Abstract:The hot spot stress distributions and stress concentration factors (SCF) of welded truss T-joints made of circular hollow section braces and concrete-filled circular hollow section chords (so-called CFCHS joints) under axial tension and compression and in-plane bending on the braces were investigated experimentally,which is a foundation for fatigue assessments of the joints.The measuring method and results of hot spot stresses on the CFCHS joints were discussed and compared with those on the welded T-joints made of circular hollow section braces and chords (so-called CHS joints) to examine the difference in behavior of the two kinds of joints.The current research points out that for the CFCHS joints the linear extrapolation method can be used for chords,whereas the quadratic extrapolation method must be used for braces.The hot spot stress distributions on the CFCHS joints tend to be more uniform and their SCFs become smaller significantly,compared with the CHS joints.Axial tension on the brace puts the CFCHS joints at a disadvantage,which produces higher SCFs than axial compression.The effects of nondimensional geometric parameters β, τ and γ on SCFs of the chords of the CFCHS joints are basically the same as those of the CHS joints,but for the braces,there is a bit difference in the effects of parameters β,τ and γ between the two kinds of joints.Concrete has the function of improving the CFCHS joint rigidity and then decreasing SCFs which is expected to increase fatigue strength,but concrete strength grade does not exert significant influence on SCFs.
