Seismic Performance And Vulnerability Analysis Of Corroded RC Rectangular Pier Under Non-orthogonal Horizontal Loads

Bridges are the lifeline of modern social transportation and play an extremely important role in earthquake disasters.However,some bridges in harsh environments are subject to a combination of environmental,construction,and man-made factors.The pier piers have serious problems of reinforcement corrosion.It is necessary to affect factors such as the angle of horizontal load,the degree of reinforcement corrosion,the location of corrosion,and the axial compression ratio.The influence of rust on reinforced concrete bridge pier’s seismic performance and its vulnerability are studied.In order to study the influence of factors such as the angle of horizontal load,the degree of steel corrosion,the location of corrosion,and the axial compression ratio on the seismic performance of corroded reinforced concrete bridge piers,nine rust corroded reinforced concrete bridge piers were fabricated for pseudo-static tests.The impact of seismic performance of reinforced concrete rectangular bridge piers,and using Opensees finite element software to build a fiber model,the seismic vulnerability of reinforced concrete rectangular bridge piers was evaluated.The main research contents are as follows:(1)Summarize the research results of scholars at home and abroad,and explore the principle of corrosion of reinforced concrete structures,mainly in two aspects: First,the internal structure of concrete is unstable,which is prone to carbonization and then damages the passivation film on the surface of the steel bar,causing corrosion of the steel bar;It is that chloride ion has strong oxidizing ability,which can destroy the passivation film on the surface of the steel bar,increase the conductivity of the solution in the pores,accelerate the flow of electrons,and accelerate the occurrence of steel bar corrosion.(2)Nine corroded reinforced concrete bridge piers were fabricated for pseudo-static test.The test results show that when the corrosion location and the rust rate are constant,the angle of the corroded reinforced concrete bridge piers will change from the strong axis to the weak axis with the loading,and the crack development rate will increase.,The maximum lateral force at the top of the pier is reduced,and it is easier to reach the limit state;when the rust location and loading angle are constant,the deeper the degree of corrosion,the easier it is for the reinforced concrete bridge pier to reach the failure state,the maximum lateral force at the pier top is significantly reduced,and the limit displacement is reduced The smaller,the smaller the area of the hysteresis loop,the more severe the pinch phenomenon,the lower the energy consumption capacity,the worse ductility,and the severe degradation of stiffness;when the degree of corrosion and the loading angle are constant,the location of the corrosion is closer to the bottom of the pier,the yield strength of the reinforced concrete bridge pier,The maximum lateral force,ductility coefficient,and equivalent viscous damping coefficient decrease more obviously,but the decrease amplitude becomes slower as the corrosion position moves up,indicating that the effect of steel bar corrosion is weakened.When the degree of rust,the location of rust and the angle of load are all the same,the larger the axial pressure ratio,the greater the maximum lateral force at the bottom of the pier,but the faster the lateral force degradation at the top of the pier,the smaller the area of the hysteresis loop,and the weaker the energy consumption capacity.,The worse the ductility.(3)Use Opensees finite element software to establish a model for numerical analysis.According to the comparison between the numerical simulation results and the test results,it can be seen that the numerical simulation results fit the test data well,and the yield points,ultimate displacements,yield loads,ultimate loads and other characteristic points are compared.The maximum error is not more than 10%,and it is basically maintained within5%.The hysteresis curve is more consistent with the test.(4)Based on the experimental research results and the finite element model,establish a finite element dynamic model of the bridge and perform seismic vulnerability analysis on the corroded reinforced concrete bridge pier.It is concluded that as the incident angle of the ground motion changes from a strong axis to a weak axis,the failure probability in different damage states increases;the deeper the degree of corrosion of the steel bar,the greater the failure probability of the reinforced concrete bridge pier in different damage states;After the rusting position is moved up,the failure probability of different damage states is reduced.When the axial pressure is relatively low,the corroded reinforced concrete bridge pier is prone to slight damage.The larger the axial pressure ratio,the higher the probability of medium,severe and collapse damage.