Mechanical behaviours of monitoring sleeved members with rigid ends at both core tube sides

The monitoring sleeved members (MSMs) are considered with light weight, excellent load-bearing capacity, superior ductility, and can be applied in long span spatial structure to monitor the capacity of the spatial structure. This paper mainly focuses on presenting the mechanical behaviours of the MSMs based on the full-range finite element analysis. The finite element model was developed to simulate the mechanical behaviors of the MSMs, which was verified by a specimen test. Based on the verified finite element model, parametric studies were carried out to investigate the influence of the core protrusion lp, the core slenderness ratio λi, the flexural rigidity ratio β, and the gap δg between core tube and restraining tube on the mechanical behaviours of the MSMs. It is concluded that (1) lp determines the control range of the restraining tube to the core tube. Local buckling of the MSMs with lp/l≤0.0406 occurs at a relatively small axial deformation. The ultimate bearing capacity of the MSMs with lp/l≤0.0406 is generally less than that of the MSM with lp/l>0.0406; (2) λi is a sensitive parameter influencing the failure mode. The smaller the core slenderness ratio λi, the less likely global buckling will occur; (3) β guarantees the control effect of the restraining tube on the core tube. β≥8.349 is needed to avoid global buckling; (4) a proper δg determining the alert moment for contact is indispensable to monitor contact status of MSMs, but it has no effect on the failure mode.