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

Abstract

为研究拱肋核心混凝土时效与施工过程共同作用所引起的屈曲前变形对钢管混凝土桁式拱肋稳定承载力的影响,建立四肢桁式钢管混凝土拱桥单拱肋的有限元模型,同时考虑时效作用与施工过程,对其出平面稳定承载力进行分析.采用UMAT对ABAQUS进行二次开发,以考虑时效作用影响及施工过程中加载龄期的变化.在此基础上,考虑长细比、含钢率等参数的影响,对四肢桁式钢管混凝土拱的出平面徐变稳定承载力进行参数分析.分析表明,兼顾施工过程影响后,在本文分析参数范围内,时效作用可使四肢桁式钢管混凝土拱的出平面稳定承载力最多降低22.5%,该影响随着长细比的增大、含钢率的降低及持荷等级的提高而增大,在设计中应予以考虑. 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.