PC基础隔震结构新型隔震层框架节点抗震性能分析

Analysis on Seismic Behavior of a New Frame Joint of Isolation Layer in PC Base-isolated Structure

基础隔震结构对于隔震层的整体性要求较高,隔震层构件的连接性能则直接影响着隔震层的整体性和抗震性能。本文针对预制装配式混凝土框架隔震结构的隔震层部分,对梁底纵筋的焊接连接方式进行了改进并开展拉拔试验,提出了一种框架节点连接方式。利用ABAQUS建立了新型隔震层框架节点与传统现浇节点的有限元分析模型,施加低周往复荷载作用,对比两类节点的整体性和抗震性能差异,并对新型隔震层框架节点的连接构造进行改进。分析结果表明:采用钢板焊接连接时,钢筋连接试件的抗拉强度与通长钢筋接近,在钢板上开槽再焊接可显著减小连接钢板的弯曲变形;预制装配式隔震层框架节点的承载能力、刚度和耗能能力均低于现浇节点,但变形能力较强;在预制梁端部增设锚固钢筋后,梁端局部区域的配筋增大,预制装配式隔震层框架节点的承载能力、刚度和变形能力均显著提高,由于锚固钢筋抑制了梁端受力纵筋的塑性发展,因此其耗能能力降低;改进的预制装配式隔震层框架节点的承载能力、刚度和变形能力均强于传统现浇节点,具有良好的结构整体性,可用于实际工程。

The base isolation structure has a high requirement for integrity of the isolation layer,and the connection behavior of the isolation layer members affects the integrity and the seismic behavior of the isolation layer directly.In this paper,the welding connection mode between longitudinal reinforcements at the bottom of the beam was improved,the tensile tests were also carried out,and a new frame joint was proposed of the isolation layer for prefabricated concrete base isolation structure.Then,the finite element models of the new frame joint and traditional cast-in-place joint were established to simulate the seismic behavior and the structural integrity under the lateral repeated loads in ABAQUS.Finally,an improved connection mode for the new frame joint was proposed by comparing the difference of seismic behavior between the two kinds of joints.The results showed that the tensile strength of the specimen which connected by grooving and welding on the steel plate was close to that of the complete reinforcement,and could significantly reduce the bending deformation of the connecting steel plate.The bearing capacity,stiffness and energy dissipation capacity of the prefabricated frame joint were lower than that of the cast-in-place joint,but the deformation capacity was stronger.The bearing capacity,stiffness,and deformation capacity of the new frame joint on the prefabricated isolation layer increased when some anchored rebars were added to the ends of the prefabricated beam,the reinforcement ratio at the end of beams also increased,at the same time,the plastic development of the longitudinal reinforcement was delayed by the anchored rebars,so the energy dissipation capacity decreased.The load-bearing capacity,stiffness and deformation capacity of the improved prefabricated frame joint were all stronger than that of cast-in-place joint,so the improved new frame joint had an excellent structural integrity,and it could be used in practical engineering widely.