The present study is about an automatic diagnostic method for the structural health monitoring. In this study, a new diagnostic method applicable to existing structures from the present moment is proposed. In the proposed method, structural condition is diagnosed without information about damaged condition. The proposed method statistically diagnoses structural condition by means of investigating the change of a response surface. The response surface is calculated as a regression model of relationship between multiple sensors. The shape of the response surface is changed reflecting the change of the structural condition. In this method, the change of the response surface statistically investigated with the F-test. In the F-test, the threshold of normal or damaged condition is decided with only theoretical F-probability distribution. This theoretical F-distribution is easily calculated using the response surface parameters. Therefore, diagnosis is conducted by means of only intact data used for the reference data. This means the proposed method doesn't require information about the damaged condition. In this study, the health monitoring system of the jet fan was developed to investigate the effectiveness of the proposed method. In this study, field test was conducted using an actual jet fan in a tunnel. In the field test, robustness of the proposed method was investigated. As a result, the structural condition of the jet fan was successfully diagnosed and effectiveness of proposed method was confirmed.
