Damage detection in beam structures using subspace rotation algorithm with strain data

Motivated by a smart structures philosophy of self-health monitoring in structural systems, a damage detection system for beam structures using subspace rotation techniques is presented. In doing so, the subspace rotation is extended from displacement-based data to strain-based data. Methods for accommodating the additional degrees of freedom of beam elements are presented. Using simulated data, the ability to locate and quantify single and multiple damage events is investigated. It has been found that the higher-order vibration modes are required to locate damage events in beams because the frequency response of beams is much less sensitive to a damage event than that of truss structures. It has also been found that condensation methods cannot be used to remove rotational degrees of freedom in the beam because of the coupled nature of the rotational degrees of freedom to the translational degrees of freedom.