含有焊缝初始裂纹的钢框架梁柱节点性能试验研究

Experimental study on behaviors of steel frame beam-column connections with initial weld cracks

为研究焊缝初始裂纹对钢框架梁柱节点抗震性能的影响,通过切割节点的梁下翼缘焊缝以形成初始裂纹,完成了7个节点拟静力试验,并分析了能量输入历程与节点连接形式对其性能的影响.试验结果表明,含有初始裂纹的节点试件SHH-1从启裂至破坏共经历了6个循环,相比于无损节点试件SHH-0持续时间减少25%,极限荷载降低8.5%,极限位移与延性系数均降低26%.节点中梁下翼缘焊缝部位若存在初始裂纹,会改变节点的裂纹扩展机理,其抗震性能也会明显降低.当加载跨幅相同且循环次数相差不大时,不同的加载制度对初始裂纹扩展机理及节点抗震性能影响较小,但突增式位移荷载会加速裂纹的扩展.H形柱-H形梁节点初始裂纹扩展速度相对最慢、抗震性能最好,其次为箱形柱-H形梁节点,箱形柱箱形梁节点性能最差.

To study the effect of the initial cracks at welds on the seismic behaviors of a steel frame beam-column connection,the weld of the beam bottom flange was cut to create an initial crack,and the pseudo-static tests of seven connections were carried out.The influences of the energy input process and the connection types on its performance were analyzed.The results show that the specimen SHH-1 with the initial crack experiences six cycles from the new crack appearance to the failure.Compared with the specimen SHH-0 without any initial crack,the loading duration,the ultimate load,the ultimate displacement and the ductility coefficients of SHH-1 were reduced by 25%,8.5%,26%,and 26%,respectively.The crack propagation mechanism can be changed by the initial crack at the weld of a bottom beam flange,and the seismic performance of the connection can be significantly reduced.When the load spans are the same and there is little difference of the cycle numbers,different loading systems have little influence on the initial crack propagation and the connection performance,but a sudden peak load can increase the speed of the connection failure.The H-shaped beam to H-shaped column connections have the slowest initial crack growth and the best seismic performance,followed by the H-shaped beam to box column connections,and the box beam to box column connections have the worst performance.