高层钢结构标准梁柱节点脆性断裂机理研究

由于焊接工艺的影响,高层钢结构标准梁柱节点中会不同程度地存在一条人工裂纹,自Northridge地震发生以后,此人工裂纹被众多学者认为是钢结构梁柱节点发生脆性断裂的主要原因之一。针对人工裂纹,以巨型钢框架节点为模型,利用高精度有限元方法得到了线弹性、弹塑性情况下人工裂纹尖端应力场的分布情况,引入断裂力学的参量———应力强度因子KI和J积分,得到应力强度因子KI与J积分值与梁下翼缘拉应力之间的关系,建立人工裂纹扩展的断裂准则,定量解释了节点发生脆性断裂的原因。

RESEARCH ON BRITTLE FRACTURE MECHANISM OF STEEL FRAME CONNECTION OF TALL BUILDINGS

There is usually an artificial crack in steel frame connections of tall buildings because of welding procedure. Since Northridge earthquake, the artificial crack is well known as a main reason of brittle fracture of steel frame connections. It is analysed a huge steel frame connection model. Using high accurate finite element method, it is also got the distribution of stress field at the tip of artificial crack. Then the fracture parameters of K1 and J are inducted. Based on the result of finite element analysis, the relationship between K1, J and outer stress is created based on numerical integration method. The fracture rule of artificial crack propagation, which can explain brittle fracture of steel frame connections is created.