En byggnad belastas inte enbart av vertikala krafter utan även horisontella krafter. Horisontella krafter uppstår från exempelvis vindlast, jordbävningslast eller vertikala laster som verkar excentriskt. Vid dimensionering av en byggnad är det mycket viktigt att man konstruerar ett stabiliseringssystem som kan ta hand om dessa krafter. I denna studie undersöks de tre vanligaste metoderna att horisontalstabilisera en byggnad på, nämligen med diagonalstag, momentstyva knutpunkter eller med hjälp av skivverkan.    Den byggnad som denna studie utgår ifrån är en stor hallbyggnad, avsedd för fotboll och är belägen i centrala Örnsköldsvik. Hallen är idag stabiliserad mot horisontella krafter dels genom profilerad plåt i taket, så kallad skivverkan, och genom diagonalstag i väggarna. Ofta användas kombinationer av de olika stabiliseringsmetoderna. I denna studie har det undersökts om det möjligt att horisontalstabilisera fotbollshallen med två andra stabiliseringssystem. Det ena systemet bestående av endast diagonalstag och det andra med endast momentstyva knutpunkter. Vidare har det även verifierats att den takplåt som sitter på byggnaden idag kan anses tillräcklig utifrån de dimensioneringskontroller som föreskrivs. De olika systemen jämförs sedan mot varandra med hänsyn till materialåtgång.    Efter genomförda beräkningar påvisar resultatet att både ett horisontal-stabiliseringssystem bestående av diagonalstag och av momentstyva knutpunkter är möjligt att utföra i fotbollshallen. Även verifiering av takplåten visar att stabilisering av taket med den befintliga takplåten var tillräcklig.    Det ska dock anmärkas att för alternativet med momentstyva knutpunkter krävs det väldigt grova pelardimensioner samt inspänningsbeslag till pelarfötterna i gavelsidan. Det gör att detta alternativ ej blir så praktiskt tillämpbart och därav är det orealistiskt att ett sådant horisontalstabiliseringssystem för just denna byggnad skulle utföras i verkligheten. Alternativet med diagonalstag har den största materialåtgången samt att det krävs väldigt många komponenter vilket gör det till ett komplext system att genomföra.    Utifrån materialåtgång blir det mer realistiskt att göra en kombination av dessa system än att använda dem var för sig. I kombinationen används momentstyva knutpunkter längs långsidan och diagonalstag används för att ta krafter mot gavelsidan. Dock blir det mest materialeffektiva stabiliseringssystemet för denna byggnad det befintliga som utgörs av diagonalstag i väggar och styv plåt i taket.   Slutsatsen som kan dras i en denna studie är att den mest fördelaktiga metod att horisontalstabilisera denna fotbollshall på är genom den metod som är använd i byggnaden idag. Det vill säga genom skivverkan i taket och diagonalstag i väggar. Att använda de alternativa utformningarna fungerar men innebär större materialåtgång. / A construction is not only exposed for vertical forces, but also horizontal forces occur and must be taken into consideration. Horizontal forces arise from, for example, wind loads, earthquake loads or vertical loads that act eccentrically. When dimensioning a building it is very important that you design a stabilization system that can handle these forces. This study examines the three most common stabilization methods for stabilizing a building against horizontal forces, namely with the use of stabilizing diagonals, rigid connections or through plane elements, also called diaphragmed action.   The building that this study is based on is a large hall building located in Örnsköldsvik which is intended for football. The building is today stabilized against horizontal forces partly by corrugated sheet in the ceiling, so called diaphragmed action, and by stabilizing diagonals in the wall. It is common for buildings to use combinations of the various stabilization methods. In this study, we have investigated whether it is possible to horizontally stabilize the football hall with two other stabilization systems. One system consisting of only stabilizing diagonals and the other one with rigid connections only. Additionally, it has also been verified that the corrugated sheet, placed in the ceiling of the building today, can be considered sufficient based on the dimensioning controls that are prescribed. Based on material consumption the different stabilization systems are then compared.   When the calculations were done, the result showed that the two options, the one with stabilizing diagonals and the other one with rigid connections, were both possible to execute as a horizontal stabilization system in the football hall. Also, verification of the corrugated sheet in the ceiling shows that stabilization of the ceiling with the existing roof sheet is sufficient.   However, it should be noted that for the alternative with rigid connections, very coarse column dimensions and clamping fittings for the column feet are required in the gable side of the building. This means that this alternative does not become so practically applicable and therefore it is not realistic that this stabilization method would be implemented in reality for this particular building. The other alternative, the one with stabilizing diagonals has the largest material consumption and requires a lot of components which makes it a complex system to implement.    Based on material consumption, it becomes more realistic to make a combination of these stabilization methods than to use them separately. In the combination, rigid connections are used along the long side and stabilizing diagonals are used to resist the forces against the gable side. But the most material-efficient stabilization system for this building will still be the existing one, consisting of stabilizing diagonals in the walls and a corrugated sheet in the ceiling   The conclusion that can be drawn in this study is that the most advantageous method of horizontally stabilizing this football hall is through the method that is used in the building today, by diaphragmed action in the ceiling and stabilizing diagonals in the walls. Using the other two stabilization alternatives for this building works as well, but it results in a larger material consumption.

