Structural damage detection from coupling forces between substructures under support excitation

This paper proposes a method to identify the coupling forces between substructures from the acceleration response of a structure under support excitation, and the local structural damage is then detected from the identified coupling forces based on dynamic sensitivity analysis. The identification equation of the coupling forces is formulated in state space, and it is solved with the damped least-squares method. The sensitivity of the coupling forces between the substructures with respect to a local change in the system parameter is derived analytically. In addition, a model condensation method is used to reduce the number of coupling forces for a more practical application. A nine-bay three-dimensional truss structure serves as an example for validating the proposed method. Numerical simulations with noisy measured accelerations show that the coupling forces between substructures are very sensitive to local changes in the system parameters and the proposed method can accurately detect the location and extent of structural damage resulting from an improved computational efficiency and accuracy.