钢结构节点在循环往复荷载作用下的超低周疲劳断裂预测

Extremely Low Cycle Fatigue Fracture Prediction of Steel Connections under Cyclic Loading

摘要:

进行了1个方钢管柱与H形钢梁直接焊接节点试件在往复荷载作用下的试验和有限元分析，采用已校准的微观断裂判据退化有效塑性应变模型(DSPS)和循环空穴扩张模型(CVGM)对其进行了超低周疲劳断裂预测，并对2个栓焊混接边柱节点试件在往复荷载作用下的试验进行了超低周疲劳断裂预测。预测断裂位置、断裂时刻对应的荷载循环圈数、梁端位移和荷载与试验结果相比均有较高的精确度。随后进行了微观断裂判据中的损伤退化参数对断裂预测结果的敏感性分析，得出损伤退化参数取值对断裂预测结果不敏感。因此，钢材微观断裂判据对钢结构节点在往复荷载作用下的超低周疲劳断裂预测有较好的适用性。

Abstract:

Low-cycle reversed loading test and finite element analysis of a welded connection specimen between square steel tube column and H shape steel beam were conducted. The calibrated micromechanical fracture criteria degraded significant plastic strain (DSPS) model and the cyclic void growth model (CVGM) were used to predict extremely low cycle fatigue fracture initiation for this specimen and the cyclic tests of two side column connection specimens with welded flanges and bolted webs conducted by others. Compared with test results, the predicted fracture location, load cycle number corresponding to fracture, fracture load and displacement have high accuracy. Subsequently, the sensitiveness analyses of damage degradation parameters in micromechanical fracture criteria to the predicted results of fracture were conducted. The results show that the predicted results of fracture are insensitive to the values of damage degradation parameters. Therefore, it is feasible to use the micromechanical fracture criteria to predict extremely low cycle fatigue fracture initiation for steel structure connections under cyclic loading.