| As a new form of energy,tower photothermic power generation has the advantages of high heat conversion efficiency,low operating cost and high operating temperature,and has a broad development prospect at home and abroad.The areas with sufficient solar energy resources and large site area in China are located in the western part of the country.The photothermic towers constructed in such areas are susceptible to the near-field effects of seismic faults.There is no explicit regulation on the structure form of the photothermic tower in the existing specification,and the consideration of the near site vibration is relatively simple.Based on this,considering the uncertainty of ground motion,the random seismic response and reliability analysis of photothermic tower considering the near field effect are carried out.In this paper,the method of superimposing a random point source model and an equivalent velocity pulse model is used for artificial pulse-type near-field seismic wave simulation.The seismic response time history of the photothermic tower structure is obtained by finite element analysis.Seismic reliability analysis of the structure is completed based on the subset simulation method and the Kriging agent model.The main research contents and conclusions are as follows:(1)Pulse-type ground motion simulation.Based on the time-history records of ground motions,the source rupture process and the site model,a point source model is selected to simulate high-frequency ground motion components.An equivalent velocity pulse model with a continuous function expression is used to simulate low-frequency pulses.According to the principle of superposition,a time-history of near-field pulsed ground motion with a given site characteristic is generated.(2)There are obvious pulses in the acceleration time history.In the power spectrum,the peak value of the pulse-type ground motion power spectrum increases significantly,and most of the energy is concentrated in the low frequency band,that is,the long-period component is rich,which further explains the pulse-type earthquake at the amplification effect of dynamic response to long period structure.This is a very different characteristic from the far-field vibration power spectrum.(3)In this paper,the finite element model of the photothermic tower structure is established,and the reliability of the prototype structure is verified based on the model test results,and the seismic response time history analysis of the photothermic tower is carried out accordingly.(4)This article superimposes the subset simulation method using the Kriging proxy model.The proxy function of the Kriging model can use limited sample points to generate a large number of samples for reliability calculation,thereby reducing the number of finite element simulations and saving time.It is suitable for more complex Reliability analysis of structural form;subset method retains its advantage in solving small failure events,and the combination of the two results in better calculation results.(5)Based on the combination of the subset simulation method and the Kriging proxy model,the seismic reliability of the photothermic tower is analyzed with the lateral displacement of the tower top and the shear force at the bottom of the tower as the limit states.The analysis results based on the limit state of the structural deformation capacity and the limit state of the bearing capacity show that the reliability level of the light and heat tower structure under the action of a 9-degree rare near-field earthquake may not meet the requirements of the specifications,and should be appropriately considered during the design process. |
