Performance of axially restrained concrete encased steel composite columns at elevated temperatures

摘要: Abstract The structural performance of axially restrained concrete encased steel composite columns at elevated temperatures is investigated in this study. An efficient nonlinear 3-D finite element model was presented for the analysis pin-ended loaded columns. restraint ratios varied from 20% to 100% axial stiffness ambient temperature. verified against published test results on temperatures. had different cross-sectional dimensions, coarse aggregates and load during fire. material properties steel, concrete, longitudinal transverse reinforcement bars as well effect confinement were considered model. interface between section bars, also allowing bond behaviour be modelled components retain its profile deformation column. initial overall geometric imperfection carefully included time–temperature relationships, deformed shapes failure, time–axial displacement failure modes fire resistances evaluated by compared results. Furthermore, variables that influence resistance comprising ratios, fire, slenderness a parametric It shown behave differently unrestrained since typical “runaway” not predicted analysis. obtained with design values Eurocode 4 EC4 generally conservative all columns, except some higher ratios.