Study On Isolated Technology And Experimental Of Continuous Bridges Based On Synergetic Force

In order to solve the seismic design problem that the longitudinal seismic inertia force of superstructure of continuous beam bridge is only carried by the fixed pier,the seismic potential of the movable pier with the same section as the fixed pier is fully exerted,based on the principle of synergetic force and capacity protection,a new kind of friction activated wrap rope device based on the mechanism of wrap rope is developed.Through the friction activated wrap rope device which is arranged at the movable pier,the movable pier and the fixed pier can bear the force synergistically,then reduce the fixed pier force and limit the displacement of the end of the beam structure,improve the continuous beam bridge longitudinal overall force effect.Taking a typical three-span continuous beam bridge as an example,the vibration reduction effect,damping mechanism,influencing factors,applicability conditions,etc.of the friction activated wrap rope device had been analyzed by shaking table test and numerical simulation,the main research contents are as follows:(1)Based on the typical earthquake damage of continuous beam bridge at home and abroad,the seismic damage characteristics of continuous beam bridge have been analyzed,and the seismic damage causes of continuous beam bridge have been summarized.Taking the continuous beam bridge as the research object,this thesis reviews the development course of the seismic isolation design thought of the continuous beam bridge and the present research situation at home and abroad,and analyzed and summarized the existing limitations of the seismic design of the continuous beam bridge,it is pointed out that the seismic potential of movable piers and the quick recovery of the bridge performance after earthquake are two difficult problems in the current seismic design of continuous beam bridges.(2)Based on the principle of synergetic force and capacity protection,the friction activated wrap rope device with releasable support functions of horizontal cooperative force and limit has been developed.Taking a typical three-span continuous beam bridge with variable cross-section as the research object,based on the similarity principle,three groups of six different shaking table test models are designed and made according to the geometric similarity ratio of 1:30,based on the seismic response of the key locations of the model structure under the excitation of seismic waves with different seismic frequency spectrum characteristics and seismic intensity,the feasibility and effectiveness of the vibration reduction of the model structure by using the friction activated wrap rope device have been analyzed.(3)The restoring force model of the friction activated wrap rope device has been established,and the results of the finite element numerical simulation and the shaking table test are checked each other,the rationality and reliability of the proposed restoring force model and simulation method are verified.Taking a typical three-span continuous beam bridge with variable cross-section as the research object,the isolation effect and isolation mechanism of friction activated wrap rope device are further analyzed through numerical simulation,the influence of the main design parameters on the seismic response of the structure and the effect of shock absorption are analyzed.(4)In order to studied the effect of the friction activated wrap rope device on the longitudinal vibration reduction and the synergistic force of the continuous beam under different structural forms and non-application scenarios,the seismic response characteristics of continuous beam bridges with different pier heights,different main spans,different number of main spans and different site conditions and the influence of pile-soil-structure interaction and traveling wave effect on the seismic response of continuous beam bridges had been studied,the applicable conditions of continuous beam bridge with the friction activated wrap rope device have been summarized.(5)Based on the results of parameter analysis and applicability analysis,considering five factors such as passive end force,initial clearance,bridge pier height,span and site condition,which have different effects on the seismic response of continuous beam bridge with equal pier height and different pier height,through the orthogonal test design,the significance of seismic response affected by the above main factors has been analyzed,the principle of the force at the passive end and the number and position of the mass rotating winding device have been also studied.(6)In order to ensure the safety of the bridge structure under the earthquake load,based on the mechanism of the friction activated wrap rope device,the seismic response of the bridge pier is taken as the control index,based on the maximum shear force and bending moment at the bottom of the movable pier,the adjustment and distribution strategies of seismic load are proposed.