RPC外包方钢管混凝土柱轴压受力性能研究

Study on mechanical behavior of CFSST columns encasedby RPC under axial compression

为了研究活性粉末混凝土(Reactive powder concrete,RPC)外包方钢管混凝土柱的轴压受力性能,以RPC厚度和长细比为参数,对6根构件开展轴压试验研究,探讨该类组合柱的破坏模式、受力机理、套箍效应和承载力。试验结果表明:外层RPC可为内部方钢管混凝土柱提供较强的约束力,在受力后期套箍效应凸显。随着RPC厚度的增加,组合柱的承载力逐渐提高;随着组合柱长细比的增大,虽然其弹性刚度和承载力逐渐降低,但延性改善。采用ABAQUS软件建立RPC外包方钢管混凝土柱的有限元模型,分析RPC强度、RPC厚度、钢管强度等级、含钢率、内部混凝土强度和长细比等参数对组合柱承载力的影响规律,可得方钢管混凝土柱发挥系数的变化幅值为0.78~1.01。在试验研究、有限元参数分析和理论探讨的基础上,借鉴钢管混凝土结构技术规范,提出了RPC外包方钢管混凝土轴压短柱和长柱的承载力简化计算方法,公式计算值与已有数据样本吻合良好。

In order to study the axial compression behavior of concrete-filled square steel tubular(CFSST)columns encased with reactive powder concrete(RPC),six specimens were tested under axial compression with the parameters of the thickness of RPC and the slenderness ratio.The failure mode,mechanical mechanism,confinement effect,and bearing capacity of the columns were discussed.The test results show that the outer RPC can provide a strong binding force for the inner CFSST columns,and the confinement effect is prominent in the later stage of loading.With the increase of thickness of RPC,the bearing capacity of the composite column increases gradually.With the increase of slenderness ratio,although the elastic stiffness and bearing capacity of the composite column decrease gradually,the ductility is improved.The finite element model of RPC encased CFSST columns was established by the ABAQUS software,and the influence of RPC strength,RPC thickness,steel tube strength grade,steel ratio,internal concrete strength and slenderness ratio on the bearing capacity of the composite column was analyzed,and the variation amplitude of the exertion coefficient of CFSST column was 0.78~1.01.Based on the experimental study,the parametric finite element analysis and the theoretical discussion,a simplified calculation method for the bearing capacity of RPC encased CFSST short and long columns under axial compression is proposed by referring to the technical code for concrete filled steel tubular structures,and the calculated values from the formula are in good agreement with the existing data samples.