钢桁梁全焊桁片腹杆与节点焊接连接细节疲劳性能试验研究

摘要

为避免焊缝交叉,钢桁梁全焊桁片中,腹杆与节点连接采用带半圆过焊孔的焊接构造.为评估钢桁梁全焊桁片腹杆与整体节点焊接细节抗疲劳性能,对其进行有限元数值模拟及疲劳试验研究.根据实际焊接细节结构特点,基于应力场相似原则完成试验模型设计.利用ANSYS建立实桥结构及试验模型的有限元模型,对应力分布状态及应力集中系数进行比较分析.采用3组9个试件,完成不同应力幅下钢桁梁全焊桁片腹杆与节点连接构造典型焊接细节的疲劳试验,通过数据拟合得到该焊接细节的 S-N 曲线.结合其他既有疲劳试验数据及欧洲规范、日本规范对该焊接细节疲劳性能进行评估.结果表明:过焊孔与翼缘焊接部位存在较大的应力集中,对焊接节点的疲劳性能有较大削弱;反复荷载作用下,过焊孔与翼缘板交接焊趾处首先产生疲劳裂纹.%In full-welded steel truss,a welded detail with cope hole was used at the connection between web member and full-welded joint to avoid crossing welds.According to the characteristics of the actual welding de-tails and based on the principle of stress field similarity,the test specimens were designed.Using ANSYS fi-nite element program,3-D finite element models of actual bridge structure and test specimen were founded and stress distributions and stress concentration coefficient were investigated.Under different stress range,fa-tigue test of welded detail at the connection between web member and full-welded joint on 9 specimens in 3 groups was finished.The S-N curve of the welded detail was obtained through data fitting.Compared with existing fatigue test data and fatigue strength of the welded detail defined in Eurocode and JSSC design code, the fatigue performance of the welded detail was evaluated.The experimental results show that the fatigue strength of cope hole details was greatly weakened due to local stress concentration around the cope holes.The fatigue cracks initiated from welded toes at flange plates inside the cope holes under cyclic loading.