Abstract: The concrete transient strain is transformed into the free expansive strain by a equivalent thermal expansive coefficient firstly; and then, based on the one-dimensional model for transient strain and the open service interface of general commercial program software, a subsroutine is developed to include the transient strain under the state of three-dimensional stress and the fire including heating and cooling; in the end, test data are used to verify the method. The comparison results show that: with the inclusion of transient strain, the deformations of structures under heating and cooling increase, and the calculation results are much closer to the test results, which demonstates the equivalent expansive coefficient is a feasible method to include transient strain explicitly.