Structural Health Monitoring model for fatigue assessment in concrete bridge decks

Certain environmental exposures can cause rapid deterioration of the steel reinforcement inside bridge decks. The concept of a steel-free deck, based on replacing the internal reinforcement with external straps to avoid corrosion, has been developed and implemented in Canada. The long-term behavior of these slabs has not been completely studied and there is still a need to understand the deterioration and residual strength under the fatigue cycles due to truck wheels loads. This research will demonstrate how it is possible to integrate Structural Health Monitoring (SHM) and reliability analysis for long-term decision making regarding safety and maintenance of these structures.;Phase Two of this project was the determination of the time-dependent behavior of steel-free deck panels under fatigue loading. Ten concrete slabs were built and then tested under high levels of fatigue loading. The characteristics of different parameters including strap strain, deck deflection and concrete crack width were studied.;Phase Three involved reliability analysis of the steel-free deck panels after applying the fatigue cycles. Because these panels are subjected to deterioration due to the cyclic loading, it was important to characterize how the strength of the panels would be reduced. Five slabs were experimentally tested by first applying fatigue cycles to accumulate damage and then testing to failure. The results have shown that the residual strength was close to the initial capacity until a critical point was reached in the crack propagation. After the critical cracking damage had occurred, the residual strength, and the safety of the deck was decreased. The reliability analysis allows engineers to assess the bridge safety condition and make the maintenance decisions.;This study outlined an overall process for the long-term monitoring of the steel-free decks specifically and generically applicable to many problems.;Phase One of this project was the identification of the vehicle loads crossing the bridge. A pattern search method is adopted to solve the bridge weigh-in-motion problem. The efficiency of this model was verified by using the results of the finite-element model for the steel-free deck bridge. Furthermore, the performance of the method was investigated by comparing statistical parameters of the analysis.