Investigation of concrete encased steel composite columns at elevated temperatures

摘要: Abstract This paper presents a nonlinear 3-D finite element model investigating the behaviour of concrete encased steel composite columns at elevated temperatures. The were pin-ended axially loaded having different cross-sectional dimensions, structural sections, coarse aggregates and load ratios during fire. material properties steel, concrete, longitudinal transverse reinforcement bars as well effect confinement ambient temperatures considered in models. interface between section bars, also allowing bond to be modelled components retain its profile deformation column. initial overall (out-of-straightness) geometric imperfection was carefully included model. has been validated against published tests conducted time–temperature relationships, deformed shapes failure, time–axial displacement failure modes fire resistances evaluated by It shown that can accurately predict Furthermore, variables influence resistance comprising fire, slenderness investigated parametric studies. is generally increases with decrease column ratio increase ratio. relationship considerably affected aggregate. obtained from analyses compared design values Eurocode 4 for EC4 conservative all columns, except 0.5 0.69 0.4.