Research On Seismic Behavior Of Prefabricated Hollow Pier With Grouting Sleeve Connection

In recent years,the bridge precast construction technology has developed rapidly in China.Prefabricated and assembled piers have the characteristics of fast construction progress and small environmental impact,and are gradually used in the construction of urban viaducts and highways.The engineering application of traditional prefabricated solid piers is limited due to heavy weight,material consumption and difficulty in hoisting.The prefabricated hollow piers connected with grouting sleeves have many advantages,such as reliable structural connection,saving concrete,reducing carbon emissions,and have certain application prospects.At present,there is little research on this kind of bridge at home and abroad,so it is particularly important to study the seismic performance of precast assembled hollow piers connected by grouting sleeves.Therefore,this paper mainly carries out cyclic loading tests on large-diameter reinforced grouting sleeves,and uses finite element simulation to conduct simulation research on different parameters of precast assembled full-size hollow piers connected by grouting sleeves for pier shafts and pile,so as to explore the seismic performance of precast hollow piers,and put forward reasonable design suggestions for the design and engineering application of hollow piers.The following research has been done in this paper as follows:1、Ten large-diameter steel bar of 40 mm grouting sleeve specimens were designed and made.Different loading systems were adopted to load the specimens.According to the loading method,the specimens were divided into high stress cyclic loading and large deformation cyclic loading.In the high stress cyclic loading group,the effect of the length of the anchorage(6d,7d,8d,10d)was studied.At the same time,two10 d length embedded specimens were also designed to carry out a large deformation and axial tensile test.Through the test phenomenon,the destruction mode of the specimens,the yield load,the ultimate load,the ductility,the load-displacement curve,and the load-strain curve,the best performance and the most economic anchorage length of the large diameter reinforcement grouting sleeves were also investigated.2、Based on the analysis of the test results of large-diameter reinforcement grouting sleeves,a design scheme of precast assembled full-size hollow piers connected by large-diameter reinforcement grouting sleeves is proposed,and the seismic performance of precast hollow piers is studied through numerical simulation.At the same time,different parameters such as axial compression ratio,longitudinal reinforcement arrangement,construction method,solid section at the bottom of pier,and loading method are selected to compare and analyze the influence of bending performance of hollow piers.On the other way,a prefabricated hollow pier model with shear span ratio of 1 is established to calculate the shear bearing capacity of hollow piers under the changes of axial compression ratio,wall thickness ratio,longitudinal reinforcement diameter and other parameters,and to compare and analyze the influencing factors on the shear bearing capacity of prefabricated hollow piers.3、Based on the above test data and results of large-diameter reinforcement grouting sleeves,a formula on calculating the bond force of large-diameter reinforcement grouting sleeves is proposed.Based on the numerical simulation results of precast assembled hollow with different parameter changes,the existing calculation formulas on different kinds of bending bearing capacity are compared and calculated.At the same time,the calculation formulas on shear bearing capacity of precast joint under bending shear coupling are proposed,which improves the design calculation method of precast assembled pier.