Fatigue load estimation for road bridges using long term WIM monitoring

As bridges form the keystone of transport networks, their safe operation with minimal maintenance closures is paramount for efficient operation. Yearly increases in the volume of heavy traffic mean a higher number of fatigue damaging load cycles. The study utilises real traffic streams from Weigh-In-Motion (WIM) monitoring within the Swiss highway network performed continuously over a number of years. The concept of a Standard Fatigue Bridge Model (SFBM) is introduced which provides long term fatigue cycle data for road bridges based on the real traffic data. An algorithm was developed which simulates vehicle passages over a bridge model and calculates fatigue load effects using the axle positions recorded in real time. This information could serve as an identification tool for bridges within a stock where fatigue is likely to be a problem and could form part of a full bridge management framework.