Study On The Seismic Performance Of New Type Rocking Isolation Bridge Piers

At present,the new type of swaying self-centering bridges structure with the characteristics of post-earthquake recovery are the focus and hotpots of seismic research of bridges.On the basis of traditional rocking isolation piers,two new types of rocking isolation piers are proposed in this paper.The seismic response regularity and seismic isolation effect of rocking isolation piers with different types of structures under different seismic intensities and site types are studied by means of shaking table tests,finite element numerical calculation and theoretical analysis.The finite element numerical calculation models of two types of piers are verified and the parametric analysis is conducted with the reasonable numerical models.At last,based on the theoretical analysis,the key problems of the anti-lift condition,anti-overturning condition,anti-slip condition,the relationship between the horizontal force in the top and the horizontal displacement,as well as the preliminary design method of the new types of rocking isolation piers are studied.The research in this paper is accomplished under the support of the national natural science foundation of China(51268027),and its main research work is as follows:(1)Two new experimental models which are called as rocking isolation piers with the high damping rubber bearing and the linear spring are presented.The structural details of this two new models are introduced.The principle and advantages of this new models are explained.(2)Taking a railway bridge as the prototype,two new types of experimental models of rocking isolation bridge piers with a dynamic similarity ratio of 1:15 are designed,the scheme of shaking table test for rocking isolation bridge piers is developed,what's more,the test models,the load condition and other test schemes are made.(3)Based on shaking table test,the acceleration response,the displacement response and the stress response of rocking isolation piers under different seismic intensities and site types are tested.Seismic response rules and isolation effects under above-mentioned factors are summarized and the optimal design scheme of two new rocking isolation piers is selected.(4)Based on the Midas/Civil finite element software,the improved two-spring models are used to simulate the seismic response under which different intensities and different site types of new rocking isolation piers,and the results of shaking table test are compared with the numerical simulation results for verification.The study shows that the improved two-spring models can correctly reflect the seismic response of the new rocking isolation bridge pier.Based on the reasonable finite element numerical models,the lifting restraint members of two new types of rocking isolation piers are parameterized.(5)Based on the new rocking isolation bridge piers with high damping rubber bearing for structural mechanics analysis model,the anti-lift condition,anti-overturning condition,anti-slip condition,the relationship between the horizontal force in the top and the horizontal displacement of the new types of rocking isolation piers are derived.The mechanical properties and mechanism of the piers are revealed quantitatively.Moreover,the concrete design methods of rocking isolation piers are put forward,in the end,an example is given to illustrate the method.