Research On The Seismic Fluid-solid Coupling Effect Of Different Cross-section Forms Of Bridge Piers

Nowadays,in the field of bridge anti-seismic in our country,the problem of deepwater bridge piers interacting with earthquake induced hydrodynamic pressure during earthquakes is a big difficulty in this field.which has caused problems in the design of bridge structures.In this paper,Three common types of bridge piers are selected as the research objects,Shaking table tests of concrete pier models with rectangular crosssection,variable cross-section rectangular and round-end cross-sections are carry out.and on this basis,the finite element models of the above three cross-section piers is numerically simulated,the effects of different water depths,different cross-section types and different river bank shapes on the dynamic response of bridge piers under earthquake action and the earthquake induced hydrodynamic pressure of the water body are studied,it provides a certain reference for the design of bridge structures considering the effect of fluid-solid coupling.The main work of this paper is as follows:(1)With reference to the common types of bridge piers in actual engineering and codes,design and carry out shaking table tests of rectangular cross-section piers,variable cross-section rectangular piers and round-end cross-section piers under the water depth of 0.0m(no water),0.6m,1.1m and 1.6m.First of all,the whole process of shaking table test of three types of bridge piers under different water depths is described in detail from the aspects of test model,test equipment and test scheme;then,the test data of various cross-section piers under different water depths are analyzed and studied.The variation laws of pier top displacement,pier bottom strain(stress)and earthquake induced hydrodynamic pressure are analyzed from different water depths,different cross-section types and different river bank shapes.The results show that different water depths and different cross-section types have an effect on the dynamic response of the pier and the earthquake induced hydrodynamic pressure,the peak displacement of round-end crosssection piers at different water depths always has the largest change.Compared with the state of 0.0m water depth(no water),the peak displacement of the pier top under 1.6m water depth has increased by 20.3%;the peak strain(stress)at the bottom of the rectangular cross-section bridge pier under different water depths always has the largest change.Compared with the state of 0.0m water depth(no water),the peak stress at the pier bottom at 1.6m water depth increases by 27.36%;in the state of 1.6m water depth,at the same height measurement point,the peak earthquake induced hydrodynamic pressure of the round-end cross-section pier is the smallest,compared with the rectangular crosssection bridge pier,the earthquake induced hydrodynamic pressure peaks at the bottom of the round-end-shaped pier are reduced by 18.3% when the reflected wave is considered,and 22.1% when the reflected wave is not considered.In addition,comparing the hydrodynamic pressure test value with the calculated value of the current code,it is shown that the hydrodynamic pressure test value exceeds the calculated value of the current code by 81% at a depth of 1.6m.The test also analyzed the influence of river bank shapes on the earthquake induced hydrodynamic pressure.(2)Based on the shaking table test conditions,the finite element models of three cross-section piers under water depths of 0.0m(no water),0.6m,1.1m,and 1.6m are analyzed.Research the influence of different water depths and different cross-section types on the dynamic response of the finite element model;then,taking a rectangular cross-section bridge pier as an example,the numerical simulation results are compared with the shaking table test results to verify the correctness of the shaking table test results.The comparison results show that the numerical simulation results have the same trend as the shaking table test results,and the specific results are also relatively close.Among them,the average error of the peak displacement of the rectangular cross-section pier is2.7% under the condition of 0.0m(no water).The average error of the peak stress is 7.4%,In general,this is reasonable.