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Pedestrian bridges formed by a flat arch
Jurík, Michal ; Stráský, Jiří (advisor)
This doctoral thesis focuses on the research of the pedestrian bridges formed by the flat arch. To understand the basic static behaviour of the flat arch it was necessary to make a study of the development of the direct flat arch as footbridge with large span and the impact of stiffness on its camber. For the mathematical modeling FEM software ANSYS were used. The calculation has shown that a design of purely concrete flat arch would demand enormous bending stiffness, which can be achieved only through a massive cross-section. The findings gained in this chapter were further used to design a unique pedestrian bridge formed by the curved in plan flat arch, where to transfer of the large bending moments a steel pipe was designed. Several variants with different span and rise of the arch in plan were tested. From the tested variants was then selected footbridge with a span of 45 m and with the rise of the arch 10 m, which seemed to be the best solution according to the calculations and it was further analyzed in detail. The studied structure is formed by curved concrete slab that is stiffened through the steel brackets on the inner side of a steel tube with a graded thickness. The external cables that are situated in the handrail pipe balance the dead load torsional moment. Designed structure and the static analysis procedure were verified on a fully functional 1:6 scale model. The thesis describes the model analogy used for the design of the model, its structural design and its implementation. Load tests on the model confirmed correctness of the design of the proposed curved in plan pedestrian bridge, its high carrying capacity and the accuracy of the developed procedure of static analysis. Results and experiences acquired from the design and the realization of model are the basis for a practical realization of studied structures. The last part of the thesis deals with the possibility of replacement of the steel components with concrete in pedestrian bridges formed
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The effective cross-section thickness and its effect on the behavior of concrete constructions
Hofírek, Radovan ; prof. ing. Jan L. Vítek, CSc. (referee) ; Borzovič,, Viktor (referee) ; Zich, Miloš (advisor)
Determination of rheological phenomenon is very difficult, because there are many unknown inputs parameters, e.g. concrete age, the size of elements, relative humidity of the surrounding environment, cement hydration rate, temperature influence, type of strain and treatment. This Ph.D. thesis deals with the effective cross-section thickness and its effect on the behaviour of concrete constructions that is how the rheological phenomena change in time as a result of the application or removal of insulation layer from the concrete surface. Long-term experimental measurements of specimens and real bridge constructions were performed. The data collected from these measurements were described, evaluated and mathematical modifications for the standards Model Code 2010 and Model B4 (B3) have been proposed. Using these new computational formulas is possible to take into consideration the changes in the effective cross-section thickness and therefore make the computational models for concrete structures more accurate.
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The effective cross-section thickness and its effect on the behavior of concrete constructions
Hofírek, Radovan ; prof. ing. Jan L. Vítek, CSc. (referee) ; Borzovič,, Viktor (referee) ; Zich, Miloš (advisor)
Determination of rheological phenomenon is very difficult, because there are many unknown inputs parameters, e.g. concrete age, the size of elements, relative humidity of the surrounding environment, cement hydration rate, temperature influence, type of strain and treatment. This Ph.D. thesis deals with the effective cross-section thickness and its effect on the behaviour of concrete constructions that is how the rheological phenomena change in time as a result of the application or removal of insulation layer from the concrete surface. Long-term experimental measurements of specimens and real bridge constructions were performed. The data collected from these measurements were described, evaluated and mathematical modifications for the standards Model Code 2010 and Model B4 (B3) have been proposed. Using these new computational formulas is possible to take into consideration the changes in the effective cross-section thickness and therefore make the computational models for concrete structures more accurate.
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Pedestrian bridges formed by a flat arch
Jurík, Michal ; Stráský, Jiří (advisor)
This doctoral thesis focuses on the research of the pedestrian bridges formed by the flat arch. To understand the basic static behaviour of the flat arch it was necessary to make a study of the development of the direct flat arch as footbridge with large span and the impact of stiffness on its camber. For the mathematical modeling FEM software ANSYS were used. The calculation has shown that a design of purely concrete flat arch would demand enormous bending stiffness, which can be achieved only through a massive cross-section. The findings gained in this chapter were further used to design a unique pedestrian bridge formed by the curved in plan flat arch, where to transfer of the large bending moments a steel pipe was designed. Several variants with different span and rise of the arch in plan were tested. From the tested variants was then selected footbridge with a span of 45 m and with the rise of the arch 10 m, which seemed to be the best solution according to the calculations and it was further analyzed in detail. The studied structure is formed by curved concrete slab that is stiffened through the steel brackets on the inner side of a steel tube with a graded thickness. The external cables that are situated in the handrail pipe balance the dead load torsional moment. Designed structure and the static analysis procedure were verified on a fully functional 1:6 scale model. The thesis describes the model analogy used for the design of the model, its structural design and its implementation. Load tests on the model confirmed correctness of the design of the proposed curved in plan pedestrian bridge, its high carrying capacity and the accuracy of the developed procedure of static analysis. Results and experiences acquired from the design and the realization of model are the basis for a practical realization of studied structures. The last part of the thesis deals with the possibility of replacement of the steel components with concrete in pedestrian bridges formed
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