This paper presents a numerical one-dimensional wave equation analysis technique for piles and pile groups subjected to seismic horizontal ground motions in liquefiable zones. The so-called Earthquake Wave Equation Analysis for Piles (EQWEAP) procedure is introduced for piles subjected to horizontal earthquake excitations. Disregarding the effects of kinematic soil–pile interaction, the seismic responses of piles can be obtained by approximating the free-field ground response analysis, the ultimate earth pressure model, and the ground displacement profiles. The nonlinearities of the concrete piles were modeled using the approximate tri-linear moment–curvature relationships. A case study and application concerns were presented. Although the analysis is in one dimension, it is found to be effective and able to provide a rapid estimation in foundation design when seismic pile behaviors are of interest. The advantages of this analysis are the time efficiency of the seismic design of pile foundations and the relative simplicity of the analysis. In addition, it suggests alternative modeling for the dynamic analysis adopting the commonly known static models and/or methods.