Failure modes and resistance of k-joints of concrete-filled steel tubular truss structures

K-joints of Concrete Filled Steel Tubular (CFST) truss structures were tested. Their size was chosen of the same scale as that of joints of real tubular structures currently used in bridges. Contrary to CHS K-joints, in CFST K-joints no failure mode with inward deformation of the chord section can occur. Hence, punching shear failure was shown to be their typical failure mode of CFST K-joints, unless any brace failure mode occurred before. Resistance of CFST K-joints to punching shear was then compared with the resistance values obtained by the Eurocode 3 and the AWS code formulae on CHS K-joints. Finally, the favourable effect on joint resistance due to additional studs welded to the interior surface of the chord tube of CFST K-joint was also investigated.