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Static and dynamic assessment of an outlook tower construction
Valíček, Jan ; Kala, Jiří (referee) ; Salajka, Vlastislav (advisor)
This thesis deals with static and dynamic analysis of an lookout tower construction. For dynamic analysis a computational model in ANSYS software is created. Static analysis is performed by Scia Engineer software. Both of this software use finite element method. It is also focused on wind load determination by Eurocode 1, structural factor calculation, modal analysis and vortex shedding. Verification of selected parts according to Eurocodes is included.
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Vibration of slender bridge structure
Kika, Ondřej ; prof. Ing. Alois Materna, CSc., MBA (referee) ; Krejsa,, Martin (referee) ; Salajka, Vlastislav (advisor)
Doctoral thesis called Vibrations of slender bridge structures deals with comparison of constructions’ responses at different load model of pedestrians. Specifically, in practice commonly used model, where there are the effects of pedestrians replaced by forces acting in a certain place on the bridge and other model, which takes into account the load of pedestrians moving along the deck. Calculations of responses are performed by finite element method in program ANSYS. To obtain extreme values of responses It is used parametric calculation using the program OptiSlang. At first responses on the simplified constructions are evaluated for load of two pedestrians, as well as the responses on real bridges for load of two pedestrians and four pairs of pedestrians. Responses are also evaluated in terms of pedestrian’s comfort during use structures and analyzed for what groups of pedestrians are criteria still met and for which it is necessary to consider about use of devices to reduce vibration. Possible applications and design process of the vibration dampers are shown on different configurations on the bridges.
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Interaction between Bridge Structure and Continuous Welded Rail
Vendel, Jiří ; Salajka, Vlastislav (referee) ; Ryjáček,, Pavel (referee) ; Plášek, Otto (advisor)
Understanding the interaction between a continuous welded rail and bridge structure is knowledge of all influences that participate in mutual coaction. Besides the material and cross-sectional characteristics of the bridge belonging to the scope of bridge design, there are several circumstances derived from external loads which have to be taken into account when designing new systems and assessing existing ones. From the physical point of view, each material has a natural tendency to change in length when the internal temperature changes. The continuous welded rail, concretely its central fixed zone, does not have this possibility due to its principle. However, if it is located on a bridge that freely expanse, the situation is significantly different. Due to the thermal expansion as well as the effects of railway transport, the bridge contributes significantly to the position and stress of the track. Usually, the most observed part of the continuous welded rail is the area above the sliding bearings of the bridge, where extremes of displacement and stress occur. Not only longitudinal expansion but also the rotation of the end of the supporting structure are the main sources of stresses at this point. This is because of the vertical load of the railway combined with the effects of traction and braking. If the exact degree of interaction between the bridge structure and the track (known as the longitudinal resistance of the track) were known, the design of a new or assessment of the existing system would have a better informative value, and we would not commit undesirable inaccuracies resulting from general normative provisions. It has been tested by many years of experience that from an operational and economic point of view, it is undoubtedly advantageous and desirable to establish a continuous welded rail wherever circumstances allow. So the goal of the research efforts is to approach more faithfully the real length limits of the bridge structure, in which
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Analysis of railway behavior on vehicles effects
Peňázová, Gabriela ; Kala, Jiří (referee) ; Salajka, Vlastislav (advisor)
The master’s thesis deals with the possibilities of railway track modeling. The computational models were created in ANSYS Classic. Simplified 2D model represents a longitudal half of classic single track construction, 3D models represent classic single track construction and RHEDA 2000 slab track. Static and dynamic response of 2D model was compared with analytical solutions by Timoshenko and Fryba. Static and dynamic responses of 3D models were analyzed and compared.
