Numerical Analysis Of The Infinite Soil-structure Dynamic Interaction Within The Framework Of Time-domain Substructure Method

Numerical analysis of structure-soil dynamic interaction has been recognized as an important part in the structural earthquake-resistant design, especially for long-span bridges and large hydraulic dams. However, due to the complexity of dynamic interaction mechanics, the structure-soil dynamic interaction is usually confined to solve in the frequency domain, which is unsuitable for nonlinear problems and makes the numerical analysis method hard to be further developed in the theory.Recently, many researches of dynamic soil-structure interaction analysis are concentrated in the time domain, because not only the problem of nonlinearity can be better simulated in the time domain than in the frequency domain, but also the typical structural responses analysis is not accustomed to working in the frequency domain. Compared with the direct method, the substructure method is more practical in the formula derivations of general dynamic equations of the system. Moreover, the substructure method is convenient to analyze the dynamic properties of the structure and unbounded soil separately. Therefore, the research with the time-domain substructure method is an important developing direction for the dynamic interaction numerical analysis.Within the framework of the Finite Element Method (FEM), by applying the Damping Solvent Extraction Method (DSE Method), the purpose of this dissertation is to develop a new practical solving procedure for the time-domain numerical analysis of the dynamic interaction, especially for some large-scale civil engineering projects. And then, many related researches are evolved in this paper, mainly including: dynamic numerical models for the infinite soil, numerical models of the seismic input waves, solution of the wave scattering problems, numerical analysis of dynamic interaction, and post-processing for the results data field, etc.1. For time-domain numerical analysis of dynamic interaction, the basic governing dynamic equations in direct method are fully derived from the usual basic dynamic equations of structure, and also the ones in the substructure method are strictly formulated according to the dynamic force equilibrium and deformation compatibility on the structure-soil interfaces. Various time-domain numerical methods applied in practical analyses can be generalized from the simplified forms of the above two governing equations, which provides theoretical basis for the subsequent works in the dissertation.2. DSE Method is an effective simple procedure for the numerical simulation of the dynamic radiation properties of infinite medium through the following two steps: first, applying artificial damping into bounded soil region, and then extracting it by shifting the frequency along the frequency axis. Based on DSE Method, it is convenient to calculate the dynamic interaction forces acting on the interface between unbounded rock and structure. A robust time-domain damping-extraction procedure is proposed in this dissertation, and the corresponding Finite Element implementation of the procedure is also described with a step-by-step numerical integration scheme, in which the convolution integrals, as required inother time-domain algorithms can be avoided. The new algorithm is very convenient to combine with the existent FEM analysis programs for the structure dynamic responses.3. As seismic excitations adopted in the time-domain numerical evaluation, the seismic velocity and displacement histories are usually also essential, other than in the traditional frequency-domain interaction analysis, which usually requires to only input the seismic acceleration records. However, due to the effects of little long-period signal noises, it is a common problem for the evidently shifted baseline existed in the corresponding displacement history by double numerically integrating the acceleration records. So, this dissertation examines the problem in detail and proposes a new simple time-frequency domain correction method to eliminate long-period errors of seismograms. Firstly, the non-zero parabola mean-c...