Bridges are vulnerable to the fatigue damage accumulation caused by traffic loading over the service period. A continuous\ngrowth in both the vehicle weight and the traffic volume may cause a safety hazard to existing bridges. This study\npresented a computational framework for probabilistic modeling of the fatigue damage accumulation of short to medium\nspan bridges under actual traffic loading. Stochastic truck-load models were simulated based on site-specific weigh-inmotion\nmeasurements. A response surface method was utilized to substitute the time-consuming finite element model\nfor an efficient computation. A case study of a simply supported bridge demonstrated the effectiveness of the computational\nframework. Numerical results show that the simulated fatigue stress spectrum captures the probability density\nfunctions of the heavy traffic loading. The equivalent fatigue stress range increases mostly linearly in the good road\nroughness condition with the growth of the gross vehicle weight. The vehicle type and the road roughness condition\naffect the stress range. The influence of the driving speed on the equivalent stress range is non-monotonic. The bridge\nfatigue reliability has a considerable increase even under a relatively high overload limit. It is anticipated that the proposed\ncomputational framework can be applied for more types of bridges.
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