冷弯薄壁型钢多肢拼合柱轴压承载力计算方法对比分析

Comparison Analysis of Calculation Methods for Axial Compression Capacity of Cold-Formed Thin-Walled Steel Columns with Built-Up Sections

以由单肢C形和U形截面拼合而成的冷弯薄壁型钢拼合截面轴压柱试验结果为基础,对采用我国现行规范与征求意见稿中有效宽度法计算的30根(6种截面,5种长度)轴压构件的极限承载力进行了对比分析。基于有效宽度法,提出了针对组合截面承载力的计算方法。比较了我国规范征求意见稿与美国规范中直接强度法的不同,基于美国规范的直接强度法利用CUFSM有限元软件对拼合截面进行建模分析,取消螺钉拼合连接部分的板件边界,将拼合截面作为一个整体进行分析,拼合部分厚度在1.0t至2.0t。对比发现:对于开口截面,厚度为1.0t时计算值与试验值之比的平均值更接近于1.0;对于闭合截面,厚度为1.2t时计算值与试验值之比的平均值更接近于1.0。

Based on experimental results of the cold-formed thin-walled steel section columns combined from the C-shaped and U-shaped sections under axial compression,the ultimate load-bearing capacity of 30 members(six different sections,five different lengths)calculated by the effective width method in the current code and exposure draft code are compared respectively.A calculating method is proposed based on the effective width method.In addition,the comparison is made to find out the difference about the direct strength method between the exposure draft of the Chinese standard and the current American standard.Through removing the screws and the boundaries of the contacts,the built-up sections are treated as a whole section in CUFSM,and the corresponding thickness of the contacts changed from 1.0t to 2.0t.It is noticed that for open sections,the average analyzed values of the groups with 1.0t thickness are closer to the experimental data than others.While for closed sections,the groups with 1.2t thickness are more accurate than others.