Research On Fire Resistant Behavior Of Completely Overlapped CHS Tubular Joints

As a member of structure, tubular joint has many advantages, such as excellent mechanical properties, quick construction and light weight. Today, completely overlapped tubular joint was widely used in the offshore structures and long-span space structures. Although some researchers have studied the stress concentration factor, static bearing capacity, failure mechanism of the completely overlapped tubular joint, the mechanical properties of the completely overlapped tubular joint under fire condition are still not familiar by people. In this paper, experimental research and finite element analysis were used to study the fire resistant behavior of completely overlapped tubular joints.First of all, there different size of the completely overlapped tubular joints have been carried out in the condition of constraint applied load and heating environment, mainly studied the influence of geometric parameters ?tl and ?ct on the fire resistance behavior of the joints. Results showed that the increase of ?tl was beneficial to improve the fire endurance time and the critical temperature of the joint, and the increase of the ?ct slightly improved the fire resistance of the test specimen.The fire resistance test of completely overlapped tubular joints were simulated by using the finite element software ABAQUS. Temperature rising characteristics, deformation characteristics and failure modes of the completely overlapped tubular joints were studied in the condition of constraint applied load and heating environment. In the finite element analysis, sub region mesh generation method was adopted. Material nonlinear analysis, geometric nonlinear analysis and a sequentially coupled thermal stress analysis were considered at the same time. The numerical simulation results were compared with the experimental results, and the results were in good agreement. It shows that it is feasible to use ABAQUS finite element software to analyze the fire resistance performance of completely overlapped tubular joints.Finally, using the verified finite element model to analyze the influence of geometric parameters(?ct, ?tl, ?ct, ?tl, ?C, ?, ?T)and load ratio n of the completely overlapped tubular joints on the fire resistance. Compared the results of the critical temperature obtained from the experiments and the FE analysis with the results calculated by the formula derived from the CIDECT and the Eurocode 3. The results showed that the equation could reasonably predict the critical temperature of completely overlapped tubular joints.