Development of an Effective Method for Calculations related to Creep

摘要

An effective method combining the retardation spectrum method from BaA 3/4 ant and derived recursive equations based on generalized Kelvin model is proposed for calculations of creep in this paper. The retardation spectrum method can convert most compliance functions into Dirichlet series, and recursive equations are derived from Kelvin element and then expanded to fit the generalized Kelvin model. With recursive equations, the storage of stress history can be avoided during creep calculations. The ACI 209R-92 model is taken as the converted model throughout the presented research. The usefulness of recursive equations is proved by comparisons with the original formulas. Moreover, comparisons between this method and an existing method are conducted, and it is found that the new method presented in this paper is more accurate, especially for aging materials. A creep test is simulated using this method embedded in FEM, and the computed results show that this method is effective in numerical methods. A complete case of early-age thermal stress of a concrete structure is conducted at last, and the results reveal that this method is feasible and stable, and as an important behavior of concrete, creep should not be neglected in calculations of thermal stress of concrete.