Construction clients have the position to continuously improve new-built from a life cycle perspective. Furthermore, they can contribute to advancement and improved competition in construction by putting more explicit and distinct requirements and by a willingness to try new, non-local contractors and new construction methods (Statskontoret 2009). Conventional construction is argued to constitute a barrier to change (Dulaimi et al. 2003). Industrialised building, with its off-site characteristics and process-orientation, is seen as a means to attain advancement in construction (e.g. Statskontoret 2009). Industrialised multi-dwelling timber framed (ITF) housing entail all of the identified advantages of industrialisation. Nonetheless, clients are not actively driving change towards industrialised construction (e.g. Engström et al. 2009) and it was indicated that one possible explanation could be that clients are uncertain (Höök 2005). The aim of this thesis is to identify client organisations' uncertainties concerning ITF housing and property, find mechanisms for why they arise and propose measures to manage uncertainty within clients' organisations. The thesis is based on three appended papers and a detached technical report (Levander 2010). Empirical data consist of interviews, economic data, documentation and a questionnaire, they have been collected from in total 27 Swedish client organisations and on 44 ITF properties, and are analysed in two case studies and one field study.The results show that the great majority of client organisations' uncertainties are a matter of equivocality. The mechanisms for the high equivocality are the high complexity and uncertainty in construction in conjunction with the novelty encompassed by ITF housing and property. The current information processing practice within the studied client organisations does not support resolving equivocality.The general conclusion is that ITF housing and property is a radical change seen from clients' perspective and represents novelty in construction technology. Thus, the ITF alternative challenges and goes beyond clients' known frame of reference and thereby causes equivocality. In order to manage and resolve equivocality, client organisations need to enable translation and transfer of frameworks and their activities must constitute challenges to their normal practice. Thus it is proposed that in order to manage uncertainty and equivocality, and thereby contribute to advancements in construction, client organisations need to work with uncertainty management. / Fastighetsägare har i rollen som beställare möjligheten att ständigt förbättra nybyggnation från ett livscykelperspektiv. Dessutom kan de bidra till utveckling och ökad konkurrens inom byggbranschen genom ett tydligare kravställande och med en vilja att prova nya, icke-lokala entreprenörer och nya produktionsmetoder (Statskontoret 2009). Traditionellt byggande hävdas utgöra ett hinder för förändring (Dulaimi et al. 2003). Industriellt byggande, med byggande i fabrik och processorientering, ses som ett sätt att nå framsteg byggandet (ex Stadskontoret 2009). Industriellt byggande av flerbostadshus med trästomme för med sig samtliga fördelar med industriellt byggande. Trots detta är inte beställarna en aktiv kraft (Engström et al. 2009), en möjlig förklaring är att kunderna är osäkra (Höök 2005).Syftet med forskningen är att identifiera fastighetsägarorganisationernas osäkerheter om den industriella träbyggnadsprocessen och om industriellt byggda flerbostadshus med trästomme (ITF-alternativet), hitta mekanismer för varför osäkerheterna uppstår och föreslå åtgärder för att hantera osäkerhet inom kundorganisationer. Avhandlingen bygger på tre bifogade artiklar och en fristående teknisk rapport (Levander 2010). Empiriska data består av intervjuer, ekonomiska data, dokumentation och en enkät som har samlats in från totalt 27 svenska fastighetsägarorganisationer och på 44 ITF fastigheter, och sedan har analyseras inom två fallstudier och en fältstudie.Resultaten visar att kundernas osäkerheter främst är en fråga om tvetydighet (equivocality). Mekanismerna bakom denna är den höga komplexitet och osäkerhet inom byggbranschen generellt, tillsammans med det nya och annorlunda som ITF-alternativet medför. Det nuvarande sättet att hantera information och kommunikation inom de studerade fastighetsägarorganisationerna stödjer inte hantering av tvetydighet.Den allmänna slutsatsen är att ITF-alternativet är en radikal förändring sett ur kundernas perspektiv och representerar nyhet i flera dimensioner. Således går ITF-alternativet utanför kundernas kända referensram och medför därigenom tvetydighet. För att lösa tvetydighet krävs att kundorganisationerna möjliggör överföring av referensramar och aktivt utmanar sina nuvarande arbetssätt. Det föreslås därför att kundorganisationer behöver arbeta med osäkerhetshantering, detta för att kunna hantera och lösa både osäkerhet och tvetydighet, och därigenom bidra till framsteg inom byggandet.

