Study On The Velocity Depended Dampers In The Seismic Reinforcement Of Existing Buildings

The seismic fortification intensity of some areas has been improved after the revision of the Code for Seismic Design of Buildings in 2016.The existing buildings in the areas where the seismic intensity has increased cannot meet the existing fortification requirements.It is obviously not feasible to demolish and rebuild all these buildings,so it is necessary to do so.Therefore,the main way to solve the problem of these buildings is to identify and reinforce the building to meet the fortification requirements and then continue to use it.Traditional reinforcement methods based on the principle of "hard resistance" are not economical and reasonable,and do not have the ability of self-regulation.Based on the limitations of traditional reinforcement methods,the concept of energy dissipation and damping has been introduced into the structural seismic reinforcement by domestic and foreign scholars,and a lot of research has been conducted on this.In China,the latest edition of Code for Seismic Design of Buildings(GB 50011-2010)has also introduced the content of energy energy dissipation and damping.Viscous dampers and viscoelastic dampers are typical velocity related dampers,which have a wide application prospect.Therefore,the application of viscous dampers and viscoelastic dampers in the reinforcement of existing buildings is analyzed and studied in this paper.The main content is as follows:(1)The research status and application of viscoelastic dampers for viscous dampers are introduced in detail.The basic principle,structural classification and mechanical model of viscoelastic dampers and viscoelastic dampers are deeply understood.The structural calculation and analysis methods are briefly introduced.(2)Using the finite element analysis software SAP2000,a three-dimensional solid model of a nine-storey existing building as the reaserch object is established.The reliability of SAP2000 modeling is verified by comparing SAP2000 with YJK model.Three seismic waves satisfying the requirements of the code are selected to analyze the time history of the original structure.The results show that the interstorey displacement angle of the structure is higher than the standard limit after the aseismic intensity is raised.(3)The additional effective damping ratio is calculated and the parameters and quantities of the damper are determined according to the additional damping ratio.According to the layout principle of damper,two reinforcement schemes are designed: In scheme 1,the damper is evenly arranged on each floor.Scheme 2,the weight coefficient method is used to arrange the dampers,and the time history analysis is compared.(4)The results show that both viscous dampers and viscoelastic dampers can effectively reduce the seismic response and improve the seismic performance of the structure.The control effect of the scheme 1 on the weak layer of the structure is poor,and the displacement angles between the strengthened layers still can not meet the requirements of the code.The control effect of scheme 2 is better than that of scheme 1 on vertex displacement,interlayer shear force,structural weak layer,seismic energy dissipation and yield degree of plastic hinge.After the reinforcement of scheme 2,the interstory drift angle of the structure tends to be uniform along the height of the layer,and all meet the requirements of the code.It shows that the method of weight coefficient can fully play the role of the damper and is more economical and reasonable.(5)The additional damping ratios of the structures strengthened by viscous dampers and viscoelastic dampers are all 7%.However,due tothe viscoelastic damper provides additional damping and additional stiffness for the structure,the control effect of the viscoelastic damper is distinctly better than that of the viscoelastic damper.The displacement angle of the structure is similar to a straight line under the action of large earthquake,and there is no obvious weak layer.