Being critical components in composite structures, the short-term structural behaviour of stud shear connectors has been extensively investigated. Despite this, there has been somewhat limited attention devoted to their time-dependent behaviour. In this paper, the results of four long-term push-out tests are reported: the test parameters including the loading age and stud diameter. The test results are shown to be simulated accurately by a finite element model established using ABAQUS, in which the long-term behaviour of the concrete is considered by implementing a stepwise approach. The numerical procedure is applied to conduct a parametric analysis, with the effects of different parameters, viz., the loading age, concrete material, external environment, stud size and reinforcement ratio being considered. Based on the numerical results, an analytical formulation is derived for the creep coefficients of composite members with different loading ages. Comparisons with FE model data shows that the derived equation has sufficient accuracy and can be applied for designing composite structures considering their long-term response.