Research On Seismic Performance Of Rubber Flexible Pipes For Seismically Isolated Buildings

Isolation technology is regarded as the most effective measure to improve the toughness of buildings and has been widely used.Due to the great deformation of the isolation layer of earthquake-isolated buildings under earthquake,high demands are placed on the deformation capacity of its pipelines.Rubber flexible pipelines are one of the commonly used pipelines for seismically isolated buildings,and their anti-seismic performance directly affects the function of buildings after earthquakes.However,there are still few reports on the research on the large deformation performance of building isolation rubber flexible pipelines.The failure state,damage,deformation capacity and bearing capacity of such pipelines during earthquakes are not yet clear.In response to the above problems,this article has carried out related research,the main research content and conclusions are as follows:The main research work of this article is as follows:(1)According to the requirements of engineering research and related industry standards.Taking the vertical rubber flexible pipe with a horizontal deformation target displacement of 400 mm as the research object,and considering different pipe nominal diameters and design lengths.A series of pseudo-static tests were carried out to study the seismic performance of rubber flexible pipes.(2)Based on the results of a series of quasi-static tests.The damage evolution mode of rubber flexible pipelines under the action of earthquake was studied.The key factors for controlling its ultimate horizontal deformation capacity and bearing capacity were found,and the relevant regression calculation formula was given.It further clarified the damage mechanism of the pipeline and established the vulnerability curve of the pipeline.(3)The ABAQUS finite element software was used to perform numerical simulation analysis on the rubber flexible pipeline,and compared with the test results,which verified the accuracy and feasibility of the numerical simulation.And the nominal internal diameters commonly used in three projects are selected,and the internal pressure of the pipe and the design length of the pipe are used as variables to further study the influence law of the ultimate deformation and bearing capacity of the pipe.The following main conclusions are drawn from the aforementioned work:1)Under the action of earthquakes,rubber flexible pipelines will undergo two key stages: safety deformation and straightening damage.2)When the design length of the rubber flexible pipe meets the requirements of industry standards and specifications,its horizontal deformation capacity can meet the engineering requirements.When the design length does not meet the requirements of industry standards and specifications,irreparable damage will occur in the event of a rare earthquake and must be replaced after the earthquake.3)The horizontal deformation capacity and bearing capacity of rubber flexible pipes are directly related to their nominal inner diameter and design length: When the design length of the pipeline is the same,as the nominal inner diameter increases,the deformation capacity of the pipeline gradually decreases.The ultimate horizontal load at the time of its failure gradually increases.Meanwhile the ratio of ultimate load for the pipe with a large and small nominal internal diameter is smaller than the ratio of correspond inner diameter.When the nominal inner diameter of the pipe is the same,the overall rigidity of rubber flexible pipes of different design lengths is basically the same;the larger nominal inner diameter pipe has a greater overall rigidity than the small nominal inner diameter pipe,but its deformability is reduced.Therefore,a longer pipe length should be designed for a pipe with a larger nominal inner diameter to ensure that it has sufficient deformability.When a large deformation occurs in the seismic isolation layer,it can ensure that the function of the pipe is not affected.4)The simulation results show that the deformation capacity of the pipeline decreases with the increase of its working pressure,and the greater the pressure,the more obvious the reduction of the pipeline deformation capacity.