Wind power is considered an efficient alternative for production of electrical energy. One advantage that wind power offers compared to conventional ways of producing energy such as fossil energy and nuclear energy is the low emission of carbon dioxide “CO2” during production of electrical energy. In the last two decades extensive research and huge resources have been focused on production of wind power around the world. In the European Union (EU) the installation of wind power has an annual growth rate of over 11% from 3.2 GW in 2000 to 11.9 GW in 2012 [1] A wind power station consists of a tower with a turbine at the top. In the tower equipment used for transforming kinetic energy in the wind and turbine to electrical energy is placed. The cost for the tower is up to 27% of the total building cost. Building higher towers increases the output of wind power as the wind becomes more constant and the wind speed increases with the increase of the tower height. To make the tower hollow to create space for equipment, decrease weight and increase bending stiffness the walls should be as thin as possible. For such thin walled structures stability is one of the most dangerous failure cases, it leads to brittle failure. The tower needs to be stiff enough to prevent instability. In addition to this, it is important to use connections with high fatigue endurance, which is no considered in this analysis.One solution to reduce transportation costs is to manufacture the tower in sections, at least for onshore towers where the access is difficult. These towers can be made from using a lattice (truss) tower or a tubular tower made from steel. By using sections of high strength steel the towers will have more structural strength with more stability and lower cost as less material is used. As many of the tubular and lattice (truss) towers are made from thin elements it is important to study buckling. Therefore, a study of optimization by geometrical analysis and comparison with the actual standards is performed. Thin plates are often made from cold-formed steel with higher yield strength. The focus of this thesis is in the evaluation and the use of thin folded plates that can be combined to form polygonal cross-sections in towers for wind turbines. An initial numerical study of a folded plate with three different polygonal cross-sections was done using the Finite Element software ABAQUS [2]. The results are compared with EN 1993 part 1-3 [3] and EN 1993 part 1-5 [4]. The FEA showed local buckling as failure mode in all cases of the folded plates. The folded plates are designed to be used as section members for tubular and lattice (truss) towers. In the design for lattice towers the thin folded plates may be connected with gusset plates at different distances over the length of the plate to form a semi-closed cross-section column. For tubular towers the plates were designed to be connected by longitudinal connections to form a tube with a polygonal cross-section. The validity of the design rules given in EN 1993 part 1-3[3], EN 1993 part 1-5 [4], EN 1993 part 3-2 [5]and EN 1993 part 1-6 [6] were used.

With increasing demand of sustainable energy production, the harvesting of wind power by using wind turbines have become increasingly important over the last few decades. Most of the wind turbine towers are made from steel. Towers are an important part of the investment in wind parks and contribute about 20% of costs for the onshore towers. It supports the nacelle and is designed to sustain wind load and load caused by the operation of the wind turbine. This thesis presents results of experimental and numerical investigations on behavior of the steel tubular tower components made of circular and polygonal cross sections focusing on resistance of the door opening. An experimental program was planned to investigate the material and initial geometrical imperfections of the down scale specimens. Investigation of the basic material properties of the down scale specimens was carried out by using coupon specimens cut off from the down scale specimens. Influences of cold forming on the properties of the material were also studied by using coupon specimens with different cold formed angles. 3D scanning laser was used to determine initial geometrical imperfection of the down scale specimens. The measured data was analyzed by Matlab and Gom Inspect software. Results from these experiments were used as input data for the numerical models. Experiments on down scale specimens of the tubular tower with polygonal and circular cross sections were performed in order to investigate structural resistance. Finite element program Abaqus was used to simulate the tested specimens in order to compare their results to the experiments. Elastic, nonlinear geometry and nonlinear materials analyses were performed in order to investigate the ultimate resistance of the down scale specimens. Comparison of resistances of the circular and polygonal cross sections with Eurocode 3 was carried out.

The current design procedures prescribed by the codes for design of steel beams at elevated temperatures require that the ultimate flexural resistance of the beam should be checked against the applied loading. This approach does not take into account the redistribution of bending moment due to fire exposure that takes place in a redundant frame. The axial and rotational restraints at the beam to column connections in such a frame play an important role as to how the beam behaves in restrained conditions when exposed to fire. This is particularly important at relatively high temperatures when the beam has undergone significant deflections and as the catenary action in the beam gradually takes over as the resisting mechanism beyond the limiting temperature prescribed by the codes.Simplified design procedures that satisfactorily describe the restrained beam behaviour should be used to avoid the high cost and complexity of finite element analysis and fire tests. A proposed simplified design procedure has been used to analyse axially and rotationally restrained beams in sub-frames in this study and the results are compared to the results from their finite element models. The finite element models of the sub-frames were validated against fire tests conducted on sub-frames. The proposed method was shown to have satisfactorily predicted the restrained beam behaviour under different load levels and temperature distributions.The validated finite element models were also used to investigate the effect of changing different parameters of the sub-frame, such as temperature distribution, boundary conditions and fire protection on the connection region. The distribution of strains in the connection components were shown to have been significantly affected by changing these parameters.

