Experimental Modal Analysis (EMA) is one of the most attractive engineering fields nowadays, which specifies in the studies of modal parameters of existing small buildings under forced vibrations. This study aims to experimentally validate the modal parameters by comparing results obtained from accelerometers with those measured using Linear Variable Differential Transformer (LVDT). Numerical methods such as Fourier transform, peak-picking, and the frequency domain decomposition (FDD) technique were used for modal parameters extraction and validation. Finite element modeling of the laboratory model, including the support flexibility, was investigated. In addition, a novel method for modal parameters' identification from the decomposed modal responses recorded by LVDT, was introduced. The experimental results showed that the natural frequencies obtained are in good agreement with the finite element method (FEM) and numerical methods. The validity of the proposed method paves the way for more effective output-only modal identification for the assessment of existing concrete buildings