冷弯不等肢复杂卷边角钢轴压试验及承载力设计方法

Experiment and Design Method of Cold-Formed Thin-Walled Steel Unequal-Legged Complex-Lipped Angles Under Axial Compression

为研究冷弯薄壁不等肢复杂卷边角钢屈曲性能和稳定承载力设计方法,对24根不同截面、长细比、宽厚比的不等肢复杂卷边角钢进行了轴压试验。试验结果表明,长细比较大且宽厚比较小的试件易发生弯扭屈曲,长细比较小而宽厚比较大的试件易发生局部屈曲或弯扭和局部相关屈曲。采用ABAQUS有限元软件对试件进行了有限元模拟,屈曲模式和承载力与试验结果吻合良好,表明建立的有限元分析模型是可行的。因此可采用经验证的有限元模型对不同长细比、卷边形式和卷边比的轴心受压不等肢复杂卷边角钢进行了参数化分析。结果表明,试件极限承载力受长细比的影响最为明显,将卷边比控制在一定范围内或改变卷边形式可提高试件极限承载力。最后将试验结果与直接强度法计算结果进行对比,表明直接强度法计算试件承载力较不安全。因此基于试验和数值分析结果提出轴心受压冷弯薄壁不等肢复杂卷边角钢构件考虑整体屈曲后强度的直接强度法修正公式,并通过对比试验结果和有限元分析结果验证了该修正公式的准确性和可行性。

To study the buckling behavior and design method of cold-formed thin-walled steel unequal-legged complex-lipped angles(CTSUCAs)under axial compression,24 CTSUCAs with different sections,slenderness ratios and width-to-thickness ratios were tested.The test results showed that the specimens with large slenderness ratio and small width-to-thickness ratio were prone to flexural-torsional buckling,while the specimens with small slenderness ratio and large width-to-thickness ratio were prone to local buckling or interaction buckling of flexural-torsional buckling and local buckling.The buckling modes and load bearing capacities analyzed by the ABAQUS finite element software showed good agreement with the test results,which indicated that the established finite element model is feasible.Then the verified finite element model was used to analyze the CTSUCAs with different slenderness ratios,width ratios of the lip to the leg,and lip forms.The analysis results showed that the ultimate capacity of angle is most obviously affected by the slenderness ratio.The ultimate capacity of angle could be increased by controlling the width ratios of lips to the leg in a certain range or changing the lip forms.The comparison between the test results and the results calculated by direct strength method(DSM)shows that the DSM is unsafe.Finally,based on the experimental and numerical analysis results,the modified DSM is proposed for CTSUCA considering the post-global buckling strength.The comparisons with the experimental and finite element analysis results show that the proposed formulae is accurate and feasible.