Study On Seismic Performance Of Prefabricated Piers Connected By Cast-in-situ UHPC Wet Joints

With the advantages of high speed construction,high quality and less influence to the surrounding traffic,prefabricated substructures is the hot issue at present.The quality of prefabricated pier joints between prefabricated elements are the most critical issue.Ultra-high performance concrete(UHPC)is used as the filling material for the prefabricated pier joints,which can improve the construction speed by using its good mechanical properties and working performance,thus it will exert the advantages of prefabricated construction technology.According to the practical engineering,this paper makes a related study on the seismic performance of the prefabricated piers which utilizing UHPC.the concrete work content is summarized as follows:(1)The structure form and construction process of prefabricated piers connected by UHPC and the method of modeling with ABAQUS software are introduced in detail.In order to simplify the modeling process,a prefabricated pier modeling plug-in was established by Python.(2)This paper takes quasi-static test of a prefabricated pier with UHPC which scale factor was 1:2.5 as the background,simulation of quasi-static test process of pier specimens based on ABAQUS.The comparison between numerical analysis and experimental results shows that:the finite element simulation can basically reflect the failure mode in the test,the calculated results are in good agreement with the experimental results,which verifies the validity of the model.(3)According to the practical engineering,the finite element analysis on the seismic performance of prefabricated pier connected by UHPC and the cast-in-place pier have been carried out.The parameters of the two kinds of piers are close to each other,which can meet the seismic demand of the bridge.The failure mode of two types piers are similar.The plastic hinge area is moved up because of the post-casting section of UHPC,and the main failure occurs at the bottom of the standard section and the connection part of the variable section.(4)The seismic performance of prefabricated piers is studied from threeaspects: height of piers,axial pressure ratio and reinforcement ratio.The results show that lower height of the bridge pier,its horizontal bearing capacity is larger,but its deformation capacity is poor,and its displacement ductility coefficient is small.Therefore,special design is needed to avoid brittle failure of the bridge piers.Increasing the axial pressure ratio of the bridge pier will enhance its horizontal bearing capacity to a certain extent,but will greatly reduce the deformation capacity of the components.The axial pressure ratio of the bridge pier should be controlled below 0.35.Increasing the reinforcement ratio of the bridge pier can improve the horizontal bearing capacity of the bridge pier but reduce the ductility performance.