ABSTRACT
Damage detection methods based on vibration testing techniques are widely applied in engineering fields. The acceleration responses are acquired by performing a detailed modal analysis. However, these parameters are usually the global features of the structure and cannot indicate local damages of the structure well. Compared to displacement modes, strain modes are more sensitive to structural stress concentration and local damages. A strain modal identification method to extract strain modes from the operating strain responses and a damage detection method based on the strain modes are presented in the paper. A 4 -span bridge model in the laboratory is used to validate the algorithms. Data is collected and analyzed for both the original and the damaged state of the bridge. Then strain and acceleration data findings are compared for both cases. The simulated damage position is detected successfully with the presented algorithm.
