Effect of joint stiffness on the stability of cable-braced grid shells

Bolted joints used in cable-braced grid shells are typically semi-rigid joints, and the joint stiffness has a significant effect on the stability of cable-braced grid shells. The effect of joint stiffness on the stability of cable-braced grid shells is studied in this paper. Based on the experimental results of improved bolted joints, finite element models of elliptic paraboloid cable-braced grid shells with bolted joints are established, and spring elements are used to simulate the joint stiffness. The effect of the joint stiffness on the nonlinear buckling load is studied by changing the joint stiffness. The main conclusions are as follows. First, the joint rotational stiffness has a significant effect on the failure mode. When the joint rotational stiffness is small to a certain extent, the failure mode of cable-braced grid shells changes from overall buckling to local buckling. Second, the nonlinear failure mode is similar to the first-order eigenvalue buckling mode and the maximal compression stress distribution. The structural integrity is weakened, and the maximal steel tube compression stress decreases with the decrease of the joint rotational stiffness. The smaller the joint rotational stiffness, the lower the utilization rate of steel strength. The results suggest that the joint stiffness of elliptic paraboloid cable-braced grid shells should not be less than 20% of the rigid joint stiffness.