An improved direct stiffness calculation method for damage detection of beam structures

An improved Direct Stiffness Calculation (DSC) technique and a new damage index, namely Stiffness Variation Index (SVI), are proposed to detect and quantify damage in beam structures. In the DSC technique, through modal displacements and frequencies extracted from a dynamic test, the modal curvature and bending moments are obtained. Therefore, the structural bending stiffness and SVI can be explicitly calculated. By comparing the calculated stiffness with that from design data of the structure, the damage location and its severity can be determined. In the improved DSC technique, the central difference method is adopted to evaluate the modal curvature, making this technique more practical. Sensitivity of measurement errors was studied through numerical simulation via comparing the SVI with other damage indices. It is observed that the diagnosis sensitivity of the SVI using the improved DSC technique is superior to most of other damage indices. For this purpose, two sets of experiments on beams with different measurement errors were analyzed to verify the improved DSC technique. Copyright (c) 2012 John Wiley & Sons, Ltd.