RESEARCH ON THE FORMATION MECHANISM OF ADDITIONAL BENDING MOMENT AND BEARING CAPACITY OF BOLT OF TYPICAL CONNECTED STRUCTURE AND STRUCTURAL OPTIMIZATION DESIGN

Considering the problem that the bearing capacity of the high-strength bolt is greatly weakened by the additional bending moment in the tensile condition of the typical connection structure, a mechanism study on the generation of additional bending moment of the bolt is carried out, and a structural optimization design method is proposed to effectively reduce the additional bending moment of the bolt. The analytical solution of the additional bending moment of the bolt is derived based on the established equivalent mechanical model of the typical connection structure. The correctness of the analytical solution is verified by numerical simulation. Considering that the bolt is subjected to tensile and bending coupled loads at the same time, the interaction of various stress distributions on the bolt across-section under different tensile and bending combinations is studied by introducing the plastic bending theory of the beam, and the plastic reduction coefficient of bending moment considering the influence of axial force is given. Based on the maximum stress failure criterion, a study on the failure criterion of bolts considering additional bending moment and bending plasticity is carried out, which has more engineering application value. Based on the mechanism, the optimization design of typical connection structure is carried out to reduce the additional bending moment of the bolt and thus improve bolt’s bearing capacity. The working mechanism of the hinged ball joint is expounded by analytical method. The sensitivity analysis of the additional bending moment of the bolt is carried out based on numerical simulation, which verifies the effectiveness of the optimization design method. The test research is then carried out and the additional bending moment of the bolt in different connection status are obtained. The test results verify the correctness and feasibility of the optimization design method. This method is capable of greatly reducing the additional bending moment of the high-strength bolt, maximizing the bearing capacity of the bolt, and improving the reliability of the connection structure.