Load-carrying Capacity And Practical Calculation Method Of A New Type Hub-Shape Joint

Great-span interspace structure is the quickest developing structure presently. Great-span interspace lattice shells structure is the bend-surface type of gridding structure, it has pole and shell inherence characteristic, has characteristic of the power in reason, cover with great span, great firm tolerance, light self-respect, sculpt richness and beauty, integrate technic economy target characteristic, is the main structure form of great-span and great-space, and has amplitude develop foreground. Joint has played a very important role in structure, as joint is the critical connection part of structure, the research for its load-carrying capacity has important realistic significance. Welded hollow spherical joints are one of the most popular nodal joints in lattice shells, a new type hub-shape joint for single layer lattice shells will be now in this thesis, and it is used because of its simple structure, definiteness of load transferring and convenient connection.This thesis investigates the structural behavior and load-carrying capacity of these joints subject to axial forces, bending moments and combined loading of the two. Through the approaches of finite element analysis, the final objective is to establish the practical calculation method. Based on the elastic-perfectly plastic model and the Von-Mises yielding criterion, a finite element model for the analysis of hub-shape joints connected with square/rectangular tubes is established, in which the effect of geometric nonlinearity is taken into account. A major parametric study is then carried out employing this model. By the researches on the stresses and deformation of the joints, structural behavior and the collapse mechanism are investigated for the hub-shape joints subject to various combinatorial loading. The Full Newton-Raphson method is used to follow the loading-deformation curve of the node, and the ultimate load-carrying capacity for different types of joints subject to various combinatorial loading is obtained. It is shown that, for hub-shape joint subject to combined axial forces and bending moments, the axial force-bending moment correlation is independent of their geometric parameters, which will significantly simplify the calculation method for the bearing capacity of the joint.Finally, based on the results of the finite element analyses, a practical calculation method is proposed for the load-carrying capacity of the joints subject to axial forces, bending moments and the combined loading. The results from this study can be applied to directing design use, and also provide a reference for the revision of relevant design codes.At last, as the hub-shape joints in practical engineering are usually multi-directional in the space, finite element analyses are carried out for the simplest four-tube orthogonal and bidirectional joints in the thesis. Some rules are obtained for the load-carrying capacity of the bidirectional joints. The practical calculation method is modified.