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Utilization of inverse reliability analysis tools for probability based design of selected structural parameters
Lipowczan, Martin ; Novák, Drahomír (referee) ; Lehký, David (advisor)
This bachelor thesis deals with the application of methodology and tools of inverse analysis in regards to probabilistic design of selected design parameters of structure. The first step was to get familiar with the probabilistic design and analysis, then understanding of the inverse analysis methodology itself which is based on artificial neural networks. After researching the topic we could get to the actual issue. To put the theory in practice easier examples were used at first. These were mathematical functions and one practical-based example, whereas the results were known in advance. This simplified a process of checking achieved values. Using software tools and especially DLNNET software allowed us to take on practical exercises. Used exercises are chosen from earlier undergraduate studies at the Faculty of Civil Engineering, Brno. The first of these was a design of reinforced concrete slab, where desired parameters were slab’s height and area of reinforcement. The second one was a design of a diagonal truss screw connection, aimed to size the screw diameter and its quantity.
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An efficiency comparison of simulation methods for artificial neural network training and inverse analysis
Nezval, Michal ; Novák, Drahomír (referee) ; Lehký, David (advisor)
The thesis deals with inverse analysis which is based on combination of artificial neural network and stochastic methods. The goal is to compare an efficiency of new simulation method Hierarchical Subset Latin Hypercube Sampling to classical Monte Carlo method and standard Latin Hypercube Sampling method used for neural network training. The efficiency is compared for a different neural network structures. The inverse analysis is then applied for engineering tasks – identification of limit state fiction parameters related to pitched-roof frame and material parameters of concrete specimen subjected to three-point bending. Finally an efficiency of Hierarchical Subset Latin Hypercube method comparing to Monte Carlo and Latin Hypercube Sampling methods is discussed.
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Utilization of cone penetration tests in the load-transfer method for bored large diameter piles
Štetiar, Juraj ; Koudela, Pavel (referee) ; Chalmovský, Juraj (advisor)
This thesis is focused on the use of the results of cone penetration tests and the method of transfer functions for the design of drilled large-diameter piles. The introductory part clarifies the theoretical basis of cone penetration testing, method of transfer functions, various material models and the regression coefficients in the nonlinear method of pile settlement calculation. The theoretical introduction will be followed by other chapters in which the theory is applied to specific practical cases. The third part consists of geotechnical interpretation of the results of two static load tests in two different localities using graphical and numerical outputs (limit load curves, force distribution along the length of the pile, dependences of displacements and deformations on the pile depth, shaft frictions and more). The next part deals with the evaluation of the CPT at the site of the load test and the compilation of the calculation profile at the site based on the obtained data. In the fifth part there will be an inverse analysis of load tests using the method of transfer functions in the software developed at the Institute of Geotechnics, Faculty of Civil Engineering, Brno University of Technology. An inverse analysis of load tests using finite elements method and obtained data from the CPT can be found in chapter 6. Within this analysis, several material models will be applied and compared to the issue. This analysis will be followed in the fifth part by a comparison of direct correlation methods for determining the ultimate pile shaft friction from CPT data with the results of inverse analysis by MTF to determine the most suitable method. Finally, from the obtained data the regression coefficients will be adjusted for the calculation of the second limit state of lone piles by a nonlinear method (according to Masopust).
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Inverse reliability analysis of prestressed bridge
Lipowczan, Martin ; Novák, Drahomír (referee) ; Lehký, David (advisor)
The proposed diploma thesis deals with the application of methodology and tools of inverse analysis for design of selected structural parameters using a fully probabilistic analysis to determine the level of its reliability. The method based on artificial neural networks is used to approximate the inverse function. The inverse analysis was carried out in two ways that differs in the method of obtaining reliability indicators. The structure analyzed in this work was an existing bridge. The year of construction is estimated approximately between the years 1955 to 1960. The bridge is located close to the Uherský Ostroh. It is a one-piece concrete slab made of MPD3 and MPD4 girders post-tensioned by tendons. Based on the 2006 and 2007 diagnostic surveys, laboratory tests, normative regulations and recommendations and, last but not least, sensitivity analyses, an inverse design of selected design parameters was performed for required limit states. Various load levels, different alternatives of design parameters and different neural network structures were studied.
