冷弯薄壁U型钢轴压短柱承载力计算的直接强度法研究

RESEARCH ON BEARING CAPACITY DESIGN OF COLD-FORMED THIN-WALLED U-SHAPED STEEL AXIAL COMPRESSION SHORT COLUMN BASED ON DIRECT STRENGTH METHOD

现行北美冷弯型钢规范中直接强度法只适用于卷边C形、腹板加劲C形、Z形、R形和帽形这些截面形式较为简单的单肢截面,但并未涉及U形截面。为研究直接强度法对冷弯薄壁U型钢轴压短柱的适用性,采用ABAQUS非线性有限元分析了16种截面尺寸、4种厚度的64根试件,并对有限元模拟得到的极限承载力、部分学者试验结果进行回归,最终得到考虑U形截面屈曲后强度的局部屈曲承载力曲线。结果表明:现有的直接强度法公式计算结果偏于不安全,对现有的直接强度法公式进行了简单的修正,修正后的直接强度法计算式精度更高。

The current North American standard defines that direct strength method(DSM)is only applied in lipped C-shaped steel, web stiffened steel with cross-section of C-shaped,Z-shaped, R-shaped and hat-shaped. These cross section forms are simple single limb section, but U shaped section is not involved. The purpose of the paper is to study the applicability of the U-shaped steel axial compression short column with direct strength method. The ABAQUS nonlinear finite element analysis was used to analyze 64 specimens, included 16 kinds of section sizes and 4 kinds of thicknesses. The ultimate bearing capacity of U-shaped steel axial compression short column and experimental results of some scholars were regressed. Besides,the local buckling bearing capacity curve of U-shaped section post-buckling strength was also taken into account. The results showed that the calculated results from the formula of direct strength method were unsafe. A simple correction of the existing direct strength formula was made, which resulted in the higher accuracy of the modified direct strength formula.