Fatigue Behaviour of T- and X-Joints Made of Square Hollow Sections.

摘要

The work presents the results of experimental and numerical research on the fatigue behavior of T- and X-joints between square hollow sections of which the brace is welded to the face of the chord, without any additional stiffeners. The work has been carried out in the framework of the CIDECT program 7K 'Fatigue behavior of uniplanar joints', and an earlier ECSC program 'Fatigue strength of welded unstiffened RHS joints in latticed structures and Vierendeel girders' (CECA Convention nr. 7210-SA/111). Furthermore, experimental results of the CIDECT program 7H 'The low cycle fatigue behavior of axially loaded T-joints between rectangular hollow sections' have been used in the work. The aim of the research programs is to establish a better design method for the fatigue strength of joints in square hollow sections, based on the hot spot stress method. The results are to be proposed for inclusion in Eurocode 3. In the experimental investigation, the strain concentration factors are measured at various locations of the joint for comparison with results of the numerical investigations and S-N curves are determined. The numerical work provides SCF values at weld toes for a range of parametric vairations in the joint dimensions. These results form the basis for a set of parametric formulae. These formulae allow the determination of the SCF values at the weld toes of the brace and chord, depending on the non-dimensional parameters.