In the scope of CIDECT and DFG projects, L-joints made of CHS have been statically tested under tension and compression loading. The results of these investigations are to be published at the 9 th ISTS (International Symposium on Tubular Structures) in Diisseldorf, Germany, 3–5 April 2001. The fatigue behaviour of Ljoints made of CHS and RHS has also been investigated in the scope of these projects. These results are presented in this paper. For the determination of the fatigue resistance of L-joints made of CHS, numerical investigations have been performed. Solid finite elements have been used, since local stress and strain distributions are of interest in this case. The stresses in the joint area have been analysed and the stress concentration factors have been calculated. Using these SCF's, a design for L-joints made of CHS under fatigue loading is now possible (e.g. crane structures). The finite element mesh has been calibrated by comparison with the results of strain gauge measurements. Additional fatigue tests up to a maximum number of load cycles (Nf= number of cycles to failure) have been used for S-N lines and the classification of detail categories. These results can be used for establishing design standards for fatigue strength of L-Joints made of CHS and RHS.
L-joints made of Hollow sections are used in different structures, such as in cranes, portal frames, light roof structures, fairground structures, bridges etc. The static behaviour of L-joints made of RHS is already investigated (DIN 18808, 1984, EC3, 1993, Mang et al, 1981). For Ljoints made of CHS, a new design concept has been developed (Karcher 2001). Fatigue tests have been performed not only on L-joints made of CHS, but also on L-joints made of RHS. Classification of detail categories could therefore be made for both these cases.
