Design Temperature Load Spectrum for the Fatigue Verification of Composite Bridges with Integral Abutments

For (low cycle) fatigue design of steel foundation piles of composite bridges with integral abutments, not only traffic loads but also temperature loads as well have to be considered. Regarding this temperature fatigue load case, no specific rules and recommendations are given in EN 1991-2 (Eurocode 1: Actions on structures—Part 2: Traffic loads on bridges). The current paper proposes a simplified temperature load spectrum, to be used for (low cycle) fatigue design of constructional steel members of composite bridges with integral abutments. Therefore, effective bridge temperature hydrographs (100 year period) are derived by means of FE-calculations for various locations based on actual weather data. They are converted into pile strain hydrographs, taking into consideration residual strains and plastic deformations. The calculations are verified by laboratory low cycle fatigue tests and monitoring results. Finally, a design temperature load spectrum is proposed, based on classified temperature variations.