Abstract:It is necessary to effectively input seismic motion on artificial boundaries to accomplish finite element simulation of the soil-structure dynamic interaction model subjected to seismic load. There are two kinds of seismic motion input methods commonly used in engineering and scientific research, including the wave input method and the vibration input method. The wave input method exhibits high simulation accuracy; however, its implementation is relatively complicated and is time-consuming. Further, the vibration input method is simple to process even though it exhibits low accuracy. In this study, a new method is proposed to provide the seismic motion input on stress-type artificial boundaries. By imposing the displacement-time history of the free field to the local substructure, containing nodes on the artificial boundaries and adjacent nodes in the soil-structure interaction finite element model, and by performing dynamic analysis, the equivalent seismic loads used to accomplish the effective input of the seismic load were directly obtained. The equivalent seismic loads were imposed on the nodes of the artificial boundaries for performing dynamic analysis. At this point, the seismic motion input and seismic response analysis of the soil-structure dynamic interaction problem were completed. When compared with the original wave input method, the proposed method avoids the complex calculation processes associated with the free field stress on the artificial boundaries and the additional forces caused by the artificial boundaries; further, it also does not require to define the directions of the loads based on the external normal directions of the artificial boundaries. The new method concisely determined the equivalent seismic loads and provided the seismic motion as input. The validity and reliability of the new method were preliminarily verified using the one-dimensional seismic response examples of homogenous elastic half-space and layered half-space.
