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The purpose of research - perfection of mathematical approaches to an estimation of durability of reinforced concrete structures. The method of research used in work is based on known positions of theories of plasticity with nonassociated flow rule and double isotropic hardening. Result of work are the basic mathematical dependences of nonlinear model of concrete on the basis of the nonassociated flow rule, and algorithm of their application for an estimation of durability of concrete and reinforced concrete bridge structures. The nonassociated flow rule is used. For the description of nonlinear compressibility of a material at the three-dimension stress state, additional loading surfaces and the plastic potential, are entered. The strength surface of durability is presented in the principle stresses space in the form of the closed volume (cap model). The loading surface is under construction as similar of a strength surface. Complexity of the received mathematical model is compensated by opportunities of calculation of designs at nonproportionate loadings. The model can be built in the general model of deformation of concrete and reinforced concrete with cracks, including - in view of cyclic and long term loadings. The practical importance consists in applicability of model for forecasting durability of statically indefinable concrete and ferro-concrete designs having damages in the form of cracks. |
