Longitudinal mechanical force mechanism and structural design of steel tube slab structures

A steel tube slab (STS) structure is a novel pipe-roof structure with significant promise as a supporting structure for underground stations. The structure is subjected to bending loading conditions during its service; therefore, research on the flexural strength of STS structures is essential. This study aimed to analyze the flexural behavior of STS structures through experimental and numerical investigation. The mechanism of forces in an STS structure was investigated using flexural tests, and the load-displacement curves, obtained during loading, were investigated in detail. Notably, the specimens exhibited highly ductile behaviors, and the structure was eventually damaged under integral bending. In addition, finite element (FE) models were established, and their accuracy was verified through tests. Detailed analyses in terms of the load-displacement curves, stress-strain development in steel tubes, flange plates and concrete, and damage modes were conducted, followed by studies on the various influencing parameters. Finally, formulae for calculating the elastic and ultimate capacity of STS structures were established. We found that the predicted results agreed well with the experimental and FE results.