Derivation of partial factor for fatigue of rebars in concrete railway bridges

The fatigue load and fatigue resistance in design verifications should be multiplied with, respectively divided by, partial factors. These factors ensure that designs comply with the structural reliability requirements of design standards. This paper derives the partial factors for fatigue of rebars in concrete railway bridges, by comparing the design verification with a probabilistic assessment using a realistic representation of the fatigue loads and fatigue resistance, together with their uncertainties. It uses factored Load Model 71 and the S-N curves of the Eurocodes as a basis for the design. Recent traffic load measurements and fatigue tests in constant and variable amplitude load available in the literature are used for the probabilistic assessment. The analysis estimates the reliability index of a structure designed with the current partial factors of the Eurocode. The conclusion is that the current partial factors in the Eurocodes might be too low.