The structural characteristics of a wharf segment may be modeled by using the simplified model due to unacceptable matrix sizes. The concept of simplified model is introduced at first. The locations of simplified model that represent original structure are determined by the locations of pile groups in defined areas. Force-displacement curve is calculated for wharf structure by pushover analysis, and simplified model is constituted applying estimated secant stiffness and effective damping according to force-displacement curve. Peak value of seismic response is estimated using elastic modal response spectra analysis and compared with simulated results from nonlinear time history analysis. It is proved that peak value of seismic response can be calculated using simplified model rapidly, and close to time history analysis result.