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Stability problems study of framed structures
Piják, Jiří ; Vlk, Zbyněk (referee) ; Zídek, Rostislav (advisor)
In the first chapter the problem of ideal member, member with initial curvature and meaning of Euler’s critical force is regarded. Parameters of stability, mainly calculation of critical loading and buckling lengths, are studied in the second part. The same part contains comparison of results of computational programs and mechanical approach. Next attention is paid to imperfections, to possibilities of determination and comparison of results on a simple member. Comparison of possible judgements of buckling on a simple beam and on frames according to ČSN EN 1993-1-1 is performed on the final part.
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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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Study of Precision of the Stability Analysis
Sotulář, Jiří ; Pilgr, Milan (referee) ; Hron, Lukáš (advisor)
The thesis deals with the precision of the stability analysis of the pressed member. The loss of stability of the bukling is determinate by using several metods, which are compared each other. The thesis is partitioned into three parts that works together. The first part deals with the theory of analysis of the buckling stability. Here is described the gradual solution of analytical analysis for real beam and here is described the final compared for ideal, imperfekt and real beam too. It is also short solved buckling by using software. In the second part is compared by using computing systems and anylitical analysis for several basic buckling systems. The results of the compared are summarised in the final graphs and tables for each solved element and systems. In the third part are designed and static checked load-bearing element of steel storage hall. The buckling beams are checked by using findings from the previous analysis.
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What wood for wood buildings?
Beránková, Jitka
Cracked beams, beetles flying out of the roof trusses, rot and mold, twisted wooden planks, and other nightmares of wooden buildings users can only become a reality if no known binding wood requirements for the wooden construction. Several principles and important information on the required wood properties are brought to you by the Timber Institute in Prague.
Fulltext:  PDF
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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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Study of Precision of the Stability Analysis
Sotulář, Jiří ; Pilgr, Milan (referee) ; Hron, Lukáš (advisor)
The thesis deals with the precision of the stability analysis of the pressed member. The loss of stability of the bukling is determinate by using several metods, which are compared each other. The thesis is partitioned into three parts that works together. The first part deals with the theory of analysis of the buckling stability. Here is described the gradual solution of analytical analysis for real beam and here is described the final compared for ideal, imperfekt and real beam too. It is also short solved buckling by using software. In the second part is compared by using computing systems and anylitical analysis for several basic buckling systems. The results of the compared are summarised in the final graphs and tables for each solved element and systems. In the third part are designed and static checked load-bearing element of steel storage hall. The buckling beams are checked by using findings from the previous analysis.
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Stability problems study of framed structures
Piják, Jiří ; Vlk, Zbyněk (referee) ; Zídek, Rostislav (advisor)
In the first chapter the problem of ideal member, member with initial curvature and meaning of Euler’s critical force is regarded. Parameters of stability, mainly calculation of critical loading and buckling lengths, are studied in the second part. The same part contains comparison of results of computational programs and mechanical approach. Next attention is paid to imperfections, to possibilities of determination and comparison of results on a simple member. Comparison of possible judgements of buckling on a simple beam and on frames according to ČSN EN 1993-1-1 is performed on the final part.
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Comparison of deterministic and probabilistic approaches to the reliability assessment of steel structures
Křivý, V. ; Marek, Pavel
This paper deals with comparison of traditional reliability assessment specified in codes and next on simulation based probabilistic approaches represented by SBRA method. The attention is focused predominantly on key points of the reliability assessment procedure of steel bar structures, i.e. representation of actions, material properties and imperfections, combining of random variables, choice of global analysis with respect to the stability effects and finally the principles of safety and serviceability assessment.
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