圆端形钢管混凝土短柱极限承载力计算方法研究

Study on calculating method of ultimate bearing capacity of round-ended concrete filled steel tube short columns

圆端形钢管混凝土短柱受力机理相较于圆形和矩形截面更加复杂,目前还没有一个定量的表达式用于计算圆端形钢管混凝土短柱轴压和偏压的承载力。为分析研究圆端形钢管混凝土短柱轴压和偏压的承载力性能,进行了8个圆端形钢管混凝土短柱轴压试验和6个圆端形钢管混凝土短柱偏压试验,分别基于双剪切统一强度理论和极限平衡理论推导出相对应的圆端形钢管混凝土短柱轴压承载力计算公式,用Python语言编制基于纤维模型法的承载力计算程序,最后提出了适用于圆端形钢管混凝土短柱轴压和偏压的统一承载力公式,并用试验数据对公式进行验证。结果表明:基于双剪切统一强度理论、极限平衡理论及纤维模型法推导的三种轴压承载力计算理论公式均具有较好的精度,满足工程要求,DBJ/T 13-51规范所计算的承载力偏小,计算结果精确度最差。推导的三种理论公式中基于双剪切统一强度理论推导的承载力计算公式精度最高,更适用于圆端形钢管混凝土短柱轴压承载力计算。最后验证了修正的圆端形钢管混凝土短柱轴压和偏压承载力统一公式的准确性,计算偏压的适用范围为e/R≤1.55。

The mechanical behavior of round-ended concrete filled steel tube(RCFST)short column is more complex than that of short columns with circular and rectangular sections.At present,there is no quantitative expression for calculating the bearing capacity of RCFST short columns under axial and eccentric loads.In order to analyze and study the axial and eccentric load bearing capacity performance of the RCFST short columns,axial compression tests were carried out on 8 RCFST short columns and eccentric compression tests were carried out on 6 RCFST short columns.Based on the doubleshear unified strength theory and the limit equilibrium theory,the corresponding calculation formulas for the axial compression bearing capacity of RCFST short columns were derived.Python language was used to compile the calculation program of bearing capacity based on fiber model method.Finally,a unified bearing capacity formula suitable for RCFST short columns under axial and eccentric loads was proposed,and the formula was verified by experimental data.The results show that the three theoretical formulas for calculating the axial compression bearing capacity derived based on the doubleshear unified strength theory,the limit equilibrium theory and the fiber model method all have good accuracy and meet the engineering requirements.The bearing capacity calculated by the DBJ/T 13-51 code is small,and the calculation result has the worst accuracy.Among the three theoretical formulas derived,the bearing capacity calculation formula derived based on the double-shear unified strength theory has the highest accuracy,and is more suitable for calculation of the axial compression bearing capacity of RCFST short columns.Finally,the accuracy of the revised uniform formula for the bearing capacity of RCFST short columns was verified,and the applicable range for calculating the bias was e/R≤1.55.