Structural damage identification based on substructure method and improved whale optimization algorithm

In this study, a method based on the substructure method, element relative modal strain energy, and improved whale optimization algorithm (LWOA) is implemented to identify structural damage. In this method, firstly, the global structure is decomposed into several substructures based on the substructure method, which greatly reduces the size of the model to be analyzed and improves the efficiency of analysis. Secondly, LWOA algorithm is used to calculate the severity of structural damage, Levy-flight is introduced to improve the performance of the whale optimization algorithm and solve the convergence problem of the optimization algorithm. The performance of the improved WOA algorithm is verified by four benchmarks. Then, the objective function is constructed by using the element relative mode strain energy index, which is mainly based on the change of the ratio of the element modal strain energy before and after structural damage to the modal strain energy of the global structure as the damage index. Finally, three examples, a numerical plane frame, an experimental simply supported beam, and an ASCE Benchmark frame, are used to identify the assumed damage under different conditions using the proposed method. It is found that the element relative modal strain energy near the damage location changes greatly after structural damage occurs, while that of the element relatively far away from the damaged element area is less affected. The results show that the method can accurately identify the exact location and severity of damage in different structures, which can effectively improve the efficiency of damage identification.