere k is the thermal conductivity. For simplicity the mathematical presentation of the heat transfer phenomena is here in general made for one-dimensional cases only. Corresponding presentations in two and three dimensions can be found in several textbooks such as [1, 2].

  • 312.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Temperature Calculation in Fire Safety Engineering2016Bok (Refereegranskat)
    Abstract [en]

    This book provides a consistent scientific background to engineering calculation methods applicable to analyses of materials reaction-to-fire, as well as fire resistance of structures. Several new and unique formulas and diagrams which facilitate calculations are presented. It focuses on problems involving high temperature conditions and, in particular, defines boundary conditions in a suitable way for calculations. A large portion of the book is devoted to boundary conditions and measurements of thermal exposure by radiation and convection. The concepts and theories of adiabatic surface temperature and measurements of temperature with plate thermometers are thoroughly explained.Also presented is a renewed method for modeling compartment fires, with the resulting simple and accurate prediction tools for both pre- and post-flashover fires. The final chapters deal with temperature calculations in steel, concrete and timber structures exposed to standard time-temperature fire curves. Useful temperature calculation tools are included, and several examples demonstrate how the finite element code TASEF can be used to calculate temperature in various configurations. Temperature Calculation in Fire Safety Engineering is intended for researchers, students, teachers, and consultants in fire safety engineering. It is also suitable for others interested in analyzing and understanding fire, fire dynamics, and temperature development. Review questions and exercises are provided for instructor use.

  • 313.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Temperature of Steel Structures2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 195-216Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Steel is sensitive to high temperature. The critical temperature of a steel member is the temperature at which it cannot safely support its load.

  • 314.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Temperature of Timber Structures2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 227-233Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Modelling the thermal behaviour of wood is complicated as phenomenas such as moisture vaporization and migration, and the formation of char have decisive influences on the temperature development within timber structures. Nevertheless it has been shown that general finite element codes can be used to predict temperature in, for example, fire-exposed cross sections of glued laminated beams [52], provided, of course, that apparent thermal material properties and appropriate boundary conditions are used. Other specialized numerical codes for timber structures have been developed, e.g. by Fung

  • 315.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Temperatures of Concrete Structures2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 217-225Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Reinforced concrete structures are sensitive to fire exposure of mainly two reasons. They may be subject to explosive spalling, and they may lose their load-bearing capacity due to high temperatures. Spalling is particularly hazardous as it may occur more or less abruptly and unanticipated. It usually starts within 30 min of severe fire exposure. It may depend on several mechanisms or combinations thereof such as pore pressure, stresses due to temperature gradients, differences of thermal dilatation and chemical degradations at elevated temperatures. Reinforcement bars of steel lose their strength at temperature levels above 400 °C. Prestressed steel may even loose strength below that level. Concrete loose as well both strength and stiffness at elevated temperature.

  • 316.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Thermal Ignition Theory2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 125-132Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    The various aspects of the subject ignition of unwanted fires has been thoroughly investigated by Babrauskas and presented in the comprehensive Ignition Handbook. This book is concentrating on the calculation of the development of surface temperature. Despite many limitations, it is often assumed that a solid ignites due to external heating when its exposed surface reaches a particular ignition temperature.

  • 317.
    Wickström, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Unsteady-State Conduction2016Ingår i: Temperature Calculation in Fire Safety Engineering, Encyclopedia of Global Archaeology/Springer Verlag, 2016, s. 25-44Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    When a body is exposed to unsteady or transient thermal conditions, its temperature changes gradually, and if the exposure conditions remain constant it will eventually come to a new steady state or equilibrium. The rate of this process depends on the mass and thermal properties of the exposed body, and on the heat transfer conditions. As a general rule the lighter a body is (i.e. the less mass) and the larger its surface is, the quicker it adjusts to a new temperature level, and vice versa. The temperature development is governed by the heat conduction equation (Eq. 1.29) with the assigned boundary conditions. It can be solved analytically in some cases, see textbooks such as [1, 2], but usually numerical methods are needed. This is particular the case in fire protection engineering problems where temperature generally varies over a wide range, often several hundred degrees.

