In order to obtain formulas of creep stress redistribution on composite beams,constitutive relations of concrete creep were established by taking an axisymmetric composite cross section subjected to moment and axial force as a research object, and the differential equations of moment and axial force redistribution with internal forces distribution method were deduced.Then practical approximate solutions were acquired through effective simplified conditions to avoid complicated calculations of exact solutions. Its accuracy was verified through an example finally.The results showed that the error between approximate and exact solutions was very small,which could achieve reasonable calculation accuracy.Concrete creep was a significant influence on a long-term stress characteristic of composite beams which must be put enough attention in computation.The internal forces distribution method can be used in a wide range as long as internal forces are converted to moment and axial force in the section neutral axis regardless of applied loading type, whether statically determinate or indeterminate structure.
