Study On Non-proportional Damping Characteristics Of Energy Dissipation And Shock Absorption Structure

With the development of vibration control technology,more and more energy dissipation and isolation structures have been constructed in practical engineering.These kinds of structures often show obvious non-proportional damping characteristics.Current analysis methods used in seismic design codes are based on the classical damping assumption,which is only applicable to structures with uniform damping distribution.For non-proportionally damped systems,this assumption will inevitably cause errors.In this paper,the nonincluding the non-proportional damping characteristics of velocity-dependent energy dissipation structures and the non-proportional damping characteristics of displacementdependent energy dissipation structures.The application range of complex mode decomposition response spectrum method(CCQC method)is analyzed and studied.The results show that the numerical results of CCQC method are more accurate and reasonable for non-proportional damping system.The main research results of this paper are as follows:(1)For regular and irregular velocity-dependent damping structures,several different damper configurations are adopted respectively,and the time-history responses and modal results of structures are calculated by the real mode superposition method and the complex mode superposition method.The results show that the effects of non-proportional damping vary with different damper configurations.Moreover,the energy dissipation structure with nonuniform damper arrangement leads to some significant non-proportional damping characteristics.In this case,compared with the complex mode superposition method,the real mode superposition method obtains different modal damping ratio and natural frequency with smaller time-history response.(2)For irregular velocity-dependent damping structures,due to the irregularity of the structure,even when the dampers are evenly arranged on each layer,they also reflect nonproportional damping characteristics.The high-order mode damping ratio and natural frequency calculated by the real mode superposition method and the complex mode superposition method are different.When the non-proportional damping characteristic of the energy dissipation structure is stronger,the internal force calculated by the real mode superposition method is lower than the calculation result of the complex mode superposition method.That is,when analyzing a non-proportional damping system,the calculation result of the traditional real mode superposition method is not safe,and the calculation using the complex mode superposition method is more reasonable.(3)In order to obtain the mechanical model of the displacement damper,a compression failure experiment is conducted on the buckling restraint brace.Loading,measurement and other steps are carried out in accordance with relevant experimental specifications.Finally,according to the sensor data in the experiment,the constitutive model of the buckling restraint brace and the accumulated plastic deformation and other parameters are analyzed and calculated,which are used for displacement-related energy dissipation design.Several equivalent linearization methods are compared and analyzed,and then the energy dissipation structure with displacement dampers is equivalent to a linear system using these equivalent linearization methods.Taking the inter-layer displacement obtained from the time history analysis as a reference index,one of the most accurate equivalent linearization methods is selected by comparing its results with the time history analysis result of the nonlinear energy dissipation structure.Then,the real mode superposition method and the complex mode superposition method are used to calculate the time-history response and modal results of the equivalent system.The results show that the main reason for the improvement of the seismic performance of the displacement-dependent energy dissipation structure is the increase in its stiffness,while the additional damping ratio brought by the dampers to the structure is relatively small,resulting in a small effect of non-proportional damping.(4)Through the theory of the complex mode decomposition method,the complex mode method and the response spectrum theory are connected,and the CCQC method based on the response spectrum is obtained.Compared with the traditional real mode decomposition response spectrum method(CQC),it proves that the two methods are unified under certain conditions.In the study of the calculation examples,the calculation accuracy of the complex mode decomposition response spectrum method(CCQC)and the real mode decomposition response spectrum method(CQC)under different damping ratios are analyzed,and the recommended values used in practical engineering are given.