套筒连接的预制拼装桥墩抗震性能研究

THE SEISMIC PERFORMANCE OF PRECAST BRIDGE PIERS WITH GROUTED SLEEVES

以灌浆套筒预埋于墩身的预制拼装桥墩为研究对象,分析了地震作用下此类桥墩墩身与承台接缝处的受力机理和套筒预埋于塑性铰区对桥墩整体受力性能的影响,进行了灌浆套筒预埋于墩身的预制拼装桥墩模型拟静力试验。在此基础上,采用数值模拟分析方法,建立有限元模型,比较了采用灌浆套筒连接的预制拼装桥墩与整体现浇桥墩的性能差异,以及不同直径的灌浆套筒对此类预制拼装桥墩抗震性能的影响。研究表明:采用墩身预埋灌浆套筒连接的预制拼装桥墩,因套筒刚度大,易在墩身套筒连接段形成刚性区域,发生墩身曲率重分布现象,导致墩底接缝处曲率增大,应变集中。此外,灌浆套筒埋置于墩身的预制拼装桥墩与整体现浇桥墩相比,等效塑性铰高度减小,位移承载能力降低,且灌浆套筒直径越大、长度越长,桥墩接缝处应变集中越明显,与整体现浇桥墩性能差异越大,导致桥墩最终破坏形式由传统的塑性铰区域混凝土破坏转变为墩底接缝处钢筋拉断。

The grouted sleeves embedded in precast column bodies were taken as the research object.The mechanical behavior of the column-to-footing joint and the influence on the overall seismic performance of this kind of bridge piers were theoretically analyzed.A quasi-static test of precast bridge piers with grouted sleeves was carried out.The difference between the seismic performance of the cast-in-place piers and the precast bridge piers with grouted sleeves was compared by a numerical simulation.The influence of different sleeve diameters and lengths on the seismic performance of the bridge piers was also investigated.The results show that the precast piers with grouted sleeves were easy to form a rigid region in the connecting section due to the large rigidity of the sleeves,and that the redistribution phenomenon of the curvature occurred in the columns,resulting in an increase in the curvature and rebar strain concentration adjacent to the end of the sleeves.In addition,the precast bridge piers with embedded grouted sleeves in the plastic hinge area were found to have a reduced displacement capacity as compared to cast-in-place piers with the same reinforcement.This phenomenon was more serious when a larger sleeve diameter was adopted.The larger the diameter and the longer the length of the sleeves,the more obvious the strain concentration at the joint,which resulted in the transformation of the final failure form of the pier from the traditional concrete failure in the plastic hinge area to steel fracture in the joint at the bottom of the pier.