Bridge Fatigue Service-Life Estimation Using Operational Strain Measurements

Fatigue service life of steel bridges subjected to cyclic live loads was studied using operational strain measurements of a full-scale bridge. Fatigue fracture can be brittle and sudden, potentially leading to catastrophic bridge collapse. A service-life index and function were proposed for determination of the ultimate service life and remaining service life of bridges. The proposed method was used to study fatigue behavior of a bolted connection of a full-scale steel bridge. A regression model was developed for calculation of the life index and the service life function. Instead of common practice of using nominal stress data, realizations of the maximum stresses were generated using the bootstrap method. This paper shows that the proposed model is applicable for service-life prediction of existing steel bridges using only a finite number of operational measured strains from heavy truck loads.