Research on the Behavior on Axial Tensile Welded Hollow Spherical Joints Exposed to Elevated Temperature

Welded hollow spherical joints (WHSJs) are commonly used joints in grid structures, and their mechanical behavior under fire will directly affect the service life and safety behavior of grid structures. Therefore, the WHSJs were heated to the specified high temperature, and the tensile experiments were performed on non-stiffened WHSJs exposed to elevated temperatures. The failure modes, axial load–displacement curves, and mechanical behavior of the non-stiffened WHSJs exposed to elevated temperature were obtained. The experiment indicates that the failure mode of the axial tensile non-stiffened WHSJs is a pull-out failure. With the increase of heating temperature, the mechanical behavior of non-stiffened WHSJs gradually declines. The ductility of the non-stiffened WHSJs gradually increases with the heating temperature. Compared with the existing studies, the load-bearing capacity reduction trend of WHSJ exposed to elevated temperature is basically similar, and the stiffener has basically no function to improve the behavior of tensile WHSJs exposed to elevated temperature. The reliability of the numerical simulation was proved by comparison with experiments. According to the finite element analysis, the design method for the mechanical behavior of the non-stiffened WHSJs subjected to axial tension exposed to elevated temperature was proposed.