Project Details

A longstanding threat to bridge safety is that bridge foundations can be susceptible to scour. This problem is compounded when the bridge foundation depth is unknown. According to the National Bridge Inventory, about 28,000 highway bridges with unknown foundation depths were recorded in 2016. Researchers have developed and investigated several methods over the years to determine embedded foundation lengths, including sonic echo/impulse response methods, bending wave method, various borehole methods, and many extensions and modifications of these methods. The borehole methods are considered reliable but expensive, and the surface-based methods are less expensive but lack the same level of reliability as the borehole methods. To address this problem, we have developed a new surface-based nondestructive test method that we call ‘effective dispersion analysis of reflections’ (EDAR). We show that EDAR is not only inexpensive, but also accurate and reliable. The method is based on accurately capturing the dispersion of waves as they propagate through a pile and is applicable to both longitudinal and bending waves. Specifically, EDAR processes measured accelerations at two distinct locations on the pile due to hammer impact, resulting in an estimate of the pile length: the analysis hinges on examining the oscillations in phase difference that are due to reflections as a function of wavenumber. We have validated EDAR using side impacts on concrete-filled steel tubes; the results consistently showed less than 5 percent error in a laboratory setting