High Strength Bolted Connection Under Cyclic Load Mechanical Model Study

High strength bolt connection is widely used in large-span Bridges and prefabricated industrial and civil construction projects due to its advantages such as easy assembly,reliable connection and not easy loosening under dynamic load.As the main nodes of the stress,the stress of the high strength bolt connection forms,the contact nonlinear problem is complex,bolt connection of structure failure under dynamic load problem is outstanding,the existing of high strength bolt connection under cyclic loading mechanics model research is immature,the mechanical models of high strength bolt connection under circulating load research has important theoretical significance and engineering application value.The high-strength bolted joints show strong nonlinearity under cyclic loading,which has a significant effect on the dynamic response of the whole structure.Finite element modeling of bolted connection under cyclic load requires consideration of contact nonlinearity,which is difficult to convergence and has low computational efficiency.Experimental research has high cost and long cycle.Therefore,based on the traditional connection contact energy dissipation model and Iwan model,based on the combination of high strength bolt connection of different failure mode of the finite element analysis and experimental research,put forward to the improvement of high strength bolt connection under cyclic loading mechanics model,a more accurate description of bolt shear,hole wall pressure more than two failure modes of phase current,It reflects the energy dissipation characteristics of different stress stages.The main work and conclusions of this paper are as follows:(1)The finite element model of high-strength bolted connection under cyclic load was established,and the rationality of the finite element model was verified by comparing the experimental results.The influence of different material parameters,preloading force and friction coefficient on the mechanical behavior of high-strength bolted connection under cyclic load is analyzed.(2)The characteristics of two failure modes of high-strength bolt shear failure and hole wall compression failure under cyclic loading were studied experimentally,the force-displacement curves of the two different failure modes were analyzed,and the energy dissipation characteristics of high-strength bolted joints under different failure modes were revealed.(3)high strength bolt connection under cyclic loading is proposed to improve mechanical model,and through the experiments on the model of force-displacement,the energy dissipation-force expression without complex modal analysis and parameter identification,and solve the equations,the results show that the proposed model can accurately describe the bolt shear,hole wall pressure loading process of two kinds of failure mode,It reflects the energy dissipation characteristics of high strength bolt connection at different stress stages.