Study Of Concrete Material Properties Based On Mesomechanics

In this dissertation concrete is considered as a two-phase heterogeneous composite material consisting of mortar matrix and aggregate on mesoscopic level. Several calssical theories and bound methods in continuum micromechanics of predicting effective elastic properties of two-phase composite materials is mostly introduced: dilute method, self-consistent method, Mori-Tanaka method, Voigt and Reuss limit,etc. Formulas of thermal expansion coefficient of concrete and formulas of average temperature residual stress of mortar and aggregate is derived from thermoelastic heterogeneous composite material homgenization theory. RVE size is respectively chosen as 200mm×200mm 300mm×300mm and 400mm×400mm.After dividing grid, the location of aggregate is random generated by Monte Carlo method, and the random aggregate concrete models are established by the compiled program with Fortran language. Those random aggregate concrete models are respectively loaded by homogeneous stress and homogeneous strain boundary condition and rising temperature. At last, finite element analysis and theoretical calculation are compared. The result of the analysis and computation shows that: Macroscopical effective elastic modulus curves based on Mori-Tanaka method agree with finite element results better; The formula (3.37) of macroscopical effective thermal expansion coefficient of concrete agree with finite element results; The formulas of average temperature residual stress of mortar and aggregate agree with finite element results.