Influence of ambient temperature on the fatigue damage of welded bridge decks

Fatigue life assessment of critical bridge members using online monitoring data has been investigated in recent years. To make an efficient evaluation, a representative block of cycles is usually defined. However, relatively small amount of data in the representative block sometimes fail to cover the change caused by temperature and increasing traffic flow, which are proved by this paper to be important regarding fatigue damage. To find the relationship between fatigue damage, temperature and increasing traffic flow, an equivalent vehicle load method is presented. The statistical disposition of traffic flow and finite element analysis have been conducted, using data from the Runyang Suspension Bridge as an example. Then the damage caused by increasing traffic flow can be estimated and eliminated from the total damage so that the temperature effect is finally obtained. It is observed that temperature has a linear effect on the fatigue damage of welded joints of bridge decks within the temperature range from −4.31 °C to 46.95 °C. Possible reasons for this temperature effect have been discussed.