ABSTRACT
Integrity of bridge supports, namely abutments, columns and piers, and foundations, can be diminished by scour, abutment and foundation movement, and seismic excitation, among other processes. Time domain reflectometry (TDR) analyses of signals pulsed through cables incorporated within the bridge structure can be employed to monitor suspected degradation of these supports. Two general approaches are described in this paper to locate and quantify damage of critical bridge support members using TDR. First, the overall stability of the structure can be assessed by monitoring movement of abutments and foundations with respect to the foundation materials. Second, columns and piers can be monitored for internal cracking. Both approaches utilize the same method of measuring deformation of metallic, coaxial cables caused by displacement or deformation of the surrounding medium. These sensing cables require an electronic monitoring system to collect both the global measurements of external displacement and local measurements of internal deformation. It is important that this system function during critical events, such as earthquakes and floods, when major damage is most likely to occur.
