Earthquake Action Analysis Of Large-diameter Prestressed Concrete Silo

In recent years,with the rapid development of economy, construction scale of all classes of silos has been enlarged gradually in china.as earthquake occur frequently in our county together with great destructibility, among all of damaging earthquake that happened at home and abroad,a large numbers of silos get great cracks, even collapse.as a result, for silos in seismic region,analysis of earthquake response is very significant.After a review of developing history of silos in our country,recent research actuality of anti-seismic theory for china and other countries is summarized, as well as, actual analysis methods of silo aseismatic design are introduced. based on all above, finite element analysis of an actual project (Prestressed Concrete Silo with a Large-diameter of 30m) is carried out with the aid of ansys. in course of this, firstly two working conditions standing for empty silo and full silo are taken into account, then, two modals are built and modal analysis goes on.afterwards, three types of seismic wave(el wave,taft wave and Lanzhou artificial wave) are chosen and time history analysis is worked out.after analysis and comparison,we can infer:1. when under the working condition of empty silo, 1st natural vibration period is 0.461s. however, when under the working condition of full silo, 1st natural vibration period is 0.224s.compared with High-rise Building of similar height, structural stiffness is very large.2. as both first vibration mode and second vibration mode of structure are not in the state of obvious torsion,structure appears good torsional behavior.3. under the action of x direction seismic wave, time history analysis rsult shows: seismic action under the working condition of empty silo is control load case;anyhow, under the working condition of full silo, seismic action is not control load case, and it should be combined with other effects ,by which the most adverse load working condition can be determined.4. top displacement of silo under three types of seismic wave is compared ,we can find that: the maximum displacements under el wave and taft wave are very near,yet that under artificial wave is relatively small. Structure natural vibration period is very close to predominant period of el wave and taft wave.This article provide some reference to structrual design,and some practical problems in project can be solved.