ABSTRACT

In practice, the hidden toe of overlapped CHS K/KK-joints are normally left unwelded due to the difficulty in the fabrication sequence. Three sets of experiments, including overlapped K-joints under monotonic loading (8 specimens) and cyclic loading (8 specimens), and overlapped KK-joints under monotonic loading (5 specimens) have been carried out to investigate how the unwelded hidden seam may affect the joint behavior. Parameters including the presence/absence of the hidden weld, geometric configuration, throat thickness of fillet welds and the loading hierarchy were investigated. Results of these tests and corresponding numerical simulations show that the welding situation of hidden seam has a noticeable effect on the stress distribution and failure mechanism, but the ultimate capacity of overlapped CHS K/KK-joints is not affected significantly except for a few of joints with special geometrical parameters. Finally, recommendations on the design and construction of overlapped CHS K/KK-joints under monotonic and cyclic loadings are presented based on the results.