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The development of high-strength concrete with a high content of el. fly ash
Roubal, David ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
This diploma thesis deals with the study of high-strength, high-volume fly ash concrete. The theoretical part of this thesis focuses on the detailed characteristic and main principles of high-strength concrete, high-volume fly ash concrete. In addition, according to the findings, the technology of high-strength and high-volume fly ash concrete, including principles of high strength, has been described. On the basis of the findings, high-strength, high-volume fly ash concrete for specific compressive strengths has been designed and created in the experimental section. These concretes were then subjected to a number of tests.
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The effect of the shrinkage reducing additives on rheological properties of high-strength concrete
Červenka, Jiří ; Kucharczyková, Barbara (referee) ; Daněk, Petr (advisor)
Master’s thesis examines the effect of the shrinkage reducing additives on rheological properties of high-strength concrete. The first part is focused on high-strength concrete in terms of their composition and properties. The second part contains a detailed analysis of the cementitious composites shrinkage problems. Total shrinkage is divided into individual elementary shrinkages. For each of them there is a detailed description of causes and factors that affect their sizes. The next part describes the basic additives used to reduce the shrinkage of cementitious composites. The experimental part is focused on verifying the effectiveness of the shrinkage reducing additives during preparation of high-strength concrete. Usage of shrinkage drains for relative strain measurement enables to determine the process of shrinkage immediately after placing the concrete in the form and to obtain the overall curve of the hight-strength concrete volume changes during its setting and hardening. At the end of the thesis, there are overall analysis and summary of the results of the performed experiments.
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Reliability Analysis of Steel Columns with Encased Web in High Strength Concrete under Compression
Puklický, Libor ; Krejsa,, Martin (referee) ; Melcher, Jindřich (referee) ; Kala, Zdeněk (advisor)
The presented paper deals with a theoretical analysis of the ultimate limit state. The results of experimental research carried out at the Institute of Metal and Timber Structures headed by Assoc. Prof. Karmazinová and Professor Melcher were applied. The geometrically and materially nonlinear solution based on the Timošenko’s solution is verified by the FEM model in the computer programme system ANSYS. The random influence of initial imperfections is taken into consideration. The FEM model also includes the influence of residual stress. In the parametric study, the influence of residual stress on the cross-section plastification is researched into, its influence on the load carrying capacity limit is, together with the influence of other imperfections, the subject of the stochastic analysis, applying the Latin Hypercube Sampling (LHS). Further on, the study proves a direct effect of the concrete part of the cross-section (combination of materials steel-concrete) on the decrease of load carrying capacity limit of the beam caused by influence of the residual stress of steel. With regard to the importance of time dependent phenomena of the concrete creep for the load carrying capacity, the studies given in the Ph.D. thesis are oriented in this respect. The parametric studies of the influence of the concrete creep having applied the Standard Eurocode 2 provide both a comparison of load carrying capacity limits when using common and high-strength concrete types, and also the variability of load carrying capacities. It follows from the comparison of the statistical analysis outputs according to the design reliability conditions of the Standard EN1990 and of the approach of Eurocode 4 that the Eurocode 4 can be recommended for dimensioning of this member type. According to the studies which we carried out, the design in compliance with Eurocode 4 can be evaluated as the reliable one. A larger set of experimental data is necessary to determine the economy.
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High rise building AZ Tower - construction technological project
Hrubá, Denisa ; Valenta, Michal (referee) ; Biely, Boris (advisor)
This master´s thesis is dealing with selected part of the construction technology project of the high-rise building AZ Tower. The main content becomes the realization of supporting gross upper structure. It compiles in detail the most optimal proposal of technological processes, working machines, schedule, control and test plan, occupational safety, environment protection, construction site equipment and last but not least, the coordination of four tower cranes. Apart from the architectural and technically impressive draft of the Czech Republic tallest building it will be interesting to deal with progress of the whole construction. New technologies and elementary construction activities adapting to work at extreme altitudes will be used.
