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Experimental study of reinforcement in light-weight concrete components
Lisztwan, Dominik ; Kocáb, Dalibor (referee) ; Vymazal, Tomáš (advisor)
This bachelor thesis describes the experimental comparison of behaviour of reinforced lightweight concrete panels. Panels are reinforced with traditional steel grid and basalt composite reinforcement. The comparison of results is based on set of data from static load tests. The results of load test are also compared to the results made with nonlinear numerical analysis by finite element method and also calculation by hand. A part of this thesis includes determination of physical and mechanical properties of used concrete.
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Experimental and numerical analysis of reinforced concrete elements
Niedoba, Jakub ; Láník, Jaromír (referee) ; Žítt, Petr (advisor)
This master‘s thesis deals with the behaviour of strengthened reinforced concrete beams. The aim was to evaluate different types of strengthening in comparison not only with each other, but also with the reference beam. Three reinforced concrete beams were fabricated for the purpose of the thesis. The first served as a reference beam, the second was strengthened with carbon lamella glued to the lower edge of the reinforced concrete beam, and the last one was strengthened with unbonded post-tensioning system. Subsequently, they were all loaded by a four-point bending. An evaluation was then carried out which shows that the two strengthened reinforced concreate beams resist the load much better than the reference beam. In the conclusion, different utilization possibilities of both methods are listed, as well as the disadvantages that must be taken into account when designing.
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Numerical analysis of the lightning on small aircraft
Krutílek, David ; Ochodnický, Ján (referee) ; Dražan, Libor (referee) ; Raida, Zbyněk (advisor)
This dissertation deals with the numerical analysis of effects of a lightning strike on an aircraft and with the design of the optimal composition of the composite structure in terms of lightning strike protection. When optimizing the composition, a simplified model of the composite nose section of an EV-55 aircraft is used. The optimization of the composite structure is based on results of experimental measurements and testing. On the simplified model of the nose part, the material composition of the composite is verified and the direct and indirect effects of the lightning discharge are numerically estimated
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Equivalent circuit realizations of the simple chaotic oscillators
Kobza, Jaromír ; Dostál, Tomáš (referee) ; Petržela, Jiří (advisor)
The aim of this paper is to introduce with basic theory the problems encountered when considering the circuit implementation of autonomous RC chaotic oscillator with nonlinearity. All oscillator prototypes are based on one type of universal oscillator circuit. This circuit is able to generate a lot of attractors on condition of different entrance parameters. The design is based on a mathematical simulation, which includes the generation of electronic circuit values. The work is focused the transformation of these values to operational circuit configuration and simulation in a circuit simulator. The final task is to acquire chaotic attractors. Oscilloscope and spectrum analyser photos will verify the operation.
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Stability problems of laminated structural glass members
Pešek, Ondřej ; Lokaj,, Antonín (referee) ; Brodniansky,, Ján (referee) ; Melcher, Jindřich (advisor)
Transparent and subtle structures are features of modern architecture. Structural glass is constructional material that provides to realize architect's visions and ideas. Glass as a constructional material is more often used as a material for primary load-bearing structures. Realization of safe, reliable and economic glass structure is real challenge for structural engineers because of absence of standards for designing of glass members and elements. Compressed members (columns), bended members (beams) and members loaded by compression and bending (beam-columns) were analysed in the frame of the doctoral thesis whereby the emphasis is being placed on the lack of stability – flexural buckling, lateral-torsional buckling and flexural-lateral-torsional buckling. Measuring of shape and amplitude of initial geometrical imperfections is a part of doctoral thesis. The theoretical analysis describes the behaviour of the member by means of solving the differential equations. The solution according to the second order theory developed for metal members is applied on structural laminated glass members with use of effective cross-sectional characteristics. Numerical analysis is focused on the use of commonly available software based on finite element method in order to predict the load-bearing resistance of laminated glass members. Actual behaviour of laminated and monolithic structural glass members was found within experimental program. The correctness of FEM model and analytical solutions were evaluated by comparing with test results. The goal of the doctoral thesis was determine of buckling curves for calculation of flexural buckling and lateral-torsional buckling resistances by the same calculation procedure as for metal members. Because of small number of experimentally tested specimens the Monte Carlo simulation was performed.
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Strengthening of axially loaded steel members under load
Vild, Martin ; Wald,, František (referee) ; Křivý,, Vít (referee) ; Bajer, Miroslav (advisor)
Dissertation focuses on strengthening of axially loaded steel members strengthened under load. Strengthening under load using welding is time and financially efficient. Plastic design can be used for members without stability problems. However, the design of members susceptible to buckling is difficult and opinions of researchers differ on this matter and there are only several experiments. The dissertation is focused on strengthening under load of members with selected cross-sections susceptible to flexural buckling. It is necessary to check the resistance of the base member weakened by the elevated temperatures caused by welding. The preload and welding – residual stress and deformations – must be taken into account for the determination of the buckling resistance of the member strengthened under load. The aim of this dissertation is to provide the load resistance of selected compressed members strengthened under load. Author performed experiments on members with the H and L shaped cross-sections and seamless tubes. Other experiments were performed on members with H shaped cross-section and rectangular hollow sections to determine the resistance of base member during welding. These served to validate numerical models which helped to increase the number of specimens for statistical evaluation. Analytical models to determine the load resistances of the base member during welding and the strengthened member were developed using experiments from literature and author’s experiments and numerical models. The simplified model is conservative and suitable for practical design. The complex model is suitable for scientific purpose and it provides both deformation and load resistance using modified imperfection factor. It provides a good agreement with the experiments. Doctoral thesis also includes practical recommendations for design and execution of strengthening under load using welding.
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Reinforcement concrete column strengthening via steel bandage
Stloukal, Štěpán ; Laníková, Ivana (referee) ; Šimůnek, Petr (advisor)
The steel bandage is an economical and effective widely used method for strengthening RC columns. Diploma thesis reviews most common design proposals for the types of the bandage with directly loaded and not directly loaded steel angles. This work also includes a comparison of the different constitutive laws for confined concrete. In order to simulate real behaviour of strengthened structure the numerical analysis has been carried out using non-linear software ATENA. According to the European standards and adopted hypotheses the simplified analytical model has been derived to be able to calculate load-bearing capacity of a strengthened column under normal force and bending moment. The proposed model considers the contribution in confinement pressure caused by steel bandage and the contribution of directly loaded angles. In addition, the direct application on real frame structure has been performed.
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