In-plane creep buckling for pin-ended concrete-filled steel tubular circular arches

The core concrete creep in concrete-filled steel tubular (CFST) arches changes the internal force distribution between steel tube and core concrete; moreover, it increases the pre-buckling deformation which will reduce the in-plane buckling resistance significantly. The classical buckling theory which assumes that the arches have linear pre-buckling behaviors and the effects of pre-buckling deformation can be ignored is not suitable for predicting the in-plane buckling of CFST arches considering creep, especially for shallow CFST arches in which the pre-buckling deformation has a notable effect on the stability behavior. Based on the creep characteristics of CFST arches and the age-adjusted effective modulus method, the nonlinear in-plane equilibrium and buckling equations for CFST arches are established by using a virtual work formulation. By solving these equations, the effect of core concrete creep on the stability of CFST arches has been adopted. In addition, the influence of creep coefficient has been investigated, and the relationship between creep buckling behaviors and service time has also been discussed in this paper.