During the last few decades the demand for renewable energy has led to a myriad of innovative solutions. The present assembling solution between two segments of a tubular tower is accomplished by conventional ring flange connection. This connection suffers from economical and technological barriers. One possible improvement could be achieved by implementing friction connections. Performance of this connection exposed to static loading is considered in this thesis. FEM is used as the main tool to improve understanding of the friction connection behaviour for application in towers for wind turbines. This new solution consists of the upper tower segment, where normal clearance holes are made and where bolts can be pre-installed, and the lower tower segment where opened slotted holes are made. It is easier to produce and 80% less expensive than traditional flange connection which leads to a total reduction of 10% to 15% of the tower costs.The influence of the level of assembling tolerances and the loss of pretension force in the bolts has been thoroughly investigated by a large number of FE models in the search for a model that is the most successful match with regards to its comparison with test data. Experiments are performed in an international project financed by RFCS, HISTWIN.The starting point is a small scale friction connection, best described as a single shear lap joint. This specimen represents a strip of the friction connection of a tubular tower. The ability of the FE models to capture three-dimensional contact problems, with realistic modelling of the assembling process and effects of the secondary bending during the loading are investigated. Resistance according to European codes, EN 1993-1-8, for the preloaded bolts is compared with the FE solutions.The second type of specimen is a down-scaled bending test of the beam. The test is used to check the performance of the connection and to calibrate the FE model. A very realistic FE model is created and compared with results from experiments. Failure modes and the respective ultimate resistances are predicted by FEA. The same model is used to investigate the influence of the gap between tubular segments and the influence of residual stresses generated in the segment which contains slotted holes on the tower resistance in bending, as well as in compression and tension. / Efterfrågan på förnyelsebar energi har under de senaste decennierna drivit fram ett stort antal innovativa lösningar. Idag är flänsar den vanligaste lösningen vid skarvar i rörformade vindkraftstorn. Det är en lösning som har både ekonomiska och tekniska brister. Friktionskoppling kunde vara en möjlig förbättring. I detta arbete studeras hur en sådan koppling skulle fungera under statisk last. FEM används som det viktigaste verktyget för att skapa förståelse för hur en sådan friktionskoppling fungerar i ett rörformat vindkrafttorn. Den föreslagna friktionskopplingen består av en övre del som har hål med bultar i längs nedre kanten, och en undre del som har skåror. Det är en konstruktion som är enklare att tillverka och som kostar 80% mindre än en traditionell flänskoppling. Det ger en total besparing för ett torn på mellan 10 och 15%. Betydelsen av det extra spelrum som tillåts för att förenkla monteringen och vad förlusten av förspänning i bultarna betyder har studerats i ett antal FEMmodeller för att hitta en modell som ger så bra överensstämmelse som möjligt med mätdata från försök gjorda i projektet HISTWIN som finansierats av RFCS. Första försöket är en liten del av hela friktionskopplingen, enklast beskriven som ett skjuvförband. FEM-modellens förmåga att beskriva den tredimensionella kontakten, en realistisk sammanfogning samt de olika böjfenomen som uppträder undersöks. De förspända bultarnas bärförmåga enligt Europakoden EN 1993-1-8 jämförs med FEM-lösningen. Den andra modellen är ett nedskalat böjtest på en balk. Modellen används för att undersöka hur friktionskopplingen fungerar och för att kalibrera FEMmodellen. En mycket realistisk FEM-modell skapas och beräkningsresultaten jämförs med gjorda försök. FEM-beräkningen ger både brottmod och brottlast. Samma modell används också för att studera betydelsen av glappet mellan de olika delarna i tornet samt betydelsen av spänningstillståndet i delen med skårorna när den belastas i både tryck och drag.