  • 318.
    Wickström, Ulf
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Anderson, Johan
    RISE Research Institutes of SwedenBorås, Sweden.
    Sjöström, Johan
    RISE Research Institutes of SwedenBorås, Sweden.
    Measuring incident heat flux and adiabatic surface temperature with plate thermometers in ambient and high temperatures2019Ingår i: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 43, nr 1, s. 51-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new more insulated and faster responding plate thermometer (PT) is introduced, which has been developed for measurements particularly in air at ambient temperature. It is a cheaper and more practical alternative to water‐cooled heat flux meters (HFMs). The theory and use of PTs measuring incident radiation heat flux and adiabatic surface temperature are presented. Comparisons of measurements with PTs and HFMs are made. Finally, it is concluded that incident radiation in ambient air can be measured with HFMs as well as with the new insulated type of PT. In hot gases and flames, however, only PTs can be recommended. At elevated gas temperatures, convection makes measurements with HFMs difficult to interpret and use for calculations. However, they can be used in standard or well‐defined configurations for comparisons.

  • 319.
    Wickström, Ulf
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Byström, Alexandra
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Sjöström, Johan
    SP Sveriges Tekniska Forskningsinstitut, Brandteknik.
    Temperature measurements and modelling of flashed over compartment fires2016Ingår i: Proceedings of 14th International Conference and Exhibition on Fire Science and Engineering, 2016, Vol. 2, s. 949-960, artikel-id 12Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes and validates by comparisons with test results a one-zone model for computing temperatures of compartment fires where flashover is reached. The model is based on an analysis of the energy and mass balance of a fully developed (ventilation controlled) compartment fire. It is demonstrated in this paper that the model can be used to predict fire temperatures in compartments with semi-infinite boundaries as well as with boundaries of insulated or uninsulated steel sheets where so called lumped heat capacity can be assumed. Comparisons are made with a series of experiments in compartments of light weight concrete, and insulated and non-insulated single sheet steel structures. A general finite element code has been used to calculate the temperature in the surrounding structures. The in this manner calculated surface temperatures yield the fire temperature as a function of time. By using a numerical tool like a finite element code it is possible to analyse fire compartment surrounding structures of various kinds and combinations of materials.Two new characteristic compartment fire temperatures have been introduced in this paper. They are the ultimate compartment fire temperature, which is the temperature reached when heat losses to surrounding structures as well radiation out through openings can be neglected, and the maximum compartment fire temperature, which is the temperature when only the losses to surrounding structures are neglected.The experiments referred to were accurately defined and surveyed. In all the tests a propane gas burner was used as the only fire source. Temperatures were measured with thermocouples and plate thermometers at several positions, and oxygen concentrations were measured in the fire compartment only opening. In some tests the heat release rate as well as the CO2 and CO concentrations were measured as well (Sjöström, et al., 2016).

  • 320.
    Wickström, Ulf
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Hunt, Sean
    JENSEN HUGHES.
    Lattimer, Brian
    JENSEN HUGHES.
    Barnett, Jonathan
    RED Fire Engineers Pty Ltd.
    Beyler, Craig
    JENSEN HUGHES .
    Technical comment: ten fundamental principles on defining and expressing thermal exposure as boundary conditions in fire safety engineering2018Ingår i: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 42, nr 8, s. 985-988Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Predicting the temperature of an exposed object or even a person is one of the most common tasks of fire safety engineering. However, the nonlinear nature of heat transfer and the challenge of changing material properties with temperature have plagued precise predictions. In addition, as methodologies are developed, one of the biggest challenges is to apply them to known scenarios where temperatures and heat fluxes have been measured. The interpretations of such measurements are, however, often clouded by the lack of common understanding of the reported values and how they shall be translated into boundary conditions to be used for calculations. This technical comment summarizes the Fundamental Principles that are crucial to properly identifying the fire exposure so that appropriate temperature predictions can be made.

