Ermüdungsverhalten unterschiedlicher Kerbdetails

Fatigue strength of different notch classes regarding post weld treatment methods and repair techniques in consideration of size effect.

In the architecture of modern steel constructions the request for filigree constructions especially for further span lengths can be achieved in an optimal way by using tubular steel trussed-girders. Designing such welded steel constructions in regard to fatigue life is possible by different methods. The critical aspect in the design of tubular trussed-girder bridges is normally represented by the local hot spot stresses at the pipe intersection. As a result of big span lengths and therefore big dimensions of the cross sections the influence of the comparatively big wall thickness has to be considered. In order to handle this size effect, different recommendations can be found in the literature to mitigate the predicted fatigue life for increasing wall thicknesses.
It was decided to initiate an AiF-research project named "Size Effect" in order to carry out fundamental investigations on bigger amounts of differently scaled specimens at the Hochschule für angewandte Wissenschaften München (University of Applied Science Munich) and the Universität der Bundeswehr (University of the German Armed Forces Munich). The investigations regarding the CIDECT projects will be done at Hochschule für angewandte Wissenschaften München and the Karlsruher Institut für Technologie (Karlsruhe Institute of Technology, KIT).
In the CIDECT / AIF- Project, following items will be reviewed:
- modification/verification of the wall thickness correction factor with new tests on different specimens/notches (X- joints, plates, beams)
- modification/verification of the area of validity of the CIDECT- Design Guide (SCF/SCNF)
- investigations on specimens treated by post-weld treatment methods (PITec and HiFIT)
- investigations on repair techniques after fatigue occurrence (by grinding and rewelding)
- investigations on repaired specimens with post-weld treatment techniques (PITec/UIT and HiFIT)
- investigations on high strength steel (S460, S960)
- additional numerical investigations
First results of the experimental investigations are presented in this paper.