In this thesis the performance of different constitutive models in ratchet simulation is investigated. Ratcheting is accumulated plastic strains which may occur when a structure is subjected to a constant load in combination with cyclic loading. In the assessment of nuclear class 1 pressure retaining component ratcheting is one of the three failure modes that are addressed and may limit the design life of nuclear pressurized components and piping systems.A steel structure subjected to a constant load in combination with cyclic loading into the plastic region undergoes a change of the material characteristics in several aspects. These cyclic material characteristics are complex and may vary for different load situations, load levels, temperatures and materials. In addition to this, the presence of a mean stress may also affect the material cyclic characteristics.In previous numerical investigations on ratcheting there has not been a sufficiently robust case of simulation. However, in most of these investigations, the simulation response is compared with ratcheting experiments which either are conducted under load levels which are not common for a nuclear pressurized component, the experimental specimen is not comparable with a pressurized component or only a few experimental tests have been conducted. Hence, it has not been settled which material characteristics need to be considered to accurately simulate ratcheting in a pressurized piping component under load levels common in a nuclear power plants. As a result of this, it is not obvious which types of constitutive material models is needed and how the model parameters should be calibrated in order to simulate ratcheting in a nuclear component accurately.As part of this thesis an extensive experimental program has been conducted on pressurized tube specimens. In total 30 test specimens made of two different materials, 316L and P235, have been manufactured and tested. In order to determine material properties, monotonic tensile load and internal pressure experiments have been performed. The remaining test specimens have been used for ratcheting experiments.The experimental results show ratcheting in the hoop direction when the tube is subjected to certain combinations of internal pressure and cyclic axial strains. The higher the pressure is and the larger the strain ranges are, the higher the ratcheting response becomes. In addition to this, also the cyclic hardening and softening behavior in the tubes axial direction and the direction of the incremental plastic strain tensor is investigated. The results show that the material cyclic hardening or softening behavior and direction of the plastic strain vector varies strongly depending on the level of primary and secondary loads.Measured ratcheting strains are compared to numerical simulations using different constitutive models. In this thesis the interrelated models of Prager, Armstrong-Frederick and Chaboche are investigated. In addition to these, the Besseling model is investigated. Among the constitutive models investigated, the Besseling multi-linear model shows by far the best agreement with the ratcheting experiments. The more advanced models are able to capture the material ratchetingbehavior, but overestimate the hoop strain in the tube tests.Investigation results also indicate that significant cyclic hardening material behavior influence the direction of the plastic stain vector and, hence, affect the accuracy of predicted results when disregarded. This effect is most apparent for the experiments subjected to high pressure and high deformation controlled loads. In the tests which experience significant cyclic hardening, the direction of the plastic strain vector starts to deviate after roughly 20 loading cycles.Simulation of ratcheting should be done with an as simple constitutive model as possible, while still capturing the essential response. Important reasons are that simple models are easier to understand and work with, and that fewer tests are needed for determining model parameters. Based on this the Besseling constitutive model is recommended for simulation of pressure equipment subjected to cyclic plastic deformation. However, if shake-down does not occur at relative early stage, effects related to cyclic softening or hardening may need to be taken into consideration.

