Study On The Dynamic Characteristics Of Frame Structures With Mass Distribution

The establishment of a reasonable seismic response analysis model is a key link in the seismic checking calculation of civil engineering structures.In this paper,an integration method of structural global stiffness matrix based on "correlation table" is proposed,which makes the integration process of global stiffness matrix more clear and simple.The stiffness matrix of structure system considering axial force is derived,and the dynamic analysis model of structure considering mass distribution is established,and the natural frequency of six-story frame structure considering distributed mass is analyzed.The experimental modal analysis and seismic response of the frame structure test model are carried out,and the rationality of the model is verified by the experimental modal analysis.The influence of distributed mass on the interstory shear force of structure is discussed.Based on the theoretical calculation and experimental analysis,a structural seismic response analysis model with reference value for practical engineering problems is obtained.Through the analysis of the stiffness matrix of structural elements under axial force,it is found that the lateral stiffness of structural members decreases under the action of gravity of distributed mass,and the decrease of stiffness increases with the increase of distributed mass.The theoretical calculation and experimental results show that the natural frequency of the structure decreases when the distributed mass of the structure is considered,and the dynamic analysis model of the structure considering the mass distribution is more in line with the actual situation.Compared with the time-history analysis and the experimental seismic excitation,it is found that the time-history response of the structure considering the distributed mass is closer to the seismic response of the structure under the experimental earthquake excitation.Compared with the time history analysis and the bottom shear analysis,the results show that if the distribution mass of the structure is not taken into account,the interlayer shear force calculated by the bottom shear method is smaller than that by the time history analysis.Compared with the time history analysis,the experimental seismic excitation and the bottom shear method,it is found that if the distribution mass of the structure is not considered,the interlayer shear force obtained by the bottom shear method is less than that by the bottom shear method,which is anunsafe analytical model.The research work in this paper can provide theoretical basis and reference for aseismic checking analysis model of actual structure.