Assessment Of Seismic Performance And Reliability Of A Self-centering Energy Dissipation Frame Retrofitted System

After decades of economic development,a large number of urban buildings have been built in our country.Since the 1980 s,the applicable seismic codes of buildings have also undergone several major revisions,and the seismic design is developing towards performance-based design.These buildings are designed and constructed according to different standards in different periods,and their seismic performance may not match the present provisions.Due to sustainable development,they should be reserved.While economic development,many buildings need to change their utilities and improve seismic performance requirements.These all need to carry on the earthquake resistance retrofitting to the existing building.In the past,the traditional retrofitting technology mainly focused on the improvement of the bearing capacity of the components,while the energy dissipation technology can improve the seismic performance of the existing buildings,which is a reinforcement method focusing on the overall performance of the structure.This reinforcement technology has a good economic significance for a large number of buildings built with previous codes.On the other hand,the reinforcement of a large number of existing buildings in service may cause interruption of building functions and cause significant interference to users.Therefore,in view of these problems,this paper conceives the reset energy dissipation frame structure to achieve the goal of combining innovative seismic technology with existing buildings to improve the seismic performance of buildings.The main research work is as follows:(1)The finite element software is used to establish a self-centering energy dissipation frame retrofitted system models with different configuration schemes.The dynamic response of the models with viscous energy dissipation braces under different earthquake excitations is studied by comparing it with the original frame.The inter-story displacement distribution of different models,the evolution process of the plastic hinge,and the additional energy dissipation elements and structural members in different stages are analyzed.The influence of the arrangement of energy dissipation elements in the reset energy dissipation frame on the structural response is discussed.(2)In view of the limitation of external construction or space conditions,a scheme of adding a self-centering energy dissipation frame to the outermost sides of the structure is proposed.The characteristics of several kinds of self-centering energy dissipation braces used to realize the self-centering and energy dissipation function are compared.A kind of variable friction energy dissipation self-centering brace is proposed and tested.The seismic responses of the finite element model of self-centering friction energy dissipation(SCF)brace in the self-centering energy dissipation frame is simulated in earthquake time history analysis and frequency domain analysis of the response.The frequency change of unfavorable excitation is found through the displacement response index,and the amplitude modulated harmonic is used as the input signal to study the residual displacement characteristics of the system in strong earthquakes.(3)The deformation and stiffness characteristics of different heights of the self-centering energy dissipation frame are analyzed,and the influence of different braces forms is compared.The parallel eigenvalues and the formula for calculating the natural period of the system are derived.The response spectrum method is used to study the inter-story shear distribution and deformation characteristics of three frame self-centering energy dissipation frame system models at different heights.During the first mode,the displacements of the top and shear force ratio of the self-centering energy dissipation frame are studied when the same building adopts different parallel eigenvalues.(4)The system is simplified as a lumped mass model.The model is programmed with MATLAB,and the random linear response of the structure is calculated by the virtual excitation method.Considering the elastic-plastic behavior of the original structure,the equivalent linearization of the system motion equation is carried out,and the time history analysis process is discretized by using the state transition method.Finally,the random response of the structure under strong earthquakes is calculated by using the pseudo excitation method.(5)Using OPENSEES and MATLAB mixed programming,based on the generalized probability density evolution theory,the structural response characteristics of the self-centering energy dissipation frame retrofitted system under non-stationary random earthquake excitation are studied,and the seismic reduction effect of the system under random excitation is analyzed.The method of fitting natural near-field ground motion is used to input artificial ground-motion signals with velocity pulse characteristics to study the structural failure probability of the system during near-field earthquakes.