Industrialised housing has increased its Swedish market share the latest ten years from 2% to 15%. Prefabrication has developed into actual industrialisation, where factories produce not only elements for site assembly, but takes wholesale responsibility for the sales, design, factory production, and assembly of houses. A higher automation in housing production puts demands on the design department to become more efficient. Design is identified as a bottleneck to further increase the production rate. Information deliveries are not produced in the needed rate. With the change from drafting to modelling in building design, opportunities are given to work simultaneously for better efficiency. The focus on BIM-supported CAD-tools has lead ICT-developers to create systems that mainly support product modelling. But, in industrialised housing, support for process efficiency is just as important.In a case study at a Swedish industrialised housing company, during a three year period, interviews, observations and design activities at the company were recorded to study what components and functionality in the design support create business value. The results show that by defining design in stages with gates, by parallel planning of activities, and by using process visualisation methods, the efficiency increased about 41 % in information deliveries. Furthermore, the use of support systems has to create both internal value for efficiency in information deliveries and external value to meet and handle client requirements in a standardised way. By releasing time from project management activities to improvements and product development the focus on the product could increase. Product development theories with axiomatic design as the foundation for a support system combines product structures with BIM functionality and process support for planning, which secures quality between disciplines in a concurrent approach. Product life cycle management (PLM) is an umbrella that manages product development in a life-cycle perspective trough a defined framework that is applicable to industrialised housing design, both for software developers and industrialised builders. / Industriellt byggande har de senaste tio åren ökat sina marknadsandelar från 2% till 15% på den svenska bostadsmarknaden för flerfamiljshus. Prefabricering har utvecklats till industrialisering, där fabriker inte bara producerar komponenter för montering på byggplats, utan tar även helhetsansvar för försäljning, konstruktion, i fabrik och för montering av bostäder. Utvecklingen av en mer automatiserad produktion ställer högre krav på projekteringen. Som en definierad flaskhals måste tid frigöras från koordinering till kärnverksamhet för att skapa förbättringar och tillåta produktutveckling. Med förändringen från ritningsbaserad till modellbaserad byggprojektering, ges möjligheten att arbeta samtidigt för bättre effektivitet. Fokuseringen på BIM-stöd med CAD-verktyg har lett till att utvecklare skapar system som i huvudsak stödjer produktmodellering. För industriellt bostadsbyggande, är stöd för effektivitet i projekteringsprocessen lika viktig. Empiri har samlats genom intervjuer, observationer och dokumenterade aktiviteter i en fallstudie hos en svensk industriell bostadsbyggare för att analysera vilka komponenter och funktioner som ett stödsystem för projektering behöver för att skapa värde för företagen. Resultaten visar att en definition av projektering i steg med gater, aktiviteter för samplanering och användandet av metoder för att visualisera processen har ökat effektiviteten med omkring 41 % för informationsleveranser. Dessutom visar studien att stödsystem bör kunna skapa både internt värde för effektiva informationsleveranser och yttre värde för att möta och hantera kunders krav på ett standardiserat sätt. Ett stödsystem, baserat på produktutvecklingsteorier med axiomatisk design som grund, kan kombinera både produktstruktur med BIM- funktioner och processrelaterade funktioner för planering och därmed säkra kvaliteten mellan discipliner för samverkande arbete. Product life cycle management (PLM) är ett övergripande koncept för hantering av produktutveckling i ett livscykelperspektiv, vilket har ett definierat regelverk som är applicerbart på industriell byggprojektering, både för utvecklare av IT-system och för industriella husbyggare.

This thesis is devoted to problems connected to heat transfer and fire dynamics in enclosures. The thesis consists of a main part which summarizes and discusses the theory of heat transfer, conservation of energy and fire dynamics. Based on these theories, some cases of different fire scenarios have been analyzed. In the end of this thesis, the reader will find Paper I-IV containing four articles on the subject.The main focus of this thesis is fire temperature development in enclosures. For that reason, firstly, some experimental studies have been done using different thermo devices for measuring temperature. Based on the experience from these studies, temperatures measured with a Plate Thermometer have been used to predict and describe in a quantitative way the thermal exposure of structures. For more accurate prediction of this thermal exposure, PT and thin thermocouples measurements have been combined.This thesis summarizes the experimental data from two different setups. One was conducted in a large enclosure 20 m by 20 m and 20 m high. This experiment scenario can be characterized as localized fire. Another experiment was conducted in a compartment in full scale with a limited fire source, without reaching flashover. This second experiment did not reach flashover and can be categorized as a two-zone compartment fire. Moreover, the thesis contains a new way of analyzing a one-zone fire model intended for the analysis of fully developed ventilation controlled compartment fires.Temperature data from the localized fire experiment were collected with different designs of Plate Thermometers (PT), small thermocouples (Ø=0.25 mm) and thermocouples fixed to a steel column. Measured data were compared with calculated data applying the concept of adiabatic surface temperature. Temperatures thus obtained by finite element calculations using the softwarecode TASEF were in the good agreement with measured steel temperatures. The full scale compartment fire was conducted in a two-story concrete building. During the experiment, data were collected with PTs and thin thermocouples at different locations inside the compartment.In the new way of analyzing post-flashover compartments fires the effects of different parameters on the fire temperature development has been analyzed. The new method of analyzing the heat and mass balances of a compartment fire has made it possible to develop simple analytical as well as numerical mathematical solutions. / 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.

