Comparison On Seismic Response Between Base Isolation And Structures With Viscous Damper

With the deepening of people’s understanding of the natural phenomenon of earthquakes,more and more attention has been paid to the hazards caused by earthquakes.On the basis of the existing traditional seismic theory,new seismic concepts emerge in endlessly.In the traditional seismic design,in order to make the building structure resist the seismic action,the seismic damage is usually mitigated by strengthening the performance(strength,stiffness and stability)of the structural components.The research shows that the traditional seismic design concept controls the earthquake damage to a certain extent,but it also brings a series of problems.Therefore,a series of energy dissipation and vibration reduction methods,such as base isolation and viscous damper,have been developed,and a new seismic design concept has been formed.Based on the previous studies,the main work of this paper is as follows:(1)Based on a 7-storey frame structure,this structure is strengthened by installing isolation seat and viscous dampers respectively.The seismic performance of the reinforced structure is compared with that of the original structure,and the difference of the two methods are compared.(2)After determining the type and parameters of isolation bearings and viscous dampers,the isolation bearings are arranged in the structure to calculate the displacement of the model under frequent earthquakes.Then the number and arrangement of viscous dampers in the structure are adjusted and the same calculation is carried out to ensure that the displacement damping rates of the two are similar.Then modal analysis of three structures is carried out: the natural vibration period of buildings strengthened with base isolation is larger than that of the original structure,while the natural vibration period of structures strengthened with viscous dampers is near,which shows that the principles of strengthening the seismic performance of the two structures are quite different.At the same time,the acceleration responses of these three structures under frequent earthquakes are compared.(3)The original frame model,isolation model and viscous damper model are respectively analyzed by nonlinear time history method.By comparing the inter-story displacement angle,acceleration response,plastic hinge development of each structure,and the energy dissipation characteristics of isolation bearing and viscous damper,It is concluded that both base isolation and viscous damper can effectively improve the seismic performance of the structure,but the improvement of the seismic performance of the isolated structure is more obvious.(4)Pushover analysis is carried out for the original frame model,the isolation model and the viscous damper model respectively.By observing the distribution and development of plastic hinges in beams and columns,it can be concluded that the two reinforcement methods effectively restrain the development of plastic hinges,but the number of plastic hinges in isolated structures is less than that in viscous dampers.By analyzing the performance points of these three models,it is concluded that the structure with base isolation has better performance.(5)When the structure is subjected to accidental action,the vertical continuous collapse may occur.Because the earthquake action is also an accidental action,the performance can also reflect the seismic performance of the structure.According to the GSA2003 code of the United States,the above three structures are analyzed,and it is concluded that viscous dampers have advantages in improving the performance of vertical continuous collapse resistance.