As the main fatal disaster of the grid structure, fire causes the stability of the space grid architecture to face serious risks. However, there is an absence of comprehensive studies on their fire resistance behavior. Based on existing experiments, this paper systematically analyzed the fire resistance behavior of the compression-stiffened welded hollow spherical joints (WHSJs). The numerical analysis shows that the fire behavior of compression WHSJs is mainly affected by the load ratio, the spherical outer diameter and thickness, the steel pipe diameter, and the inner diameter of the stiffener. With increasing wall thickness, the critical temperature and fire resistance limit show a decreasing and increasing trend, respectively, but the overall change is small. The fire performance of the compression-stiffened joint declines as the load ratio rises, and the decreasing trend becomes gradually slower. Under the same load ratio, the larger the spherical outer diameter, the better the fire resistance behavior of the compression-stiffened joint. Improving the spherical wall thickness can greatly increase the fire resistance of the compression-stiffened joint, but the critical temperature is not much improved. The larger the spherical outer diameter and the stiffener opening diameter, the worse the fire resistance performance. The recommended and calculated values of critical temperature provided by the specifications cannot precisely obtain the fire resistance temperature of compression-stiffened joints. Thus, a calculation formula for the fire resistance behavior of compression-stiffened WHSJs was offered. It will provide a reference value for the fireproof design of spatial architecture and further revision of the fire safety specification of steel structures.
Qiu et al. (Mon,) studied this question.