Dynamic Response Analysis Of Spherical Reticulated Shell Considering Joint Stiffness Under Impact Load

Large-span spatial structures are various in form,beautiful in shape and reasonable in force.They are more and more used in various buildings such as stadiums,opera houses,railway stations and airport terminal buildings.They are not only the symbol of national building level,but also the symbol of national economic,cultural and civilized development.Therefore,they have become the focus of seismic,shock and wind resistance research in the field of Engineering structures.With the application of large-span reticulated shells in large public buildings,many researchers began to consider the performance of reticulated shells under accidental loads such as explosion and impact.Although impact load belongs to accidental load,in recent years,the impact of impact on structure has attracted more and more attention of researchers due to terrorist attacks,high-altitude falling objects and other reasons.At present,numerical analysis is the main method to study the impact performance of reticulated shells,supplemented by scale test.In the past,the numerical simulation of reticulated shell impact is mainly based on ANSYS/LS-DYNA.In order to simplify the calculation,the reticulated shell is usually modeled by beam element,and the piecewise linear plastic material model is chosen for the material model of steel.When choosing beam element,the spherical joints of reticulated shells are simplified to rigid points.This finite element analysis method does not consider the influence of the size and thickness of hollow spheres on the stiffness of joints.In this paper,the SHELL161 shell element in ANSYS/LS-DYNA software is used to simulate steel tubular members and hollow spherical joints.A refined finite element model of joints is established,and the dynamic response of joints under impact load is analyzed.Based on the reliability of the refined finite element analysis method,the model of K6single-layer spherical reticulated shell joints is established,and the dynamic response of different parameter joints under impact load is analyzed.The whole structure of K6single-layer spherical reticulated shell is established.The refined model is used to study the dynamic response of reticulated shell structures with joint stiffness under impact loads,and compared with the traditional beam element model.The main research contents are as follows:(1)A numerical simulation method for single-layer reticulated spherical shells considering joint stiffness.A refined numerical simulation method considering the geometrical dimensions of welded spherical joints is proposed.In this method,thesteel material model is chosen as the Cowper-Symbols rate-dependent constitutive model suitable for impact action,and the contact algorithm is based on the penalty function method.(2)Using different sizes of cross-shaped hollow spherical joints as test models,based on 30 different joints.The displacement,acceleration and strain data of key joints are collected under impact load test conditions,and the dynamic response analysis of the whole process from elastic state to failure state is carried out.A refined finite element model of the joints is established.The validity of the numerical simulation method considering the stiffness of the joints is verified by comparing with the dynamic response test results.(3)Establishing a refined model of multi-group spherical reticulated hollow ball joints.By analyzing the plastic deformation,impact force,displacement and energy of the joint under impact load,the dynamic response of different thickness nodes under impact load and different impact objects are studied.The influence of density,different impact velocity,different impact angles,different rod diameters and different cross-section forms on the dynamic response of the joint.(4)The refined model of K6 single-layer reticulated spherical shells and the traditional beam element model are established.The dynamic response modes of reticulated shells under different impact velocities and mass are analyzed,and the impact force,displacement and energy of the two models and their effects on the dynamic response of reticulated shells under each response mode are also analyzed.