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Material nonlinear solution of beam structures
Kabeláč, Jaromír ; Krejsa,, Martin (referee) ; Návrat,, Tomáš (referee) ; Němec, Ivan (advisor)
The dissertation deals with solution of beam and frame structure considering material nonlinearity. The finite elements method (FEM) was used as calculation method. The objective of the dissertation was to develop and test finite beam element considering material nonlinearity. A detailed analysis of the problem provided a group of formulations of beam element. Part of the dissertation´s results has been, in several forms, implemented in commercial software. Beam element focused on solution of stress over solid cross sections is introduced in the theoretical part. In terms of topology it is a classical prismatic beam element with two nodes. Six degrees of freedom for translations and rotations are defined in each node plus 7-th degree of freedom for warping function from torsion. Load form axial force, bending moments, primary torsion, shear forces and eventually bimoment for secondary torsion were considered in cross section. Several variants of formulations were created according to inclusion of loading components into material nonlinearity and according to numeric integration method. Inclusion of geometric nonlinearity and fire resistance calculation are discussed in the dissertation. The above mentioned formulations were tested on prototypes as described in the application part which also provides information on the general procedure, architecture and technologies used for implementation of knowledge from the theoretical part into commercial FEM software. The dissertation shows implementation of plasticity for shell, solutions of cross section characteristics and stress on cross section, implementation of beam element with material nonlinearity and module for fire resistance of column. The above mentioned implementations of theoretical conclusions are the main outputs of the dissertation. These implementations are available in thousands of installations throughout Europe where being used at projection of significant constructions.
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Static and dynamic analysis of Prestressed bridge structure
Hokeš, Filip ; Nečas, Radim (referee) ; Kala, Jiří (advisor)
The main objective of the thesis is to perform static and dynamic analysis of prestressed concrete bridge structures in computational system ANSYS. For the analysis was chosen footbridge over the river Svratka in Brno. In relation to this topic are solved various types of modeling prestress at a finite element level. Before analyzing the footbridge is analyzed in detail the static system and the corresponding final geometry of the structure. Knowledge of the functioning of the static system is used to build the computational model of the structure, on which is subsequently performed static and dynamic analysis.
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Analysis of plastic bearability of plates
Rozsypalová, Veronika ; Hradil, Petr (referee) ; Němec, Ivan (advisor)
The subject of this thesis is analysis of the plastic bearability of plates. The first part is dedicated to a description of pertinent theories. It is primarily a theory of material nonlinearity and plasticity, including a description of plasticity models, which are commonly used in engineering analysis. Next is the hinted theory of geometric nonlinearity and discusses the key principles of limit plastic bearability of plates. This thesis includes ultimate strength calculations of plates of selected shapes, their solution by both, a manual calculation and using computational software. The obtained values are subsequently evaluated. The appendices contain the procedures for modelling in the computational programs RFEM and ANSYS.
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Implicit and Explicit Method in nonlinear Dynamics
Vaněčková, Adéla ; Hradil, Petr (referee) ; Němec, Ivan (advisor)
The final thesis „Explicit and Implicit methods in nonlinear dynamics“ deals with the issue of geometrical and physical nonlinear analysis of structures exposed to seismic loading by the methods of direct integration of equations of motion. Solution by the explicit and the implicit method is compared for three material models. While the differences between the results of the explicit method and the implicit Newmark method are small as expected, the differences are substantial between the results of different material models. However, these differences are explained and they are in full concordance with the theoretical assumptions for the pertinent material models. The conclusion of the final thesis is check of correctness of the results of the new module of the program system RFEM for both tested numerical methods and all three analyzed material models. (linear elastic, plastic Drucker-Prager and the Mazars damage model). With sufficient precision of results, both explicit and implicit numerical methods showed to be suitable for seismic analysis. The implicit method can provide several times faster calculation than the explicit one, but the determination of the optimal time step is problematic and time consuming, so the suitability of use of both methods for seismic analysis is comparable.
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Detail analysis of complex connection in the structure
Hokeš, Filip ; Hradil,, Petr (referee) ; Kala, Jiří (advisor)
The main objective of the thesis is to find and describe dependence between load carying capacity of a pin connection and a pin hole drilling. The dependence will be made in according to standard ČSN EN 1993-1-8, by theoretical solution and finally by finite element method in the ANSYS system. The second objective of the thesis is focused on a verification of load test results by numerical methods. Numerical solution will be made up in two analysis with different types of finite elements. The most fiiting model will be used as a basis for description of the relationship between capacity and diameter of drilling.
