High-cycle fatigue behaviour of welded thin SHS-CHS T-joints under in-plane bending

• Published in: Advances in Steel Structures pp. 1043 - 1050
• Main Authors: Mashiri, F.R., Zhao, X.L., Tong, L.W., Grundy, P.
• Format: Book Chapter
• Language: English
• Published: Elsevier 2002
• ISBN: 9780080440170; 0080440177
• DOI: 10.1016/B978-008044017-0/50122-0

T-joints made up of square hollow section (SHS) chords and circular hollow section (CHS) braces are used in the road transport and agricultural industry. The hollow sections are thin-walled with thicknesses less than 4mm. Static tests are carried out on welded thin-walled SHS–CHS T-joints under in-plane bending load to determine the linear response between applied load and deformation. The loads corresponding to the linear part of the load-deformation curves are used in subsequent fatigue tests and result in a high cycle fatigue response. A formula for determining the maximum linear response moment in an SHS–CHS T-joint is derived as a function of brace diameter to chord width ratio, β and chord width to chord wall thickness ratio, 2γ. Fatigue tests are carried out to determine through-thickness fatigue life (N3) and an end of test fatigue life (N4). The fatigue data from the welded thin-walled SHS–CHS T-joints is compared to the S-N data of welded thin-walled SHS-SHS T-joints and found to be within the same scatter band. The chapter carries out an analysis in terms of the classification method, which shows that there is a minimal difference between the fatigue design S-N curve obtained by using N4 instead of N3, when the inherent scatter in fatigue data is taken into account.