No abstract

The objective of the study is development of a creep kernel recording form, which allows obtaining representations for creep curves calculation. Based on the elastic-creeping body theory a possibility of the high-rate creep movement analytical study has been shown. A creep kernel, which contains a formula to describe the aging material properties, has been built. Essential stages of the proposed creep kernel formation have been given. The correspondence of the proposed calculations to real processes has been proved by a comparison with experimental data. In the numerical implementation, decomposition of integration elements into power series has been used. A possibility of calculating functions for a long time interval has been shown. Creep kernel parameters have been determined on the basis of experimental data of early age concrete samples by minimizing the standard deviation of theoretical and empirical values.

No abstract

No abstract

The issues of modeling and calculation of a section of a main pipeline reconstructed by a composite coupling are considered. Such a section is a two-layer composite cylindrical structure. At the heart of the construction а model are provisions and the hypothesis of the classical theory of shells (variant of L. I. Balabukh — V. I. Novozhilov) and the theory of deformation of composite structures (A. R. Rzhanitsyn). The aim of the work is mathematical modeling and study of the tensely deformed state (TDS) in the field of installation of the coupling. The problem of calculating a section of a pipeline repaired in accordance with the composite-coupling technology (CCT), which is under the action of internal hydrostatic pressure, is considered. A mathematical model of deformation of a two-layer circular cylindrical shell is presented in the form of a system of differential equilibrium equations and boundary conditions. Shear tension in the interlayer seam are taken into account.