Cellulose-based materials draw their good mechanical properties from the cellu-lose crystal. Improved understanding of crystal properties could lead to a wider range of applications for cellulose-based materials, Cellulose crystals show high axial Youngs modulus. Cellulose can attain several allomorphic forms which show unique structural arrangements in terms of both intra-molecular and inter-molecular bonding, as well as unit cell parameters and chain packing. Although several studies have confirmed that mechanical tensile properties of cellulose differ between different allomorphic forms, few reports have investigated the deformation mechanisms explaining the differences.In the first part of this thesis, the tensile elastic Youngs modulus of cellulose allo-morphs Iβ, II and III I were calculated under uniform conditions using Molecular Dynamics simulation techniques. As expected, a difference in modulus valuesc ould be observed, and the cooperative nature of energy contributions to crys-tal modulus is apparent. The allomorphs also show large differences in terms of how contributions to elastic energy are distributed between covalent bonds,angles, dihedrals, electrostatic forces, dispersion and steric forces.In the second part of this thesis, the cellulose Iβ and II allomorphs were sub-jected to a more detailed structural study. The purpose was to clarify how the deformation of the central glucosidic linkage between the monomer units depends on the hydrogen-bonding structures. This was carried out by studying simulated vibrational spectra and local deformations in the crystals.The results presented in this thesis confirm the differences in the tensile elastic properties of these cellulose allomorphs. These differences can in part be explained by the different intra-molecular hydrogen bonding patterns between allomorphs. Deformation mechanisms are discussed. The results are in supportof the so called ”leverage effect” proposed in the literature. The present analysis shows significant differences in details of deformation mechanisms compared with previous simpler analyses. / <p>QC 20150518</p>

QC 20110616

QC 20110620

The aim of this thesis was to evaluate new buildings with low-temperature heating systems in terms of energy consumption and thermal comfort, and to pay some attention to energy savings and indoor air quality. To reach this aim, on-site measurements as well as building energy simulations using IDA Indoor Climate and Energy (ICE) 4 were performed. Results show that the investigated buildings with low-temperature heating system could meet the energy requirements of Swedish regulations in BBR (Boverkets byggregler), as well as provide a good level of thermal comfort. Implementing variable air volume ventilation instead of constant flow, i.e. decreasing the ventilation air from 0.35 to 0.10 l·s-1·m-2 during the whole unoccupancy (10 hours), gave up to 23 % energy savings for heating the ventilation air. However, the indoor air quality was not acceptable because VOC (volatile organic compound) concentration was slightly above the acceptable range for one hour after occupants arrive home. So, in order to create acceptable indoor air quality a return back to the normal ventilation requirements was suggested to take place two hours before the home was occupied. This gave 20 % savings for ventilation heating. The results of this study are in line with the European Union 20-20-20 goal to increase the efficiency of buildings by 20 % to the year 2020. / <p>QC 20130612</p>

