| Current methods for non-destructive testing of bridge cables for corrosion suffer from several significant drawbacks. They are not able to pinpoint the location of the corrosion, nor are they able to detect corrosion processes that are inactive at the time of measurement. A more powerful non-destructive technique for locating and classifying faults in bridge cables is introduced and developed in this dissertation. This approach applies time-domain reflectometry (TDR), a technique for analyzing electrical transmission lines, to bridge cables. We show that the transmission line model can be applied to bridge cables, and we analyze the asymmetric two-cable transmission line to determine the electrical parameters of interest. We also develop models for the various types of commonly-encountered cable defects, and show what types of waveforms will be seen by measurement instruments if these defects are present. We verify our results using both computer simulations and measurements taken on fabricated cable sections with "built-in" defects, demonstrating that TDR is an effective way to detect the location and extent of corrosion in bridge cables. While this dissertation considers only the application of TDR to bridge cables, this method of non-destructive evaluation may also be applied to other steel reinforced structures by developing appropriate models. |
