Seismic Performance Of UHPC Grouted Corrugated Pipe Prefabricated Pier Joints

UHPC grouting corrugated pipe connection technology has the advantages of guaranteeing grouting plumpness,reliable anchorage and convenient construction,so it has a broad application prospect in assembled bridge pier engineering.However,as a new type of connection method,the seismic performance of UHPC grouting corrugated pipe joint is the focus of prefabricated piers,and the force transfer reliability and failure mechanism of the joint are urgently needed to be explored.In this paper,UHPC grouting corrugated pipe prefabricated bridge pier joint is taken as the research object.Considering the influence factors such as large diameter longitudinal bar,axial compression eccentricity and socket mortise joint structure,the research method combining experiment and finite element calculation is adopted to carry out the following research work:(1)Quasi-static test of UHPC grouting bellows assembled piers was carried out.Taking into account the three influencing factors of connection structure,axial compression eccentricity and large diameter longitudinal bar,three groups of 6 reduced scale pier specimens were designed to carry out quasi-static test.By comparing the failure modes,hysteresis curves,skeleton curves,reinforcement and concrete strain data of each specimen,the influence of each factor on the seismic performance and failure mechanism of bridge piers is analyzed.The results show that ductile failure of plastic hinge area occurs in all specimens,and longitudinal bar fracture occurs in large-diameter steel bar specimens.The seismic performance of UHPC grouting corrugated pipe prefabricated bridge pier is slightly lower than that of cast-in-place joints.The seismic performance of UHPC grouting corrugated pipe joint with tenon structure is basically the same as that of cast-in-place joints.The seismic performance of the largediameter longitudinal bars is weaker than that of the cast-in-place specimens due to the fewer rebars and uneven local stress.Eccentric axial compression weakens the bearing capacity of the eccentric side of the assembled pier,increases the bearing capacity of the non-eccentric side,and increases the ductility performance and energy dissipation capacity of the component.(2)The finite element analysis of seismic performance of UHPC grouting corrugated pipe joint was carried out.The finite element software ABAQUS is used to carry out numerical simulation analysis on the specimen of the scaled bridge pier designed in this paper,comparing with the test results to verify the validity of the finite element.The calculated results are in good agreement with the experimental results.On this basis,considering such factors as reinforcement ratio of longitudinal reinforcement,diameter of longitudinal bar,axial compression ratio and axial compression eccentricity distance,seismic performance parameters of UHPC grouting corrugated pipe prefabricated piers were analyzed.The results show that the increase of the ratio of longitudinal reinforcement is beneficial to the improvement of the bearing capacity and seismic performance of the pier.Under the condition of constant reinforcement ratio of longitudinal reinforcement and uniform cross-section stress,increasing the diameter of reinforcement has little effect on the performance indexes of bridge piers.(3)The applicability of HRB400 C45 steel bar in assembled piers is discussed.Using ABAQUS finite element software,combined with the test results of C1 specimen with large diameter longitudinal bar connection,the seismic performance of UHPC corrugated pipe connection joint with HRB400 C45 large diameter longitudinal reinforcement is analyzed.The results show that:Under the same reinforcement ratio,the pier with C45 steel bar has the same bearing capacity and stiffness as the pier with C25 steel bar,but the energy dissipation capacity and seismic performance of the joints are reduced,and the longitudinal reinforcement fracture will occur in the pier column when the horizontal load is large.The uneven load on pier section should be considered in the application of large diameter steel bars.