The finite element method (FEM) is commonly used to design the reinforcement in concrete slabs. In order to simplify the analysis and to be able to utilize the superposition principle for evaluating the effect of load combinations, a linear analysis is generally adopted although concrete slabs normally have a pronounced non-linear response. This type of simplification in the modeling procedure will generally lead to unrealistic concentrations of cross-sectional moments and shear forces. Concrete cracks already at service loads, which leads to redistribution of moments and forces. The moment- and force-peaks, obtained through linear finite element analysis, can be redistributed to achieve a distribution more similar to what is seen in reality. The topic of redistribution is however poorly documented and design codes, such as the Eurocode for concrete structures, do not give descriptions of how to perform this in practice. In 2012, guidelines for finite element analysis for the design of reinforced concrete slabs were published in a joint effort between KTH Royal Institute of Technology, Chalmers University of Technology and ELU consulting engineers, which was financially supported by the Swedish Transport Administration. These guidelines aim to include the non-linear response of reinforced concrete into a linear analysis. In this thesis, the guidelines mentioned above are followed to obtain reinforcement plans based on crack control, for a fictitious case study bridge by means of a 3D finite element model. New models were then constructed for non-linear analyses, where the reinforcement plans were implemented into the models by means of both shell elements as well as a mixture of shell and solid elements. The results from the non-linear analyses have been compared to the assumptions given in the guidelines. The results from the non-linear analyses indicate that the recommendations given in the aforementioned guidelines are indeed reasonable when considering crack width control. The shell models yield crack widths equal to approximately half the design value. The solid models, however, yielded cracks widths that were 15 - 20$\%$ lower than the design value. The results show that many factors attribute to the structural behavior during cracking, most noticeably the fracture energy, a parameter not featured in the Eurocode for concrete structures. Some limitations of the models used in this thesis are mentioned as well as areas for further improvement.

Metasurfaces are arrays of subwavelength meta-atoms that shape waves in a compact and planar form factor. During recent years, metasurfaces have gained a lot of attention due to their compact form factor, easy integration with other devices, multi functionality and straightforward fabrication using conventional CMOS techniques. To provide and evaluate an efficient metasurface, an optimized design, high resolution fabrication and accurate measurement is required. Analysis and design of metasurfaces require accurate methods for modeling their interactions with waves. Conventional modeling techniques assume that metasurfaces are locally periodic structures excited by plane waves, restricting their applicability to gradually varying metasurfaces that are illuminated with plane waves. In this work, we will first provide a novel technique that enables the development of accurate and general models for 1D metasurfaces. This approach can be easily extended to 2D metasurfaces. Due to the remarkable importance of accurate characterization of metasurfaces, we will provide a rigorous method to characterize 1D metasurfaces. Finally, we will provide an accurate approach to fabricate and characterize 2D metasrufaces.

