热轧方、矩钢管受弯构件承载力设计方法研究

RESEARCH ON THE DESIGN METHODS FOR BEARING CAPACITY OF HOT-ROLLED STEEL SHS/RHS UNDER BENDING

研究非薄柔截面热轧方、矩钢管抗弯极限承载力的设计方法。采用有限元软件ABAQUS建立考虑残余应力和初始几何缺陷的数值模型,并将有限元结果与已有试验结果进行对比,以验证有限元模型的可靠性。参数分析了不同截面高宽比以及板件宽厚比的受弯构件极限承载力,将有限元计算结果与欧洲EN1993-1-1标准、美国ANSI/AISC 360-10标准和GB 50017—2003《钢结构设计规范》以及连续强度设计方法计算结果进行对比,研究当前各类设计方法的精确度。EN 1993-1-1和GB 50017—2003利用构件板件宽厚比,将截面抗弯承载力划分为塑性设计以及弹性设计,计算结果存在不连续性;ANSI/AISC 360-10采用以屈服弯矩和塑性弯矩为端点的线性设计曲线对非厚实截面进行设计,使得非厚实截面的部分计算结果偏于保守。基于数值计算结果建议将GB 50017—2003中热轧方、矩钢管的塑性发展系数取为1.1。相比现有标准中推荐的设计方法,连续强度设计方法反映了截面承载力与构件截面正则化宽厚比的连续关系,并能有效利用非薄柔构件钢材应力强化的性能,是一种更为有效的设计方法。

In order to evaluate the design methods for hot-rolled steel non-slender square and rectangular hollow sections（SHS/RHS） under bending,the finite element（FE） software ABAQUS was used to establish numerical models,which considering both the residual stress and initial local geometric imperfections. The finite element analysis results were compared with the experimental results,which verified the reliability of the finite element model.The parametric analysis of ultimate bearing capacity of flexural members with different height-width ratios and widththickness ratios of member section was conducted. The FEM results were then used to evaluate the accuracy of resistance predictions computed by the current code recommending design methods in EN 1993-1-1,ANSI/AISC360-10 and GB 50017—2003,and the Continuous Strength Method（CSM）. According to the width-thickness ratio of member section,the flexural bearing capacity of member could be devided into plastic（partial plastic） design and elastic design in the codes of EN 1993-1-1 and GB 50017—2003,and the calculated results were discontinuous.The linear design curve with yield moments and plastic moments as endpoints was used to design non-conpact sections in American Code ANSI/AISC 360-10,and some calculated results of non-compact sections were conservative.Based on the FEM results,it was suggested that 1. 1 could be used as the plastic development coefficient for hotrolled SHS/RHS in Chinese code GB 50017—2003. Compared with the existing design methods in those codes,the CSM could reflect the continuous relationship between the section bearing capacity and the normalized width-thickness ratio of the member section,and effectively use the stress strengthening performance of non-slender steel member,thus CSM could be regarded as a more effective design method.