2019 CSCE Annual Conference - Laval (Greater Montreal) Conference
Dr. Leon Wegner, University of Saskatchewan
Corrosion is a major factor that causes degradation of reinforced concrete structural elements, especially in cold regions where de-icing salts are used extensively. It is difficult to assess the remaining capacity of a corroded reinforced concrete member based on visual inspections alone, and therefore to determine whether the member has an adequate level of safety. Structural health monitoring (SHM) can provide real-time information about a structure’s actual condition, thereby mitigating the risk of failure if the structural condition is worse than presumed, or extending the service life and saving the replacement costs if it has an adequate level of safety.
This paper describes the results of a laboratory-based experimental study undertaken to evaluate the effectiveness of an SHM technique for determining the bending moment capacity of a corroded reinforced concrete beam and its remaining level of safety in terms of the reliability index. The SHM technique is designed to estimate the remaining effective cross-sectional area of the reinforcing bars after corrosion, which can then be used to predict the remaining structural capacity and service life, as well as the degree of certainty associated with these predictions. Three batches of reinforced concrete beams were subjected to different levels of accelerated corrosion before being tested under service load levels while gathering data using several different types and combinations of instrumentation. The accuracy of each beam’s capacity estimate will be determined based on the measured failure load. In addition, the reliability index associated with each combination of instrumentation and level of corrosion will be calculated. Finally, a life-cycle cost analysis for each beam and monitoring system will be performed, based on a target reliability index, and the value of implementing SHM systems will be discussed.
The preliminary results of this study show that the SHM technique can predict the remaining effective area within 10% error. Also, with the additional information provided by the SHM systems, the uncertainty of the structural capacity decreased, the structural reliability increased, and the maintenance and replacement cycles of the structure could be optimized. Therefore, this topic will be of interest to infrastructure owners and inspectors, and, due to the popularity of public-private partnership (PPP) projects across Canada in recent years, structural designers and contractors may also have interest in this topic.