| It is an important guarantee for the rapid development of economy to construct National Infrastructure Engineering. To explore the clean energy, several high dams and nuclear power plants are being built in seismic zones of western China, as well as eastern coastal area of China. Obviously, the seismic safety is crucial to such structures. With the support from China-Germany Joint Research Project GZ566, in-depth research has been conducted regarding the safety evaluation of large-scale complicated structures.1. To improve the accuracy and efficiency of time-domain model of unbounded soil, the influence of the key factors on the Damping Solvent Extraction Method (DSEM) is systematically investigated from analytical analysis and numerical simulation, and a deep discussion is completed on the simulation mechanism of dynamic characteristics of unbounded domain. And then, Damping Solvent Stepwise Extraction Method (DSSEM) is proposed by applying the relatively larger artificial damping in the bounded soil firstly and then employing a stepwise extraction process of damping, that is, the introduced artificial damping are divided into smaller parts to assure the convergence and extracted step by step, which can simultaneously decrease two sources of error in the implementation of DSEM. This method provides a more efficient and accurate way to calculate the interaction forces of the unbounded soil due to the fluctuation energy of reflected waves and the undesirable effect of artificial damping are completely removed as much as possible. Furthermore, the proposed method is applicable to practical engineering with irregular soil domain. Meanwhile, based on the solution of acceleration, an implicit DSEM integral algorithm firstly is proposed to solve the problem of explicit and implicit integral algorithm with different time steps on the interface between structure and soil region and combine with dynamic analysis of structures conveniently. Moreover, verification and validation studies are performed by using typical examples. And optimal parameters of this model are recommended for future use.2. Operability is the necessary condition of generalizing the model of structure and soil interaction to engineering application. A time-domain model based on User Programmable Features (UPFs) for implementing the Damping Solvent Stepwise Extraction (DSSE) method within commercial finite element software ANSYS is presented. In this model, a damped soil element is developed to consider the effect of artificial damping which is introduced in the soil; also, a3D compact viscous-spring boundary element is established to further reduce the amplitudes; and a practical external-interface is developed with ANSYS to evaluate the interaction forces at the structure-foundation interface. In addition, the DSSEM is implanted into the platform of ANSYS by means of the APDL and GUI. And then, the reliability and validity of this new model is verified by the typical numerical examples. Furthermore, the presented model is used for studying the influence of heterogeneity of unbounded soil on interaction forces, and the numerical result shows it is able to solve the dynamic problems which encountered in the inhomogeneous unbounded soil.3. This study’s aim is to develop an integrated dynamic analysis technique based on soil-structure interaction. Firstly, an Interface-Coupling element is established at the interface between structure and soil to consider the effect of artificial damping on structure. Meanwhile, in order to assure the convergence and accuracy of system of soil-structure, a dynamic nonlinear iteration technique is proposed in the form of increment. And then, based on the platform of ANSYS, a numerical model of soil-structure is built to solve the nonlinear dynamic problems of complex structures. Moreover, this numerical model is expanded by introducing the nonlinear model of structure and micro damage law of large scale concrete. Finally, from the dynamic nonlinear analysis of the system of Dagangshan arch dam, it is shown that the accuracy and efficiency of numerical model are pretty good. Also, applicability of EDE method is justified by damage process of Koyna gravity dam under strong earthquake.4. To be used in the practical engineering is the ultimate aim of Structure-Soil interaction (SSI) model. Based on the proposed SSI model, some practical engineering problems were studied. Firstly, analysis of floor response spectra is completed for a CPR1000reactor plant, and it is helpful to evaluate the compatibility of soil for nuclear power plant under earthquake. Then, considering the safety of train running on bridge, a time-variant model of high-speed vehicle-rail-bridge-foundation system is developed for the earthquake response analysis, and it provides convenient and efficient way to solve the complicated problems of engineering. In addition, considered the proposed vibration isolation project for the base of sophisticated equipment, a3D compact viscous-spring boundary element is constructed to simulate the effect of structure-soil-structure dynamic interaction; also, vibration isolation optimization model is presented. According to the practice, varied vibration isolation measures and influencing factors were compared and comprehensively analyzed. From the analysis, an optimal vibration isolation measure is proposed to meet the requirement, and the investment of engineering is decreased and the progress is speed up due to this optimal measure. |
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