Advanced Ground-Penetrating Radar Techniques for Evaluating Deterioration in Bridge Decks

Evaluation of the structural condition of reinforced concrete bridge decks is essential for maintaining the safety and longevity of the transportation infrastructure. This study investigates the application of ground-penetrating radar (GPR) for the quantitative assessment of bridge deck deterioration. A waveform inversion using the frequency-domain finite element method (FEM) was employed to improve the interpretation of GPR data. The method was validated using synthetic data, confirming its effectiveness in detecting and imaging deterioration and rebar delamination through velocity variations. GPR data were collected from a test-bed specifically designed to simulate different types of bridge deck deterioration. The analysis focused on applying waveform inversion to test-bed data for assessing deterioration that may occur in real bridge decks. Frequency analysis identified critical frequency bands related to deterioration, which were used as parameters in the inversion. The inversion results of the GPR data showed that velocity variations corresponded to the deterioration zones. Furthermore, field data collected from the Geumgu Bridge in South Korea were analyzed to evaluate the practical applicability of the proposed inversion method. The removal of background values, combined with instantaneous amplitude analysis, was initially applied to identify deteriorated areas, followed by waveform inversion for a quantitative assessment of the damage. The velocity values obtained from waveform inversion were converted to dielectric constants, allowing for the identification of deteriorated zones. The results confirm that the waveform inversion of GPR data is an effective tool for evaluating bridge deck deterioration.