A Study on 1D and 2D Seismic Site Response Analysis in a Complex Sedimentary Basin

Abstract In this study, the seismic behavior of the Persian Gulf Bridge’s complicated basin was evaluated using the FLAC 2D software based on the finite difference method (FDM). A 1D modeling for the soil profile at each pier position of the bridge and a 2D modeling for all piers located on the sedimentary basin was performed. To verify the results of the numerical models, the 1D responses obtained from the FLAC 2D and 1D DEEPSOIL software were compared using the viscoelastic soil behavior. Finding the responses of the bridge piers represents the vital role of the sedimentary basin effects and its 2D geometry on seismic ground motion responses. The results indicated that the seismic responses of the 2D and 1D analysis, such as the seismic wave amplification, predominant period, and the PGA in the complex basin site, differed. Moreover, the 2D amplification effects of the basin site were more prominent than the results of the 1D model in the periodic range of 0.5 to 1 second in a specified profile. Finally, the response spectra obtained from the basin surface at each pier position were compared with the standard design spectrum of the AASHTO code.