Three-dimensional (3D) planetary general circulation models (GCMs) have been derived from global climate models used to project 21st century changes in Earth's climate. GCMs are used to address questions regarding the climate-and habitability aspects of terrestrial planets within the solar system and assess the habitability of planets outside of the solar system, so called exoplanets. The development of GCMs has given rise to various results for concepts essential for determining potential habitable exoplanets such as the Habitable zone, hence intercomparison studies are of interest. In this project, the climate of an exoplanet with a static thermodynamic ocean will be modelled using ROCKE-3D, an open-source (3D) GCM developed at the NASA Goddard Institute for Space Studies. This is done in order to simulate the climate and examine how the simulations compare to other GCMs. The climate simulation will also be applied to an Earth-like planet in order to determine how an Earth-like climate will impact the results. We find that the climate on a rapidly rotating Aquaplanet receiving a G-star spectral energy distribution is surprisingly Earth-like. By contributing to a higher albedo, the ocean ice fraction of a rapidly rotating Aquaplanet was shown to impact the temperature and humidity structure considerably, despite the absence of Ocean Heat Transport. However, small differences between the simulations with and without sea ice were found for a tidally locked Aquaplanet receiving a M-star spectral energy distribution, which indicates that ROCKE-3D is not shutting off sea ice properly. Generally, ROCKE-3D shows similar results as CAM4 for the G-star runs and for the M-star, ROCKE-3D shows similar results to LMDG. / Tredimensionella (3D) planetariska allmänna cirkulationsmodeller (GCM) har härletts från de globala klimatmodeller som används för att projicera 2000-talets förändringar i jordens klimat. GCM används för att bemöta frågor om klimat- och beboelighetsaspekter av jordlika planeter inom solsystemet och bedöma beboeligheten för planeter utanför solsystemet, så kallade exoplaneter. Utvecklingen av GCM har gett upphov till olika resultat för begrepp som är väsentliga för att bestämma potentiella beboeliga exoplaneter såsom den beboerliga zonen, därför är jämförande studier av intresse. I detta projekt kommer klimatet för en exoplanet med ett statiskt termodynamiskt hav att modelleras av ROCKE-3D, en öppen källkod (3D) GCM utvecklad vid NASA Goddard Institute for Space Studies. Detta görs för att simulera klimatet och undersöka hur simuleringarna står sig i jämförelse med andra GCMs. Klimatsimuleringen kommer också att tillämpas på en jordliknande planet för att avgöra hur ett jordliknande klimat kommer att påverka resultaten. Vi finner att klimatet på en snabbt roterande vattenplanet som mottar en G-stjärnig spektral energifördelning är överraskande jordliknande. Genom att bidra till ett högre albedo visade havsisfraktionen av en snabbt roterande Aquaplanet att påverka temperatur- och fuktstrukturen avsevärt, trots frånvaron av havsvärmetransport. Små skillnader mellan simuleringarna med-och utan havsis påvisades för en tidvattenlåst vattenplanet som mottar en M-stjärnig spektral energifördelning, vilket tyder på att ROCKE-3D inte bortser havsis ordentligt. Generellt visar ROCKE-3D liknande resultat som CAM4 för en G-stjärna. För en M-stjärna visar ROCKE-3D liknande resultat som LMDG.

No / This paper presents a two-stage hybrid optimization algorithm based on a modified genetic algorithm. In the first stage, a global search is carried out over the design search space using a modified GA. The proposed modifications on the basic GA includes dynamically changing the population size throughout the GA process and the use of different forms of the penalty function in constraint handling. In the second stage, a local search based on the genetic algorithm solution is executed using a discretized form of Hooke and Jeeves method. The hybrid algorithm and the modifications to the basic genetic algorithm are examined on the design optimization of reinforced concrete flat slab buildings. The objective function is the total cost of the structure including the cost of concrete, formwork, reinforcement and foundation excavation. The constraints are defined according to the British Standard BS8110 for reinforced concrete structures. Comparative studies are presented to study the effect of different parameters of handling genetic algorithm on the optimized flat slab building. It has been shown that the proposed hybrid algorithm can improve genetic algorithm solutions at the expense of more function evaluations.

yes / This paper presents experimental results of three continuously supported concrete slabs reinforced with basalt-fibre-reinforced polymer (BFRP) bars. Three different BFRP reinforcement combinations of over and under reinforcement ratios were applied at the top and bottom layers of continuous concrete slabs tested. One additional concrete continuous slab reinforced with steel bars and two simply supported slabs reinforced with under and over BFRP reinforcements were also tested for comparison purposes. All slabs sections tested had the same width and depth but different amounts of BFRP reinforcement. The experimental results were used to validate the existing design guidance for the predictions of moment and shear capacities, and deflections of continuous concrete elements reinforced with BFRP bars. The continuously supported BFRP reinforced concrete slabs illustrated wider cracks and larger deflections than the control steel reinforced concrete slab. All continuous BFRP reinforced concrete slabs exhibited a combined shear–flexure failure mode. ACI 440-1R-15 equations give reasonable predictions for the deflections of continuous slabs (after first cracking) but stiffer behaviour for the simply supported slabs, whereas CNR DT203 reasonably predicted the deflections of all BFRP slabs tested. On the other hand, ISIS-M03-07 provided the most accurate shear capacity prediction for continuously supported BFRP reinforced concrete slabs among the current shear design equations.

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No abstract is provided. / Thesis / Master of Engineering (MEngr) / Scope and contents: In this report, a method for calculating the longitudinal shear capacity of the slab of simply-supported steel-concrete composite beams is presented. The method is based on analysing the stresses at failure of the concrete elements located at the slab shear surface. In this analysis, the slab width and the shear span are found to be two main parameters that have been neglected in the empirical solutions previously adopted.

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