Fatigue behavior of UHPFRC and its implementation for design

The fatigue behavior of UHPFRC in the range of high number of fatigue cycles is relevant for fatigue-prone elements of structures like bridges. Experimental and analytical research, conducted over the last 15 years by the authors and their team, on the fatigue behavior of UHPFRC, R-UHPFRC and composite elements consisting of R-UHPFRC and reinforced concrete are summarized in view of implementation for fatigue design. The existence of a fatigue endurance limit was evident at stress levels due to maximum fatigue loading corresponding to 40 to 60 % of the ultimate resistance. Subseqeunetly, fatigue design provisions are deduced and proposed for the fatigue strengthening of reinforced concrete bridge deck slabs by means of a layer of R-UHPFRC as well as for the fatigue dimensioning of R-UHPFRC structural elements. The application of these fatigue design provisions is illustrated by means of two realized UHPFRC bridge projects.