EFFECTS OF JOINTS ON THE BUCKLING RESISTANCE OF ANGLE MEMBERS MADE OF S460 STEEL -EXPERIMENTAL INVESTIGATIONS

Energy production is undergoing radical changes in Europe, with the development of more sustainable production means. These changes require a complete overhaul of the power transmission network, with the construction of new lines and, in particular, new transmission towers with higher load-bearing capacities than in the past. To meet this demand, the design of new towers, typically made of steel angles, requires increasingly the use of high-strength S460 steel. In the literature several studies provide experimental evidence regarding the buckling resistance of pin-ended angle members made of high strength steel, allowing the validation of the relevant design procedures. However, this is not the case for high strength steel angles with bolted connections on one leg at their extremities, like those used for bracing members in lattice towers. To fill this gap, a research project called "New Steel" has been recently launched. This project involves investigations aiming to study the influence of the structural joints at the extremities of S460 angle members on their buckling resistance through experimental, numerical, and analytical studies. The present paper firstly describes an experimental campaign conducted in the framework of this project and summarises the obtained results. A critical discussion of the findings follows and finally, an assessment of the accuracy of the design methods as recommended in the existing normative documents (such as EN 50341-1 and prEN 1993-3) is presented through comparisons to the experimental results.