The study on simultaneous identification of structural damages and loads

Unknown structural damages and loads usually coexistent together. Aiming at this problem, this paper develops a practical method in a time domain for their coexistent identification based on Virtual Distortion Method (VDM). In VDM, virtual distortions are introduced to simulate structural damages, and responses of the damaged structure can be estimated quickly. This article firstly extends VDM into real structures with multiple element distortions using finite element theory, and then unknown loads and virtual distortions are reconstructed simultaneously via the measurements and an intact structural model. Then the damage extent and type are recovered by a relation between the virtual and actual distortions. A damaged cantilever aluminum beam is used in the experimental verification. Both load and damage (extent and type) are successfully identified. The identification is performed off-line as well as online by the application of a moving time window and a load shape function.