(贵州大学土木工程学院, 贵阳 550025)

摘要: 为了验证应力加权损伤模型( SWDM)对相贯节点在单调荷载作用下延性断裂预测的适用性,对正交设计的 23 个 X 形圆钢管相贯节点进行有限元分析。 应用空穴扩张模型( VGM) 和 SWDM,得到了荷载和断裂点损伤度曲线,通过洛德角参数的变化,分析了断裂点的应力状态,对比了 VGM 和 SWDM 预测结果;运用 ABAQUS 子程序模拟了焊缝破坏 过 程,分 析 了 节 点 几 何 参 数 对 焊 缝 承 载 力 的 影 响。 结 果 表 明: SWDM 预 测 的 断 裂 荷 载 要 低 于VGM,断裂点的应力状态是由轴对称拉伸或压缩状态向平面应变状态的趋势变化,通过引入洛德角参数,SWDM 能准确地模拟节点在不同应力状态下的损伤累积,预测精度高于 VGM,适用性更好;焊缝的开裂始于鞍点处,并迅速向冠点发展,导致节点破坏;节点支主管壁厚一定时,支主管外径比和主管径厚比越大,焊缝承载力越低;《 钢结构设计标准》 (GB 50017—2017)中焊缝承载力计算公式未考虑焊缝受力不均匀的影响,计算结果会出现偏不安全的情况。

关键词: 相贯节点; 应力加权损伤模型; 空穴扩张模型; 断裂预测模型; 焊缝承载力

中图分类号:TU392. 3 文献标志码:A 文章编号:1002-848X(2022)13-0099-07

DOI:10. 19701 / j. jzjg. 20211180

Fracture prediction and bearing capacity analysis of weld of tubular circular hollowsection X-joints

HAN Han, ZHENG Tao, WANG Xudong, HUANG Zhenghua

( School of Civil Engineering, Guizhou University, Guiyang 550025, China)

Abstract:In order to verify the applicability of stress-weighted damage model( SWDM) to the prediction of ductile fracture of tubular joints under monotonic loading, the finite element analysis was carried out on 23 tubular circular hollow section X-joints with orthogonal design. Using void growth model( VGM) and SWDM, the load and fracture point damage curves were obtained, the stress state of the fracture point was analyzed through the change of Lode angle parameters. The prediction results of VGM and SWDM were compared. ABAQUS subroutine was used to simulate the weld failure process, the influence of joint geometry parameters on weld bearing capacity was analyzed. The results show that the fracture load predicted by SWDM is lower than that predicted by VGM. The stress state of fracture point is a trend change from axisymmetric tensile or compressive state to plane strain state. By introducing the Lode angle parameter, SWDM can accurately simulate the damage accumulation of joints under different stress states. The prediction accuracy is higher than that of VGM, and the applicability is better. The cracking of the weld starts at the saddle point and develops rapidly to the crown point, leading to the destruction of the joint. When the wall thickness of branch pipe and main pipe is constant, the larger the outer diameter ratio of branch pipe and main pipe and the diameter thickness ratio of main pipe, the lower the bearing capacity of weld. The calculation formula of weld bearing capacity in Standard for design of steel structures ( GB50017—2017) does not consider the influence of uneven stress of weld, and the calculation results will be unsafe.

Keywords:tubular joint; stress-weighted damage model; void growth model; fracture prediction model; weld bearing capacity