Damage diagnosis of steel frames using vibrational signature analysis

This paper presents a structural diagnosis technique using "vibrational signature" analysis and the concept of strain mode shape (SMS). When a structure experiences a damage or change, a new state of force equilibrium is realized. This change of force distribution can be noted from the SMSs of the structure measured before and after the damage. The magnitude of the changes reflects the degree of forces redistributed. Since force redistribution is, in general, greatest near the damaged area, the location of damage is implicitly identified by the severity of the SMS change. A steel model frame was tested in the laboratory to substantiate this approach. Results show that locations of minor damage (specified change) in the frame can be pinpointed.