PBL加劲型方钢管混凝土外隔板式节点受拉性能试验研究

Tensile performance of concrete filled square steel tube exterior-diaphragm connections stiffened with PBL

为得到新型PBL加劲型方钢管混凝土外隔板式框架节点的受拉性能、并初步验证其抗震性能,开展了6个方钢管混凝土节点试件的受拉试验,试件类型包括普通方钢管混凝土节点、普通方钢管混凝土外隔板式节点、新型的PBL加劲型方钢管混凝土外隔板式节点以及去除外隔板后的PBL加劲型方钢管混凝土节点。通过对比分析各试件的破坏特征、初始刚度、屈服和极限荷载、变形组成、支板或隔板应变与应力分布,着重研究了PBL纵肋的设置对新型节点受拉性能的改善,以及去除外隔板对新型节点受拉性能的影响。研究结果表明:相较于普通方钢管混凝土节点和普通方钢管混凝土外隔板式节点试件,PBL加劲型方钢管混凝土外隔板式节点试件由于同时设置了外隔板和PBL纵肋,因此其在拉力作用下不仅初始刚度、屈服荷载和极限荷载得到大幅度提升,而且节点区域的变形集中得到了明显的缓解,节点附近的应变和应力分布变得更加均匀。因此,新型框架节点具有优越的传递钢梁翼缘拉力的能力,可以实现地震作用下的梁端屈服破坏模式,应具有优越的抗震性能。而在新型节点的基础上去掉外隔板后,试件的初始刚度、屈服和极限荷载、节点区域附近的应变和应力分布均匀程度均有一定程度的降低,即其传递钢梁翼缘拉力的能力有所降低。该文研究成果可为进一步开展新型节点的受拉承载力计算方法、节点抗震性能的研究奠定基础。

To obtain the tensile performance and preliminarily validate the seismic behavior of a novel type of concrete filled square steel tube(CFSST)exterior-diaphragm connections stiffened with PBL,tensile experiments on six CFSST connection specimens were carried out,including the ordinary CFSST connections,ordinary CFSST exterior-diaphragm connections,novel CFSST exterior-diaphragm connections stiffened with PBL and CFSST connections stiffened by PBL and with exterior-diaphragm removed.By comparing the failure modes,initial stiffness,yield load and ultimate load,deformation components,strain and stress distribution of branch plates or diaphragm of different specimens,the improvement due to the PBL ribs and the effects of removing the exterior-diaphragm on tensile performamce of novel connection specimens were studied emphatically.It is found that,compared to ordinary CFSST connection and CFSST exterior-diaphragm connection specimens,CFSST exterior-diaphragm connection specimens stiffened with PBL,due to applications of both exterior-diaphragm and PBL ribs,possess much higher initial stiffness,yield load and ultimate load,relieved deformation concentration and much uniform strain and stress distribution in connection region.Hence,the novel type of connection has excellent load transmission capacity of tension in steel beam flanges,so that the connections showld possess excellent seismic behavior due to the failure mode of yielding of beam ends.After removing exterior-diaphragmfrom the novel CFSST connections stiffened with PBL,however,initial stiffness,yield load and ultimate load,and strain and stress uniformity in branch plates were reduced,and the load transmission capacity was decreased.The research results laid the basis for further researches on calculation method of tensile capacity and seismic behavior of connections.