Shaking Table Test Of Frame Structure With Isolation Bearings And Dampers

The isolated structure decreases the dynamic response of structure under seismic load by extending the structure period.Seismic isolation design of structures has good economic benefits in high intensity areas.With the development of seismic-isolation technology and stable performance of isolation bearing product,the isolated structure has been widely used in high-intensity areas in China.However,if the displacement response of isolation bearing exceeds the design displacement under strong seismic load,the structure will be seriously damaged.Therefore,it is of great significance and application prospect to apply energy dissipation technology to isolation bearings in order to reduce the displacement response of isolator.At present,only a few experiments focus on the response of structures controlled by vicious damper and friction pendulum isolator under seismic load.In this paper,experimental research and simulation analysis are carried out for friction pendulum bearings and viscous dampers respectively.On this basis,a full-scale shaking table test of isolated structure controlled by friction pendulum bearing and viscous damper is carried out.The main work and conclusions of this paper are as follows :(1)A sine wave displacement loading test is carried out for the viscous damper,and the damping coefficient and damping index are fitted to establish the damping force-velocity design curve of the viscous damper.Then a displacement loading test of the friction pendulum isolation bearing under constant vertical load is carried out,and the mechanical analysis model of the friction pendulum isolation bearing was established.The comparison with the test results shows that the model can reflect the dynamic characteristics of isolation bearings well.(2)A five-story full-scale isolation steel frame model of 7.2 m × 4.2 m × 13.6 m with a weight of 70 tons is designed.By inputting seismic waves with different spectral characteristics,the responses of the frame structure controlled by the combination of isolation bearings and dampers under different amplitude ground motions are compared.The test results show that the damping effect of the friction pendulum isolation bearing is good.Under the combined control of the viscous damper,the displacement of the isolation layer of the test structure is small,and the upper structure is always maintained in the elastic state.Due to the existence of static friction force,there is residual displacement of the friction pendulum isolation bearing after the test.(3)A numerical model of shaking table test is established.By comparing the test results,it is found that under the same test conditions,the simulation results can well reproduce the time history curves of floor acceleration and isolation bearing displacement,and the peak error is small.When the initial residual displacement of friction pendulum bearing is large,the difference of peak acceleration response between simulation and test is greater.(4)Based on the numerical model,the influence of viscous dampers on the overall response of the structure is further explored.The analysis shows that the displacement response of the isolation layer can be effectively reduced by setting viscous dampers,but the acceleration response of the upper floor increases slightly.Under near-fault pulse ground motion,the friction pendulum bearing will have greater displacement response.