Study On Seismic Performance Of Friction Damper Cam Response Amplification Device And Isolated High-Speed Railway Single Pier Bridge

High-speed railway has become the main trend of traffic development in China because of its advantages including rapidity,safety,comfort and convenience.To ensure the seismic safety of high-speed railway bridge,friction pendulum isolation bearing is used as the main isolation device of high-speed railway bridge because of its strong bearing capacity and self-resetting ability.However,due to the unpredictability of earthquakes and the frequent occurrence of rare earthquakes in recent years,the isolation bearings may be invalid due to excessive displacement,which may eventually leads to the destruction or even collapse of bridges.Therefore,it is an important scientific issue in the field of seismic prevention of high-speed railway bridge to explore the limiting methods under large earthquake with different magnitudes,which has important theoretical significance and engineering application value.The traditional bridge limiting devices mainly include dampers,tie rods,cables,and blocks.However,under the strong earthquakes,if the damper with larger tonnage and larger stroke is used,the cost will be higher and it will be difficult to resist the earthquake action beyond expectation;cable and pull rod are also easy to exceed their limiting capacity under strong earthquake;as for the blocks,the hard collision caused under strong earthquake will have adverse effects on the bridge structure,and they are difficult to repair after being damaged by earthquakes.Therefore,it is vitally important to develop a new isolated bridge limiting device.In summary,a new type of limiting device,namely Cam Response Amplification Device of Friction Damper(CRAD-FD),is developed by using cam mechanism,ball screw pair,thrust bearing and friction damper,and theoretical and experimental research is also carried out.Then,a large number of parameters are analyzed for single-degree-of-freedom system.Finally,the simplified isolated high-speed railway single pier bridge model is simulated and analyzed,mainly including:1.Action mechanism and restoring force model of CRAD-FD: based on the research and application of bridge limiting measures and response amplification technologies,CRAD-FD was proposed.The structure of CRAD-FD is introduced.Its action mechanism was also analyzed.In addition,the theoretical calculation formulas of response amplification such as damping force,displacement,velocity and acceleration were deduced.Based on that,the theoretical restoring force model of CRAD-FD was put forward by MATLAB program was compiled.Taking sine wave displacement control loading,variable amplitude displacement control loading,triangle wave displacement control uniform speed loading and seismic wave loading as an example,CRAD-FD was numerically simulated and analyzed.The influence of the changes of the parameters such as ball screw pitch,disc eccentricity,and coefficient of friction on CRAD-FD response amplification was given.A tandem type CRAD-FD was proposed and its action law was studied.2.CRAD-FD performance test research: according to the test conditions,the pseudo-static test scheme was formulated and the CRAD-FD device was manufactured.Pseudo-static tests were carried out on CRAD-FD under multiple working conditions,and the mechanical properties of CRAD-FD were obtained.The mechanical properties of CRAD-FD were simulated by MATLAB programming.And the simulation results were compared with the experimental data,which verified the effectiveness of CRAD-FD response amplification effect.3.Seismic response analysis of CRAD-FD single-degree-of-freedom system: the single-degree-of-freedom damping control analysis program was compiled by MATLAB.Time-procedure analysis was carried out on six typical seismic waves.The seismic response of the single-degree-of-freedom system under no control,FD control and CRAD-FD control was compared.On this basis,the response spectra of single-degree-of-freedom structureunder no control,FD control and CRAD-FD control was analyzed under the action of typical seismic waves,and the acceleration response spectra,velocity response spectra,displacement response spectra,energy response spectra and energy consumption ratio response spectra were given;by changing CRAD-FD parameters,a large number of parameters were analyzed for single degree-of-freedom system;the high-speed railway single pier bridge with friction pendulum isolation was equivalent to a single-degree-of-freedom isolation system,and the time-procedure analysis was carried out on it to obtain the rule of the control effect of CRAD-FD.4.Seismic response analysis of CRAD-FD isolated two-degree-of-freedom system:firstly,the layout and installation of CRAD-FD in the bridge were introduced,and the friction pendulum isolated high-speed railway single pier bridge was equivalent to the isolated two-degree-of-freedom model,Then,damping control analysis program of two-degree-of-freedom was compiled by MATLAB.The seismic responses of two-degree-of-freedom system under under no control,FD control and CRAD-FD control were given by using time-procedure analysis on typical seismic waves and the control effects of acceleration and displacement of main girder and pier were compared and analyzed respectively;then,by changing the friction force of the friction damper in CRAD-FD,the time-procedure analysis of the two-degree-of-freedom system was carried out,and the control effect of CRAD-FD with different friction force was given;thirdly,the time-procedure analysis of the two-degree-of-freedom system under no control,FD control and CRAD-FD control and under six typical seismic waves(PGA = 0.4g,0.6g,0.8g)was carried out.The control effect of CRAD-FD was given,and the limit performance of CRAD-FD was evaluated;finally,the CRAD-FD control system was analyzed economically.