Fatigue tests on connections of hollow sections made of high-strength steel with shape-optimized gusset plates

Structures made of hollow sections are often used in the construction of steel bridges, agricultural machinery and trucks. Due to secondary bending moments and local stress concentrations at the connection between brace and chord these joints have a low fatigue strength. In case of high-strength steels, a decisive fatigue design leads to larger wall thicknesses and dimensions of the hollow sections and thus to uneconomical constructions. In the course of the research project FOSTA P1442 truss joints of hollow sections made of high-strength steels were reinforced by attached and plugged through gussets plates to increase the fatigue strength by relocating the most critical detail at the weld toe to areas subjected to lower stresses. At the University of Applied Sciences Munich, 35 large-scale fatigue tests on hollow section K-joints with differently shaped gusset plates were performed to verify the results of the Finite Element Analysis. In order to verify the applicability of the results to real structures, two trusses with a span width of 6 meters were tested. Based on the data of the experimental tests, a fatigue design recommendation for connections of hollow sections with gusset plates could be developed. Within this paper the set-up and results of the fatigue tests are summarized. © 2023 The Authors. Published by Ernst & Sohn GmbH.