| Based on the large universal finite element software ANSYS, finite element analysis models of layered soils, superstructure, and soil-pile-superstructure coupling system are established respectively, and researches on vibration response characteristics of each systems under different spectrum characteristics of seismic excitation are carried out in the time domain.1. Seismic Response Analysis of SoilViscous-spring artificial boundary is used to simulate the soil boundary effect. Drucker-Prager soil constitutive model is chosen to simulate soil nonlinearity. Finite element analysis model of layered soils is established, forward calculations of different spectrum characteristics of seismic waves are carried out. Based on Fourier transform method, spectrum characteristics of seismic waves before and after forward calculations are compared, and soil filtering and amplification effect are studied.2. Seismic Response Analysis of SuperstructureBased on traditional seismic response analysis of superstructure, adopting the assumption that foundation is absolute rigid and its all degrees of freedom are constrained, instead of the traditional seismic input method, bedrock peak acceleration is revised and forward calculation is also carried out. According to the result of forward calculation, characteristics of vibration responses of frame superstructure and frame-shear wall superstructure under different seismic excitation are studied respectively, the effect of structure stiffness, damping and spectrum characteristics of seismic excitation on structure acceleration response, displacement response, structure deformation and inter-story displacement angle are discussed. With seismic forward calculation, the filtering effect of soil is considered, and seismic energy dissipation is truly expressed.3. Seismic Response Analysis of soil-pile-superstructure coupling systemCompatible finite elements for soil, pile, foundation and superstructure are reasonably selected, viscous-spring artificial boundary is adopted to simulate soil boundary effect. The finite element model of soil-pile-superstructure coupling system is established; characteristics of vibration responses of frame superstructure and frame-shear wall superstructure under different seismic excitation are studied respectively, and seismic responses obtained with and without considering interaction effect are compared. The influences of soil-pile-superstructure interaction on the superstructure seismic responses are discussed. Seismic responses of superstructure with different length of piles and different elastic modulus of soils under different seismic excitations are studied, and the impacts of pile length and soil elastic modulus on superstructure seismic responses are discussed. |
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