The main objective of this research is to develop a numerical model for the analysis of frost damage to masonry and implement it in a program for 3-dimensional analyses of masonry structures using the finite element method. It is shown that the standard FE approach in analysing masonry structures is not economical, so a homogenization technique was used to substitute composite masonry material with an equivalent homogeneous one. Parametric studies of relationships of property between constituents and the equivalent material are presented together with validation of the procedure. Masonry, or its constituents, is treated as a brittle material with a tensile cut-of failure criterion. Again, in order to achieve more computational efficiency, homogenization technique is used to represent cracked material. A set of freeze-thaw tests are described which are important in detecting the most influential factors controlling frost durability of masonry. Models of frost action are investigated on a micro scale - scale of individual pores. A stochastic network model is developed with an aim to investigate permeability characteristics of the porous material. The results of these calculations are used in providing information necessary to calculate stress due to the frost action. Typical examples of frost damage to masonry are simulated showing good agreement with the expected results. The following conclusions are drawn: * The major cause of damage to masonry is the expansion of water on its phase change from a fluid to a solid phase in the 'sealed container' conditions. * Micro structural properties of the material are the most important single factor in deciding the amount of internal loading on the material matrix caused by ice formation. In order to calculate this loading simulation of the process on the micro scale is required. * It is confirmed that a high fraction of small pores in the porous structure causes higher level of frost susceptibility.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:637824 |
| Date | January 1997 |
| Creators | Kralj, B. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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