Three-dimensional Dynamic Analysis Of Prestressed Concret Cylinder Pipe(PCCP) Buried Underground

Prestressed Concrete Cylinder Pipe(PCCP),Because of its excellent characteristics,has been widely concerned about and applied in various fields of engineering.However,the three-dimensional dynamic analysis of PCCP,especially the PCCP elbow structure is comparatively not enough.Due to the frequent occurrence of earthquake natural disasters,it is very important to analyze the seismic response of PCCP elbow considering the seismic action.In this paper,the 3-D FE models of PCCP elbow is established by large-scale finite element analysis software ANSYS,and the dynamic responses of PCCP elbow under earthquake are obtained.Several influence factors are considered in the analysis: boundary conditions,site conditions,incident angle(angle between seismic wave and underground PCCP axis),peak amplitude of seismic wave,peak acceleration and so on.From the analysis of the results,the following conclusions are obtained:(1)The 3-D dynamic characteristics of PCCP elbow under three different kinds of boundary conditions,namely,simple boundary,viscous boundary and viscoelastic boundary conditions are compared.And the results show that the viscoelastic boundary is the artificial boundary closest to the actual situation.(2)The effect of different seismic wave incident angles on the PCCP elbow is that,the dynamic stress of the PCCP elbow decreases with the increase of the incident angle of the seismic wave.When the angle between the seismic wave propagated and the axial direction of the tube is zero,the dynamic stress is the biggest.(3)The dynamic response of underground PCCP elbow structure does not change obviously with the acceleration peak of the seismic wave.(4)The results show that the stress and strain values of the underground PCCP elbow structure are increasing with the increase of the displacement peak of the seismic wave,and the trend is obvious.(5)The horizontal displacement peaks of the typical nodes are different under the three types of ground(silt,silty sand and silty clay).The closer the node is to the elbow,the smaller the horizontal displacement peak of the node;The peak displacement of a typical node is relatively small in a harder site,and it is big in a softer site.The results obtained in this paper agree with the findings of the seismic damage investigation.The results and conclusions of the paper can be used as references for similar structures in seismic design.