隔震建筑柔性管线的抗震性能试验研究

Experimental study on seismic performance of flexible pipelines used in base isolated buildings

隔震建筑的隔震层在罕遇地震作用时会发生较大的水平位移,这要求穿越隔震层的竖向管线系统必须采用柔性连接以维持建筑的使用功能。尽管相关规范、规程规定了柔性连接管线的构造方式,但其真实的变形能力尚缺乏试验研究。本文对具有不同密封构造(橡胶型、金属型和石棉型)和连接接头(抓斗式和卡套式)的柔性管线进行了循环加载试验,所有试件均预先充水加压至1.0 MPa或2.5 MPa,以密封泄漏、力学指标下降作为判断构件失效的依据。试验表明橡胶密封圈和金属密封圈能够有效地防止柔性管线的泄漏,而采用石棉密封圈的试件泄漏位移远小于另外两种密封圈。抓斗式接头用于柔性管线的连接是可行的,而卡套接头不能提供同等水平的抗震性能。定义了柔性管线损伤极限状态和损伤指数,得到了试验易损性曲线。建立了柔性管线力学模型,利用试验数据对其关键参数进行识别,以性能点力学指标为依据,准确再现了试件抗震性能,为建立整体结构多元模型奠定了基础。

Large horizontal deformation is expected in the base-isolation layer of an isolated building when being caught by a rarely-occurred earthquake, which necessitates a flexible connection of pipelines from the foundation to the superstructure to accommodate such large deformation. Although related design codes stipulate the configuration of flexible pipeline connections, the real deformability and seismic performance are lack of experimental investiga- tion. Three types of seals, namely rubber-based seal, metal-based seal and asbestine-based seal, and two types of connections, i. e. , the grab-type joint and ferrule fitting joint, are tested in this study. All specimens were cyclically tested with the pipes filled with pressurized water, either at l. 0 MPa or 2.5 MPa. The water leakage and the me- chanical degradation were taken as the failure of specimens. It was observed that the asbestine-based seal leaked at smaller deformations than the other two types of seals. And it was not easy for the ferrule fitting joint to realize the complete boundary of in-filled liquids. Damage states and damage index of the flexible pipeline are defined based on the test results, together with their seismic fragility curves. Finally, the mechanical model for the flexible pipeline is proposed and the associated parameters are identified from the experimental data. Judged by the forces at specific performance points, the model is able to reproduce the seismic behavior of flexible pipelines accurately, which provides basis of mega model of hospital buildings for seismic performance evaluation.