Probabilistic response of prestressed concrete bridges to fatigue

The paper presents a model for the analysis of the response of prestressed concrete bridges to fatigue. Due to fretting effects, fatigue is mostly important in concrete bridges with post-tensioned tendons where cracking is present due to unexpected external loads or design assumptions (partial prestressing). The model considers the non-linear sectional response due to the material constitutive laws and cracking. Cracking may be due to service loads, thermal gradient and differential settlements between foundations. The uncertainties inherent to the main variables involved in the fatigue process are also dealt with. The randomness in the fatigue strength of materials is considered through the definition of probabilistic S-N curves for reinforcing and prestressing steels, based on the available results of tests involving fretting fatigue in the case of prestressing tendons. (C) 1998 Elsevier Science Ltd. All rights reserved.