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- 2017
“上”形截面钢梁弯扭联合作用下整体稳定性分析
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Abstract:
为对“上”形截面钢梁弯扭联合作用下的整体稳定性进行分析，采用有限元数值计算方法，通过失稳模态考虑构件L/1 000（L为跨径）的几何初始缺陷，对比已有文献试验结果，验证了模拟方法的正确性，在此基础上，对跨中集中荷载和满跨均布荷载作用下的简支“上”形截面钢梁整体稳定性进行分析，通过曲线拟合给出了“上”形截面钢梁整体稳定系数计算公式，分析了荷载偏心距和跨径对稳定承载力及弯扭效应分配的影响。研究结果表明：通过失稳模态考虑构件L/1 000几何缺陷可以准确地计算稳定承载力；“上”形截面钢梁整体稳定系数的取值较国标规范工字梁小，且均布荷载较集中荷载小；“上”形截面钢梁的稳定承载力随着偏心距和跨径的增加逐渐降低，且影响程度也逐渐变小；偏跨比较大时，失稳破坏主要由扭转效应引起，偏跨比较小时，则主要由弯曲效应引起；集中荷载较均布荷载更容易使“上”形截面钢梁失稳；使用《冷弯薄壁型钢结构技术规范》（GB 50018―2002）进行“上”形截面钢梁的整体稳定性验算会偏于不安全。
In order to analyze the overall stability of “上”-section steel girder under combined bending and torsion, finite element method was used and L/1 000 (L?was span) geometric imperfection was considered by buckling mode. Compared with experiment data of existing literature, the veracity was verified. On the basis above, stability of “上”-section steel girder under concentrated load on mid？？span and uniform load on full span were respectively analyzed. A formula of “上”-section steel girder overall stability coefficient was proposed by curve fitting, and the effects of load eccentricity and span on stability bearing capacity and proportion of bending and torsion were also analyzed. The study results indicate that stability bearing capacity can be accurately calculated by considering L/1 000 geometric imperfection through buckling mode. Overall stability coefficient of “上”-section steel girder was less than I-girder specified in China’s code for design of steel structures, which under uniform load is less than concentrated load. Stability bearing capacity of “上”-section steel girder reduces as the increasing of load eccentricity and span, and the degree of influence also reduces as well. Buckling failure is induced mainly by torsional effect in the large ratio of eccentricity and span, and is induced mainly by bending effect in the small ratio of eccentricity and span. It will be unsafe using Technical Code of Cold-formed Thin-wall Steel Structures (GB 50018―2002) to check the overall stability of “上”-section steel girder
