Bridge redundancy can be described as the capacity that a bridge has to continue carrying loads after suffering the failure of one or more main structural components without undergoing significant deformations. In the current AASHTO LRFD Bridge Design Specification, two-girder bridges are classified as fracture critical, which implies that these bridges are not inherently redundant. Therefore, two-girder bridges require more frequent and detailed inspections than other types of bridges, resulting in greater costs for their operation. Despite the fracture-critical classification of two-girder bridges, several historical events involving the failure of main load-carrying members in two-girder bridges constructed of steel plate girders have demonstrated their ability to have significant reserve load carrying capacity. Relative to the steel plate girder bridges, steel box-girder bridges have higher torsional stiffness and more structural elements that might contribute to load redistribution in the event of a fracture of one or more bridge main members. These observations initiated questions on the inherent redundancy that twin box-girder bridges might possess. Given the high costs associated with the maintenance and the inspection of these bridges, there is interest in accurately characterizing the redundancy of bridge systems. In this study, twin steel box-girder bridges, which have become popular in recent years due to their aesthetics and high torsional resistance, were investigated to characterize and to define redundancy sources that could exist in this type of bridge. For this purpose, detailed finite element bridge models were developed with various modeling techniques to capture critical aspects of response of bridges suffering severe levels of damage. The finite element models included inelastic material behavior and nonlinear geometry, and they also accounted for the complex interaction of the shear studs with the concrete deck under progressing levels of damage. In conjunction with the computational analysis approach, three full-scale bridge fracture tests were carried out during this research project, and data collected from these tests were utilized to validate the results obtained from the finite element models. / text

TITLE OF THE WORK Physical preparation for the military part of the talent exam at Military Department of the Faculty of Physical Education and Sport in Prague. DEFINITION OF THE PROBLEM It is necessary to pass the special physical exam to be admitted for studying at Military Department. The content of this exam is significantly different from other physical activities and the preparation for it may cause several problems to the candidates. MAIN GOALS The main goal of this diploma thesis is to create a package of the exercises used for improving technical and fitness part of the performance primarily in the military part of physical exam. PLAN OF PROCESSING After extensive research of the available documents the package of the exercises will be created. KEYWORDS Army Physical Fitness, Rope ladder climbing, Load carrying, Special Physical Preparation

The subject of this master's thesis is a static and structural design of a Load-carrying steel structure of railway bridge with bottom steel deck of the span of 42 + 60 + 42 m over the Labe river in Děčín. A solid steel beam forms the main load-bearing structure of the bridge reinforced with truss-work. The truss-work is made up of an open top chord and diagonal strut without secondary vertical struts. The calculations were done in compliance with valid ČSN EN documents.

The Master Thesis describes knowlege in thrust bearings with solid segments. Contains analysis of thrust bearing used in NR/20SJ turbochargers. Further designs new thrust bearing with enhancement of load carrying capacity. The new thrust bearing and the old one are tested and compared.

The load-carrying steel structure of the shopping centre is proposed in two versions. The more advantageous version is elaborated in detail. The roof structure is designed using three-dimensional curved trusses with glass roofing and the structure rests on steel columns. The ground plan dimensions of the steel structure are 120 by 73 meters.

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The femur is the longest limb bone found in humans. Almost all the long limb bones found in terrestrial mammals, including the femur studied herein, have been observed to be loaded in bending and are curved longitudinally. The curvature in these long bones increases the bending stress developed in the bone, potentially reducing the bone’s load carrying capacity, i.e. its mechanical strength. Therefore, bone curvature poses a paradox in terms of the mechanical function of long limb bones. The aim of this study is to investigate and explain the role of longitudinal bone curvature in the design of long bones. In particular, it has been hypothesized that curvature of long bones results in a trade-off between the bone’s mechanical strength and its bending predictability. This thesis employs finite element analysis of human femora to address this issue. Simplified human femora with different curvatures were modeled and analyzed using ANSYS Workbench finite element analysis software. The results obtained are compared between different curvatures including a straight bone. We examined how the bone curvature affects the bending predictability and load carrying capacity of bones. Results were post processed to yield probability density functions (PDFs) for circumferential location of maximum equivalent stress for various bone curvatures to assess the bending predictability of bones. To validate our findings on the geometrically simplified ANSYS Workbench femur models, a digitally reconstructed femur model from a CT scan of a real human femur was employed. For this model we performed finite element analysis in the FEA tool, Strand7, executing multiple simulations for different load cases. The results from the CT scanned femur model and those from the CAD femur model were then compared. We found general agreement in trends but some quantitative differences most likely due to the geometric differences between the digitally reconstructed femur model and the simplified CAD models. As postulated by others, our results support the hypothesis that the bone curvature is a trade-off between the bone strength and its bending predictability. Bone curvature increases bending predictability at the expense of load carrying capacity.

