| Timber piles are still used widely for supporting bridges, piers, wharves and other marine structures. As they age it becomes critical that their in-situ condition be assessed so their remaining service life can be evaluated. The Sea Grant program of the National Oceanic and Atmospheric Administration sponsored research projects in the Civil Engineering Department of North Carolina State University to investigate the application of wave propagation theory in timber pile condition analysis.;The techniques involve dispersive flexural wave propagation tests to determine if the condition of the pile can be related to wave velocities, to wave intensities or to a signal's changing spectral content. Tests were conducted using both laboratory models and field timber piles. The results show that piles' conditions can be related to their dispersive wave speeds.;One of the major concerns of installed timber pile condition evaluation is how to find a pile's overall length. Currently, there are three mathematical methods available for finding the overall length from the dispersive time record. These three methods are the Fourier phase, Short Kernel, and Hilbert phase methods. A comparison of these three methods can be beneficial to the engineers who attempt to find overall lengths of installed timber piles.;Time records are needed to compare these three methods, but a problem associated with the real time records is that not all of the true lengths of the installed piles are known. The only way to obtain the true lengths of the installed piles is to pull them out after the tests. Since the piles tested are still in service, this task is formidable. An alternative is to use synthetic data. With different levels of complexity imposed to the synthetic data, these three methods can then be compared. The performance of the three methods on overall length calculation has been evaluated based upon the six groups of data. The test results show that the SKM has a better performance in finding the overall length. |
