Static behaviors of axially-loaded multiplanar hybrid KTX-joint

With rapid development of the spatial tubular structures, the joints required to connect the tubular members are becoming increasingly complex. In this study, a static loading test was conducted on the full-scale multiplanar hybrid KTX-joint under axial loads. Nonlinear finite element model was established with the gusset plate and reinforced fillet weld geometries accurately simulated. Failure mechanism of the hybrid KTX-joint was analyzed and the effects of fillet weld size were preliminarily investigated. Based on the validated finite element model, a parametric study was carried out to investigate the effects of geometric and loading parameters of KT-plane brace members on ultimate bearing capacity of the hybrid KTX-joint under two loading patterns. Several design suggestions were proposed and practical formulas calculating ultimate bearing capacity of the hybrid KTX-joint were obtained. The conclusions are as follows: the established finite element model is capable of simulating static behaviors of the multiplanar hybrid KTX-joint; chord wall buckling in X-plane is typical failure mode of the hybrid KTX-joint; ultimate bearing capacity of the hybrid KTX-joint increases approximately linearly with the increase of reinforced fillet weld size; larger diameter ratio, wall thickness ratio and overlapping ratio are suggested for the hybrid KTX-joint to achieve larger ultimate bearing capacity; the fitting formulas show good agreement with the results obtained from finite element analyses.