Volume 39, Issue 4 (July 2011)
An Approach on Damage Detection of Beams Using Operational and Numerical Modal Analyses
The study presents an application of a damage detection approach for beam like structures that is based on both operational and numerical modal analyses results obtained from undamaged and damaged cases of a structure. The effectiveness of this approach is assessed by performing investigations on a column model. In the first step of this approach, the damaged member of the column is determined by comparing the mode shapes of the undamaged and damaged cases. For this purpose, the changes on the vectors defined as the differences between the undamaged and damaged mode shapes for each mode are observed. It is assumed that the abrupt change in these vectors shows the existence of the damage. In the second step, the numerical model of the column is created and calibrated according to the experimental results obtained from the undamaged case. To find the damaged section, a step-by-step analysis on the pre-identified member of the column model is performed numerically. For this reason, the natural frequencies obtained from the numerical modal analyses of the column for the damaged case are compared with the experimental results. The minimum difference between the numerical and experimental results indicates the presence of the damage on this section. The approach used in this study provides an important contribution that the number of structural members to be analyzed is limited instead of analyzing all structural members.