National Repository of Grey Literature 21 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
The assessment slender bridge structure subjected to dynamic loads and design of the damping devices
Řehová, Jana ; Hradil, Petr (referee) ; Salajka, Vlastislav (advisor)
This master thesis deals with the dynamic analysis of a footbridge. Computational model of the footbridge was created using ANSYS software. The model was subjected to dynamic wind load in longitudal and lateral direction. Furthermore pedestrian load in lateral direction was analyzed. Afterwards, due to unsatisfactory response to the pedestrian laod, a tuned mass damper was introduced to reduce the vibration. This lead to decrease in the vibration to a satisfactory levels, as is shown in the analyses of the model.
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.
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.
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.
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.
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.
The solution of dynamic response of hydraulic steel structures interacting with fluid
Feilhauer, Michal ; Králík,, Juraj (referee) ; prof. Ing. Alois Materna, CSc., MBA (referee) ; Salajka, Vlastislav (advisor)
Behaviour prediction of hydraulic steel structures with the view to surrounding influences in various design dispositions is a fundamental condition for operational reliability assessment of the analyzed construction. Reliable characteristics of construction behaviour defined by the specification of its movement within changes caused by time and environmental influences is of great importance. In currently used engineering mechanics formulation it concerns setting the response of the defined construction or its part to the given time variable mechanic load. Required response values, which are necessary for evaluation terminal dispositions of capacity and usability of the construction, are trans-location and tension, or values thence derived. Calculation is basic means for response prediction of construction. The thesis presented deals with complex multi-physical behaviour problems of water supply constructions in fluid structure interaction. There are presented various approaches to calculations of static and dynamic qualities of constructions. These approaches are divided into so called “direct method”, which is based on direct connection between two physical fields and the calculation is performed by the method of final elements, and so called “indirect method” , which is based on connection of two physical fields by means of various interfaces, which are described in this thesis. In case of indirect method, the calculation of running liquid is performed by the method of final volumes and the construction calculation is performed by the method of final elements. Within the scope of this thesis, static and dynamic responses of water supply constructions have been solved with the use of the above mentioned approaches. The results of the calculations in the scope of this thesis have been compared with the findings of performed experiments. The final part of the thesis describes the results and generalized findings gathered from the tasks by various approaches.
Dynamic analysis of bridges structures
Prokš, Tomáš ; Salajka, Vlastislav (referee) ; Hradil, Petr (advisor)
The diploma thesis deals with dynamic analysis of cable-stayed steel pedestrian footbridge. The dynamic response of pedestrian-induced vibration was studied. The response of structure exeeded standard acceptance limit. Due to the effect of installed Tuned Mass Damper was studied. Motion equations of single and two degree of freedom model were solved in program MATLAB and the results were compared with numeric model in ANSYS.
An assessment of a bridge construction on a dynamic load
Součková, Markéta ; Kala, Jiří (referee) ; Salajka, Vlastislav (advisor)
Diploma thesis deas with static and dynamic analysis of a steel arch footbridge. The footbridge structure 3D model was created in program ANSYS 12.1 and afterwards were made static and modal analysis on this computational model. Based on the results of~modal analysis was applied to design of dynamic wind loading on the model according to norms ČSN EN. The effects of this burden has been calculated steady response at resonance from harmonic analysis according to ČSN P EN 1991-2-4. To report according to ČSN EN 1991-1-4 was designed substitute quasistatic forces corresponding loads of wind on the construction and for evaluation was used static analysis.
Dynamic Analysis of Track
Kulich, Pavel ; Salajka, Vlastislav (referee) ; Plášek, Otto (advisor)
The diploma thesis deals with analytical description of vehicle - track dynamic interface. There are described basic analytical models which are subsequently extended in order to get a more precise description of dynamic phenomena. The aim is to compile a model that faithfully describes the dynamic phenomena in the track. These new compiled models are qualitatively compared with data obtained by measuring in the track.

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2 Salajka, Vojtěch
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