Development of Novel Methodology for Assessing Bridge Deck Conditions Using Step Frequency Antenna Array Ground Penetrating Radar

Ground penetrating radar (GPR) has emerged during the last decade as a nondestructive testing method for assessing the subsurface condition of infrastructure components. However, the use of step frequency ground penetrating radar (SF-GPR) antenna arrays has been limited due to the significant complexity of postprocessing data analysis. One objective of this study was to investigate how SF-GPR can provide the necessary input for assessing the bridge deck condition at both project and network levels so as to be used in routine condition assessment of about 3,000 bridge decks distributed along the state of Maryland. For being able to do so, key bridge deck condition parameters were identified and selected with bridge engineers at the Maryland state highway authority responsible for bridge inspection monitoring. This paper presents the proposed methodology for monitoring and reporting such key condition assessment parameters (including concrete surface condition, concrete cover, deck thickness, top rebar condition, and surface elevation). Results from two bridge deck structures are presented herein as an example to demonstrate the use of the suggested methodology and analysis. Furthermore, fuzzy sets analysis was introduced in order to compare the conditions of different deck spans of the same bridge or between different bridges. The use of SF-GPR increased data collection speed and improved bridge deck condition assessment in relation to traditional methods (such as coring, chain drag, and chloride concentration) and reduced condition assessment monitoring cost because the GPR surveys are faster to perform and may require minimal traffic control in relation to the data collection speed. The proposed methodology has been successfully used for monitoring the bridge deck conditions of several hundred bridges in Maryland, and thus it can be adapted and implemented elsewhere where SF-GPR surveys may be considered for bridge deck condition assessment.