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Analysis of concrete pipe using fracture-mechanical models
Bejček, Michal ; Šimonová, Hana (referee) ; Řoutil, Ladislav (advisor)
This bachelor thesis is focused on plain concrete pipe analysis in consideration of design problems. The introduction describes concrete pipe including imposed standards. The next part contains a summary of the calculation methods used nowadays. The thesis explores whether the fracture-mechanical calculation is sufficiently apt and therefore can be applied for the pipeline design. A number of pipe profile models was constructed and analysed for this purpose. The calculation based on the finite element method with applied crack band model was executed by software ATENA 2D. The crushing strength, which is compared to real tests data, is determined in models with altered input figures. The thesis also studies the negative effects on carrying capacity including material degradation.
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Fracture Analysis of Cube- and Cylinder-shaped WST Specimens Made of Cementitious Composites with Various Characteristic Length
Řoutil, L. ; Veselý, V. ; Seitl, Stanislav
The paper is focused on finding reasonable proportions for both cube-shaped and cylinder-shaped silicate-based composite specimens subjected to wedge-splitting tests. The analysis is conducted using finite element method code with an implemented cohesive crack model. The aspect of the material's brittleness, related to the heterogeneity of the material and described by what is termed as the characteristic length of quasi-brittle material, is accented. The results yield some recommendations for the determination of parameters of nonlinear fracture models for cementitious composites by means of wedge splitting tests of laboratory specimens of the two standard shapes.
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Analysis of concrete pipe using fracture-mechanical models
Bejček, Michal ; Šimonová, Hana (referee) ; Řoutil, Ladislav (advisor)
This bachelor thesis is focused on plain concrete pipe analysis in consideration of design problems. The introduction describes concrete pipe including imposed standards. The next part contains a summary of the calculation methods used nowadays. The thesis explores whether the fracture-mechanical calculation is sufficiently apt and therefore can be applied for the pipeline design. A number of pipe profile models was constructed and analysed for this purpose. The calculation based on the finite element method with applied crack band model was executed by software ATENA 2D. The crushing strength, which is compared to real tests data, is determined in models with altered input figures. The thesis also studies the negative effects on carrying capacity including material degradation.
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Influence of stress concentrator geometry on fracture parameters values of quasi-brittle materials
Frantík, P. ; Keršner, Z. ; Klusák, Jan ; Řoutil, L. ; Seitl, Stanislav ; Veselý, V.
To assess the reliability of building structures, values of fracture mechanical properties of their materials have to be known. In the case of cement-based composite types the basic parameters are ascertained on the basis of evaluation of the response of specimens conducted to a test in a suitable testing configuration. Three-point bending specimens with a central starting notch are the most frequently used specimens for laboratory testing. The influence of the stress concentrator – starting central edge notch – in a three point bend specimen on the resulting values of fracture toughness was studied in author’s papers: a crack initiation at the notch tip was numerically simulated. It was shown that the values of fracture toughness obtained for specimens with larger widths of starting notch can be overestimated.
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Influence of vertical compresive force on level of constraint in cubical specimen for wedge splitting test
Seitl, Stanislav ; Klusák, Jan ; Dymáček, Petr ; Řoutil, L. ; Veselý, V.
The subject of the contribution is to gain new aspects of knowledge about the fracture behaviour of cementitious building materials by the wedge splitting test (WST). The particularly, the paper investigates the influence of the vertical compressive force Pv, that represents a reaction of the bottom support of the specimen, on the fracture parameters via tools of the two-parameter fracture mechanics. The effects of the vertical compressive force, Pv, on the plastic and fracture process zones are examined.
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