This paper notes an integrated method that intertwines Structural Health Monitoring (SHM) with exponential regression modeling in order to determine fatigue life of prestressed concrete bridge girders under cyclic loading. The research was conducted with emphasis on the aging Al-Rayhanna Highway Bridge in Iraq, on which strain gauges and accelerometers were used to observe the stress responses given operational traffic loads. The analysis that was carried out with the American Concrete Institute (ACI 318 -19) fatigue equation, based on the collected data, showed there was a clear exponential dependency in the stress range ( \(\Delta \sigma \) ) and the Fatigue Cycles to failure (N). A predictive Fatigue Cycles to Failure model was built, which is written as Number of Cycles to Failure = 19.307 × e (− 0.278 × Stress Level (MPa)), and it has a robust correlation (R2 = 0.953) with the experimental data. The model indicates that the minimum stress level (0.672 3.228 MPa) leads to maximum fatigue life of 16 million cycles, whereas the maximum stresses (5.784 MPa and 8.34 MPa) enable fatigue life to be reduced to 1.94 million cycles and 3.93 million cycles, respectively. These findings underscore the essential role of the magnitude of stress on material durability and offer important findings in the field of engineering. Miner rule analysis totaled missing 55.78% damage, which would indicate that much fatigue life was still available, but monitoring should continue. The results point to the role of Structural health monitoring techniques in determining the integrity of structures and use a decent reference to predictive maintenance of aging infrastructure. The study would help in providing a better fatigue life prediction procedure and help in decision-making with regard to the structure of the bridge in terms of its cyclic loading.