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Prediction of load-displacement behaviour of large diameter piles using the finite element method
Dvořák, Tomáš ; Miča, Lumír (referee) ; Chalmovský, Juraj (advisor)
The master thesis deals with the inverse analysis of instrumented load tests of bored piles in cohesionless and cohesive soils. Evaluations of the detailed monitoring are compared with the results of inverse analyses. Inverse analyses are preformed using the finite element method with an advanced material model considering the higher stiffness within very small strains in PLAXIS and alternatively using the load-transfer method in PMpLTO. The difference of pile-soil interaction in different soil types is discussed and the difference in the process of shaft friction mobilization is also evaluated. In cohesionless soils values of shaft friction are many times higher due to the increment of radial stress which is caused by effect of constraint dilatancy in shear zone at pile-soil interface.
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Utilization of cone penetration tests in the load-transfer method for bored large diameter piles
Štetiar, Juraj ; Koudela, Pavel (referee) ; Chalmovský, Juraj (advisor)
This thesis is focused on the use of the results of cone penetration tests and the method of transfer functions for the design of drilled large-diameter piles. The introductory part clarifies the theoretical basis of cone penetration testing, method of transfer functions, various material models and the regression coefficients in the nonlinear method of pile settlement calculation. The theoretical introduction will be followed by other chapters in which the theory is applied to specific practical cases. The third part consists of geotechnical interpretation of the results of two static load tests in two different localities using graphical and numerical outputs (limit load curves, force distribution along the length of the pile, dependences of displacements and deformations on the pile depth, shaft frictions and more). The next part deals with the evaluation of the CPT at the site of the load test and the compilation of the calculation profile at the site based on the obtained data. In the fifth part there will be an inverse analysis of load tests using the method of transfer functions in the software developed at the Institute of Geotechnics, Faculty of Civil Engineering, Brno University of Technology. An inverse analysis of load tests using finite elements method and obtained data from the CPT can be found in chapter 6. Within this analysis, several material models will be applied and compared to the issue. This analysis will be followed in the fifth part by a comparison of direct correlation methods for determining the ultimate pile shaft friction from CPT data with the results of inverse analysis by MTF to determine the most suitable method. Finally, from the obtained data the regression coefficients will be adjusted for the calculation of the second limit state of lone piles by a nonlinear method (according to Masopust).
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Multilevel Determination of Mechanical Fracture Parameters of Concrete from Wedge Splitting Tests
Lipowczan, Martin ; Šomodíková, Martina ; Lehký, David
The paper presents the results of a part of the research focused on the development of a complex experimental–computational methodology for determining the values of mechanical fracture parameters of concrete independent of the specimen size and geometry. For this purpose, laboratory wedge splitting tests were carried out on specimens of three different sizes with two different notch depths. Based on the experimentally obtained responses of the test specimens, the fracture mechanical parameters of all specimens were identified by inverse analysis. The obtained parameters were used in the numerical simulation of the tests and analysed in terms of their dependence on the size of the initial uncracked ligament.
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Inverse reliability analysis of prestressed bridge
Lipowczan, Martin ; Novák, Drahomír (referee) ; Lehký, David (advisor)
The proposed diploma thesis deals with the application of methodology and tools of inverse analysis for design of selected structural parameters using a fully probabilistic analysis to determine the level of its reliability. The method based on artificial neural networks is used to approximate the inverse function. The inverse analysis was carried out in two ways that differs in the method of obtaining reliability indicators. The structure analyzed in this work was an existing bridge. The year of construction is estimated approximately between the years 1955 to 1960. The bridge is located close to the Uherský Ostroh. It is a one-piece concrete slab made of MPD3 and MPD4 girders post-tensioned by tendons. Based on the 2006 and 2007 diagnostic surveys, laboratory tests, normative regulations and recommendations and, last but not least, sensitivity analyses, an inverse design of selected design parameters was performed for required limit states. Various load levels, different alternatives of design parameters and different neural network structures were studied.
|
|
|
An efficiency comparison of simulation methods for artificial neural network training and inverse analysis
Nezval, Michal ; Novák, Drahomír (referee) ; Lehký, David (advisor)
The thesis deals with inverse analysis which is based on combination of artificial neural network and stochastic methods. The goal is to compare an efficiency of new simulation method Hierarchical Subset Latin Hypercube Sampling to classical Monte Carlo method and standard Latin Hypercube Sampling method used for neural network training. The efficiency is compared for a different neural network structures. The inverse analysis is then applied for engineering tasks – identification of limit state fiction parameters related to pitched-roof frame and material parameters of concrete specimen subjected to three-point bending. Finally an efficiency of Hierarchical Subset Latin Hypercube method comparing to Monte Carlo and Latin Hypercube Sampling methods is discussed.
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