National Repository of Grey Literature 14 records found  1 - 10next  jump to record: Search took 0.01 seconds. 
Experimental determination of factors affecting the static modulus of elasticity of concrete using non-destructive testing methods
Kocáb, Dalibor ; Bílek,, Vlastimil (referee) ; Pazdera, Luboš (referee) ; Cikrle, Petr (advisor)
The Ph.D. thesis deals with one of the most important characteristics of hardened concrete; i.e. the modulus of elasticity. The thesis aims to describe and evaluate the important factors that affect the final value of concrete modulus of elasticity, especially those that can be influenced during construction. Another aim is to find ways to determine the static modulus of elasticity of concrete by non-destructive means (primarily ultrasonic pulse method, resonance method and use of electronic rebound hammers), thus to determine the possibility of creating calibration curve for NDT determination of the modulus of elasticity.
Fluorine detection by means of Laser-Induced Breakdown Spectroscopy
Jaworková, Magdalena ; Pořízka, Pavel (referee) ; Prochazka, David (advisor)
This work concerns the Laser Induced Break-down Spectroscopy LIBS and it´s usage in detection of fluorine in specimens. This method and the particular methods of measurements suitable for fluorine detection are analysed in theoretical part. The sensitivity of particular methods such as usage of buffer gases (He), change of ambient pressure, usage of double laser pulse (DP–LIBS) or detection of molecular bands are compared in experimental part.
Study of the development, trends and innovations in shotcrete technology
Záruba, Jiří ; Hela, Vlastimil (referee) ; Hubáček, Adam (advisor)
The Bachelor thesis is focused on the study of development, trends and innovations in shotcrete technology. The main target of this thesis is to summarize new procedures in shotcrete technology. Secondary targets include a description of basic properties of sprayed concrete, introducing new trends and technology in recent years. The next sub-goal is to propose experiment that will try new ways of testing shotcrete. Based on these secondary targets is possible to evaluate the current situation in shotcrete technology and fulfil the main objective of this thesis.
Possibilities of laboratory preparation and testing of shotcrete
Helan, Tomáš ; Hela,, Vlastimil (referee) ; Hubáček, Adam (advisor)
The master's thesis is focused on the posibility of laboratory testing of shotcrete. The important point of the thesis is properties comparison of shotcrete made in laboratory with vibrating press and concrete with the same recipe made by spraying machine. The influence of shotcrete recipe, type and dosage of accelerating ingredient is also examined.
Water quality analysis using colorimetry
Kovaldová, Eliška ; Zumberg, Inna (referee) ; Čmiel, Vratislav (advisor)
This bachelor's thesis deals with the analysis of water quality using colorimetry. Part of the work is an introduction to the physical and chemical parameters of water, as well as optical methods, which include photometry, spectrophotometry and colorimetry, and an introduction to regression analysis. These methods and analysis are followed by a practical part by measuring pH, nitrate and water hardness using a spectrophotometer and an AS7262 visible light sensor with a SparkFun development board. At the end of the work there is a comparison of absorption spectra, calibration curves and linear regression parameters of both methods.
CALIBRATION FUNCTIONS FOR EDGE CRACKS UNDER SELECTED BENDING LOADS.\n\n
Seitl, Stanislav ; Miarka, Petr
Fatigue cracks are found during the regular structural inspections. To precisely\ndescribe/suggest of fatigue cracks propagation throughout structure and for designed\nservice life, the knowledge of calibration functions is important. The cracks usually\npropagate from the edge or the surface of the structural element. The theoretical model\nof fatigue crack propagation is based on linear fracture mechanics (Paris law). Steel\nstructural elements are subjected to various bending load (three- and four-point bending,\npure bending etc.). The calibration functions for the edge cracks are calculated for\nvarious load and appropriate polynomial function independent on the distance are\nproposed for 3PB and 4PB load.
Comparison of calibration functions for short edge cracks under selected loads
Seitl, Stanislav ; Miarka, Petr ; Malíková, Lucie ; Krejsa, M.
Attention to the fatigue cracks in steel structures and bridges has been paid for long time. In spite to efforts to eliminate the creation and propagation of fatigue cracks throughout the designed service life, cracks are still revealed during inspections. Note, that depending on location of initial crack, the crack may propagate from the edge or from the surface. The theoretical model of fatigue crack progression is based on linear fracture mechanics. Steel specimens are subjected to various load (tension, three- and four-point bending, pure bending etc.). The calibration functions for short edge cracks are compared for various load and the discrepancies are discussed.
A numerical investigation of the stress intensity factor for a bent chevron notched specimen: Comparison of 2D and 3D solutions
Seitl, Stanislav ; Miarka, Petr ; Sobek, J. ; Klusák, Jan
In the contribution, normalized stress intensity factors for three- and four-point bending specimens with a chevron notch is introduced by varying the chevron notch angle and length. The three- and two-dimensional models of bent chevron notched specimens in the software ANSYS were prepared by using possible symmetrical conditions. The 2D model was used with variable thicknesses of the layers representing the characteristic shape of the chevron notch (with the plane stress boundary condition). The numerically obtained results from the 2D and 3D solutions are compared with data from literature.
Experimental determination of factors affecting the static modulus of elasticity of concrete using non-destructive testing methods
Kocáb, Dalibor ; Bílek,, Vlastimil (referee) ; Pazdera, Luboš (referee) ; Cikrle, Petr (advisor)
The Ph.D. thesis deals with one of the most important characteristics of hardened concrete; i.e. the modulus of elasticity. The thesis aims to describe and evaluate the important factors that affect the final value of concrete modulus of elasticity, especially those that can be influenced during construction. Another aim is to find ways to determine the static modulus of elasticity of concrete by non-destructive means (primarily ultrasonic pulse method, resonance method and use of electronic rebound hammers), thus to determine the possibility of creating calibration curve for NDT determination of the modulus of elasticity.

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