The Analysis Of Anti-seismic Factors Of High-pier Long-span Continuous Rigid Frame Bridge

High-pier Long-span Continuous Rigid Frame Bridge is a widely used form in bridge engineering whose seismic response is quite different from the common span bridges.The anti-seismic performance of this bridge can be influenced by many factors with different degrees, such as the section form of bridge pier section, the height of bridge piers, the properties of the stiffness ratio of the bridge pier,the pile-soil effection,thaveling wave effect and the nonlinear of structure. The study of anti-seismic factors of the rigid frame bridge which can be used to improve the design quality and ensure the safety of the bridge structure is of great theoretical and practical significance. Using large finite numerical simulation software MIDAS/Civil and focusing on researching the influences to anti-seismic performance of the bidge caused by pile-soil interaction and parameters of the piers,the thesis has got the following five major conclusions:Firstly, the section type of double-shaft thin-wall piers has great effects on both the higher modes and the vertical modes participation factors of high-pier long-span continuous rigid frame bridge. The anti-seismic of hollow piers is better than solid ones.Secondly, when the span of double-shaft thin-wall pier is between L/12-L/30, the bridge has almost the same dynamic characteristics,while the shears and moments at the bottom of piers increase progressively with the expansions of span. However, when the span varies between L/2～0L/25, the shears and moments at the bottom of the piers change within5.5%and the displacements change within2%.Thirdly, if both high and low piers exist in one high-pier long-span continuous rigid frame bridge, the whole stiffness enlarges in three directions as the relative elevation enlarges. But the bending moment and the shear of high pier present a decreasing trend compared to an increasing trend presented of the low pier when the relative elevation enlarges.Fourthly, considering the pile-soil effect, the dynamic characteristics of the high-pier long-span continuous rigid frame bridge change and the natural frequency decreases which makes the whole structure softer. The pile-soil effect has even greater influences on transverse frequency. The response spectrum analysis and the calculation results of elastic time-history both show that if the bridge is under the elastic state,the moments at the bottom of the piers decrease,while the shear and the displacement actions increase.Finally, the elastic-plastic time-history analysis of the high-pier long-span continuous rigid frame bridge in rare earthquakes present: considering the pile-soil effect, the moments at the bottom of the piers of the bridge decrease and the shear becomes more complicated. When the seismic oscillation is input laterally, the plastic hinge first appears at the bottom of the pier. And the plastic hinge’s deformations of consolidation model are larger than that of the pile-solid model.When the seismic oscillation is input longitudinally, the plastic hinge’s deformations at the top of piers appear earlier than that at the bottom, and pile-soil model at the top is larger than the consolidation model while pile-soil model at the bottom is less than the consolidation model.