External forces generated due to earthquakes, wind, and blasts cause damage to the structure by which its structural integrity gets compromised. A method is to be developed to find the current state of the structure after the damage has occurred. This can be done by finding the natural frequency of the structure using modal analysis. In this study, a two-storey steel frame bolted structure has been studied experimentally on a one-dimensional shake table. Results obtained through the experiment have been verified using the numerical study of the same structure. COMSOL Multiphysics was used for additional numerical analysis, and the various eigenfrequencies and mode shapes were identified. Additionally, numerical research was carried out to simulate damages ranging from 10 mm to 20 mm, and the findings indicate that the natural frequencies decrease as the damage increases. Thus, Modal analysis can be used to determine the current state of the structure. For various mode shapes, the experimental and numerical frequency variations are 0.37, 1.61, and 3.16 %, respectively.