Research on the Flexural Performance of Cross-shaped Plate Semi-rigid Bolted Joints for Large-span Single-layer Space Grid Shell

Assembly joints are crucial to structures, and this paper proposes a cruciform plate assembly joint suitable for large-span single-layer grid shell structures. The joint consists of circular steel pipes, cruciform steel plates, angle steel, rectangular connection cover plates, circular cover plates, and high-strength bolts. Circular steel pipes,cover plates, and cruciform steel plates are welded in the factory, while cruciform plates, angle steel, and rectangular cover plates are connected using high-strength bolts on-site. By setting angle steel, rectangular connection cover plates, and cruciform steel plates bolt connections, when the joint is subjected to bending loads, angle steel and rectangular connection cover plates can initially bear the bending loads, thereby protecting the cruciform steel plates inside the joint from damage and enhancing the bending resistance of the joint. Utilizing finite element simulation methods, a finite element model of the new connection joint was constructed, and the effect of variables such as the thickness of cruciform plates and angle steel on the bending resistance of the joint in-plane and out-of-plane was analyzed. Through parametric studies of the dimensions of each component,the influence of these factors on the in-plane and out-of-plane bending resistance of the new connection joint is determined. The research results show that the cruciform joint formed by connecting angle steel with rectangular cover plates exhibits excellent performance in terms of bending stiffness and load-bearing capacity. By adjusting the thickness of the cruciform plate, the number of bolts, and the thickness of angle steel and cover plates, the initial bending stiffness and bending load-bearing capacity of the joint can be regulated. Meanwhile, based on rigid joint design methods,theoretical design of the semi-rigid joint was conducted, and the results show that this method can ensure that the design bending moment of the joint basically reaches the yield bending moment of circular steel pipes, fulfilling the design specifications and enhancing joint safety.