Two stages damage detection in structure based on modal data

A two stages method is presented by which the measured mode shapes and modal frequencies are used to respectively detect the location and magnitude of single or multiple damages in a structure. The first step is to determine the damage location using the concept of Local Frequency Change Ratio based on mode shapes. The second step is to determine the size of damage based on changes in the modal frequencies. Several damage cases are studied using simulated data to examine the performance of the method. Results illustrate that the presented approach is very simple and effective to locate and quantify damages in a structure.