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Use of thermographic methods for diagnostics of concrete bridges
Janků, Michal ; Hobst, Leonard (referee) ; Matula, Radek (referee) ; Cikrle, Petr (advisor)
This dissertation is focused on the research of the applicability of the thermographic method in the diagnosis of concrete bridges in the Czech Republic. The theoretical part characterizes selected defects of concrete structures and the principle of their detection. The practical part describes the measurements made in the laboratory on the test specimen and the field on the concrete bridge. Most attention is paid to infrared thermography, ground-penetrating radar and ultrasonic pulse-echo method. Based on the results of the dissertation, recommendations for the use of the thermographic test method in practice were developed.
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Design of instrument for the analysis of crack initiation and propagation
Šubrt, Stanislav ; Andrš, Ondřej (referee) ; Houška, Pavel (advisor)
The main goal of this thesis is to get an insight into a field of non-destructive testing using potential drop techniques that have nowadays become the standard not only in the fatigue and loading tests but also in the industry. These methods can serve to non-destructively and continuously measure material specimens, thickness, corrosion losses, deformations, spectroscopy and detection and analysis of crack geometry. They can help to identify materials and measure material changes over time. The second part of this thesis deals with designing the aperture for detection of cracks in steam and product piping using potential drop technique modified by Ing. Ladislav Korec, CSc. Last part deals with extensive testing, experimenting and evaluation of the aperture.
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Detection of Failures and cavities in structures using radar
Tkadleček, Petr ; Anton, Ondřej (referee) ; Cikrle, Petr (advisor)
The bachelor‘s thesis describes non-destructive testing and methods, which are used in civil engineering. It is focused on the detection of failures and cavities in concrete structures. In the first part the methods are described and compared. The second part describes experimental measurements on concrete structures, which contain failures. The results are described and interpreted. The used methods are compared. It was evaluated, which of these methods is suitable for the detection of failures and cavities in structures.
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Monitoring and Analysis of Corrosion of Reinforcing Steel in Reinforced Concrete Elements and Structures Using the Acoustic Methods
Timčaková, Kristýna ; Semerák,, Petr (referee) ; Medveď,, Igor (referee) ; Vaněrek, Jan (referee) ; Chobola, Zdeněk (advisor)
The dissertation thesis deals with the study of non-destructive acoustic methods as instruments for monitoring and analysing corrosion of reinforcing steel in reinforced concrete elements. Four acoustic methods were selected for this task - the impact-echo method, the nonlinear acoustic spectroscopy method, the acoustic emission method, and the ultrasonic pulse velocity method. To verify the functionality of these methods, testing was carried out on three sets of reinforced concrete samples that had been exposed to the effects of sodium chloride, which corroded the embedded steel reinforcement in these samples. Suitable parameters were proposed for individual acoustic methods to monitor corrosion of the reinforcements. In addition, experiments were designed to demonstrate the ability of the selected acoustic methods to reveal the corrosion of steel reinforcement and its influence on the concrete matrix and to assess the condition of the degraded elements and structures. The analysis of the measurement results based on their comparison shows the advantages and disadvantages of the individual methods and of their practical applications. To verify the results, correlation with common methods that are currently used for the study of corrosion was carried out and included for example the electrical resistivity measurement of the reinforcement and simultaneous monitoring of the sample surface using a confocal microscope to record the development of microcracks during the degradation.
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Survey and Diagnostics of Reinforced Concrete Structure
Filipu, Martina ; Heřmánková, Věra (referee) ; Anton, Ondřej (advisor)
The master´s thesis deals with concrete properties and it introduces problematics of building survey. In each part the study deals with diagnostic methods used for building construction. Then it closely examines selected methods, which are used for recognisability of steel reinforcement in concrete. In the practical part I conducted two engineering surveys of reinforced concrete industrial buildings. The main aims were to identify the position of reinforcement in selected elements of crane runway and to evaluate the quality of used concrete. The last part of thesis is focused on static assessment of short corbel of crane runway.
