Corrosion fatigue effects on life estimation of deteriorated bridges under vehicle impacts

• Fatigue life of deteriorated bridges is evaluated.
• Road surface deterioration and structural corrosion are modeled.
• The fatigue strength reduction is sensitive fatigue life estimation.
• The sectional loss is not sensitive to fatigue life estimation.

Corrosion fatigue is more detrimental that of either one acting separately. The safety and reliability are greatly endangered by the combined effects from environmental corrosions and vehicle-induced fatigue damages, which could possibly lead to a catastrophic failure. In this paper, the corrosion fatigue effects on life estimation of deteriorated bridges subjected to dynamic vehicle loads are evaluated based on a reliability-based approach. Both the road surface deterioration and the structural member corrosion are considered in the vehicle-bridge dynamic system for stress range estimations. Varied material corrosion rates, vehicle types, vehicle speeds, and time-varied road surface conditions are considered. At the end of each stress block, the fatigue life is estimated by evaluating the cumulative probability of failure. The effects of the corrosion induced area loss and moment of inertia reduction are limited and are much less than the random effects from road surface condition. Corrosion induced fatigue strength reduction have a large effect on fatigue life. More than 60% reduction of fatigue life is predicted for different corrosion levels. The fatigue strength reduction is found more sensitive for the fatigue life estimation. With the refined vehicle-bridge dynamic analysis model and a refined material corrosion model, it is possible to assess the time-variant damages from random vehicle loads, environmental corrosion and their combined effects.