中美规范关于卷边槽形受弯构件承载力比较分析

新近纳入北美规范NAS 2004的直接强度法对冷弯型钢构件的畸变屈曲要求单独验算,但《冷弯薄壁型钢结构技术规范》(GB 50018-2002)对此还无明确规定。在总结冷弯型钢构件畸变屈曲性能的基础上,对其承载力计算方法给予介绍,由简化模型计算得到的受弯构件的畸变屈曲弹性临界应力中,引入直接强度法计算“规范”(GB 50018-2002)附录中卷边槽形受弯构件的承载力。结果表明,附录中部分截面的受弯承载力由畸变屈曲控制。同时,NAS 2004与“规范”(GB 50018-2002)计算结果的比较表明,“规范”(GB 50018-2002)的计算规定虽安全,但太过保守。因此,提出将翼缘屈曲系数调高至3.0的建议。

COMPARISON AND ANALYSIS OF LIPPED CHANNEL FLEXURAL MEMBERS' CAPACITY CALCULATED BY SPECIFICATION NAS 2004 AND GB 50018-2002

A separate check on distortional buckling of cold-formed steel members exists in Direct Strength Design Method(DSM) newly accepted by North American Specification NAS 2004.But no specific design rules for it in "Technical Code for Cold-Formed Thin-Walled Steel Structure"(GB 50018-2002).A summary of distortional buckling behavior is presented.The calculated method of distortional buckling members is introduced and analyzed.Based on the critical elastic distortional buckling stress calculated by simplified analytical model,the bearing capacities of lipped channel flexural members in appendix of GB 50018-2002 are calculated by DSM;and the calculated results show that the bearing capacity of some lipped channel flexural members is governed by distortional buckling.According to the comparisons of calculated results by DSM with results by GB 50018-2002,the conclusions can be drawn that provisions in GB 50018-2002 are safe but too conservative.So a design suggestion that increases the buckling coefficient of flange to 3.0 is proposed.