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Simulation of nonlinear response of construction materials and problem of identitifaction of material parameters
Hokeš, Filip ; Kala, Zdeněk (referee) ; Krejsa,, Martin (referee) ; Kala, Jiří (advisor)
The issue of parameter idenetification within numerical simulations can be considered a necessary step in the use of mathematical models, such as complex material models of building materials utilized in finite element method. The problem is particularly epmhasized in the case of anisothropic materials but also in the case of concrete, which behaves differently in tension and compression and which shows different response under rapid-dynamic and long-term loading. Correct capture of the concrete response in the computation requires usage of plasticity theory, damage theory, visco-elasticity and visco-plasticity or their mutual combinations. It results in development of material models and rheological schemes with large amount of parameters that are not commonly available in standards. The disseration presents application of meta-heuristic algorithm Particle Swarm for parameter identification. The success of the method is demonstrated in a pair of cases, first on the identification of elastoplastic material model parameters from stress strain diagram and then to identify the values of stiffness constants and viscosities of the rheological scheme from a creep curve.
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Material nonlinear solution of beam structures
Kabeláč, Jaromír ; Krejsa,, Martin (referee) ; Návrat,, Tomáš (referee) ; Němec, Ivan (advisor)
The dissertation deals with solution of beam and frame structure considering material nonlinearity. The finite elements method (FEM) was used as calculation method. The objective of the dissertation was to develop and test finite beam element considering material nonlinearity. A detailed analysis of the problem provided a group of formulations of beam element. Part of the dissertation´s results has been, in several forms, implemented in commercial software. Beam element focused on solution of stress over solid cross sections is introduced in the theoretical part. In terms of topology it is a classical prismatic beam element with two nodes. Six degrees of freedom for translations and rotations are defined in each node plus 7-th degree of freedom for warping function from torsion. Load form axial force, bending moments, primary torsion, shear forces and eventually bimoment for secondary torsion were considered in cross section. Several variants of formulations were created according to inclusion of loading components into material nonlinearity and according to numeric integration method. Inclusion of geometric nonlinearity and fire resistance calculation are discussed in the dissertation. The above mentioned formulations were tested on prototypes as described in the application part which also provides information on the general procedure, architecture and technologies used for implementation of knowledge from the theoretical part into commercial FEM software. The dissertation shows implementation of plasticity for shell, solutions of cross section characteristics and stress on cross section, implementation of beam element with material nonlinearity and module for fire resistance of column. The above mentioned implementations of theoretical conclusions are the main outputs of the dissertation. These implementations are available in thousands of installations throughout Europe where being used at projection of significant constructions.
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Implicit and Explicit Method in nonlinear Dynamics
Vaněčková, Adéla ; Hradil, Petr (referee) ; Němec, Ivan (advisor)
The final thesis „Explicit and Implicit methods in nonlinear dynamics“ deals with the issue of geometrical and physical nonlinear analysis of structures exposed to seismic loading by the methods of direct integration of equations of motion. Solution by the explicit and the implicit method is compared for three material models. While the differences between the results of the explicit method and the implicit Newmark method are small as expected, the differences are substantial between the results of different material models. However, these differences are explained and they are in full concordance with the theoretical assumptions for the pertinent material models. The conclusion of the final thesis is check of correctness of the results of the new module of the program system RFEM for both tested numerical methods and all three analyzed material models. (linear elastic, plastic Drucker-Prager and the Mazars damage model). With sufficient precision of results, both explicit and implicit numerical methods showed to be suitable for seismic analysis. The implicit method can provide several times faster calculation than the explicit one, but the determination of the optimal time step is problematic and time consuming, so the suitability of use of both methods for seismic analysis is comparable.
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Detail analysis of complex connection in the structure
Hokeš, Filip ; Hradil,, Petr (referee) ; Kala, Jiří (advisor)
The main objective of the thesis is to find and describe dependence between load carying capacity of a pin connection and a pin hole drilling. The dependence will be made in according to standard ČSN EN 1993-1-8, by theoretical solution and finally by finite element method in the ANSYS system. The second objective of the thesis is focused on a verification of load test results by numerical methods. Numerical solution will be made up in two analysis with different types of finite elements. The most fiiting model will be used as a basis for description of the relationship between capacity and diameter of drilling.
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Static and dynamic analysis of Prestressed bridge structure
Hokeš, Filip ; Nečas, Radim (referee) ; Kala, Jiří (advisor)
The main objective of the thesis is to perform static and dynamic analysis of prestressed concrete bridge structures in computational system ANSYS. For the analysis was chosen footbridge over the river Svratka in Brno. In relation to this topic are solved various types of modeling prestress at a finite element level. Before analyzing the footbridge is analyzed in detail the static system and the corresponding final geometry of the structure. Knowledge of the functioning of the static system is used to build the computational model of the structure, on which is subsequently performed static and dynamic analysis.
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