基于合理的钢管混凝土数值本构模型,采用截面分层法,提出基于部分正弦曲线的模型柱法。利用钢管混凝土偏压柱最不利截面的曲率与正弦幅值的关系,对不等端弯矩钢管混凝土偏压柱进行承载力分析,计算结果与试验结果吻合良好;之后分别采用等效弯矩法和等效长度法,探讨了含钢率、钢材强度、混凝土强度等级、构件长细比和最大偏心率对等效长度系数曲线和等效弯矩系数曲线的影响,指出国内已有规程建议的等效系数的不足;通过大量参数分析,提出不等端弯矩钢管混凝土偏压柱承载力长度等效系数实用计算公式,该公式计算结果与国内外79组不等端弯矩钢管混凝土偏压柱承载力的试验结果相比偏于安全。研究成果可为钢管混凝土柱设计提供参考。
Based on a numerical constitutive model of concrete filled steel tubes, a layer method was applied and a fiber model based on partial sinusoidal curves for concrete filled circular steel tubular (CFST) columns was proposed. Utilizing the relationship between the curvature of the least favorable section and sinusoidal amplitude, a FORTRAN program was developed, and the behavior of CFST columns under eccentric loading of unequal end-moments was analyzed. The analysis results are in good agreement with the experimental results in the literature. The influences of significant parameters, such as steel ratio, yield strength of steel, strength grade of concrete, the slenderness ratio and eccentricity ratio, on the equivalent column length coefficient curves and the equivalent moment coefficient curves were discussed by using equivalent column length coefficient method and equivalent moment coefficient method, respectively. The shortcomings in the existing Chinese specification of the equivalent coefficient were pointed out. Through parameter analysis, a practical calculation formula for the equivalent column length coefficient for the beam-columns under eccentric loading was proposed. Reliability of the design method was validated by the test results of 79 specimens from the country and abroad.