STUDY ON SYNTHESIS METHOD OF VERTICAL GROUND MOTIONS FOR NEAR-FAULT REGIONS CONSIDERING THE CHARACTERISTICS OF SOURCE AND SITE CONDITION

The safety of structures under high risk conditions in near-faults regions has been paid more and more attention. A synthetic method of near-faults vertical ground motions considering source characteristics has been established. A mathematical model is established, which takes fault type, magnitude, depth of rupture top, fault distance and shear wave velocity as variables, and the correlation matrix of model parameters is given. The simulated ground motion reflects the most adverse effect characteristics of actual near-fault ground motions (non-stationary intensity and frequency, variability of source parameters). The significance of regression parameters is verified by statistical parameters and residual plots. The accuracy and rationality of the proposed method are verified by comparing the difference between the model parameters proposed in this study and previous results, as well as the consistence degree of the time history and response spectrum between the simulated ground motion and the actual ground motion. Compared with the trigonometric series method, the proposed synthesis method has fewer parameters, and the intensity and frequency nonstationary can be considered with only 7 parameters. Compared with the multiplicative coefficient method, the frequency characteristics of ground motion simulated by the proposed method match the vertical component records. It can be combined with the horizontal component ground motion simulation method proposed previously to form a three-dimensional ground motion simulation method, which can be used for structural analysis and design of structures with important fortification requirements, and can also be used for areas lacking actual ground motion records.