Experimental Investigation of a Fan-Shaped Assembled Joint for Curved Lattice Shells

A new fan-shaped assembled joint for curved lattice shell structure is proposed, which is mainly composed of three parts: fan-shaped component, central rib plates and high-strength bolts. Different from the traditional welded joints, the main sections of this joint are prefabricated by the factory and assembled on site using high-strength bolts, which not only reduces the welding work but also avoids overhead welding, and reduces the construction difficulty and risk. In addition, the joint is connected without cover plates, fully reflecting its semi-rigid characteristics, and also facilitating later maintenance. The static comparison experiment between the assembled joint and the welded joint was conducted for exploring mechanical characteristics of the joint. A total of six full-scale joint specimens were tested with the type and loading condition as test variables. The strain distribution, load-displacement curve, moment-rotation curve and failure mode of the key parts were analyzed, and the weak parts and the influence of bias pressure were obtained. The evolution process of mechanical characteristics under uniaxial compression and bending was analyzed by finite element method and compared with the experimental results. Through the experiment and finite element analysis, the following conclusions can be drawn: under uniaxial compression, the fan-shaped assembled joint shows the same mechanical performance as the welded joint, the force is reliable, the deformation is small, and the axial stiffness is very close during the whole process of loading. Under the eccentric compression, the axial stiffness of the fan-shaped assembled joint decreases significantly, indicating the influence of the compression-bending combination on the joint should be considered in the practical engineering application. In the bending test, the failure process of the fan-shaped assembled joint experiences three stages: 1) the elastic stage(<81.5 kN·m), in which the joint shows good bending performance; 2) the elastic-plastic stage(81.5-142.6 kN·m), in which the bending stiffness decreases markedly, and the rotation increases gradually owing to bolt slippage and deformation of the bolt hole wall; and 3) the plastic failure stage(>143 kN·m), in which the bolt is brittle and the specimen fails, indicating that the key to improving the bending stiffness of the fan-shaped assembled joint is improving the shear strength of the bolt. The final failure mode, stress distribution, and bending moment-rotation curve of the finite element analysis are in good agreement with those of the experiments.