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The development of high-strength concrete with a high content of el. fly ash
Roubal, David ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
This diploma thesis deals with the study of high-strength, high-volume fly ash concrete. The theoretical part of this thesis focuses on the detailed characteristic and main principles of high-strength concrete, high-volume fly ash concrete. In addition, according to the findings, the technology of high-strength and high-volume fly ash concrete, including principles of high strength, has been described. On the basis of the findings, high-strength, high-volume fly ash concrete for specific compressive strengths has been designed and created in the experimental section. These concretes were then subjected to a number of tests.
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|
|
Reliability Analysis of Steel Columns with Encased Web in High Strength Concrete under Compression
Puklický, Libor ; Krejsa,, Martin (referee) ; Melcher, Jindřich (referee) ; Kala, Zdeněk (advisor)
The presented paper deals with a theoretical analysis of the ultimate limit state. The results of experimental research carried out at the Institute of Metal and Timber Structures headed by Assoc. Prof. Karmazinová and Professor Melcher were applied. The geometrically and materially nonlinear solution based on the Timošenko’s solution is verified by the FEM model in the computer programme system ANSYS. The random influence of initial imperfections is taken into consideration. The FEM model also includes the influence of residual stress. In the parametric study, the influence of residual stress on the cross-section plastification is researched into, its influence on the load carrying capacity limit is, together with the influence of other imperfections, the subject of the stochastic analysis, applying the Latin Hypercube Sampling (LHS). Further on, the study proves a direct effect of the concrete part of the cross-section (combination of materials steel-concrete) on the decrease of load carrying capacity limit of the beam caused by influence of the residual stress of steel. With regard to the importance of time dependent phenomena of the concrete creep for the load carrying capacity, the studies given in the Ph.D. thesis are oriented in this respect. The parametric studies of the influence of the concrete creep having applied the Standard Eurocode 2 provide both a comparison of load carrying capacity limits when using common and high-strength concrete types, and also the variability of load carrying capacities. It follows from the comparison of the statistical analysis outputs according to the design reliability conditions of the Standard EN1990 and of the approach of Eurocode 4 that the Eurocode 4 can be recommended for dimensioning of this member type. According to the studies which we carried out, the design in compliance with Eurocode 4 can be evaluated as the reliable one. A larger set of experimental data is necessary to determine the economy.
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|
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High rise building AZ Tower - construction technological project
Hrubá, Denisa ; Valenta, Michal (referee) ; Biely, Boris (advisor)
This master´s thesis is dealing with selected part of the construction technology project of the high-rise building AZ Tower. The main content becomes the realization of supporting gross upper structure. It compiles in detail the most optimal proposal of technological processes, working machines, schedule, control and test plan, occupational safety, environment protection, construction site equipment and last but not least, the coordination of four tower cranes. Apart from the architectural and technically impressive draft of the Czech Republic tallest building it will be interesting to deal with progress of the whole construction. New technologies and elementary construction activities adapting to work at extreme altitudes will be used.
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|
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The effect of the shrinkage reducing additives on rheological properties of high-strength concrete
Červenka, Jiří ; Kucharczyková, Barbara (referee) ; Daněk, Petr (advisor)
Master’s thesis examines the effect of the shrinkage reducing additives on rheological properties of high-strength concrete. The first part is focused on high-strength concrete in terms of their composition and properties. The second part contains a detailed analysis of the cementitious composites shrinkage problems. Total shrinkage is divided into individual elementary shrinkages. For each of them there is a detailed description of causes and factors that affect their sizes. The next part describes the basic additives used to reduce the shrinkage of cementitious composites. The experimental part is focused on verifying the effectiveness of the shrinkage reducing additives during preparation of high-strength concrete. Usage of shrinkage drains for relative strain measurement enables to determine the process of shrinkage immediately after placing the concrete in the form and to obtain the overall curve of the hight-strength concrete volume changes during its setting and hardening. At the end of the thesis, there are overall analysis and summary of the results of the performed experiments.
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