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The analysis of track response to railway vehicles
Kopeček, Josef ; Plášek, Otto (referee) ; Salajka, Vlastislav (advisor)
The diploma thesis deals with the assembly of numerical models of classical track using the finite element method in several variants. Models are compared with results obtained on analytical models. More complex models simulate the real behavior of a track running on a railway vehicle. The purpose is created methodology of modeling the railway track for use in static and dynamic analysis.
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Analysis of dynamical behaviour of slender structures and design of device to reduce vibration
Hanzlík, Tomáš ; Krejsa,, Martin (referee) ; prof. Ing. Alois Materna, CSc., MBA (referee) ; Salajka, Vlastislav (advisor)
Thesis deals with the modeling of pedestrian excitation of structures and obtaining the corresponding dynamic response of the structure. The trend of modern slender structures places more emphasis on the accuracy of modeling pedestrian dynamic excitation, which is difficult because of the intelligent behavior of pedestrians and the biological nature of the modeled pedestrian. First part of the thesis deals with traditional models of pedestrian excitation, based on application of pedestrian ground force to the model of construction. Models are explored on a model of slender footbridge for many different excitation variants in order to explore the specifics of the force excitation application and the structure response calculation. In second part of the thesis biomechanical pedestrian models are developed, including inertial forces, to calculate the pedestrian interaction with the structure. Parametric studies carried out on simplified structural models research the influence of design parameters of biomechanical models on dynamic response. The aim is to obtain a more accurate model of the pedestrian-construction system for refinement of the design of structures. The design of a tuned mass dampers for the reduction of pedestrian induced vibrations is also explored. Tuned mass dampers are devoted to parametric studies that deal with the influence of design parameters of the damper on the efficiency and design requirements of the device. The aim is to explore the design parameters and their influence on the efficient and economical design of the device. In the thesis were developed two biomechanical models, a simple biomechanical model with one vertical degree of freedom and a bipedal model of a human walking. Models have proven a certain degree of interaction when exciting light footbridges by one pedestrian. Bipedal model then also brought a partial insight into the mechanics of walking and the causes of pedestrian contact forces.
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DYNAMIC ANALYSIS OF THE SOIL-FOUNDATION INTERACTION
Martinásek, Josef ; prof. Ing. Alois Materna, CSc., MBA (referee) ; Kanický,, Viktor (referee) ; Salajka, Vlastislav (advisor)
Thesis deals with problems of the soil-structure interaction. In the theoretical part is described the approach to mathematical modeling of structure-foundation-soil interaction. The subsoil models are further described in detail, including the models with piles (both static and dynamics models). In the next chapter there is described the dynamics theory of the systems with single or more degrees of freedom. There is also an analysis of propagation, reflection and refraction of mechanical one-dimensional waves (P-wave, S-wave) and spatial waves (P- wave, SV-wave, SH-wave) and waves in homogeneous half-space (R-wave L-wave). The numerical analysis is logically sorted from hand calculation of the parameter change influence on the modal characteristics to complex computational FEM model of the machine with a foundation on piles placed in the spatial block of soil. Numerical studies aim to determine the influence of the subsoil model on the modal characteristics and thus confirm the absolute necessity of the subsoil model in tasks of dynamics. The next goal is to determine the appropriate key parameters of the computational model: the size of finite element, suitable shape of subsoil model, suitable inclination of boundary condition and suitable boundary conditions. For creating of set of computational models was used language APDL in conjunction with ANSYS software interface. All used input files are listed in the Annex.
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Dynamic analysis of track
Mojžíšek, Dominik ; Salajka, Vlastislav (referee) ; Plášek, Otto (advisor)
The diploma thesis deals with descriptions of vehicle - track dynamic interface. There are described basic analytical models of railway track. The numerical models are created by using finite element methods with moving load simulated axle of rail vehicle. The aim of thesis is to create the model which most accurately describes the dynamic phenomena in the track. The results from models are compared with data obtained by measuring in the track. Next aim of thesis is to determine dependency of rail cross-sectional characteristics on equivalent rail head wear and then on rail deflection.
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