A general method of calculating stress redistribution due to differential creep in concrete structures

Abstract A method of calculating the variation with time of stress resultants in a loaded concrete structure whose members exhibit differential creep strains is presented. An arbitrary time function ϑ(t) is chosen to express the variation of creep deformations of structural concrete and a normalized new function F(t) is introduced. The solution of the problem at this stage is assumed to be carried out on a full section where compatibility of deformations is ensured. The proposed method leads to a compatibility system of linear differential equations the number of which depends on the degree of indeterminacy of the structure. The Runge-Kutta numerical procedure is employed for the solution of the differential system. The application of the method to the solution of some standard engineering structures is presented and the differential equations are developed. A numerical example of a reinforced concrete portal frame loaded for eight months, is carried out. The variation of the stress resultants with time are presented numerically and graphically. A listing of the computer programme developed is also presented.