  • 321.
    Yahia Darwish, Savo
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Skog, Richard
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Suppressing Torsional Buckling Effects of Angle Members: Application on lattice towers2017Självständigt arbete på avancerad nivå (yrkesexamen), 300 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Wind towers are a today under a global development and many countries put more focus on this environmentally friendly way of producing electricity. The performance requirement increase and at the same time the wind towers should be economical. One way of achieving better performance is to build higher towers which increase the harvesting efficiency. One way of achieving high towers is to use a lattice structure. High lattice towers require more material and have a more demanding structural design. By using cold form steel angles as columns for the lattice tower the aim is to achieve a high utilization ratio of the steel angels. Angle members are susceptible to torsional buckling, which is often the critical mode. It is thus essential to enhance their torsional response.

    The four columns in a lattice tower are restrained against sideway displacements by the braces and diagonals, which limits their flexural bucking length. In contrast, restraining the torsional rotations is challenging. As angels are susceptible to torsion and the flexural buckling length is decreased, the flexural-torsional interaction becomes significant.

    The objective of this study is to investigate thin walled angle members under compression. The idea for this project is to increase the torsional properties of an angle by lacing together the free ends of its two legs. If the lacing acts like a plate the angle columns can behave similar to a closed section.  The aim will be to increase the buckling resistance of the angle column. The design is assessed through GMNIA investigations in the FEM program Abaqus and compare laced columns to their unlaced counterparts. Using this method the result will show how the buckling resistance and buckling mode is affected by the lacing.

    The results of this study showed that lacing had a positive effect on columns in cross-section class 4. Columns in these two classes reached a higher buckling resistance and the buckling mode shifted from torsional buckling to localized buckling. The result showed increased effect by using a higher density of lacing.

  • 322.
    Öhman, Kristoffer
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    The Crocodile Nose Connection: Design and laboratory tests on a novel connection for structural hollow sections2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    De goda egenskaperna och den ideala formen gör det cirkulära tvärsnittet uppskattat av arkitekter. Vid anslutningar av dessa tvärsnitt är det idag vanligt att använda knutplåtar. Kniv-plåtanslutningar där knutplåten förs in i en öppning i änden av det cirkulära tvärsnittet är det mest använda förbandet idag. På grund av rörets abrupta slut i detta förband är det inte estetiskt tilltalande enligt arkitekter.

    Ett alternativ för kniv-plåt-förbandet är Crocodile Nose-förbandet (CN-förbandet). Fördelarna med CN-förbandet är frånvaron av det abrupta slutet och den utstickande knutplåten, vilket görden uppskattad av arkitekter. I detta förband är det cirkulära tvärsnittets kanter nerfasade, vilket skapar två semielliptiska skärytor på båda sidor av röret. På dessa skärytor svetsas lämpliga plåtar med kälsvetsar. Plåtarna är formade på ett sådant sätt att när de är svetsas på plats är orienteringen av den utstickande delen parallel med rörets axel. Ett mellanrum mellan de utstickande delarna skapas så att knutplåten kan föras in och bultas fast tillsammans med röret.

    Fyra olika provkroppar av CN-förbandet testas för att hitta den bästa utformningen. Tvåprovkroppar har en avstyvning mellan plåtarna. Skillnaden mellan närvaron av avstyvningen och frånvaron av den är undersökt. Resultaten visade att provkropparna med avstyvningen fick enmarkant högre brottlast, upp till 413 % högre. För att även hitta den optimala vinkeln på skärytan har två olika vinklar undersökts. I detta fall visade resultaten att provkropparna med den mindrevinkeln gav en högre brottlast, upp till 40 % högre. Även en kontroll på svetsen som binder ihopplåtarna med röret är gjord. Denna kontroll gjordes med hjälp av en antagen beräkningsmodell.Resultatet visade att beräkningsmodellen endast är giltig för provkropparna utan avstyvningen.Beräkningsmodellen måste därför utvecklas, så den kan användas för samtliga dimensioneringsfall.

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