This paper presents a systematic procedure and details of the use of experimental and analytical modal analysis of a welded structure used for vibration based damage identification. First an experimental modal analysis was conducted on the undamaged welded structure model used for vibration based damage identification. Using impact hammer test, when the test structure is fitted to the multi-axis electro dynamic vibration shaker .In this experimental modal analysis frequency response functions are calculated from measured input force and output response of a structure using piezoelectric accelerometers from the frequency response function the peaks were identified. To compare the experimental modal analysis values finite element modal analysis was conducted using ANSYS software version 11.0. It has been observed from the results the natural frequencies obtained from the experimental modal analysis and ANSYS software version 11.0 shows a good consistency in comparison.