The DSE Method In Time-domain For Dynamic Interaction Analysis

Numerical analysis of structure-soil dynamic interaction has been recognized as an important part in the structural earthquake-resistant design. Recently, many researches of dynamic structure- soil 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, by applying the Damping Solvent Extraction Method (DSEM), the purpose this dissertation is to develop a new practical solving procedure for the time-domain numerical analysis of the dynamic interaction. And then, many related researches are evolved in this paper, mainly including: the implementation of theoretic formulae based on DSE Method, modes of the seismic input waves, a method using different time increments in different regions and numerical analysis of dynamic structure-water interaction based on the DSE Method, etc.1. DSE Method is an effective 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. The 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 in other time-domain algorithms can be avoided. The algorithm is very convenient to combine with the existent FEM analysis programs for the structure dynamic responses. And then, the simple Predictor-Corrector Explicit Integrator Algorithm is applied to the above procedure, which contents astringency and precision with the need of projects.2. For the numerical analysis of the dynamic interaction, seismic velocity and displacement histories are usually also necessary, other than in the traditionalfrequency-domain interaction analysis, which requires to only input the seismic acceleration record. But now, the corresponding velocity and displacement are obtained from the abundant seismic acceleration records by stepwise integral. This method results in not only the lose of convulsionary communication but also the evidently shifted baseline existed in the corresponding displacement history. In fact, the dynamic analysis of only inputting the acceleration records is ordinary in engineering application. Then, the sub-regional stepwise solution procedure based on only inputting the acceleration records is presented in this dissertation to perform the dynamic soil-structure interaction analysis in time domain. The procedure is convenient to analyze the nonlinear properties of the structure separately, which is a new way for the dynamic analysis in the time-domain interaction.3. The numerical analysis of dynamic structure-soil interaction is implemented through the following two parts: first, calculating the dynamic interaction forces acting on the interface between unbounded rock and structure and then the solution of the basic dynamic equations of structure. Therefore, it is important to choose a logical numerical integral method for the interaction analysis. The Predictor-Corrector Explicit Integrator Algorithm is applied to the rock-domain procedure, which contents astringency and precision with the need of projects but requires extraordinary small time increment. The implicit integrator algorithm which is unconditional tranquilization usually is applied to the structure-domain. Thus, the method using different time increments in different regions is proposed to solve the dynamic analysis of the soil-structure interaction. In the soil regions, the small increments are used, while in the regions of structure, a comparative big time increments are used. Thus the efficiency of computation has been improved.4. Applying the analogy of motion equations between elastic-body and fluid, the finite element formulation of elastic-body can be used in fluid computation, which makes the fluid-structure coupling system has an unitary formulation for the seismic resistant computation. On this condition the DSE Method is applied to the dynamic analysis of the fluid-structure interaction. Thus, the dynamic interaction force acting on the interface is the hydrodynamic pressure.Based on the proposed analysis methods, detailed implementation codes are also described in the dissertation. And then, the related computing programs which offer credible numerical applications are developed. Evidently within the framework of FEM, the above works make up of a complete numerical analysis procedure for the dynamic interaction in time domain.