Seismic Response Analysis Of Deep-water Pier Considering Pier-water Interaction

With the development of social economy,more and more deep-water bridge engineering plays an increasingly important role in transportation industry.The Morison equation method is used to establish the equivalent model of deep-water bridge piers to analyze the dynamic response of structures with the effect of pier-water interaction under earthquake action.Not only the physical concept is clear,but the efficiency of seismic response analysis is improved.Reasonable selection of hydrodynamic coefficient to calculate hydrodynamic force is the key to correctly analyze the dynamic response of deep-water bridge pier under earthquake action.However,previous studies mainly focused on the value of wave hydrodynamic coefficient,while the value of hydrodynamic coefficient under the static water conditions caused by earthquakes has not been explained in detail.Moreover,under different water depth environment and structure type working conditions,the dynamic response law of deep-water bridge piers also needs to be further explored.This paper,by using finite element software ANSYS Workbench,extracted from small scale section bridge pier numerical model role in the structure of hydrodynamic force instantaneous measured values,according to the least squares theory with MATLAB to solve the hydrodynamic coefficient of seismic action,in the case of ignore resistance coefficient,the inertial force coefficient obtained by quantitative analysis and compared with existing literature specifications verify its rationality,and gives the inertial force coefficient under different sectional deep-water piers value Suggestions.Finally,based on the analysis results of inertia force coefficient,the equivalent model of deep-water bridge piers under earthquake action is established,and the dynamic response of deep-water bridge piers under different depth of entry ratio and slenderness ratio is analyzed,so as to provide reference suggestions for practical engineering application.The results show that:(1)the natural vibration frequency of the bridge pier decreases with the increase of the depth of entry ratio and slenderness ratio,and the influence of the higher order frequency is greater than that of the lower order frequency;(2)The greater the depth of entry ratio is,the more significant the dynamic influence of dynamic water effect on deep water pier is;(3)within the scope of the 14 ～ 100 slenderness ratio,dynamic response of four indicators present different change trend,the pier top displacement peak increases with the increase of pier slenderness ratio,the bottom of the pier shear force and the pier bottom peak bending moment is presented with the increase of slenderness ratio is decreasing trend,and the pier top peak acceleration response in the slenderness ratio is about30 maximum;(4)By comparing with the finite element model based on potential flow theory,the correctness of the equivalent model in this paper is verified,and it is concluded that the model accuracy is relatively accurate when the water entry depth ratio is less than 20% or the slenderness ratio is between 18 and 25.