Impact of Testing Configuration and Data Analysis Approach on Detection of Delamination in Concrete Bridge Deck with Sonic Methods

摘要

Accurate condition assessment of concrete bridge decks will lead to a more mechanistic andreliable bridge management system, which is currently of a great concern to transportationagencies. In this study, two sonic-seismic methods, impact echo (IE) and ultrasonic surfacewaves (USW), were used to characterize material properties and identify fabricateddelaminated areas inside a concrete bridge deck. The reliability of the IE and USW methodsis impacted not only by the strengths and weaknesses of the methods but also by the mannersof data collection, interpretation and presentation. The data obtained from the two methodswere visualized in both traditional and checkerboard format. The checkerboard formatlocates the delaminated areas more precisely since the smoothing algorithm is avoided in thiscontouring method. This observation is more critical as the density of data collection isreduced. The evaluative power of each method and their combination, in terms ofdetectability and accuracy, was also compared and discussed. The combined results fromUSW and IE methods are preferred to the individual results of each method since theyprovide redundant and complementary results that reduce the uncertainty in identifying thedefects without any additional overhead in field data collection. A relation between the sizeof the defect and measurement density was recommended through evaluating the bridge deckat three different measurement densities. The measurement spacing should be equal to or lessthan the smallest defect that is deemed critical by the owner agency.