In this paper, the two-scale random field model is introduced within the framework of the elastic-plastic stochastic damage mechanics for representing the spatial variation of concrete. A framework for stochastic nonlinear response analysis is developed, where the probability density evolution method is adopted to quantify the propagation of randomness in concrete structures, and the two-scale random field model is applied to represent the spatial variation of concrete. The proposed framework is demonstrated by an illustrative example, which address the stochastic nonlinear response of the reinforced concrete frame structure.