STRENGTH ESTIMATION OF SLENDER STEEL CONCRETE COMPOSITE COLUMNS

1.提出了无支撑对称框架柱的有效长度系数的计算公式。利用能量法得到了柱子有效长度的计算公式，并对其进行了修正，以弥补不安全估计的影响。结果表明，用该公式计算得到的有效长度与正确值吻合较好。采用两种不同的方法计算了不同型钢截面型钢混凝土组合柱的屈曲荷载。一种是采用切线弹性模量理论，将钢材和混凝土视为一个整体。第二种是强度叠加法，将钢柱和混凝土柱分别计算的屈曲荷载的简单和作为屈曲荷载。通过对比两种强度，检验了叠加强度的准确性，并提出了基于叠加强度法的钢混凝土组合柱屈曲强度的简化设计方法。3.进行了方钢管混凝土柱的轴心和双向偏心受压试验。选取屈曲长高比、偏心距大小和偏心荷载角作为试验参数。对力量和行为进行检查。得出的结论是：利用本文提出的单轴偏心受压柱强度公式，可以预测双向偏心受压柱的最大强度。

1. A formula for evaluating an effective length factor of column in unbrased symmetrical frame is proposed. An equation for an effective length of column is obtained by using the energy method, and it is modified to compensate for unsafe estimation. It is shown that the effective length obtained by proposed formula agrees well with the correct value.2. Buckling load of steel concrete composite columns with various steel sections is calculated in two different ways. One is performed using the tangent modulus theory, considering steel portion and concrete portion behave as a one body. The second one is the method of superposed strength in which a simple sum of separately computed buckling load of steel and concrete columns is regarded as a buckling load. By comparing with two strengths, accuracy of superposed strengths are examined, and simple design method for evaluating the buckling strength for steel concrete composite columns is proposed on the superposed strength method.3.Concrete filled square steel tubular columns were tested under concentric and biaxially eccentric load. As the experimental parameters, the buckling length-section depth ratio, magnitude of eccentricity and angle of eccentric load are selected. Strength and behavior are examined. It is the conclusion that : the maximum strength of columns under biaxially eccentric load are able to predict by the previously proposed strength formula of columns under uniaxially eccentric load.