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Right now, the world is facing a challenge of reducing carbon emissions. Existing buildings account for one-third of the world's carbon emissions. The construction and real estate sector in Sweden is facing the challenge of combining a high rate of construction with demands on reduced climate emissions. Energy use in the construction and real estate sector corresponded to about 40 percent of Sweden's total energy use in 2020, where heating in the construction and real estate sector accounts for the largest share. To build more energy-efficient buildings, it is important to insulate them well. In the Swedish National Board of Housing, Building and Planning's building regulations Chapter 9, it is specified that buildings should be designed so that energy use is limited by efficient use of electricity, low heat loss, and low cooling needs. The Swedish building regulations also specifies values for the primary energy factor, average heat transfer coefficient, and installed electrical power for heating. The purpose of the thesis is to investigate the climate impact that follows from choosing a larger window area than the minimum requirements in the Swedish building regulations. This will be achieved through calculations of the climate impact of energy use and materials which are affected by the window area. The method consists of calculations of energy use, daylight simulations, and climate calculations, where four examples of exterior wall designs were compared with each other. Calculations were made on the following exterior wall options: the object's original design, where energy and material use were established. Varying window areas where VIP-Energy was used to simulate energy use. Varied window area with the same amount of concrete even though wall area increases, and an option when a new thickness was calculated for thermal insulation depending on the wall's average heat transfer coefficient. VIP-Energy was used to determine energy use in the object studied, as well as with variations in window and wall area. The climate calculation formed the basis for determining the climate impact of variations in material use depending on the window area. The results show that varying the window and wall areas leads to an increase in climate impact A1-5, which has been determined to have a maximum increase of 8.5 percent, mainly due to the increasing amount concrete which is a result of the window area decreases by 37.3 percent. In the scenario with reduced insulation, the results show that when the window area varies, the thickness of PIR insulation can be reduced by 64 percent. When varying the window and wall areas and assuming the same amount of concrete, the results show a lower climate impact of 8,500 kg CO2-eq per floor, corresponding to 18 percent. In the two cases where material, operation, and insulation vary, it is shown that varying insulation initially results in lower impact with a 25 percent reduction in area. The conclusion is drawn that the material and dimensions of windows affect the building's carbon footprint, although in this case, concrete has the greatest impact.

A large part of the environmental impact of society today comes from the construction and real estate sector. With the new law on climate declarations for buildings, the interest in building materials with a low climate impact has increased. The only building material, that is considered to be fully renewable and climate neutral, is wood which is widely available in Sweden. However, there are several challenges when wood is used as a construction material, where one has proven to be for the case of structuraltimber in tall buildings. When prefabricated modules are assembled into multi-storey houses, there are challenges to avoid buckling in the strong direction.In this thesis, rotational stiffness in bottom rails of Cross-Laminated Timber (CLT) and structural timber is studied for eccentric load. The aim is to investigate possible advantages in terms of rotational stiffness if a CLT bottom rail is used instead of one made from structural timber. The idea is that a bottom rail with greater rotational stiffness contributes to higher buckling loads. The rotational stiffness is examined through experiments in which four different sets of bottom rails and wooden studs are loaded with six different eccentricities in a hydraulic press. The displacement and deformations of the wooden samples are documented through a digital image correlation system and are then analyzed. The results show that a CLT bottom rail has a higher rotational stiffness than a structural timber bottom rail, which is visible in a studied range based on a calculated theoretical angle-change according to a comparable load case from beam theory. In load case 2 with an initial eccentricity of 20 mm, the bottom rail of CLT in size 40 x 95 mm had a rotational stiffness that was almost three times as high as that of structural timber.The measured rotational stiffness was applied in an approximate calculation model to estimate the contribution of the bottom rail in stabilizing a structural timber stud. By interpreting the results of the calculations according to the second order theory, a relationship was established in which the factor β for effective buckling length was calculated for the different load cases. The calculated factor β shows that the CLTbottom rails contribute to the reduction of the effective buckling length in the order of 28 % for bottom rails with a width of 95 mm and 18 % for the bottom rails of width 170 mm.

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