Abstract：In this study, the contact stiffness of discrete element model for beam structure is deduced by energy conservation law based on the contact model of traditional discrete element method. By introducing the layered beam theory into the discrete element method, the judging criterion of plasticity of contact is given and the stiffness coefficient of contact after going into plasticity is derived, so that the discrete element method can be used to solve the elasto-plastic problem of beam structures. The strain-based fracture criterion of the discrete element method is defined, and then it is applied to solving the fracture problem of beam structure. The Hertz model suitable for collision problem is selected, and the setting method of Hertz model stiffness is given. Finally, the improved discrete element method is used to simulate the whole impact testing process of single-layer reticulated shell with elastoplasticity, fracture and collision considered, so that this method can be verified. Numerical simulations on single point and multi-point impacts of Kiewitt single-layer spherical reticulated shells are carried out. The differences in failure mode, impact force, joint displacement and support reaction of single-layer reticulated shell subjected to single point and multi-point impact are analyzed.
