STRENGTH ESTIMATION OF SLENDER STEEL CONCRETE COMPOSITE COLUMNS

1. 提出了非基对称框架柱有效长度系数的计算公式。利用能量法得到了柱的有效长度方程，并对其进行了修正，以补偿不安全估计。计算结果表明，该公式计算的有效长度与正确值吻合较好。对不同型钢截面钢-混凝土组合柱的屈曲荷载进行了两种不同的计算方法。其中一种是采用切线模量理论，考虑到钢部分和混凝土部分是一体的。第二种是强度叠加法，将分别计算的钢柱和混凝土柱的屈曲荷载简单相加作为屈曲荷载。通过对两种强度的比较，检验了叠加强度的准确性，并在叠加强度法的基础上提出了钢-混凝土组合柱屈曲强度评定的简单设计方法。对方钢管混凝土柱进行了同心和双轴偏心荷载试验。实验参数选择屈曲长截面深度比、偏心载荷大小和偏心载荷角度。检查力量和行为。结果表明：利用所建立的单轴偏心荷载下柱的强度公式可以预测双轴偏心荷载作用下柱的最大强度；

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.