Comparison of analytical and difference sensitivity methods for structural damage identification

The sensitivity-based damage identification method receives much attention due to its ability to identify structural damages at element level. This paper aims to discuss the influence of two different deduction algorithms of sensitivity matrix, the analytical method and the numerical difference method, on the parameter identification results of structures with the same identification index. In order to compare the difference between the two sensitivity-based damage identification methods, the frequency-domain mode shape and the time-domain acceleration response information are used as the updating objectives, respectively. And then, the sensitivity matrices of the updating objectives to the same identification index, structural element stiffness parameters, are respectively derived based on the analytical method and the numerical difference method. Finally, a simply supported box girder bridge is used to illustrate the difference between the two sensitivity-based methods. Numerical simulations with initial model errors and measurement noise show the two types of methods both can accurately detect local damages and identify unknown initial model errors. The presence of random noise has some bad effect on the identified results of structural parameters, but the identified accuracy is still acceptable for normal noise level