Study On Simulation Method Of Near-fault Multi-dimensional Single-point And Multi-point Ground Motions Considering Characteristics Of Source And Site

Because of the directional effect,near-fault ground motions have a significant effect on long-period structure.At the same time,near-fault ground motions have a significant vertical component,which has a significant impact on structures such as super-tall buildings and subway structures.In seismic response analysis of long-span structures,the directional effect and significant vertical component of near-fault multipoint ground motions should not be neglected.In view of the shortage of near-fault ground motions and imperfection of simulation methods of ground motions,this paper studies the simulation methods of near-fault multi-dimensional single-point and multidimensional ground motions,aiming to enrich the input method of near-fault ground motions.The main research work and results of this paper are as follows:(1)Two models of near-fault ground motions are established.Based on singlepoint pulse model and filtered white-noise model,a near-fault single-point ground motion model in horizontal and vertical directions is established.A multi-point pulse model and the corresponding calculation method of non-uniform effect are proposed,and existing envelope function model is optimized.Based on the proposed multi-point pulse model and trigonometric series model,a near-fault multi-point ground motion model in horizontal and vertical directions is established.The multi-dimensional singlepoint ground motion model represents the following characteristics: pulse characteristics,high-frequency characteristics,intensity and frequency non-stationarity.The multi-dimensional multi-point ground motion model represents the following characteristics: pulse characteristic,high-frequency characteristic,wave-passage effect,partial coherence effect and intensity non-stationary;(2)The parameters of ground motion model are predicted considering the characteristics of earthquake source and site.The model parameters are identified by fitting the records of horizontal component and vertical component in the near-fault ground motion database.The distribution parameters of model parameters are fitted,and the distributions of model parameters are transformed into normal distributions.The regression prediction equations for model parameters are established,which take fault type,magnitude,depth at the top of fault,fault distance,shear-wave velocity of soil and directivity characteristics as explanatory variables.The accuracy of the regression prediction equations is verified by statistical parameters and residual graphs.The influencing factors of model parameters are analyzed and the correlation among model parameters is analyzed;(3)The simulation methods of near-fault multi-dimensional single-point and multi-dimensional multi-point ground motions considering the characteristics of earthquake source and site are established.The rationality of the proposed simulation method of multi-dimensional single-point ground motions is verified by comparing with ground motion records.The rationality of the proposed simulation method of multi-dimensional multi-point ground motions is verified by comparing with the target ground motion and its properties.The simulated multi-dimensional single-point ground motions have the same natural randomness(time-history and response spectrum)as the ground motion record set for the same source and site characteristics.The simulated multi-dimensional multi-point ground motions have the same time-history and response spectrum as that of the simulated multi-dimensional single-point ground motions,and are consistent with the target coherence.