The Application Of RVE To Research In Mechanical Properties Of Masonry Structure

As an ancient structure, masonry structure is widely used all around the world. It accounts for a significant proportion in our existing industrial and civil buildings owing to its unique strengths, and a large number of buildings (especially residential construction) will be dominated by masonry structure in the future for a long period of time. However, due to the nonuniform physical properties of masonry materials and the complex relationship between the constituent phases of masonry under the external load, the theoretical study of masonry structures can't come up with the practice of masonry engineering, which prevents the application of masonry in engineering.In this thesis, the equivalent process from composition of brick masonry to the representative volume element (RVE) has been studied by means of experimental research, micro-mechanical model and finite element simulation based on the masonry homogenization theory. The mechanical properties of masonry structures have been discussed, mainly to work in the following areas:1. The status of masonry structure have been summaried, including the history, development, advantages and disadvantages, etc. All of the directions and methods used in the study of masonry structure currently have been introduced, which focused on the homogeneous theory and application of masonry used in this article.2. Based on the existing experimental conditions, the mechanical properties of common concre- te brick and mortar, uniaxial compressive strength and the shear-compressive complex strength of RVE have been tested, and the characteristics of damage and the situation of cracks development have been described in diteil. The compression damage stages and the various shear-compressive failure modes of RVE have been summaried, and the develop trend of the composite curves related to shear and pressure has been found, which provided the basis for the numerical calculation.3. Taking the synergy effect of the constituent phases into account, the mechanical properties of the basic cell (1/4RVE) have been analyzed using the homogenized micro-mechanical model of masonry. The equivalent elastic properties of the basic cell (elastic modulus, poisson ratio and shear modulus, etc.) have been derived, which seem to represent well the results obtained with the finite element method.4. Based on the finite element analysis software (ANSYS), the stress-strain relations of RVE under a variety of load cases have been simulated, which povided the equivalent elastic properties, the strength envelope in the stress invariant space and the elastic-plastic constitutive matrix of RVE in the macro level. The failure modes of RVE under different stress condations have been described, and the yield surface has been formulized approximately.5. The influence of the scale effect on the results of the finite element simulation has been verified, using the method of cumulative RVE, and the results show that forced displacement loading is more consistent with the assumptions of homogenization theory, which can effectively reduce the adverse effects of complex constraints and loading patterns in the equivalent process.6. The equivalent parameters of RVE obtained by experimental study, mechanical model and finite element analysis were compared, and the homogenization theory was then utilized to the finite element analysis of a practical test. The results represented well the results obtained from the experimental research, which indicated that the homogenization method can reflect the original mechanical properties of masonry structures to a certain extent. Therefore, the research of homogenization theory of masonry materials in this thesis provides a more simple and effective method to carry out large-scale finite element analysis of masonry structures.