Seismic Performance Analysis Of High Speed Railway Pier With HRB500 Steel Bars Under Saline Soil Environment

The pier is the main load-bearing component of the bridge structure,and it is also an important lateral force resistance component under the action of an earthquake.This paper is based on the seismic safety problems of high-speed railway bridges in saline soil environment in China,the influence of durability damage of HRB500 reinforced High-speed Railway Pier material on its seismic performance in saline soil environment was studied,based on ABAQUS software,the seismic fragility of Highspeed Railway Piers along and across the bridge direction in the whole life cycle in saline soil environment is studied.The main contents and conclusions of this paper are as follows:(1)The mechanism of chloride ion erosion suitable for saline soil environment was analyzed,considering the reinforcement corrosion,the reasonable material constitutive relation is selected,and the finite element model of corroded reinforced concrete column and HRB500 round ended pier column is established,through the numerical simulation of low cyclic loading,the calculation results are compared with the existing test data to verify the rationality of material constitutive relationship and modeling method.(2)The influence of reinforcement ratio of longitudinal reinforcement and stirrup,stirrup strength and axial compression ratio on seismic performance of HRB500 round ended pier column is analyzed by orthogonal test.The results show that the longitudinal reinforcement ratio,axial compression ratio and stirrup strength have significant effects.With the increase of longitudinal reinforcement ratio,the ultimate bearing capacity of pier column increases,when the ratio of longitudinal reinforcement increases from 0.6%to 1.6%,the ultimate bearing capacity of the pier column increases by 71.73%;With the increase of axial compression ratio,the displacement ductility coefficient of pier decreases.When axial compression ratio increases from 0.05 to 0.25,the displacement ductility coefficient of pier decreases by 22.93%;With the increase of stirrup grade,the energy dissipation capacity of pier column increases.(3)Considering the durability damage in service period,the nonlinear time-history analysis is carried out along the bridge direction and across the bridge direction based on the practical engineering piers,the variation of seismic response of pier top displacement,pier bottom shear and equivalent plastic strain with service time is studied.The results show that the displacement of pier top increases with the increase of service years,and the increase degree of pier top displacement along the bridge direction is greater than that of the transverse bridge direction during the service period:With the increase of service years,pier bottom shear has a relatively small change;the equivalent plastic strain at the bottom of the pier is larger and increases with the service life.(4)Based on the incremental dynamic analysis(IDA)method,the seismic vulnerability surfaces of bridge piers in different damage states under different earthquake directions in the whole life cycle are established,and the effects of different earthquake input directions on the failure probability of bridge piers are compared and analyzed.The results show that the transcendence probability of each damage state increases with the increase of service time,and also increases with the increase of PGA,and the increase degree of the damage state along the bridge is greater than that in the transverse direction.Taking the PGA of 1.0g as an example,the exceedance probability of complete failure of bridge piers with 100 years of service increased by 20.59% and4.54% respectively under the earthquake action of the bridge along the bridge direction and the bridge under the earthquake action of the transverse bridge.