Experiment Study On Seismic Performance Of Precast Column And Cushion Connected With Grouting Holes

Rapid prefabrication and assembling technology of bridges has the advantages of short on-site operation time,high construction efficiency and little impact on the surrounding environment.It is the development direction and research hotspot of bridge construction at present.In bridge prefabrication technology,the connection mode and reliability performance between prefabricated components are the key issues.Based on this,the research group proposed a "reserved grouting hole connection" method with fast construction speed and strong reliability,and obtained its tensile performance and minimum anchorage length through pull-out test,but its seismic performance has not yet been studied.In this paper,the quasi-static test and finite element analysis are used to study the seismic performance of the connection,which provides experimental basis for the engineering application of the connection.The main work is as follows:(1)Based on the similarity principle,four shrinkage specimens of prefabricated pier and abutment with the same size of pre-grouting holes are designed.The size of pier column is 300 x 300 x 2200 mm,the size of cap is 370 x 700 x 430 mm,the strength of concrete is C30,the type of connecting steel bar is HRB400,and the diameter of steel bar is 12 mm.The anchorage length is 6 d,12 d,18 d and 24 d(d is the diameter of steel bar),respectively.(2)The quasi-static test was carried out to study the effect of anchorage length of connecting steel bar on the seismic performance of piers,and the seismic performance of the connection was compared with that of the whole cast-in-situ and grouting sleeve joints.The hysteretic curve,ultimate bearing capacity,ductility,stiffness degradation,residual displacement and energy dissipation capacity were used to study the seismic performance of the connection.The results show that when the anchorage length of the connecting steel bar is 12 d or more,the hysteretic curve of the precast pier-platform scale specimens is fuller,the bearing capacity and ductility are more than 90% of the cast piers,the degenerated stiffness is close to the degenerated stiffness of the cast-in-situ specimens,the residual displacement is close to the cast-in-situ specimens,and the equivalent viscous resistance.The equivalent viscous damping is more than 95% of cast-in-situ specimens.It shows that the connection mode has good seismic performance.(3)Based on the quasi-static test results,the finite element model of the specimens is constructed by using Abaqus software,and the parameters of the seismic performance are analyzed.The influence of concrete strength(C40,C50,C60)and axial compression ratio(0.3,0.5,0.7)on the seismic performance of the piers connected with pre-grouting holes is analyzed.The results show that when the concrete strength is C60 and the axial compression ratio is 0.5,the bearing capacity of the prefabricated piers is the largest,and the mixing is the best.The ductility of prefabricated pier is the best when the strength of concrete is C40 and the axial compression ratio is 0.3.The calculation basis is provided for the seismic design of piers.