The current standards for design of steel beams are divided into four classes based on the slenderness of cross-sectional parts. Depending on the section class a beams load capacity is either determined by a plastic, elastic or a reduced elastic model. The division between cross-sections calculated by a plastic and an elastic model is today done in a very harsh way with no smooth transition. This leads to a large difference in the calculated resistance for the sections located near the class limits. Elasto-plastic sections are in the current situation calculated as purely elastic and their large plastic reserve is not considered in the current standards. The ambition of this study was to develop an appropriate interpolation model for elasto-plastic sections which gives a finer transition between the plastic and elastic region. To verify the proposed interpolation model were a large range of beams with varying slenderness modeled in the FEM program Abaqus. The beams have been restricted to include only simply supported HSQ-beams. The results obtained were found to indicate that Eurocode generally seem to overestimate the capacity of plastic cross-sections in section class 1 and 2, in some cases by up to 10%. With this insight focus ruled over from the interpolation model to instead look closer into the accuracy of the limit values in Eurocode. Overall, the results points to that Eurocode overestimate the bearing capacity the closer the elastic area you get. In the elastic area the load capacity instead shifts into being underestimated, which in turn shows the lack of an interpolation model. There are a number of possible reasons why Eurocode seems to overestimate the bearing capacity in some cases. The largest impact on the results seems to be the initial deflection of the internal parts. It is possible that the introduced deflection in Eurocode is too far from the allowable manufacturing tolerances that can actually occur in reality. Other factors such as choice of buckling lengths when the slenderness is determined and the effect of residual stresses may also affect the ultimate load bearing capacity. Too big conclusions should not be made by the results of this study given the limitations made, but the results nevertheless indicate that there are deficiencies in the classification of cross-sections in Eurocode and that further research should be carried out.

Developers and architects have limited possibilities to design and offer customized apartments. The use of conventional construction systems, with load-bearing walls in concrete and vertical HVAC shafts, tends to lead to standardized floor layouts, which are difficult to modify over time. In this thesis, a timber structural system that promotes flexible housing is developed. The structural system allows free positioning of apartment dividing walls, independent plan layouts on each floor and free window positioning in the facades. The structural system is also designed so that renovation and remodeling of the building can be performed in an easy and efficient way, so that flexibility is maintained during the lifetime of the building. The study focuses on the structural aspects of the building, but also includes assessments with regard to fire safety, acoustic properties and production. Omniplan AB's project BoLag has been used as a case study. The project is a part of the building exhibition LinköpingsBo2017, and omniplan has high ambitions for this project to be at the forefront of innovation. Two main concepts are applied to the building: Flexibility and the use of a timber structural system. The shape of the building plot, regulations in the zoning plan and omniplans visions were used as preconditions in the work. Modern timber structures normally use some level of prefabrication. Many suppliers of timber structural systems have developed their own building systems, more or less open. None of these standardized systems provides the flexibility that omniplans project demands. Therefore, a high level of planning is required. The result shows that it is possible to apply a flexibility concept on residential buildings with a timber structural system. The objectives are reaches by utilizing a concept that is commonly used in office buildings, where flexibility often is crucial. A beam and post system of laminated timber eliminates the need for load-bearing walls, allowing for a plan layout that varies from floor to floor. A HVAC space in the floor slabs, instead of vertical shafts, facilitates free placement of bathrooms and kitchens. Timber building technology is developing rapidly, and hopefully the specific properties of timber can be used to develop the housing industry in general. This study shows that the use of timber has potential for innovative construction.

QC 20110616

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