焊接管节点疲劳研究综述

为加深对焊接管节点疲劳问题的认识，对焊接管节点名义应力法、热点应力法、切口应力法和断裂力学法4种常用疲劳评估方法应用现状和存在问题进行介绍，从疲劳效应（热点应力集中系数）和抗力（热点应力幅S N曲线）2个方面对首推的热点应力法研究现状进行总结，探讨了管节点结构形式的发展趋势。结果表明:焊接管节点常用四大疲劳评估方法中名义应力法应用最广，但过于保守，热点应力法最被推崇，但仍有待进一步完善，切口应力法实施难度大，尚未在规范中使用，断裂力学法则适用于剩余疲劳寿命评估；对于传统的圆形和矩形钢管节点，已形成了较为系统的热点应力评估方法，对热点应力集中系数最大值可能发生位置、外推区域、热点应力集中系数计算公式、壁厚效应修正系数等方面进行了明确的规定；在传统的圆钢管和矩形钢管节点基础上，创新节点形式，提出了钢管混凝土节点、PBL加劲型钢管混凝土节点、圆管 方管节点和鸟嘴式节点，对比传统钢管节点，钢管混凝土节点热点应力集中系数降幅在25%以上，PBL加劲型矩形钢管混凝土节点降幅在50%以上，圆管 方管节点和鸟嘴式节点降幅则介于圆形钢管和矩形钢管节点之间。

Review of Fatigue Behavior in Welded Tubular Joints

In order to deepen the understanding of fatigue problem of welded tubular joints, the application status and existing problems of four frequently used assessment approaches including nominal stress approach, hot spot stress approach, notch stress approach and fracture mechanics approach were introduced. The current research of hot spot stress approach, which was the most suggested, was summarized in the aspects of fatigue effect and fatigue resistance. The structural development trend of tubular joints was explored. The results show that in the four frequently used approaches, the nominal stress approach is the most widely used, but it is over conservative. The hot spot strees approach is the most suggested and it needs to be perfected. The notch stress approach will be applicable in an assessment of residual fatigue life. The comparatively systematic hot spot strees approach is proposed for traditional circular and rectangular tubular joints, and possible position of maximum hot spot stress, extrapolation region, equations for hot spot stress concentration factor, thickness correction factors are specified. Based on the traditional circular and rectangular tubular joints, the structure of joints is innovated, and the concrete filled steel tube joints, concrete filled steel tube joints stiffened with PBL, circular hollow section rectangular hollow section(CHS-RHS) joints, bird beak square hollow section(SHS) joints are proposed. Comparing with traditional joints, the hot spot stress concentration factor of concrete filled steel tube joints and concrete filled steel tube joints stiffened with PBL reduce more than 25% and 50% respectively. The hot spot stress concentration factor of bird beak SHS joints is between circular tubular joints and rectangular tubular joints.