Damage identification of structures with substructural flexibility

Structural health monitoring systems rely on algorithms to detect potential changes in structural parameters that may be indicative of damage. For a large-scale structure, the local damage usually introduces slight change to the global modal data, which makes the local damage difficult to be detected. This paper proposes a new substructuring method for the damage detection of a structure. The global structure is divided into manageable substructures. The modal data measured on the global structure are disassembled for obtaining the independent substructural dynamic flexibility matrices, under the force and displacement compatibility constraints. Afterwards, the substructural flexibility matrix is decomposed into its eigenvalues and eigenvectors to be used as the indicators for damage detection. Since the substructuring method concerns the local area by treating it as an independent structure, the substructural eigenparameters are more sensitive to the local damage than the global eigenparameters. The proposed substructuring method is integrated with probability and statistical analysis upon a laboratory-tested portal frame structure.