This paper presents the experimental studies of two partially overlapped CHS K-joints specimens (Specimens S1 and S2) with through brace subjected to basic and combined loads. The stress analysis of the joints revealed the maximum stress concentration factor (SCF) to be located on the brace side. Then, the maximum SCF was compared with existing Efthymiou's formulae. It is observed that the Efthymiou's formulae are over-conservative in in-plane bending load case (IPB), but in axial load case (AX) are not conservative. In addition, the fatigue life was also compared with existing S-N curves. The S-N curve was found to be marginally conservative for first specimen, but it was not conservative for other one.

This paper describes the testing results of two full-scale partially overlapped circular hollow section (CHS) K-joints. The two specimens were designed in such a way that partially overlapping is inevitable in order to eliminate the eccentricity of the resulted joints. Experimental studies were carried out by applying static loadings at the end of the through braces of the joints. The stress distributions of the partially overlapped CHS K-joints tested under the three basic loading cases (axial (AX), in-plane (IPB) and out-of-plane bending (OPB)) and their combinations were carefully recorded during the test. For each specimen, experimental study was carried out to investigate the stress concentration factor (SCF) and the hot spot stress (HSS) distributions along the brace-chord intersections. The experimental results obtained show that even for a simple combination of AX and IPB loading cases, the maximum HSS could be located either on the brace side or the chord side of the joints. The SCFs obtained from the experimental studies are compared with the SCF formulae suggested by Efthymiou and Durkin [1] and those from finite element analyses. It is observed that Efthymiou's formulae may not be completely suitable for the design of partially overlapped CHS K-joints.