OICC Press Journal of Solid Mechanics 2008-7683 12 4 2020 09 30 Vibration of Timoshenko Beam-Soil Foundation Interaction by Using the Spectral Element Method 607 619 EN S Hamioud Department of Civil Engineering, University of Jijel, Jijel, Algeria S Khalfallah Department of Mechanical Engineering, National Polytechnic School, Constantine, Algeria S Boudaa Civil Engineering Department, University of Constantine, Constantine, Algeria Journal Article 2020 09 30 This article presents an analysis of free vibration of elastically supported Timoshenko beams by using the spectral element method. The governing partial differential equation is elaborated to formulate the spectral stiffness matrix. Effectively, the non classical end boundary conditions of the beam are the primordial task to calibrate the phenomenon of the Timoshenko beam-soil foundation interaction. Non-dimensional natural frequencies and shape modes are obtained by solving the partial differential equations, numerically. Upon solving the eigenvalue problem, non-dimensional frequencies are computed for the first three modes of vibration. Obtained results of this study are intended to describe multiple objects, such as: (1) the establishment of the modal analysis with and without elastic springs, (2) the quantification of the influence of the beam soil foundation interaction, (3) the influence of soil foundation stiffness’ on free vibration characteristics of Timoshenko beam. For this propose, the first three eigenvalues of Timoshenko beam are calculated and plotted for various stiffness of translational and rotational springs.