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The Economic, technical and scientific developments have contributed to the emergence of composite structures. Where composite structures between steel and concrete are increasingly increasing in use in the construction industry. The reason for this is due to the system's efficiency in structural, economical and constructional aspects and that engineers can utilize both construction materials. Steel-concrete composite structures are mostly used in buildings and bridges in the form of composite beams, composite floors and composite columns. Extensive experimental and theoretical studies have previously been conducted on composite structures. It is to provide a better understanding on the behavior of the construction system and its components under applied loading. In this study, experimental trials and theoretical calculations have been conducted to investigate the load bearing capacity of concrete-filled steel tubes. An important goal of the study has been to investigate the difference between concrete-filled steel pipes with and without the impact of shear studs. Economic and time frames have limited the study to using only scaled samples and only one concrete and steel grade. The survey comprised a total of three trial series. Series 1 consisted of only steel pipes, series 2 consisted of concrete-filled steel pipes and series 3 consisted of concrete-filled steel pipes reinforced with shear studs. The study is presented with a careful review of theoretical calculations, sample production and experimental trials. The results show that Series 2 consisting of concrete-filled steel pipes had a characteristic compressive strength of 54,6 kN and a minimum standard deviation of 1,46 kN. By reinforcing concrete-filled steel pipes with shear studs, a characteristic compressive strength of 51,8 kN and a standard deviation of 4,06 kN were obtained. It is a decrease in the characteristic compressive strength value compared with concrete-filled steel pipes without the impact of shear studs. Series 1 with only steel pipes had a characteristic compressive strength of 44,1 kN and a standard deviation of 6,86 kN, which was the highest standard deviation.

Historically, most of the climate impact of a building has derived from the buildings operational phase. However, recent studies show that the climate impact of the construction phase of a building is of the same dimension as the operational phase. Current building regulations regard the energy performance of buildings, excluding any obligations of reporting the environmental impact of the building during its life cycle. In 2017, Boverket was commissioned by the Swedish government to develop a proposal for a new climate declaration of buildings based on a life cycle perspective. The application of life cycle analysis in the Swedish building and construction sector is limited, and in particular when considering single-family buildings. Thus, the aim of the thesis is to investigate the applicability of the life cycle analysis methodology to single-family buildings and compare with former studies on multi-family buildings. This is done by studying the climate impact of a single-family building through a life cycle perspective. Simulations are done in the simulation tools VIP Energy and Byggsektorns miljöberäkningsverktyg BM. The result of the study show that the climate impact of the building is equally distributed during the building’s constructional and operational phase, accounting for 50.1 % and 49.9 % relatively. The total climate impact through the life cycle of the building is 541 kg CO2-eq/m2 Atemp, which is somewhat consistent with results of previous studies on multi-family buildings. The result also shows that the material production and the energy use are the processes that contributes the most to the climate impact during the life cycle of the building. Furthermore, the result indicates that there are no significant differences in the methodology of life cycle analysis between single-family and multi-family buildings.

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Orepasses and ventilation shafts are examples of mine infrastructure that are subjected to increasingstresses as the production in the Kiirunavaara mine moves to deeper levels. Falloutsand damages in these kind of excavations are already occurring and the problem can be expectedto increase in the future. Information about the rock mass properties is necessary in order to predict the extent of stressinduced failures in the future. The main focus of this thesis was to calibrate rock mass strength parameters by using numerical models in combination with observations of actual damages. Orepasses are affected by wearing from falling rock, which can be difficult to take into account in a numerical model. Damages from ventilation shafts were therefore chosen as input in the numerical modeling. A material model for brittle failure was used in the calibration. Damage mapping of several ventilation shaft was done and damages with typical stress-induced characteristics were chosen for the calibration of strength parameters. Most of the calibration calculations were successful. Final results for each parameter were calculated as mean values from all successful calibrations. The result from the calibration was thereafter used as input values in a prognosis calculation for stress-induced damages in future mining. Two ventilation shafts with varying distance to the orebody were analyzed. The stress situation for future mining was simulated for two upcoming production levels, 1165 and 1223. The prognosis results showed that stress-induced failures will increase in both quantity and severity. The modeling results showed stress-induced failures with a depth up to 50 cm. It was also concluded that the horizontal distance to the orebody has a large influence on the occurrence of stress-induced failures in ventilation shafts.