In the present work, we deal with both analytical/numerical and experimental modelings of seismic metamaterials, designed to protect buildings and civil infrastructures from incoming seismic waves. By using Floquet-Bloch transform, it is possible to strongly reduce the size of numerical model compared to a fully simulated model. Indeed, the numerical mod-eling comes down to the study of the eigenproblems defined on a primitive cell representative of the whole periodic medium. Existence of frequency bandgaps, one of the main issues of metamaterial, is analysed. Moreover, using reduced laboratory samples of soil with periodically distributed holes or concrete inclusions, actual efficiency of the studied seismic metamaterials is tested and compared with the analytical/numerical prediction. The comparison highlights the similarities observed between experimentally recorded transfer functions and numerically predicted bandgaps.