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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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Family house load-bearing structure composed of thin-walled steel members
Bulíček, Radek ; Melcher,, Jindřich (referee) ; Karmazínová, Marcela (advisor)
The aim of the bachelor thesis is to design and verify load bearing members of single-storey family house composed of thin-walled cold-formed elements. Parking space for cars of timber members is the part of the house, too. The family house is in rectangular plan with dimensions of 9.5 x 10.5 m. The roof of the house is hipped, on the side of the house with the parking place rafters are associated with garage rafters. The following elements were statically assessed: structural members of the house roof (rafters, collar tie, roof bracing), structural members of the ceiling (ceiling beams), reinforcing timber frame, external and internal load bearing walls (columns), load bearing elements of the parking space (rafters, purlins, columns). All assessments were performed according to currently valid standards. The calculation showed that the resistance and serviceability of all components are satisfied.
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Analysis of transport aircraft damage during of terrorist attack
Čížková, Markéta ; Jetela, Václav (referee) ; Petrásek, Miloslav (advisor)
In its theoretical part, the diploma thesis deals with the reasons leading to terrorist attacks and a brief list of some attacks on aircraft. It also focuses on the aircraft as the target of a terrorist attack, especially the aircraft kite as the major researched part. The conclusion of the theoretical part summarizes a list of types of aircraft fuselage structures in respect of design solutions for load transfer. The practical part determines the extent of damage caused by a missile with a fragmentation warhead. This scope is then applied to the illustrative case. In the following chapters, the calculation of the critical force of a panel loaded with pressure depends on the different nature and extent of damage. Then the work highlights the evaluation of the obtained results, which are also summarized in the conclusions of the work.
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Evaluation of risk of buckling in columns with inaccuracies in geometry and load
Fischer, Jiří ; Fuis, Vladimír (referee) ; Burša, Jiří (advisor)
The aim of this thesis is to analyse applicability range of relations for a critical load at buckling for columns with deflection from ideal column – initially curved column or eccentric load. The solution of this thesis is analytical and it comes from solving the differential equation of the deflection curve. This equation has different general solutions for both assumptions. The result achieved in this thesis is general recommendation for maximal values of eccentricity of load according to cross section. Next result is recommendation of maximum curve according to cross section. The chosen cross sections are circular, square, rectangular and thin tubes.
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Evaluation of geometry effect on structural panel stability with the use of Finite Element Methods
Klepiš, Daniel ; Augustin, Petr (referee) ; Katrňák, Tomáš (advisor)
This bachelor thesis deals with the problem of loss of stability of a reinforced wing panel. Within the research part of the thesis, an overview of the types of instabilities is created, thanks to which it is possible to verify the phenomena occurring in the whole area of progressive loading of the panel. The classical concept of longitudinal section reinforcement is enriched by an unusual type of so-called tree reinforcement inspired by the bionic structure of the leaf. For the panel modified in this way, two models are created in which selected dimensional parameters are changed. All the variations are numerically calculated using nonlinear analysis in MSC Patran/Nastran. For comparison of the calculated panels, a series of graphs are produced showing the force transfer and the percentage increase in the maximum force transfer with loss of stability. The selected variant of the parametric model is also compared in terms of mass increase. This allows a better verification of the appropriate panel for further detailed analysis.
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Buckling of Plastic Specimens Manufactured by 3D Printing
Seidler, Lukáš ; Horák, Marek (referee) ; Löffelmann, František (advisor)
The bachelor’s thesis deals with the problematics of loss of stability in specimen created using the 3D printing technology. The beginning is devoted to a quick familiarization with the problems of 3D printing and a quick overview of the common faults present in the final products. For the purpose of testing the stability there were designed special testing specimens. Their theoretical values of critical force were than calculated using analytical and Finite Element approach. These values were than verified by testing the specimen inside a LabTest 6.500 machine and results were evaluated as per norm. The results clearly indicates that the theoretical force values are always bigger than the measured ones. Differences between these two are compared in multiple of graphs at the end of this thesis.
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Collection of solved examples from Elasticity and Strength
ŠIMANOVÁ, Petra
The thesis is designed as a brief teaching text for the course Technical Mechanics II at the Faculty of Education of the University of South Bohemia in České Budějovice. The topics included in the thesis are simple tension, simple compression, simple shear, simple bending, simple torsion, buckling. The theory is supplemented by examples with annotated solutions for each type of stress. The thesis also contains several complex problems on dealing with multiple types of stresses on a structure. The work can be used by teachers of the subject in preparation for classes and by students in self-study or in preparation for various examinations or tests.
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ACT - according Palaščáková Špringrová - Influence on Backeche during the Pregnancy and Puerperium
Baranová, Eva ; Vondráková, Ivana (advisor) ; Hylmarová, Ludmila (referee)
Author: Eva Baranová Institution: Department of Rehabilitation, Faculty of Medicine, Charles University in Hradec Králové Title of Bachelor's thesis: ACT® - Influence on Backache during the Pregnancy and Puerperium Supervisor: Mgr. Ivana Vondráková Number of pages: 105 Number of pictures: 40 Number of charts: 24 Year of defense: 2014 Keywords: ACT® - Acral coactivation therapy® /Ingrid Palaščáková Špringrová, acra, buckling, straightening, ontogenetic, positions, pregnancy, puerperium Bachelor thesis deals with the method ACT® - acral coactivation therapy and its application of back pain in pregnancy and in the postpartum period. In the theoretical part of this thesis is the anatomy of the spine, planes and dimensions of the pelvic stabilizing system of the spine and the importance of muscle systematization . Another chapter is a method of ACT® - acral coactivation therapy, which describes its principles. The last chapter is about pregnancy itself, change of it and nourishment. The practical part included two case reports of pregnant patients with back pain. Both attended the outpatient rehabilitation. They were treated conservatively, one with low back pain, the one with a sore a lower thoracic and upper lumbar spine. Each of the patients there is done input and output kinesiology examination,...
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Stress-strain analysis of the railway bridge in Zahrádky near Česká Lípa
Abdul moghni, Abdul rahman ; Vosynek, Petr (referee) ; Fuis, Vladimír (advisor)
Cílem této bakalářské práce je využití deformačně napěťové analýzy na Železniční most v Zahrádkách u České Lípy. Konstrukce mostu byla zjednodušena a vymodelována jako nosníková konstrukce. První část bakalářské práce byla věnována získávání vstupních dat a základních informacích z technické dokumentace mostu. V nosníkovém modelu bylo využito několik zjednodušení. První model považujeme za staticky neurčitý, zatímco druhý jako staticky určitou konstrukci. Každý model tedy obsahuje zátěž z důvodu vlastní váhy a zatížení způsobeno projíždějícím vlakem. Z důvodu objemnosti rovnic, využíváme k výpočtu software Maple. Zkontrolovali jsme i mezní stav vzpěru pro oba modely, avšak jsme uvažovali pouze zatížení vlastní váhou a zatížení způsobeno vlakem. Po získání analytických dat bylo důležité tyto výsledky ověřit. Toto bylo docíleno využitím metody konečných prvku za pomocí programu Ansys. Veškeré výpočty byly provedeny pro 2D modely. Jediná výjimka je numerická sekce, kde byl přidán 3D model za účelem porovnání s 2D modelem.
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