Estimation of Deterioration Due to Corrosion in the RC Members Using Higher Harmonics

In general, vibration-based condition assessment techniques rely on monitoring the changes in the modal frequencies of a structure, which may not provide an objective diagnosis in case of missing prior information. Instead, tracking and measuring the higher harmonics of the natural frequencies caused by any damage in the dynamic response of the structure can be used for the damage quantification. This type of nonlinear vibration-based monitoring can be realized by performing higher-order spectral (HOS) analysis, which is widely popular for the inspection of machinery systems, whereas limited studies are available regarding the civil engineering structures.

As a rare application, herein, a HOS based diagnostic technique is adapted to estimate the deterioration in corroded reinforced concrete members. The proposed diagnostic technique, which utilizes the higher order spectral analysis, is demonstrated on two laboratory-scale RC poles. The poles are first subjected to the impact vibration tests, and then the recorded transient signals are analyzed with the proposed technique to extract the diagnostic index which is a measure for the damage. The preliminary test results manage to discriminate the corroded pole from the intact one, whereas further study is planned to investigate the sensitivity of the diagnostic index with respect to the level of the damage.