ABSTRACT
Seismic behavior of an underground hollow structure is often analyzed using a pseudo-static shear strain method. In this method, a pseudo-static shear strain estimated from a peak particle velocity and a shear wave velocity of the surrounding soil is imposed on the underground structure. Various forms of such “racking” analysis are used in practice. When an underground structure is located at a relatively large depth, studies suggest that such an approximate method should be adequate, particularly for flexible structures. For underground structures closer to the ground surface, however, it is not clear whether this approximate method would be adequate. Under these conditions, sometimes seismically induced dynamic earth pressures are used in a pseudo-static way to evaluate the seismic behavior of structures. To evaluate these effects of the depth of structures on their seismic behavior, FLAC was used to perform seismic soil-structure interaction analyses under both dynamic shaking conditions and pseudo-static racking conditions. The results from the FLAC analyses suggest several shortcomings of the traditional methods, indicating a more rigorous method using dynamic programs such as FLAC may be necessary under certain conditions.