The load-carrying and energy-dissipation capacities of ultra-high-performance concrete (UHPC) under dynamic loading are evaluated in relation to microstructure composition at strain rates on the order of 10⁵ s⁻¹ and pressures of up to 10 GPa. Analysis focuses on deformation and failure mechanisms at the mesostructural level. A cohesive finite element framework that allows explicit account of constituent phases, interfaces, and fracture is used. The model resolves essential deformation and failure mechanisms in addition to providing a phenomenological account of the effects of the phase transformation. Four modes of energy dissipation are tracked, including pressure-sensitive inelastic deformation, damage through the development of distributed cracks, interfacial friction, and energy released through phase transformation of the quartz silica constituent. Simulations are carried out over a range of volume fractions of constituent phases to quantify trends that can be used to design materials for more damage-resistant structures. Calculations show that the volume fractions of the constituents have more influence on the energy-dissipation capacity than on the load-carrying capacity, that inelastic deformation is the source of over 70% of the energy dissipation, and that the presence of porosity changes the role of fibers in the dissipation process. The results also show that the phase transformation has a significant effect on the load-carrying and energy-dissipation capacities of UHPC for the conditions studied. Although transformation accounts for less than 2% of the total energy dissipation, the phase transformation leads to a twofold increase in the crack density and yields nearly an 18% increase to the overall energy dissipation. Microstructure-behavior relations are established to facilitate materials design and tailoring for target-specific applications.

La compréhension et la modélisation d'un contact lubrifié en présence de texturation nécessitent une description physique très fine pour comprendre les analyses contradictoires et pour expliquer les résultats très différents en termes de performance présentes dans la littérature internationale. De nombreuses études théoriques et expérimentales ont montré que la texturation des surfaces pourrait améliorer les caractéristiques tribologiques des contacts. La capacité de charge, le coefficient de frottement et la résistance à l'usure sont les principales caractéristiques susceptibles d'être améliorées. La texturation de surface fait appel à de nombreux paramètres géométriques, qui peuvent agir de façon très différente selon le contact. Enfin, les phénomènes supposés expliquer l'apport de la texturation ne font pas l'unanimité dans la communauté scientifique. Ainsi, les différentes contradictions font que ce domaine de recherche est en pleine évolution.Dans ce contexte scientifique, l'objectif principal de cette thèse est de conduire, à travers une étude théorique et numérique approfondie, vers une meilleure compréhension des effets induits par la texturation dans un contact lubrifié. Les paramètres géométriques, essentiels par rapport aux phénomènes physiques générés, font l'objet d'une analyse étendue. Les éléments théoriques obtenus à travers cette étude permettront une optimisation opérationnelle de tous types de dispositifs fonctionnant dans un milieu lubrifié. Parmi ces nombreuses applications, la butée en régime hydrodynamique a été choisie afin d'illustrer la pertinence des résultats de nos recherches. / Understanding and modeling a lubricated contact in the presence of surface textures requires a refined physical description in order to comprehend and explain the contradicting results that are currently presented in international literature. An increasing number of theoretical and experimental studies have shown that surface texturing could improve the tribological properties of lubricated or even dry contacts. The load-carrying capacity, the friction coefficient or the wear resistance are the main characteristics that can be improved through texturing. Nevertheless, the lubrication mechanisms that might explain these effects are still the subject of debate within the scientific community. These various contradictions have lead to a significant development of this particular field of research. In this scientific context, the main objective of this thesis is to lead, by means of a thorough numerical and theoretical analysis, towards a better understanding of the physical effects induced by surface texturing in lubricated contacts. The geometrical parameters, which are essential with regard to the generated effects, are submitted to a detailed investigation that also takes into account the influence of the operating conditions (surface speed, viscosity, ambient pressure etc.). The theoretical conclusions obtained throughout this investigation should lead to an improvement in texture design and should allow an optimization of most devices operating in lubricated conditions. Among these various applications, the hydrodynamic thrust bearing has been chosen in order to illustrate the relevance of our findings.

The master thesis focuses on the design of a Load-carrying steel structure of railway bridge with bottom steel deck of the span of 28 + 45 + 23 m. The bridge is situated in the municipality of Třebestovice. Four variants of solution have been calculated. Two variants are made by plate main beams of variable profile, the next alternative was made by truss structure and the fourth variant consist of a combination of plate main beams with truss stiffener in the middle span. The most optimal solution was processed in detail. The calculations were done in compliance with valid ČSN EN norms.