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Development and use of non-destructive testing methods from the point of view of forensic engineering
Bílek, Petr ; Vala, Jiří (referee) ; Vodička, Jan (referee) ; Hobst, Leonard (advisor)
Concretes reinforced by, using distributed steel reinforcements (fibres) are known as fibre-concrete. In case of disturbances or accidents of concrete structures reinforced with wires, it is necessary to carefully examine the actual implementation of dispersed reinforcement. Fibre concretes belong to modern building materials whose possible applications have not been fully utilized so far. Have been mainly used for floor structures loaded with factory halls and warehouses. Recently, thanks to well-known physical and mechanical properties of fibre-concrete, there were numerous attempts of designers, and namely investors, to utilize this kind of materials for support structures either. Favorable properties of wire-concrete can be utilized if there is a necessity to increase the resistance of concrete to stresses exceeding its strength, cyclic stress or impact stress. Daily practice shows to prove that the applications of fibre-concrete in such structures lead to the economic success. Necessary condition for successful application of steel fiber reinforced concrete in constructions however consists in its uniform dispersion, a homogeneous distribution of the wires throughout the volume of the structure. In case of inappropriate processing and deposition of the mixture during the manufacturing process fiber-concrete structures, the fibers are often unevenly distributed. Wires itself represent unfavourably shaped mixture components and they are extremely deteriorating its workability. A grouping of wires may be encountered as well, which reduces the overall homogeneity and the quality of steel fiber-concrete structures. If the homogeneity of fibre-concrete is not kept, the material possess different properties in various parts of the structure (for example, tensile strength), which can lead to defects in the structure (generation and development of cracks). The relevant lower reliability of the structure which is caused by unequal distribution of fibres (wires) in concrete volume can lead to damage of the property as well as the safety and the human lives can be jeopardized. Hence it is necessary to secure the effective control of the fibre-concrete homogeneity in ready support fibre-concrete structures. Contemporary homogeneity control is still ongoing on fresh blends, but if the fibre-concrete hardened and is a part of the construction, no known reliable methods are currently in available to test the homogeneity of the fibre-concrete on the structure without its destruction. The methods developed to control the concentration of wires in wire-concrete structures are based mostly on magnetic or electromagnetic properties of wires. The thesis deals with the development of the magnetic method in situ using permanent magnets for monitoring the distribution of fibers in hardened steel fiber-concrete structures. The test principle is based on measurements of the changes in magnetic field strength of permanent magnets which are induced by a change in wire distribution in steel fibre-concrete structure. Test is characterized as a so called local- failure- test using a small diameter core drill. In this sense it is a semi-destructive method.
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Primary Calibration of Acoustic Emission Sensors
Keprt, Jiří ; Mazal, Pavel (referee) ; Hájek, Karel (referee) ; Beneš, Petr (advisor)
The aim of the doctoral thesis is the problem of the primary calibration of acoustic emission sensor. In the introductory chapters, there are the results from the study of literature in field of AE and primary calibration of AE sensor summarized. The practical part of the thesis is aimed on realization of the primary calibration of AE sensors by different methods. The standardized methods of step function calibration and reciprocity calibration were practically realized as a part of the research on the same aparature. The method of reciprocity calibration with wideband excitation was practically realized too. The comparison between results from each used method was realized and the influences of the different sources of uncertainty and the different configuration of the calibration aparature on the step function calibration and the reciprocity calibration were determined. The uncertainties were determined for each realized methods. The recommendations for the calibration by the different methods on the available calibration aparature were presented. All the proceses of the reciprocity primary calibration was automated by the programmed software and the channel switcher. The UT 1000 (s.n. 169) by Physical Acoustic Corporation was used as the calibrated sensor for the comparison of the results of the calibrations.
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Automation of test line for flaw detection of railway wheels
Hubený, Marek ; Matz,, Václav (referee) ; Pásek, Jan (advisor)
This thesis describes the design and implementation of a control system for testing line using ultrasonic testing and magnetic particle testing. The test line is designed for non-destructive testing of railway wheels with detection and localization of surface and subsurface defects. The thesis describes the design and operating principles of the test line. On this basis, the design of a control system that controls various processes throughout the test line is clearly described. The proposed control system was implemented in the industrial application.
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Inductive sensor
Koleček, Tomáš ; Bejček, Ludvík (referee) ; Beneš, Petr (advisor)
This bachelor thesis deals with indukčnostního-loaded impedance sensor, which is used for non-destructive materials testing. Describes a procedure for measuring the eddy current method using a straight coil. This thesis includes the final locus corresponding literature ferromagnetic and non-ferromagnetic for the measured material. The last part deals with the analysis of the appropriate choice of operating point derived from the sensor readings.
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Evaluation of cold kinetic deposition technology (Cold Spray)
Buček, Tomáš ; Zimáková, Jana (referee) ; Binar, Tomáš (advisor)
Cold spray or Cold gas dynamic spraying is actually new process for coating application. Origin of Colds technology spray is thermal spray. Cold spray technology has some advantages therefor any other common thermal technology. Cold spray technology has unique properties mainly due to low deposition temperatures and the physical principle of layer growth. Master’s thesis has focused on the possibility of use for corrosion protection. Accelerated corrosion tests were performed in a condensation chamber with samples of aluminium substrate and low pressure cold sprayed copper layer. The formation of corrosion was evaluated by acoustic emission and metallographic analysis. The anti-corrosion properties of copper have been considered in practical design, as have the unique antibacterial and virus inactivating properties.
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