ABSTRACT
Thermal load contributes to fatigue damage and affects the structural behavior of steel bridges. To take the thermal effect into consideration, this paper proposed an innovative evaluation method for fatigue assessment of steel bridges. The thermal stress of fatigue category details were decomposed according to the decompositions of thermal load. Then the fatigue damage caused by thermal stress was calculated based on S-N curves and Miner’s cumulative damage theory. Taking a railway steel box girder bridge as case study, the temperature monitoring was carried out and the thermal stress was calculated using the proposed method. Results show the daily cumulative fatigue damage can reach 4.2×10-7 influenced by traffic load, but the daily cumulative fatigue damage can reach 4.7×10-7 if the thermal load is considered, which indicates that the proposed method is applicable to the evaluation of steel box girder bridges. The case study also shows that the fatigue damage caused by long-term temperature cannot be ignored.
