支管在轴向荷载作用下Q460C高强钢T型圆管节点疲劳性能试验研究

对8个支管承受轴向荷载的Q460C高强钢T型圆管相贯节点分别进行热点应力试验和疲劳试验研究，将热点应力试验结果与现有热点应力集中系数计算公式进行对比验证分析，通过疲劳性能试验观察疲劳裂纹的发展过程和疲劳破坏模式，并对比分析了CIDECT和DNV疲劳设计规范中圆管节点疲劳S-N曲线对于高强钢管节点的适用性。研究表明，疲劳裂缝首先出现在67.5°到90°附近应力集中较大的区域（鞍点附近），然后迅速沿着相贯线向冠点处发展，并在裂缝末端产生沿主管轴向的横向裂缝。通过试验结果与已有规范的对比分析表明，CIDECT建议的S-N曲线应用于支管承受轴向荷载的Q460C高强钢圆管节点的疲劳寿命预估在某些情况下是偏于不安全的，而DNV规范的计算值过于保守，因此同样也不适合于Q460C高强钢圆管节点的疲劳性能分析。

Experimental study on fatigue behavior of Q460C high strength steel welded tubular T-joints under axial loading

8 T-joint specimens made of circular hollow section (CHS) with Q460C high strength steel under axial loading on the brace were tested to determine the stress concentration factors (SCF) at hot-spot locations and investigate the fatigue behavior. The test results were compared with those predicted by the current design method and the fatigue failure modes were obtained. It was observed that the visible crack first occured near the saddle position and then propagated along the intersecting line toward crown position. By comparing results of the test and current design methods, it was found that the predicted results based on the methods in CIDECT and DNV did not agree well with the test results. The results of DNV were conservative while the method of CIDECT was unsafe in some cases, which revealed that the methods of CIDECT and DNV were both not suitable to analyze the fatigue behavior of CHS joints with Q460C high strength steel.