P 816 – Optimal application of hollow sections and cast steel nodes in bridge construction with the usage of steel S355 up to S690


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P 816 – Optimal application of hollow sections and cast steel nodes in bridge construction with the usage of steel S355 up to S690

Lattice girder structures made of steel hollow sections gain more and more popularity, especially in bridge buildings, due to their advantages under constructional and design aspects. However, the realization of bridges made of hollow sections is hindered because the usually needed profiles are out of range of the available design codes. These are based mainly on fatigue tests with sections of comparatively small wall thickness and on research work in the offshore industry using sections with considerably higher slenderness. For an increased utilization of this architecture and a more efficient realization of bridges made of steel hollow sections specific design rules are necessary, which include sections with large wall thickness and low slenderness as well.
In a preceding research project on this topic singleside welded end-to-end connections and K-joints between hot rolled seamless hollow sections and joints made of cast steel have been investigated. In the current project the work is carried on and added with different material up to steel grade S690 and wall thickness up to 40 mm. With these investigations the relevant former results for designing joints made of cast steel and their connections to hollow sections could be brought to a wider statistical basis. Besides the tests performed on single-side butt welded connections between hot-rolled hollow sections and sections made of cast steel also tests on complete trusses were carried out. Furthermore, repair welding has been  performed on previously damaged members what lead to a remarkable extended fatigue life. Due to similar properties the results can be transferred to steel-steel connections also. Finite element investigations with regard to  misalignment and different wall-thicknesses have been carried out additionally as well as detailed measurements of residual stresses and finite element welding simulations. These investigations are accompanied by a study on cost efficiency. With this the creative impact and the influence of engineering architecture is discussed. All together lead to a cost efficient approach in planning this type of structures.
For the practical use and for an easy integration in standards and rules the details  investigated have been edited according the notch detail catalogue of DIN EN 1993. Detail categories for bridge relevant butt weldsBauin different variants for bending and tension loads are given. With this the category 71 has been found representative for butt welds under tension in all variants. For butt welds under bending two classes are given, category 100 and 112, depending on the variant of the butt weld. Together with the study of the cost efficiency of the variants experimental verified and economic solutions can be chosen for each kind of application. The results gained within this project represent a useful complement of the previous research work and represent in form and content a necessary supplement in practice.
The research project has been carried out at Versuchsanstalt für Stahl, Holz und Steine, Karlsruher Institut für Technologie KIT, at KoRoH GmbH Kompetenzzentrum Rohre und Hohlprofile, at Büro für Ingenieur-Architektur und dem ICOM Steel Structures, École Polytechnique Féderale de Lausanne EPFL. FOSTA has accompanied the research work and has organized the project funding from the Foundation for Steel Application Research.

Only available in german language.

T. Ummenhofer, S. Herion, M. Veselcic, R. J. Dietrich, A. Nussbaumer, F. Zamiri

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