倒置外露灌浆套筒装配式柱脚节点抗震性能研究

通过自振特性测试和竖向荷载作用下的低周往复荷载试验,对比分析了倒置外露灌浆套筒装配式柱脚节点与传统现浇及现行装配式柱脚节点的整体性及抗震性能。结果表明,倒置外露灌浆套筒柱脚节点试件(NPC)的整体性与传统现浇试件(RC)基本相当,现行装配试件(TPC)测试所得的各阶自振频率基本均低于RC和NPC。三种柱脚节点在失效破坏时均出现了塑性铰,且两个装配式柱脚节点较现浇试件其塑性铰、柱身开裂高度均上移约1个灌浆套筒高度,宜适当延长箍筋加密区。三种柱脚节点的刚度退化规律相同,延性系数均在3.0以上,NPC的耗能能力显著优于RC和TPC。RC、TPC、NPC对应的开裂位移角分别为1/430、1/393、1/479,对应的极限位移角分别为1/24、1/22、1/22,均分别大于规范限值,满足抗震设防要求。

Seismic Behavior of Prefabricated Column Foot Joint with Inverted Exposed Grouting Sleeve

Through test of natural vibration property and horizontal low cycle reciprocating load test under vertical load,the integrity and seismic behavior of the inverted exposed grouting sleeve prefabricated column foot joint and the traditional cast-in-place and current prefabricated column base joint were compared and analyzed.The results show that the integrity of the specimen of inverted exposed grouting sleeve column base joint(NPC)is the same as that of the traditional cast-in-place specimen(RC).The natural frequencies of current assembled specimen(TPC)are lower than those of RC and NPC.Plastic hinge appears in all three kinds of column foot joints when they failed,and the height of plastic hinge and column body crack of two prefabricated column foot joints moves up about one grouting sleeve height compared with RC,the densified area of stirrup should be extended properly.The stiffness degradation law of the specimens is the same,the ductility factors are all above 3.0,and the energy dissipation capacity of NPC is significantly better than that of RC and TPC.The corresponding crack displacement angles of RC,TPC and NPC are 1/430,1/393 and 1/479 respectively,and the corresponding limiting displacement drift are 1/24,1/22 and 1/22 respectively,which are greater than the code limits,meeting the seismic fortification requirements.