Structural Damage Identification using Experimental Modal Parameters and Correlation Techniques

This study presents new damage identification algorithms based on modal strain energy-eigenvalue ratio (MSEE). Firstly, a method using a simplified term of MSEE called geometric modal strain energy-eigenvalue ratio (GMSEE) is developed. Damage is identified by optimizing the correlation level between a measured GMSEE change vector and a numerical one. The method requires only measured modal parameters (i.e., natural frequency and mode shape) and geometric information of the structural element. Secondly, a modification of this method is presented considering use of the full term of MSEE. The modified method is capable for damage identification with fewer modes compared with the original one. Thirdly, in order to enhance the efficiency of the proposed algorithms, an improved technique is proposed for the optimisation procedure. The technique refers sensitivity-weighted search space, which helps reduce the effect of measurement noise on low-sensitivity elements. Performance of the proposed damage identification algorithms and enhanced technique have been validated with a simple numerical model and some experimental models of various scales from small to large.