ABSTRACT
Overlapped Circular-Hollow-Section K-joints are widely used in large span structures in China. In practice, the hidden toe of this type of joints is normally left unwelded due to the difficulty resulted from the fabrication sequence. It is thus necessary to investigate how the unwelded hidden seam may affect the behaviour of overlapped CHS K-joints. This paper reports seven static tests on uniplanar overlapped CHS K-joints with hidden seam unwelded under axial loading. Among these 7 specimens, parameters including the overlapped ratio, the brace-to-chord diameter ratio, the brace-to-chord thickness ratio, the brace inclination, the throat thickness of fillet welds, the unbalanced loading at the joint as well as the loading hierarchy reversal were varied to study their effect on the joint behaviour. In order to study the effect of the hidden seam on the behaviour of the connection, three additional specimens with the hidden seam welded were also tested for comparison purposes. Results of these tests show that the welding situation of the hidden seam has some effect on the stress distribution and failure mechanism, but the static ultimate capacity of the overlapped CHS K-joints is not affected significantly given that the through brace is under compression. When the brace-to-chord thickness ratio is smaller, the local failure is the main failure mechanism observed. Comparison of the joint capacities obtained from the tests with strength prediction from current design codes was presented.
