This paper focuses on the correlation between frequency of a structure and degree of damage by testing a full-scale beam both statically and dynamically. To improve the quality of test data and reduce the effort for identifying the fundamental frequency of the beam, preloads are applied to the beam before conducting the dynamic tests. Test results have confirmed that the frequency of the beam itself depends on the load history while that of the beam plus sufficient preloads can be identified independently. This is because preloads can keep cracks open so that the cracked beam vibrates in a linear fashion