Combining computer fluid dynamic, CFD, models with finite element, FE, models to calculate temperature in fire exposed structures can reduce design temperatures in structures while still obtaining the level of structural fire safety stipulated by society. A better understanding of heat transfer and the concept of adiabatic surface temperatures, AST, the transition of data between models can be simplified and more accurate temperature predictions can be made.The thesis focuses on heat transfer calculations by employing AST in particular, and how this can be used as a means of coupling any CFD and FE-analysis code. The thesis presents a method for performing FE-analysis of the thermal response with input data calculated with the computer code FDS, Fire Dynamics Simulator. Parallel to this, the heat balance equation in FDS is tested and an alternate numerical algorithm is developed and tested.Firstly, a verification model is developed to test the radiative and convective part of the existing heat balance equation in FDS. An alternate numerical algorithm for calculation of the heat transfer at surfaces is developed as a more homogenous alternative for CFD codes.Secondly is a study on how to extract AST from an arbitrary point with direction in a CFD calculation using an infinitesimal surface. Instead of modeling numerous small surfaces for extracting AST, a post processor is developed to calculate AST independent of any modeled surface. For CFD codes, such as FDS that depend on a rectilinear grid, this enables calculation of AST in any direction, not only directions normal to the Cartesian planes.Finally, a comparison is made between different methods for calculating temperatures in steel with AST from numerical fire dynamics/modeling calculations. In this thesis there is a comparison between simplified Eurocode techniques, simple finite element analysis and advanced finite element analysis. This study shows the benefit of understanding heat transfer in numerical codes and to implement the concept of AST in a proper way.This way, the concept of combining numerical fire dynamics calculation with numerical (or simplified) thermal calculations can be better understood and implemented.

During recent years wind energy has established as an alternative to commonenergy sources. To advance its competitiveness, the costs for the constructionof a wind tower have to be reduced. One possible option is the use of frictiongrip joints instead of flange connections to join various tower segments in atubular steel tower. Additionally, the time necessary for installation andmaintenance of the bolts in these connections can be decreased, not only forimplementation in tubular towers but also in lattice towers.Four different bolt types have been investigated with respect to the ease ofinstallation and maintenance on the one hand and structural applicability on theother hand. The latter one is mainly defined by the behaviour of the pretensionforce in the bolts. Various influences on the reduction of clamping force areexperimentally checked, such as the type and thickness of coating, thethickness of the clamping package and external loading.The slip factor, which plays an important role in friction connections, isexperimentally achieved in a test on a double shear lap joint. The experiment isthoroughly examined by a finite element analysis, which models the interactionbetween bolts and plates.In various numerical analyses the influence of steel grade and possibleassembling tolerances on the resistance of a friction joint is investigated bothfor single and double shear lap joints.Shortages of EN 1993 parts 1-8 and 1-12 for the use of slip critical joints areidentified. / På senare år har vindenergi blivit ett allt vanligare alternativ till de mertraditionella energikällorna. För att ytterligare stärka konkurrenskraftenbehöver installationskostnaden för vindkraftverken minskas. Ett sätt att göradetta är att använda friktionsförband istället för att sammanfoga flänsarna hosde olika segmenten i vindkraftverk uppbyggda av stålrör. Man kan dessutomminska den erforderliga tiden för att montera och underhålla skruvarna i dessaförband, vilket inte bara gäller för rörkonstruktioner utan även förvindkraftverk av fackverkstyp.Fyra olika sorters skruvar har undersökts, å ena sidan avseende hur enkla de äratt montera och underhålla, å andra sidan avseende den strukturellatillämpligheten. Den senare beror huvudsakligen på beteendet hosförspänningskraften i skruvarna. Olika sorters påverkan påfastspänningskraften har undersökts experimentellt, exempelvis ytskiktenstjocklek, klämlängden samt den påförda yttre lasten.Friktionskoefficienten vid glidning, som har en viktig roll i friktionsförband,har erhållits experimentellt genom försök med ett tvåskärigt skjuvförband.Försöken har utvärderats noga med FE-analyser, där interaktionen mellanskruvar och plattor har modellerats.Inverkan av vald stålsort samt utförandetoleranser har undersökts genomnumeriska analyser för både enskäriga och tvåskäriga skjuvförband.Brister i EN-1993 del 1-8 och 1-12 har identifierats vid användning av förbandsom är känsliga för glidning

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.