Evaluation of elastic in-plane flexural rigidity of unstiffened multiplanar CHS X-joints

Tubular structures have been widely applied in offshore structures and civil buildings in past decades. Some research has been carried out on rigidity of unstiffened circular hollow section (CHS) joints with various types, e.g. T-, Y-, K- and X-joints by former researchers. However, limited investigations on the in-plane flexural rigidity of multiplanar CHS X-joints which are commonly used in single-layered latticed structures are found in available literatures. In this paper, first a finite element model was calibrated through comparison with test results, and then a numerical parametric study on elastic axial rigidity of multiplanar unstiffened CHS X-joints was carried out using the calibrated models with package ABAQUS. Based on the parametric results, an in-plane flexural rigidity formula for the joints was fitted. Finally, a comparison among the different formulae in predicting joint rigidity of unstiffened CHS X-joints was carried out, which indicated a good reliability of the proposed formula.