Q345B钢框架梁柱节点焊缝低周疲劳试验

为了研究不同加载制度下的钢框架梁柱节点焊缝低周疲劳性能,设计并完成了六个足尺全焊接梁柱节点焊缝低周疲劳试验,研究了节点焊缝的疲劳裂纹萌生及扩展规律,分析了循环幅值、加载历程对节点疲劳性能的影响,比较了在常幅、变幅及随机荷载作用过程中的疲劳损伤累积程度。结果表明:在三种加载制度下,梁翼缘焊接孔处焊趾最易萌生疲劳裂纹,最终断裂的路径均为焊接孔焊趾裂纹斜向发展,与翼缘焊缝端部裂纹汇合,造成全截面断裂;试件直接经历等幅大变形对节点的疲劳性能较为不利,经历由小变形到大变形的加载过程更能发挥耗能能力;常幅加载的幅值越大,节点累积损伤的速率越快,越早发生疲劳断裂.

Low-cycle fatigue test of Q345B steel frame beam-column connection weld

In order to study the low cycle fatigue of steel frame beam-column connections under different amplitude regimes, the low-cycle fatigue test of six full-scale all-welded beam-column connections were designed and finished, and the fatigue crack initiation and expansion of welds was studied.The influence of cyclic amplitude and loading history on the fatigue performance of the connections was analyzed, and the cumulative degree of fatigue damage during normal amplitude, variable amplitude and random load was compared. The results show that under the three amplitude regimes, the welding toe of the flange welding hole isprone to fatigue cracking, and the final fracture path is the oblique development of the welding holes weld toe crack, which merges with the edge weld of the flange weld to cause full-section fracture. It is disadvantageous for the fatigue performance of connections to directly experience large deformation with equal amplitude. The loading process from small deformation to large deformation can give full play to the energy dissipation capacity. The larger the amplitude of loading, the faster the cumulative damage rate of connections, and the earlier the fatigue damage occurs.