Out-of-plane creep buckling behavior of quadri-trussed CFST arches

The out-of-plane creep buckling analysis was carried out on quadri-trussed concrete-filled steel tubular (CFST) arches by finite element method to investigate how the pre-buckling deformation induced by the construction process and the time effects influence their out-of-plane stability. All the material properties, which account for time effects and the variation of age at loading during construction, were implemented in ABAQUS with UMAT subroutines. An extensive parametric study was carried out to numerically investigate the out-of-plane creep buckling behavior of quadri-trussed CFST arches. Considered parameters include the slenderness of the arch, the steel ratio, et al. It concludes that the prebuckling deformation induced by construction process and time effects can reduce the out-of-plane buckling loads by up to 22.5% within the range of parameters considered in this paper. Such effects are more pronounced in slender arches with higher sustained loading level or lower α ratio, which need to be accounted for in the design.