Response spectrum method based on effective-modes superposition for seismic analysis of aboveground structure considering soil-structure interaction

Abstract

The modal superposition response spectrum method (RSM) has been widely applied in seismic analysis and the design of aboveground structures. The RSM considering SSI has evolved; however, most methods use substructure models to simulate SSI effects. The direct method can simulate the SSI effect more accurately but is rarely used in the RSM because the high degree of freedom required for soil significantly reduces the efficiency of modal analysis. To address these challenges, first, an efficient analysis technique is proposed that is based on iterative static analysis. This method can efficiently obtain the effective frequencies and modes of aboveground structures from the SSI system. Subsequently, the effects of the site shear wave velocity and different boundary locations on the structural effective frequencies in the SSI system are investigated by the proposed method. Finally, the effective-modes superposition RSM is proposed for seismic response analysis of aboveground structures while considering the SSI. Examples are provided to demonstrate the effectiveness of the effectives-mode superposition RSM in the seismic analysis of aboveground structures.